These incredible images show the breathtaking journey of Rosetta’s Philae lander as it approached and then rebounded from its first touchdown on Comet 67P/Churyumov–Gerasimenko on 12 November 2014.
Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
The mosaic comprises a series of images captured by Rosetta’s OSIRIS camera over a 30 minute period spanning the first touchdown. The time of each of image is marked on the corresponding insets and is in GMT. A comparison of the touchdown area shortly before and after first contact with the surface is also provided.
The images were taken with Rosetta’s OSIRIS narrow-angle camera when the spacecraft was 17.5 km from the comet centre, or roughly 15.5 km from the surface. They have a resolution of 28 cm/pixel and the enlarged insets are 17 x 17 m.
From left to right, the images show Philae descending towards and across the comet before touchdown. The image taken after touchdown, at 15:43 GMT, confirms that the lander was moving east, as first suggested by the data returned by the CONSERT experiment, and at a speed of about 0.5 m/s.
The final location of Philae is still not known, but after touching down and bouncing again at 17:25 GMT, it reached there at 17:32 GMT. The imaging team is confident that combining the CONSERT ranging data with OSIRIS and navcam images from the orbiter and images from near the surface and on it from Philae’s ROLIS and CIVA cameras will soon reveal the lander’s whereabouts.
[Ed’s note – added for clarification: Touchdown occurred at 15:34 GMT spacecraft time (with the signal received on Earth at 16:03 GMT); the image marked ‘touchdown’ in the graphic above was taken after touchdown, at 15:43 GMT, but clearly shows the evidence of the touchdown event when comparing with an image taken previously]
The insets are provided separately below (the timestamps are recorded in the filenames).
All images credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Discussion: 336 comments
Magnificient and sad.
The comet is tumbling in space – surely at some point the craft will receive sun light and the batteries can recharge.
The auxiliary batteries need enough power to boot up. Apparently they get only 3 minutes of sunlight, and they need 5 minutes.
They should have used Energizer batteries- I hear those are really good, even in space….
Let´s hope so. It would be great… greater, I mean.
The craft is experiencing a temperature of 3’K or so.
Differential thermal contraction has already destroyed it’s electronics.
Not 3K its 150K to 220K about right now and it might be close to 270K once at perihelion. 3K you have in inter galactic space.
In fact, 3K is the lowest it gets, the base of Big Bang radiation, I think. Yeah, believe it must have got much colder than they claim- this baby orbited out to Jupiter in it’s endless odyssy.
It is just the beginning of an incredible fire that will produce hundreds, maybe thousands, of corresponding missions to find the answers we need to return to our roots. This team deserves all the credit they are getting; and if the mission stops here, it has still been an awesome accomplishment. My hopes are for technology to improve at break neck speed, so we may find a solution to how to support 9 or 10 billion people comfortably; with only about 1 billion jobs and a hell of a lot of robots!
I am rooting for the success of your hopeful scenario, but the figure 9 or 10 billion bothers me. Clearly that would be a natural stopping point in the near future, but what is the optimum number in the long term? Getting a consensus on that is a critically important decision — yet at the present time, we don’t even know the order of magnitude. Everything about our future depends on determining the right range. Exobiologists, roboticists, geographers and researchers in many related fields would be wise to begin that discussion now.
maybe we should colonise Mars – that would give us a lot more space
Poignant (NBC) ? Sad? I don’t get it. Where’s the pathos? It’s a machine, for heaven’s sake, bouncing on a rock in space!
Perhaps it’s the thought of all the people involved seeing over a decade of hard work and anticipation dashed by unfortunate circumstances. I’m sure a lot will be learned regardless, every science mission is a success, even the failures. But that the harpoons didn’t deploy and secure the lander for its primary mission is a huge let down.
Although I’m sure someone will be along soon with a cute sad cartoon on an anthropomorphised lander crying in the cold darkness…
There’s always a relevant XKCD (forum post).
https://forums.xkcd.com/viewtopic.php?f=7&t=110380&start=960#p3689165
It is just a machine like the Mona Lisa is just a piece of canvas with smudges of paint. This machine is the culmination of the technological prowess of centuries of ingenuity, imagination, calculation, daring and will, all in concert to an unforeseen goal. Anyone that finds this machine will see what we humans are.
The efforts encapsulated include by-gone giants that could not have imagined such an accomplishment, and wide eyed school children that will do even more.
@aj. Well put. You are absolutely right
And it has served it’s purpose.
Mission accomplished, and done very well.
I too am deeply inspired by the mosaic showing Philae’s leap (as well as by every part of this mission).
No one has said out loud, but judging by the path that Philae took, it seems we came REALLY close to losing it off the edge of the comet where it would be gone forever. Whew!
@aj,
Well then the universe must be having a great laugh…. at our expense!
Sure! And let us keep in mind that technics in Philae are 10 years old… on these days we are abble to operate a baby in a pregnant… guess a 2014 baby Philae would have been received better tools to grasp firmly on this charming
67P !
Just to clarify, what happened wasn’t an unforeseen goal – it was never a goal to stop in a shadow; it was an unforeseen result.
It is the embodiment of the hopes and dreams of many people, some of whom have dedicated their whole professional lives to make this mission happen. Their expertise, skills, and enthusiasm are what this machine is made of. So yeah, it’s ok to have an emotional response to its fate.
Couldn’t have put it better than this, Doekia.
Getting a little itchy for some updated material! I know the team is working round the clock, and we do support that, but how can we help???
“The final location of Philae is still not known, …”
I posted on esa flickr what I belive was the trajectory and final landing of Philae in relation to the wider picture of the comet.
https://www.flickr.com/photos/europeanspaceagency/15811486195/
I’ve been waiting til the excitement about the Philae Landing has abated to post this. I imagine that this is as good
as any place to post this. I was planning to put it in my Geomorph Gallery, but in recognition of the success of the Philae mission, it’s going into the Philae Gallery.
This ia a Poster Session-style presentation of the Geomorphology of the Agilkia Landing SIte
https://univ.smugmug.com/Rosetta-Philae-Mission/Philae
Starting with a Basemap:
https://univ.smugmug.com/Rosetta-Philae-Mission/Philae/i-sMKb8KR/0/L/Agilkia_landing_site_mosaic–OSIRIS–geomorph-terrain_basemap–ROLIS-L.png
and
a Geomorph map:
https://univ.smugmug.com/Rosetta-Philae-Mission/Philae/i-x8LjfCB/0/L/Agilkia_landing_site_mosaic–OSIRIS–geomorph-terrain_basemap–annot-L.png
with Discussions of several deposits and terrains.
–Bill
Nice analysis, Bill!
Just wanted to let you know – nice work and even nicer to share it with us all 🙂
Thank you
I’ll forever now have this image in my head of a comet sneezing to produce the deflated terrain. Surely, if the structure allows, such sneezes may eventually destroy the comet. There’s another image for you. Achoo! Poof…
Personally, I’ve spent a lot of time scrutinizing every detail of the first (and perhaps only ever) image Philae acquired of its current resting place between a rock and a hard place: https://blogs.esa.int/rosetta/2014/11/13/welcome-to-a-comet/.
As a result, I posted the following observation a few hours ago on the 13/11/2014 thread.(https://blogs.esa.int/rosetta/2014/11/13/welcome-to-a-comet/#comment-201481)
But I believe it deserves a wider audience, such are its implications, so I’m posting it again here (like you, I imagine that this is as good as any place to post it):
OTHER LONG, STRAIGHT, HELICOIDAL FEATURES OBSERVED IN PHILAE’S FAMOUS FIRST IMAGE!
In the famous close-up image acquired by Philae of the rocky wall it is stuck up against (https://blogs.esa.int/rosetta/2014/11/13/welcome-to-a-comet/), many bloggers commented on the thin, dead-straight, apparently braided feature which is clearly visible at the bottom of the image, towards the right,. There seemed to be general agreement, given just how straight and braided it appears, that it had to be a man-made object such as the antenna which provides data to the CONSERT instruments.
I remained sceptical myself, since the fairly precise alignment of this feature with that of the wider rock strata around it seemed to be too coincidental to be the result of mere chance. Above all, no mission scientist has since confirmed the “antenna” hypothesis. My interpretation was and still is that this is a natural feature of the comet surface and that its shape was produced under the effect of a rotating current field, as in electric discharge machining processes (both natural and industrial).
MY HUNCH IS PROVED TO BE CORRECT BY CLOSER SCRUTINY OF THE REST OF THE IMAGE. Zoom in (x5) on the bright rocky feature at the top of the image, slightly right of centre, just below the twin-peaked, jagged feature standing out against the background darkness. You will see, on the left-hand edge of that brighter patch, what resembles two (or perhaps even three) parallel spiral nails like those used by roofers down here on Earth, complete with their heads…! Just compare them with the nails shown here on a nail manufacturer’s website (the first that came to hand):https://www.threestar.name/_d273566042.htm.
There is no way that these features, which presumably measure not much more than a couple of inches in length, can have anything to do with Philae and they are certainly not imaging artifacts, so the very similar (albeit slightly larger) feature at the bottom of the image certainly doesn’t have anything to do with Philae either.
Given the intense scrutiny which this unique close-up image of the comet’s surface has necessarily been subjected to by mission scientists ever since it was transmitted four days ago, I’m a little disappointed (but not really surprised…) that this new feature has not yet been pointed out and commented on.
The Philae image represents just one or two square metres of the comet’s surface, imaged in the most random way imaginable. Statistically, there are hence likely to be millions of similar, spiral-nail-like features, at different scales, all over the comet’s nucleus.
Almost literally, the features we see in this image are just two or three more nails in the coffin of standard comet theory…
Yes, thanks for sharing. What a superb presentation. Well done indded. Are you watching this ESA? When do we get your science?
Thanks, folks. I have other areas under evaluation and when I get enough nice photos for documentation I’ll do other poster presentations.
I’m just an amateur boffin– wait til the Big Guns come out with their papers next year. And hopefully my interpretations won’t be too embarrassing.. 🙂
Strange little world…
–Bill
An idea to find Philae. Would it be enough power to turn on her laser beam for a few seconds? If OSIRIS can take a long exposure picture, then you will spot her position. Would it work?
Not possible because Philae is in idle mode due to low battery.
Can’t wait to see the final touchdown spot.
This is the most amazing thing I’ve witnessed since my daughter’s birth day.
Keep on going with this good working.
Regards.
Fantastic to see! Beautiful mosaic of Philae’s landing.
สุดยอดแล้ว…from Thailand
Holly cow! That second touch down spot would have been p e r f e c t … but now so close from the sun in this little bit of shadow… – just some few meter’s from more sunlight. That’s just unfair. However … what a luck, that Philea didn’t just hit this huge rock nearby and dead… so – in the end … a blessing in disguise. Gambaru Philea!
Amazing set of pictures.
@Anjin I think Philae is in mid ‘air’ on its way to touchdown #2 in that last picture.
@TimT – yes, you are right. I should have read the text to the end. It isn’t the final position, what we do see there… Still thrilling…
You mean Touchdown spot #3. The first touchdown point in the sequence is actually #2.
…just jumping for shadow… like a human… at side of the giant rock…
Great work!!
The “so-called” east direction means that the lander was moving towards the former “B” landing site, the crater that ESA already signalled on Thursday as being the likely final landing point. Perhaps the lander is just somewhere a bit “at south”, if compared to the area presented by ESA.
No plausible trace af “lander’s shadow” in the 15:43 picture? This could help understanding the local height of the lander.
Haring, a good shot again.
What does exactly mean “moving east” when talking about a comet? I thought such object had not any relevant magnetic field that may allow to define any cardinal point. Any explanation?
thanks.
I think is more referential than scientific. Since the comet is a “rubber duck,” obviously the head goes on top, so when looking down on the head, East is counter-clockwise.
Or, the axis of rotation… good call everyone. I rescind my previous theory 🙂
You don’t need a magnetic field to have an inherent cardinal grid, so to speak, just a rotation which means it has an exist and a direction. 67P rotates with an approx 12-hour period, the long dimension through its equator.
not ‘exist’, should be ‘axis’
I think they don’t refer to magnetic but to the geographical poles according to the rotation. (right-hand rule).
So there shouldn’t be north or south poles, just positive and negative poles.
But I think that you just use NSEW directions out of habit.
see also: https://en.wikipedia.org/wiki/Poles_of_astronomical_bodies#Geographic_poles
@Danilo: On Earth, geographic directions are not necessarily defined by the magnetic field, but using the Earth’s rotation axis. Same is probably be used for the comet.
South being the pole rotating clock-wise.
Please allow me to present a provisional coordinate system:
North and South just the Counter-rotating and rotating poles. Meridians being those dictated by the local sun-hour in the photo at discussion. So we could say: at 15:00 30º N 🙂
Humbly asking for a HiRes Simple Comet-Mundi.
Probably in reference to the angle of rotation.
In general an object can rotate on multiple axes but most of the times rotation stabilises (more or less) on a single axis due to gravitation interaction with other, massive bodies. (Even though these same forces can induce other effects, like precession and nutation) Fortunately, this single axis rotation is also the case with 67P. (Here the gif showing 67P rotation: https://www.esa.int/spaceinimages/Images/2014/10/Shape_model_of_comet)
Thus, you can define North and South with respect to the axis of rotation according to the “right hand rule”: put yourself in a position so that you see the abject rotating anti-clockwise, then “north” is up.
Well, here at Earth, we have magneic North, and geographic North.
I guess for a comet like P67, with no magnetic field, you can establish a geographic North and a South as those points were the rotation axis crosses the surface. East will match with the direction and sense of the rotation at surface, while West will be same direcion, oposite sense.
That way, sunrise will be seen looking East, and sunset Looking West.
Just my best guess.
“…with no magnetic field…”
I am not so sure of that 🙂
Think is part of a future surprise package.
This is going to be fun.
Like they’ve said, North/South is defined by the rotational axis.
The “north pole”, North Polar Axis, is located near the dusty plain on the “Neck”, which has the nice dust jest and the string of boulders. The Big Bolder Cheops is on a plain near the equator at a longitude of 0 degrees. The “Site B crater”, just below the Agilkia landing site, is on the equator and at a longitude of 180 degree. Looking at the recent Navcam, OSIRIS and ROLIS full-frame images of the this paer of the smaller lobe, “North” is more of less up, “East” is to the right and :West is to the left.
This is a tops-turvy little world. It is composed of two spheroids linked by a neck. much like a dumbell. Near the poles, the longitude and latitude lines look “normal”. Near the equator ant 0 and 180 degrees longitude, the lines look “normal”. Elsewhere , they can go crazy.
It’s going to be interesting to see what the cartography people come up with for a map of this world. My suspicion is that it’ll be a three-part map: on for the large lobe, one for the small lobe an d another for the neck. Anyway else can end up with severe distortion.
–Bill
Amazing.
The first touchdown was at 15:34 GMT. The image on the far right shows the lander at 15:43, i.e. 9 minutes later. In that period of time it has moved about 321 meters. (Calculated using the scale of the 17 m squares.) This means the ground speed was about 0.6 m/s.
The time from the first to the second touchdown was 110 minutes. At constant ground speed, Philae would travel about 3900 meters during that time.
This distance is larger than the extension of the small lobe on which the landing site is located. Conclusion is that the current position of the lander may well be in the neck region or on the large lobe.
Mistake in the numbers.
Corrected: Distance of the far right picture to first touchdown site is 206 m, ground speed is 0.38 m/s (excellently corresponding to previously estimated velocities).
Total travel is then 2518 m, still larger than the extension of the small lobe.
Michael, I think you are right. It’s easy to reference the points shown above in the wider field of this image from last week, and you can eyeball nine-minute intervals and realize Philae was off the map in about an hour.
https://blogs.esa.int/rosetta/files/2014/11/ESA_Rosetta_OSIRIS-NAC_Landing_site_50km.png
The escape velocity of the comet 67p is about 0.5 m/s, so, your calculation is not exact, cuze at 0.6 m/s Philae would have to jump into space.
Not only the speed of an object that want to leave a body is important, also its vector angle and direction is essential if you want to leave this comet with a speed jus a bit over its nominal escape velocity. With and against the spin direction is of essence as one example.
hmm… I think you should also take account of the “orbit style” effects. I mean, the rebound trajectory is a true elliptical orbit, not a linear shift towards east. So you have to take in account the second law of Kepler: the angular speed is not constant. So at the top of the first rebound, philae was moving angulary relatively slower.
No @Michael Feuerbacher, you must use the scale of the base pic (0,28 m/px) to calculate the distances in the base picture. Don’t use the scale of the inserts. See my calculation below.
Hi Michael,
I don’t think you can do such calculations without taking into account at what angle those images where made. You assume that they where made from straight above. Which most certainly is not true…
Hi Michael:
“…At constant ground speed,”
Equatorial, ground speed. This is ‘planetary’ travel. Coriolis trajectories needed. Anyone can input this in an orbit simulator?
Something get really wrong here in term of image/timing.
According to this: https://www.esa.int/Our_Activities/Space_Science/Rosetta/Three_touchdowns_for_Rosetta_s_lander
Touchdown time are 15:34, 17:25 and 17:32 GMT comet time.
How can we have a touch point visible at 15:43 ?!? not plausible
If we don’t have a touch point visible at 15:43 (false positive) what coud explain the sudden direction change of this supposed Philea bounce?
The last “evidence” is time-stamped 15:43? Do you mean 17:43 – hence final location of Philae?
Sorry but what is fluffy here is not the comet it is really the presented “evidences”
Also please could you provide vector of cometoid rotation on the picture? East means absolutly nothing so to speak.
No doekia,
the picture taken at the 15:43 refers to a moment AFTER the touch moment. The toudh moment was 15:34.
In fact at 15:43 you just see a small cloud in the socalled “touchdown point”: the lander is already many meters away…
My bad!! could you delete my previous comment please.
17/11/2014 at 17:16
Thx
😉 No proble doekia… It’s a rather complex matter and it takes a while to approach it correctly…
doekia:
It’s all right. Philae had its first touchdown at 15:34. The picture at 15:43 was taken, then, nine minutes after that toushdows. That’s why in that inset you can only see the footprint of the craft…
The image labelled ‘touchdown point’ shows evidence of an impact at some point between 15:18 & 15:43, so that correlates with the first touchdown at 15:34.
From that point Philae changes direction and moves eastward. The second or third touchdown points are not shown here. The 15:43 image is showing Philae drifting towards the second touchdown point (so not touched down).
> How can we have a touch point visible at 15:43
You can see the marks that resulted from the touchdown (at 15:34) in the picture that was taken 7 minutes later (15:43).
> The last “evidence” is time-stamped 15:43?
That is the time the last picture was taken. Possibly there are many other (later) pictures that are looked at to find traces of the lander and its further trajectory.
The first touch down was at 15:34 and the first image in the above sequence AFTER that very same touch down has been made at 15:43 and there you can see some disturbed dust or whatever (a darker spot or a few darker spots merged together).
Af 15:43 actually Philae was up in space again – see the inset to the right.
This tells me that with that one image taken at 15:43 they got both the first touch-down point and they got Philae during the first jump off the surface over that dark shadow.
The final location of Philae is not shown here. These images here were taken too early to see the final touch down spot.
That’s my interpretation of the images. I don’t see any inconsistencies.
The *picture* of the touchdown point was taken at 15:43 – some minutes after the touchdown (and bounce) had occurred. It is compared with a “before” pic (at 15:18) to show that the landscape had changed because of the touchdown – thus they know exactly where it initially touched.
Something completely wrong with the time stamps. We need clarification otherwise absolutely NOTHING can be assumed or calculated from the published data/image.
Cometoid, Doekia? Could you please extended a little in this nomenclature?
“What does exactly mean “moving east” when talking about a comet? I thought such object had not any relevant magnetic field that may allow to define any cardinal point. Any explanation?”
Magnetic fields have nothing to do with geographical coordinates or directions. Rotation defines coordinates, and the nucleus does rotate. Assuming we are using a right-hand rule for rotation, north is defined by the sense of rotation, and east derives directly from that in the same sense it does on Earth.
I’ve always assumed that the north pole was defined by which rotational axis is located in the north side of the plane of the solar system (which is an extension of the Sun’s equator). This is north no matter which way the planet rotates.
For example, Venus has a proper north pole on the north side, but rotates “left” (clockwise)instead of the usual “right” and it is said to have retrograde rotation.. Uranus’ rotational axis is “tilted” on it’s side with a polar inclination of barely 8 degrees, and the pole that is barely north is the North Pole. And also, it has retrograde rotation.
–Bill
Yes, that definition is still used for planets and their moons, but NOT for dwarf planets, minor planets, their moons, or comets: https://en.wikipedia.org/wiki/Poles_of_astronomical_bodies
Thanks, Johan.
First the New Math got me, and now it’s the New Cartography.
Right-hand rule it is.
–Bill
Something does seem inconsistent in the reported times. Elsewhere I’m seeing first contact at 15:33, second at 17:26 and final landing at 17:33.
See https://io9.com/that-was-a-bumpy-landing-can-philae-still-complete-its-1658275758
The images weren’t taken at the touch down times. The last image of the above sequence has been made after the first touch down. The other images have been made before that first touch down.
Hmm. If team know when Philae got sun light, and team can know where is comet and where is sun, maybe it possible to calculate aproximate area where to search of Philae in future. I was so impressed ESA team work. It is all amazing. Go go go!
I am excited to see these images, waiting for any news from ESA every minutes since the “three times landed” announced. Looks like Philae had a happy jump and left those footsteps. Looking forward to see more images recording the final jump.
Than you for sharing these beautiful pictures. I wish you’ll find where Philae is resting soon as well.
whatever is being done is just great. We are exploring an unknown territory that also far far away and cannot be done without technology… search for Philae in itself is as exciting..
Would it be possible to estimate the mechanical properties of the of the surface from the “hit marks” of the touchdown? Impact velocity and properties of the Philae and its legs are known, diameter and to some extent depth of the dips can be seen from the picture. Perhaps with “a bit” of modelling this could give some independent rough numbers for the properties of the surface? (When MUPUS was only partially successful, and this is another spot anyway).
Common sense. Right is east, left is west etc.
Thank you Rosetta Mission team!!
The picture that hit my heart most last week was the “FAREWELL PHILAE” picture. I don’t know why but surely it did. And then again by this one!
I think I am seeing a figure of something challenging to achieve what had not been achieved before.
As an explorer, Philae might have been filled with feeling of thrills and excitements and perhaps some worries as the landscape of Agilkia getting closer and wider in front of him (which is something the mission team must have felt if they were on Philae I’m sure).
https://blogs.esa.int/rosetta/2014/11/17/osiris-spots-philae-drifting-across-the-comet/#comment-201905
dx = 731px x 0,28 m/px = 204,68 m
dy = 41px x 0,28 m/px = 11,48 m
d = sqrt(dx^2 + dy^2) = 205 m (horizontally, projected to ground)
t = 15:43(:30) – 15:34:06 = 564 s
v = d/t = 0,3635 m/s
Distance D after 1:51 hours:
t = 1:51 h = 6660 s
D = v*t = 2421 m
Ergo:
Philae has flown a long way between touch-down 1 and 2 (as I have calculated before). Far more than 2 kilometers!
It will be in the neck region or even beyond that on the inner side of the bigger lobe towards the neck.
Jörg, check my post of 17:14 (correcting a scaling mistake).. We did the same calculation and obtain essentially the same results.
I think the distance of the ground path will be significantly smaller than 2.4km, because the direction of the gravity vector changes along the path and slows down the horizontal speed.
I’ve tried to visualize Philae’s 2.4km (or shorter) flight path on our 3D model:
https://sternwarte-sankt-andreasberg.de/wo-ist-philae-gelandet/
Hi Michael. Thanks a lot for your 3D model. Could you add the rotation curvature to that line? For 2 hours it would move the ending point a 1/6 of circumference. As is now there is no insolation there.
In my opinion it’s very difficult to add the rotation.
The rotation would only change the trajectory if Philae would have changed its latitude. AFAIK the first touch-down was close to the equator and the flight path after that touch-down was basically to the east from that point on, so still along the same latitude.
I have to correct myself:
The lander basically touched down on the equator of 67P, but then it moved nearly perpendicular to the equator towards the North pole (North in terms of counter clock-wise rotation).
This means that towards the neck region it was exposed to an increasingly strong Coriolis force that bended its flight path to the right (seen in flight direction).
if you look at this image …
https://blogs.esa.int/rosetta/files/2014/11/ESA_Rosetta_NAVCAM_141106_Mosaic.jpg
… Philae came from the smaller lobe, flew down the neck into the shadow region and bend to the left into the dawn area of the neck.
A 2.4 km way would end somewhere near the day/night line in the lower left quadrant of that image.
To see the spin axis of the comet, use this animation:
https://photojournal.jpl.nasa.gov/archive/PIA18419.gif
But Jörg, that white line in the 3D model ends at the ‘night side’. Still believe is not quite a paralleled trajectory.
Yes Logan, correct.
With my correction above (trajectory NOT along equator but perpendicular to it) the line will bend to the left of the shadow side and will end close to the day/night line.
This is due to the Coriolis pseudo force the deviates the trajectory the more the lander moves into higher latitudes.
It would be a perfect fit to the final lighting conditions experienced by Philae.
This:
https://photojournal.jpl.nasa.gov/archive/PIA18419.gif
is not an accurate reference. What’s meant to be “North”, is rotating clockwise.
Refer to this instead:
https://www.esa.int/spaceinimages/Images/2014/10/Shape_model_of_comet
Another correction!:
JPL/NASA got it all wrong. Their animation (link above) shows the comet rotating in reverse direction. The true direction can be seen on these early Rosetta images:
https://earthsky.org/space/as-the-rosetta-spacecraft-approaches-its-target-comet
So the North pole is on the sunlit side and the South pole is on the dark side.
The trajectory of Philae after first touchdown will bend to the left (seen in flight direction), not to the right.
I’ve added the rotation to the 3D model. I hope I got it right.
https://sternwarte-sankt-andreasberg.de/wo-ist-philae-gelandet/
Beautiful! Thanks a lot Michael 🙂
Michael, IMHO you got it completely right.
This is exactly what should happen when the lander moves north from its equatorial first touchdown point. Good work! Thanks.
Michael, towards the (current) end of this comment list @doekia has posted a link to a Youtube video of the landing time line. It shows the comet rotating in the opposite direction (North pole on the sunlit side, South pole on the dark side). This made me search for more evidence about the real spin axis and spin direction. Result: It looks like the animated GIF posted by JPL/Nasa rotates in the WRONG direction! Here are two links, that clearly show that the South pole is on the dark side:
https://earthsky.org/space/as-the-rosetta-spacecraft-approaches-its-target-comet
https://www.esa.int/spaceinimages/Images/2014/07/Shape_model_of_comet
Especiall the first one is very clear as it shows real images of the rotation in 20 minute steps.
In essence this means that the trajectory will not bend towards the right side (in flight direction) but towards the left!
It is a real pity that we have to combine scattered bits and pieces all the time. A repository of reliable data, images and animations would be a big help.
By the way, from this picture
https://blogs.esa.int/rosetta/files/2014/11/ESA_Rosetta_NAVCAM_141106_Mosaic.jpg
it’s clearly visible that the published 3D model is very inaccurate. The neck is much too wide in the model.
Why hasn’t ESA published better 3D data? Obviously they have better data, as can be seen here:
https://www.sculpteo.com/blog/2014/10/15/land-spacecraft-comet/
They could even publish a 3D gravitoid 🙂
Another approach is to use a rotational frame of refernce. If we use a horizontal velocity of 0.38 m/s, and assume the lander is 2000 metres above the centre of mass,, the the rotational velocity is about 0.00019 radians per sec. the lander will travel about 1.27 radians in 6660 seconds or about 72 degrees. So I agree with Michael Koch, and others – it is in the neck.
A better solution requires orbital mechanics simulations, eg:
https://www.wired.com/2014/11/modeling-philaes-double-bounce-comet-landing/
I tried it but the solution depends very sensitively on the the mass distribution of the comet, but it is always well down the “dark side” of the comet.
Sorry that should be the solution depends very sensitively on the the mass distribution of the comet and the vertical velocity of the lander.
One further point. 67P rotates in 12.4 hours. In 6660 seconds that’s about 54 degrees. Could it be the apparent horizontal motion of Philae is largely rotation of 67P?
Like this new approach. Please take it as a ‘two potatoes’ aproach. Somewhere around the lower left of this:
https://blogs.esa.int/rosetta/2014/09/26/cometwatch-21-24-september/
Near to body ‘wall’ of the neck’s trench.
Yes logan, My guess is that Philae is somewhere near the terminator – the boundary between the light and dark regions – that runs roughly;y horizontally across the neck (from small to large lobe) in this photo. The region includes the rough spur that contrasts with the rest of the smooth collar.
Another recent photo of the same region is here:
https://blogs.esa.int/rosetta/2014/11/20/cometwatch-17-november/
Mt thinking is this: Philae bounced down the left side of the crater is this image:
https://blogs.esa.int/rosetta/files/2014/11/ESA_Rosetta_NAVCAM_141106_Mosaic.jpg
As 67P rotates, the small lobe will move from left to right. Philae will follow a ballistic trajectory during its nearly 2 hour bounce, during which the comet rotates 60 degrees. So rather than land in the seasonally dark southern hemisphere, Philae has landed near the terminator near the left of this photo and experiences 1-2 hours of sunlight per rotation.
If you extend your yellow line about 20% i think you found Philae. The reason that i believe that the line should be a bit longer is that the lander gets closer to the common mass centre as well as to the narrow neck and its angular velocity increases as the trajectory gets an inward spiral form. A bit of the pirouette effect occurs as the momentum is preserved due to increase the angular speed when the radius is shortened.
Agree with Cometsalker. As soon as it went into the ‘night side it began aceleration 🙂
Do you have to give an additional angle? Not forgetting that Rosetta was shooting from an oblique orbit. Is this photo composite giving surface or flight coordinates? 🙂
(This was remembered to all of us by Daniel).
Errata: should say [Should you]
Be careful, over 2 hours, the comet has rotated (a lot), Rosetta has moved. So the apparent movement above the surface depends on the projection angles. A certainly very elegant problem to solve, but the availability of data being what it is, it is practically reserved to Flight dynamics and friends…
The order of magnitude is certainly good though: more than a km and less than 10 😉
Hi JP. So, somewhere in the surroundings of the Neck’s East side .
I think you are right and once entering the neck region its trajectory gets real complex due to the gravity vectors huge variation due to the comets shape and the fast rotation of the comet, its a random walk.
More like “Drunkard’s Walk” for any Niven fans (Bellamy’s yacht in ‘Grendel’), considering it was all started by landing on one or two of three legs.
OK, that’s geometry, than there’s also Isaac Newton (irregural vector of gravity force) and also unexpected hard walls suddenly appearing in the dark in front of the trajectory… 😉 I believe that with our information, it’s practically impossible to understand where Philae landed even if it’s very likely that it dropped beyond the crater of the landing site “B” since it travelled almost 2 hours at known speed.
Damned! I hate being so prophetic! Today ESA issued the news that… an unexpected hard wall suddenly appeared in the dark in front of the trajectory.. like I wrote above (really it was just a matter of probabilities…). Now it seems really almost impossible to understand where Philae has landed.
Calculating the trajectory without knowing any detail about the impact is practically impossible.
We can only hope that ESA can extract some info from the data made available after the final landing during the rather short (but extarordinary!) scientific work session.
Hey guys, you are certainly all very right that this is a very rough approximation. But let me comment on some statements anyway:
The fact that the flight does not happen over a flat surface is probably not as big a problem as you think. While the changing gravity vector does indeed slow down the original horizontal movement, gravity basically bends the flight path down and the speed component perpendicular to the gravity vector does not change that much. Basically the whole flat calculation is transformed into a bended coordinate system. On a real sphere I guess the result would not be very different from the flat calculations. But it is true that the gravity vector on 67P is very different from a sphere. And this will in fact have some influence.
Speaking of the rotation I do not see a big effect of it at all. If I understand the reports correctly, Philae landed close to 67P’s equator and moved east along that equator. So basically it did not change the latitude very much and the angular velocity of the terrain under Philae stays nearly the same. This angular velocity is already contained in the distance we measured over the first 9 minutes, so it is contained in our calculations and does not change. It actually changes with the height of Philae (the lander gets slower than the ground when it climbs higher) but as the trajectory was very flat (probably less than 500 m over ground) this can also be ignored in a first approximation.
So in the end the biggest error factor will be the non spherical shape of the comet. But I guess that we will still see a result close to 2.4 km in the end.
Any bets again me?!? 😀
BTW: Very nice work Michael Koch! I was waiting all the time for somebody to do such a projection on a 3D model! Super Arbeit. Danke! 😀
When ESA first presented the facts that Philae had bounced, they talked about the first bounce being about 1 km high and 1 km wide. I don’t know what they based that on, but they don’t seem to agree that the trajectory was very flat.
Johan, it is safe to say that they were very wrong. If their initial assessment of 0,38 m/s after first touch-down was correct, then the trajectory has an extremely sharp angle and is flat over the ground.
With the above horizontal speed of 0,3635 m/s you can calculate that the angle was about 17°. Also the shadow of the first appearance of Philae after touch-down (86 s after touchdown) allows an approximation that also results in an angle of less then 30°.
I guess their estimations were based on an estimated deflection angle. We know more now as we have spottet the vessel twice after touch-down.
Uhmmm… You’re laoding tons of approximations.
If I watch at the videos where 67P is seen rotating I get the impression that moving towards the socalled “east” is very, very far from an equatorial trajectory. I would say, almost perpendicular.
And more in general what I highlighted before, any sudden obstacle (a steep cliff) can stop the flight everywhere, well before the 2.4 km: this is in the wisdom of statistics rather than geometry. Also consider the fact that Philae seems to have landed right against a cliff… 😉
Hi Haring, you are absolutely right: while the touchdown was close to the equator the trajectory was NOT along the equator at all, it was more along a longitude meridian as you suggest. Sorry for that mistake. The result is that the more the probe flies away from the equator the more it will hurry on ahead of the rotation of the ground below it (Coriolis pseudo force). This will considerably bend the flight path from North direction (in terms of counter-clockwise rotation pole) to North-East direction.
The distance covered along this path will still be in the +2 km range as it is known that there was no other impact (cliff or whatever) for 1:51 hours.
Thank you for confirming my “impression”. You’re doing a lot of work, I think the best calculations we can find here on this blog (at least on the blogger side, ESA has so many more instruments that… they are on another planet).
It’s quite difficult to speculate on “directions” and “distances” but 2 km is very far from the information provided from ESA and I believe that you did the right calculations, even if maybe the neck was not reached.
The difference could be in the angle of Philae at the touchpoint. I suspect that the lander hit the ground with a very low angle (less than 45°, perhaps even less than 30° and bounced forward with a similar angle, after having danced a bit on the sand.
I fear the reason for bouncing is more than .
Unfortunately is truly hard to have a precise idea of the angle just looking at the pictures. The famous picture “after-the-bouncing”, shows that Philae is very close to its shadow, but we don’t have references in height, we don’t know the angles between osiris and the 67P surface at the touchpoint, nor the angle between the sun and 67P.
Have you found any way for measuring the angles?
Sorry, the missing statement in my near post should be read “I fear the reason for bouncing is more the angle than the hard soil”
A general comment concerning the supposed change in flight trajectory (direction) after 1st touchdown:
From the pictures it appears that there is a change in direction, which does not make sense in terms of conservation of momentum. I honestly think, there is no change in direction ,but that it all boils down to the perspective from which the pictures were taken. Imagine the camera looks upwards at the bottom of a flat plane. Now imagine an object nearing this plane from the bottom in a steep angle. The collision will have absorbed a great deal of the vertical and horizontal velocity and the object will bounce of at a shallower angle and at slower speed, but it will not have changed the direction to ground reference. So, if you picture the above, you will notice that the camera will see a virtual kink in the flight path, which only reflects the different inclinations of the flight path to ground reference before and after collision. Having said this, this projection matter needs to be accounted for, when trying to extrapolate the ground trace of the flight trajectory after the 1st touchdown incident. (I’d like to upload a picture showing this – but I’m not sure where?)
To correct my comment above: There can be indeed a slight change in direction if the probe started spinning after touchdown, which it indeed did (they noticed some wobble in the signals from the probe after 1st touchdown). This is similar if one would throw a horizontally aligned wheel, which is spinning around the vertical axis in an angle onto the ground. Upon contact, part of the spin will be converted into a velocity vector, which is not aligned with the ground trace of the flight path. For the probe it was the other way around. It was not spinning before touchdown and then probably touch the ground with one leg first, which induced a spin and therefore a slight change in flight direction. From the probes 2nd moment of inertia and the spin frequency, this change in direction can be quantified.
Jens, literally ANY change of direction is possible if the deflecting surface is not plain horizontal. This is completely overlooked by most commenters here. If Philae e-g- touched the ground with one leg on a bolder it could reflect in a very unexpected way.
Hi Jens. Imgur is quite fast to begin with.
Sorry, there is a mistake in one of my assumptions:
The trajectory is NOT along the equator but basically perpendicular to it towards the pole. See my correction comment for an updated conclusion.
Are you sure about that the direction of the bounce is along the equator
As far as I can understand by looking at the few ‘maps’, images and videos I can find of the comet that tell the direction of north, is that Philae approached along the equator but was moving south-southeast after the bounce.
You can see more in my comment further down.
Hi Lars,
after re-evaluating all images and animations the lander’s first touch-down was close to the equator but the trajectory after the first bounce NOT along the equator (as I argued wrongly in my first statements) but perpendicular to it towards the North pole (spin-axis with counter-clockwise rotation when seen from above). This leads to a curved trajectory. See my corrections above.
Thanks Jorg! Even if this is a simplification, it feels like a valid conclusion…
Joerg,
See my comments in this thread below about using a rotational frame of reference. In this situation either linear or simple rotational will be approximate, but Philae has clearly gone “round the bend” into the “dark side”.
I updated the NAVCAM and OSIRIS combination I made earlier to include these new positions. I had to reduce the brightness of the comet somewhat so that the white pixels I use for Philaes position would show up. I’ve also circled them just so it is easier to see. Note that this is just roughly done, it’s not the positions might be a few pixels off.
https://i.imgur.com/4m4WqAN.png
If you want one without the circles then look at https://i.imgur.com/JFuFuHv.png.
As a reminder, this is then gives the position of Philae at (roughly):
20 minutes before first touchdown.
14 minutes before first touchdown.
11 minutes before first touchdown.
1 (~1,4) minute after first touchdown.
9 minutes after first touchdown.
We also know that the second touchdown took place 111 minutes after touchdown, while the final landing took place 118 minutes after touchdown. So it does seem it would have made it quite far, although once again I would like to point out that we aren’t dealing with a stationary, flat surface.
Images are a combination of CAMA20141112153532snip_paint.png (Credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0) and ESA_Rosetta_OSIRIS-NAC_Landing_site_50km.png (Credits: ESA/Rosetta/MPS, for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA) that were posted on the ESA Rosetta blog.
Amazing work! Are there any OSIRIS images beyond 15:43 available (or scheduled for download) that would allow to spot Philae and plot the further trajectory?
Excellent clarification Daniel. It would appear that Philae has bounced off the back of the head and is hidden somewhere on the “Dark Side”.
https://blogs.esa.int/rosetta/files/2014/11/ESA_Rosetta_NAVCAM_141106_Mosaic.jpg
From this image we see that the “south west” edge of landing site B, which Philae is heading for is an almost sheer drop. This is an area of the comet’s surface that remains in shadow at this point in its orbit. Since Philae does see some sunlight it suggests that the second landing point is a little south of the equator on the short end of the big lobe. This area has not been seen in the NAVCAM or OSIRIS images published, probably because it was always in darkness and could not be imaged. In the 5 days since Philae finally landed, images of all the sunlit northern hemisphere must have been taken, yet Philae has not been found. OSIRIS can see a fair way into the Infra Red where Philae would show up more, so it is beginning to look like she has landed in a spot that can’t be easily imaged, that is the “Dark Side” of the comet.
The good news about this is as 67P approaches the sun the southern hemisphere will receive more and more sunlight at a greater energy intensity and Philae may become active again when the show really gets going. The only image I can find which shows the type of terrain she might be in is one of the top ten NAVCAM images released at the beginning of last week. The foreground of image 4 is located on the big lobe on the edge of the “Dark Side”.
https://www.esa.int/Our_Activities/Space_Science/Rosetta/Highlights/Top_10_at_10_km
The surface in this foreground area appears very similar in character to the formation in the 2 image mosaic from CIVAS.
https://www.esa.int/var/esa/storage/images/esa_multimedia/images/2014/11/welcome_to_a_comet/15048351-1-eng-GB/Welcome_to_a_comet.jpg
Philaes communication window accurately predicted, suffered initially from intermittent interruption. Rosetta would have been above the horizon of the head lobe and initially seen past the edge of the head to contact Philae, but as the comet and Rosetta move the irregular profile of the edge of the head lobe would come between orbiter and lander. As Rosetta climbs higher above the horizon and the body lobe comes fully into view the signal would remain uninterrupted. The signal also was cut short sooner than expected, possibly as the neck region moved into the line of sight.
As usual I am speculating and reasoning as I go along so please don’t take this as a real explanation, its just an extrapolation from the direction Philae was heading. No complex calculations of velocity, ballistic trajectories and distance travelled. Without the initial angle of take off from the initial landing point no meaningful calculation can be done. The gravity vectors of this crazy shaped object are not straight forward either, and a brief glimpse of a gravity intensity map during the landing day interview with the NASA lead project scientist, suggests the value of g is not at all constant across the surface of the comet. Me, I’ll stick to rule of thumb guesses and leave the calculations to those with the required data.
Wise conclusions that I agree completely, after being frustrated while tryng understanding something more of this puzzle.
If it appears fully reasonable that Philae jumped beyond the crater of the site “B”, honestly we must admit that it’s almost impossible to determine with precision where it finally landed, at least with the information showed.
Not only gravity but also local obstacles or simply different heights could greatly change its final position. In conclusion Philae was even lucky not having crashed against any rock wall.
Let’s wait and see if ESA people is able to get useful information from the data collected.
One question anyway arises: is the “Dark side” really dark or tumbling exposes it regularly to light? If the comet really tumbles, the whole surface should be periodically enlighted. But perhaps the comet has a preferred way of rotating that keeps really dark the dark side.
One consideration.
Examining the first 3 pictures depicting Philae while landing in this thread, I measured roughly the same dimension in number of pixels.
This could mean that the descent rate was slow, while there was an horizontal component in the relative movement (maybe due to the rotation of the comet?). Maybe Philae had a strong horizontal component in its relative speed when it touched down the first time and this could explain why he travelled so distant.
Next time I would plan for a nearly vertical landing…
As an additional disclaimer that I really ought to have added to begin with: the pictures of Philae are taken from the side, rather than straight above the lander (remeber that Rosetta changed course a while after having released Philae). This means you aren’t just looking at the movement across the surface (the ground track), but also its jump into space.
Even if Philae had jumped straight up from the initial touchdown point and landed back down on exactly the same spot, it would still move around on these images. So that’s one additional reason as to why you can’t just draw a straight line from the touchdown point to the final landing site by using the lander as seen on these images as a “ruler”.
This bit of data has calmed a lot of headaches, Daniel. This was a known bit from the published orbit simulation. We just didn’t remember. We should let Flight Dynamics do their work.
Thank You very much Daniel for posting up this extra image. That is certainly beyond the call of duty and so stunning. It is quite obvious that Philae did not rebound in the same linear direction as approach.
This WILL help relocate Philae and yes, Philae WILL be found and I would not be at all surprised that Philae will reawaken.
Andrew R Brown
What we cant forget is that Philaes apparent movement over the comet is a result of 2 different components. 1, movement from the comets rotation around its axis and 2, Philaes elliptical orbit around the comet after the bounce.
The comet is rotating in space, and Philae is also orbiting in space. The rotation is the easier part to calculate as its movement is fairly linear and constant however we need to know where North is. I’ve taken Daniels image and rotated it to have what I believe is North up. I’ve also made a few annotations about the 2 separate parts of the apparent movement. https://www.dropbox.com/s/8bypv3dong2g62q/Philaebounce.png?dl=0
Before landing, Philaes apparent movement over the comets surface was mainly due to the comets rotation. I believe Philae was pushed off Rosetta roughly in the equatorial plane and falling pretty much straight down. (There is also a small apparent movement due to Rosettas orbit and Philaes height above the comet)
On touchdown Philae received an impulse from the comet causing it to bounce off, into an elliptical orbit in space. This impulse directed Philae initially towards south-southwest. Combined with the rotation of the comet we get an initial apparent motion over the comet towards south-southeast.
During the hop, the comet will continue to rotate and its pretty easy to calculate how much. 54 degrees. Philaes orbit however is more complex maths that I don’t know fully. What I do know is that Philaes orbits vector over the ground is acting quite a bit against the comets rotation vector. Initially it takes away around 1/3rd of the rotation movement, it all depends on what direction is actually north, what’s the distance from the comets spin axis to the touchdown point and so on.
As Philae is moving further south the orbit vector will veer clockwise over the ground counteracting the rotation even more, and slowing Philaes movement to the south. Combine this and Philaes movement over the surface will not be a straight line but curved towards the north. How big or small this curve is all depends on the exact properties of the orbit of Philae.
So we can basically say that Philae will be less than 36 degrees (2/3rd of 54) latitude east from the touchdown point. That takes us maximum just past the rim of the large crater on the smaller lobe. So Philae is not in the neck region, its still on the head. We also know it will be on a curved line north of a straight line between the initial touchdown point and the sighting of Philae after the bounce. That’s about as much as we know.
The flight dynamics team will already have made their calculations knowing way more in detail the actual angles and positions involved. They also have Concert triangulation data at their hands. I’m confident they will find Philae soon.
The plot thickens.
https://blogs.esa.int/rosetta/2014/11/21/homing-in-on-philaes-final-landing-site/
The Concert triangulation data agrees with my very basic assumptions above.
Lets hope OSIRIS can finally find Philae now.
I hesitate to comment among obviously much more scientific minds than mine, but like so many, I’m loving this mission.
Do we think it was just the lack of gravity and failure of harpoons and thruster that caused the “hopping” or is it possible that something smashed into it to move it and is it possible this same lack of gravity pushed it into the underside of the cliff which stopped its forward momentum causing it to rest in the shadow of the big cliff (ultimately allowing it to conduct it’s mission)?
Regardless, it’s been an awesome week. I’ve looked at everything on Earth a little differently this week. Thanks for the great interaction with everyone!
I really love what you did!
You spot Philae in the shadow of a cliff but on the panorama posted in ” how and where is Philae” there is something looking like philae a little bit more east , that means later . A bright spot and a tripod shadows . What do you think?
Haven’t been so exited since 1969 !
Looks like a lot of the readers want to participate in the Philae chase. It’s nice but I have doubts that posting all those small calculations mastered by a 10 years old kid on speed and distance (remember the problem of the two trains leaving station A and B, etc) are helpful at all to the ESA scientists.
I mean, don’t you think that the guys able to fly rosetta to a comet didn’t do d=v*t the second they saw the pictures ?
Anyway, very nice mosaic: it’s cool to see the different positions as well as the three impacts from the 3 feet of Philae on the 1st landing.
@Guili, what’s wrong with amateurs (and maybe a smattering of scientists) trying to explain with limited facts what could have happened to Philae? Granted that we do not have all the information that the Rosetta scientists have at their disposal, but we may have the same smarts, and there is nothing wrong with trying our best to explain the facts.
Curiosity is the mother of invention, and no one has a right to criticize enthusiasm for science and maths. Long live the ever searching minds and creative talents that abound everywhere you look!
Oh, but absolutely they have done that and with far better math and models. But don’t you understand the fun in trying ourselves?
And remember that many in the community found Philae on the first image after touchdown BEFORE ESA confirmed that it was there.
This is fun. Maybe not for you but still for me. 🙂
Hi Jörg. You are absolutely right 🙂
@Guili, you make a valid point. It goes to the heart of public policy debate around ESA or any national space venture. Many scientists are looking at the data already, why indulge so much discussion and speculation?
One thing I would like to add, is that the discussion itself does, indeed, have an important purpose. A part of any public scientific activity is to inspire and engage people to look at unusual and tough problems, when normally people would not have the interest or time to invest much effort thinking about scientific matters. But space is exciting and engaging, and you see so much activity here in this blog because it is so very captivating to be involved real-time in history unfolding. Our generation has the opportunity to have a front seat to real exploration. You could say that inspiring interest in science and technology within society is another benefit of the Rosetta mission, over and above the knowledge gained in itself.
Not to mention the fact there may just be a few rocket scientists reading the blog and looking at data as well 🙂 . Sometimes you only need a little bit of the right data to be able to make meaningful contributions!
Sometimes a little bit of the wrong thinking is needed to make the scientist realize a new route.
Best comment yet 😉
Hi Guili, i think that the people at ESA are not much smarter than the average engineer or the average manager in just about any high tech industry or university.
The difference is that we less minded are not in stress and have no policies to brake us. We do mistakes too but don’t care much about that. If someone at ESA makes errors, and trust me this happens, then the situation is a lot different on a personal level. The reason flight dynamics is so superior to the other teams is that they have a lot of redundancy and the errors have efficiently been filtered away and never affected the mission. The landing sequence error is not due to flight dynamics, but due to a poor command set starting in a wrong way from touch down, this was in my eyes an error. Its easy to look backward an see whats wrong but its almost as easy to look forward and with proper handling be prepared for all of the possible scenarios. Without a proper quality management system and other processes you would not dare to drive a modern car or step into a plane if not those tools are used by the manufacturers of those devices. The same goes for this kind of projects but some times the eagerness wins over quality.
It looks like we would have a thrilling sequence if one of the Philae cameras was set to take pictures at an interval beginning some minutes before landing!
So true Marcelo!
I guess they simply did not expect to do multiple hops and still survive and land safely. The current scenario is extremely unexpected.
BTW in 15:43 touchdown point point close up, we see something that looks like three tiny craters. Is that an accident or coincident by change of illumination comparing to “before” picture, or Philae’s legs made 1 or 2 or 3 of them??
Been so very exciting! So very little shade on the comet, but Philae was about to find it…. Thank all of you for the greatest achievement of recent space exploration!
Looking at the images Daniel has put up the horizontal speed is similar before and after first landing. But the direction quite different, what could cause this type of bounce.
Thanks to all at ESA for all the science, and for keeping us up to date with the news.
A striated, ice surface?
That could explain the ‘flipping’ too.
That ‘solid’ ice could explains the ‘reboot’ too.
This sound too much ‘winter Olympics’ 🙂
One continues gobsmacked. This is such wonderful work, I wish I was 40 years younger so that I might contribute.
May your funding wax plenteous for many years to come!
Surely the touchdown time would be about 15:30 (not 15:43) if it was going at the same speed as the other observations?
Would it be possible for Philae, after recharging its secondary battery, to push himself in a better position by the following procedure?
– Determine a direction to move Philae
– Unreel the harpoons that fired to an extent, that would allow a controlled displacement in the desired direction
– Use the MUPUS or SD2 experiment to give Philae a push
– The lines, connecting the harpoons to Philae let it behave like a captive balloon and limit its movement
As I don’t know a lot of details, like line length, available force of the SD2 or MUPUS and so on, my idea is a pure guess.
Would the control center be willing to release some details, what options of movement, force, actual weight of Philae on the comet and so on? It would certainly be worth a try to pool the available hardware options and try to investigate in recover options.
very cool pics. very nice tele. 🙂
good luck to everybody finding that lil mole. my math with that values here got it at ~3720m off. circular in unknown midair. not taking into account the vector rotation of the comet in 2 hours. i don’t see that rotation from the pictures neither the sun shadows. mean trajectory calculation. i like that science tho. 😀
I believe the early reports of the 2-bounce landing indicated that the total distance traveled was 2km. I wondered, at the time, how this was possible given that the entire comet is 2.5 km. However, that assumes it did not change direction at the second bounce. But still the distance between first and second bounce seems like it would have drifted into space given the position of the landing target on the head of the comet.
On 15th, Philae’s system voltage was near about 21.5 V.
After about 2 and a half day, what it would be now? And what difference does it make in tracing the Lander!
I am waiting for one of major news outlets to pick up and run with the present tense headline above “OSIRIS spots Philae drifting across the comet” and report that Philae is currently drifting around the comet (because you had to read 2 entire sentences to see that this was from photos take on Nov 12, and that OSIRIS is a camera, not another spacecraft that happened to be in the area shooting photos of the comet.
The news coverage of this event, at least in the U.S. has been incredibly inaccurate, late and uninformative.
Most news agencies are still reporting the “first bounce” photo as the final resting place (despite no shadows, no crater, no cliff in the photo, and the fact that an object detached from its own shadow must be airborne). These small details all seemed to be missed. ESA also referring to the first bounce as a “landing” does not help matters.
And despite hundreds of spectacular hi-resolution images posted on the ESA Flickr site, most news agencies are using cartoon illustrations.
This is a truly remarkable feat for humanity; its in stark contrast to the humanity currently being played out in the middle east.
On a more scientific note – what is the engineering logic involved with the recharge of the batteries? what is the condition for it to resume communications? will it progressively become charged over a longer period of time? or will it reach a certain level and resume communications?
Keep up the great work guys!
¿Nobody notice strange Philae’s Y axis rotation ?
When watching the simulation of lander deployment, it is obviously unlikely that Philae could have ever touched down again on 67p once past the depression of site B. Most likely little P rest on (in) the slopes of the farthest rim. Beyond that point: space. No other possible place, than within the area already pointed out by the navigation crew. And by the way, think about it: would they be wrong?
cliffhanger…
Copy that, Jacob.
Well, moving at a speed less than escape velocity will eventually lead to a new touchdown, but that would have to be after a long flight across to the other lobe, and then the communication window would have changed by a lot more than a bit?.. Let’s all just wait for flight dynamics next wonder.
On flying over the ‘night side’ Philae was really high in the sky with diamonds 🙂
This means that the previous bright dot on old touchdown picture (one with the dust) was also Philae. All three points are on the same line, times and distances are also consistent. Curvature is not relevant in this small part of the trajectory and the with the view from above. Horizontal speed component is than 0.29 m/s (not 0.5 m/s, that is an error). We know that after rebound speed was reported as being 0.38 m/s. So, it is possible to calculate rebound angle, arccos(29/38)=40,25 degrees. With known value of rebound speed vector (0.38m/s), it is possible to calculate trajectory. Philae is not on the top of the small lobe at all. He is beyond large cliff on the right, actually somewhere on the dark side of the small lobe, possibly on the neck, or even on the internal side of the big lobe.
I checked ‘Where is Rosetta’.
P67 will be near to sun in few months, i hope it can come back.
P67 looks to have around 2 years and half orbit around the sun. So, can we expect the module leave idle mode each 2.5 years?
Around august 2015 and next oportunity at december 2017? or module will be degradated before 3 years?
what do you think?
thanks.
The first two insets are separated by ~5 minutes, and the second and third by ~4 minutes, but the third and fourth by ~20 minutes. Why is that? Are there no photos between 15:23 and 15:43, or is the lander more difficult to spot in that time period?
Philae is more difficult to spot during that period.
There are certainly enough images of Philae’s trajectory post first bounce to narrow down the location of the second bounce and the final resting place. 😀
I hope the ROLIS camera was active throughout and I wonder if CIVA captured a partial pan at the bounce sites as Philae was moving very slowly under that weak gravity?
Andrew R Brown.
Absolutely unbelievable!!
Do you remember the wild wild west movies? Those mirror ‘telegraphs’? Philae is the mirror. At least one of Rosetta cameras should have diaphragm. Set to minimum. Point to center of search area. You are going to need a controled ‘paning’l. Flight dinamics: You could be the heroes. Give us a static long exposure shot.
[Remember that one of the cameras is able to do low-res movies].
Truly unfortunate to land in dark spot of all the open fields, although it may have been only way to stop moving. Try relocating again if possible.
However, this proves to be very excinting mission, a movie material. Hope for long life and happy end 🙂
are these photographs in B&W or is the comet really that gray?
The comet really is that grey. 😀
I’m sure the scientists can use the information from these photos.
It’s really amazing that you can see three depressions at the touchdown site. It looks like the feet made a “dent” and then maybe the material formed a larger funnel shape. Does fine sand on Earth produce a similar effect? Of course, the low gravity will make the behaviour of particles different on the comet.
Congratulations to the team on both the navigation to the comet and the landing!
Looks like Philae is now ‘between a rock and a hard place’
Hopefully, there will be more light when it gets closer to the sun. Or, maybe, a geyser will lift the lander and deposit it in a more favorable location!
The view – both from Rosetta and from Philae (if powered) – should be incredible, as the comet nears the sun. Looking forward to it!
Very well.
I would add, in addition to being a flat surface is necessary to consider that the pictures do not give a sense of perspective (the third dimension).
The phase before the first contact is descending, not horizontal!
I expect, therefore, that the second phase (1 hours , 51 min) have the same characteristics, to a reduced extent.
In the calculations of the distance that it is essential to take into account the elevation reached (speed of impact , energy absorption by the dampers, gravity , ascent rate…).
My contribution to this:
an analysis of the site of first contact shows that only two feet have touched the ground (those to the right) (not utter east and west :))
At this point the lander has received an upward thrust that it has put in counterclockwise rotation.
Immediately after the third foot slammed into the ground near the first two and straightened the lander, or reversed rotation.
I am not able to do the calculations, but I think that anyone who is able to bring the mission to the comet after a run of 10 years will be able easily. . .
Go Team!!
Firstly, thank you to everyone at ESA, their professionalism and dedication has been utterly inspirational. A magnificent achievement.
After seeing a montage of images trying to locate Philae, I decided to have a go myself. I thought that ESA might release more great images like the above.
It isn’t pretty, and it is just based upon knowing scale (metres per pixel), the touchdown / bounce times, and the published velocity during each bounce.
A low-res version can be found here:
https://twitter.com/SimplicityCom/status/534396429075480576
When I checked the ESA blog and twitter at around 14:00 UTC, I was pleased to find this new post. I’m almost on the right path.
My knowledge of Physics etc is pretty slim, so I had no idea how to work out how the rotation, shape etc… of 67P would affect Philae’s path – instead I used a cone originating at the first touchdown point, drawing two lines to the position of Philae just 1m:26m into its first bounce, and its shadow.
The ESA images above show my topmost line is quite close to the actual position, later in the bounce path.
If my end point is correct, Philae came pretty close to flying past the edge of the large “crater”!
Any thoughts?
For your viewing pleasure I upscaled and matched the two shots of Philae’s landing spot, adding inset of Philae when it was still above terrain from another image for size comparison. I’m not sure which features are Philae’s footprints and which are just clouds of dust which did not settle yet. There are at least two ways how to put Philae on those marks since Philae rotated by uncertain amount since the inset photo from 15:14.
https://imgur.com/VMmayIR
The landing was made on one leg, it made a twist and put down the second leg in a skew tumbling to the third leg and debounced. As simlpe as CHA CHA CHA.
You’ve done it again Kasuha. I just could not get an idea of how Philae bounced in the pictured direction, but this little graphic shows that the depression to the right is significantly deeper than the other two. After comparing the close up of todays picture, the landing site mosaic of OSIRIS from 30Km and the ROLIS image from 40m above the initial touchdown point, I have tried to get an idea of the changes in surface elevation in the area where the feet touched the ground.
In the earlier OSIRIS image. There are three darker depressions near to the boulder. These can easily be identified on the ROLIS image. From those it is possible to work out what and where the square of slightly darker spots seen in the OSIRIS image are on The ROLIS image. These are key, because The footprints of Philae lie within this square. Todays image also shows this square of darker patches and the position of the footprints relative to them. Thus the footprints can be related to the ROLIS image.
The landing gear of Philae straddles a small mound about 60 to 70cm high, with one foot the one at 11 O’Clock slightly higher than the one at 7 O’clock and the one at 3 O’clock maybe 40 to 50cm lower than both of them. I don’t know what the ground clearance of the landing gear is, but from the pictures and animation it is about a third of the height of the main body, which is 1 metre. This implies when the third and last foot hit the ground the lander bottomed out against this mound. one side of which faces in the direction Philae took off.
Until I saw your graphic I could not be sure in what order the feet hit. I am afraid my level of expertise with graphics is very limited, so I can’t show annotated graphics, but if you can have the three images open at the same time and zoom in as close as your system will allow, while not descending into meaningless pixels, it is possible to get a very good idea of exactly what the spot Philae first touched down on looks like.
https://www.esa.int/spaceinimages/Images/2014/11/OSIRIS_spots_Philae_drifting_across_the_comet
https://www.esa.int/spaceinimages/Images/2014/11/Comet_from_40_metres
https://www.esa.int/spaceinimages/Images/2014/10/Philae_s_primary_landing_site_from_30_km_a
As an aside, I initially thought the three little active vents seen on the ROLIS image might have been responsible, but with the greater precision of the footprints over the dust/shadows seen before, it turns out the vents are about 3m away from the landing spot. Unfortunate, because CIVAS would have got a fantastic close up of an active vent on the surface.
Thanks to Holger and his team for these incredible images, to see Philae in flight is amazing, but all the detail of the comet surface is fantastic. It is going to be interesting to see if there are any visible changes from the other OSIRIS images of Agilkia (Site J), taken earlier in the mission.
The image of the soft surface reminds me of the 1998 Mars Polar Lander mission which failed upon landing and crashed into the surface. In that case, the retro rockets caused the landers legs to flex before it hit the surface, but the sensors read the flex as if it were on the surface, cutting the main engines to early and crashing at a high velocity.
This looks like the exact opposite problem, caused by over correction for that failurE. Now, I presume, every rocket scientist does not want to repeat that error so they programmed the harpoons to not fire until they wer certain it was on solid surface, and did not expect to land in a sand dune, as the photo indicates.
From which angle in the photo library does the neck’s collimation look like this? Seems to be near one of the two sides of it.
https://blogs.esa.int/rosetta/files/2014/11/ESA_Rosetta_Philae_CIVA_FirstPanoramic_woLander.jpg
Hi Logan. I remember the CIVAS guy saying that was glare from the sun, so it is not jets from the neck.
Hi Robin. Thanks for the bit of data. Sun and Neck collimation brightness should be orders of magnitude different as for any doubt.
Noawadays, sun light reflecting on what? [no atmosphere]
Camera’s narcissus effect use to be rounded.
Can one estimate the height to the “horizon”?
Hi Lodaya. If those are collimations. It’s no that far, angularly speaking.
Just like to add my congratulations everyone involved in the project. This is not just science ‘being done’, but will also act as an inspiration for the next generation.
A couple of questions:
Looking at the images, there appears to be a change of direction after the first touchdown – is this an illusion or an actual physical change? If so, what might have caused it?
Also, in the final (15:43) image, am I seeing the lander at an angle to the ‘horizontal’ (not seen in the pre-landing images), or is this simply a trick of the light/resolution?
Is it known if Philae remained “vertical” relative to the surface plane after the bounces. Wouldn’t a bounce most likely impart an end over end rotation however small? Are we lucky that the craft just happened to land on its feet with the second and third landings?
I guess that the flywheel that stabilises the lander in its “horizontal” plane also gets an input from other gadgets what horizontal is and adjust the lander to a proper position. The rotation around the vertical axis is slow and of no concern.
Great fun.
There is a lot of info distributed in these blogs. To much for me to find my way. It would not be a loss of effort to summarize it once in a while.
Things I don’t get yet:
– I read the first impact was almost vertical. How does this show from the pictures? Is Rosetta always in the same spot during the different pictures?
– the comet rotates. How is it that the apparent trajectory after the first impact looks to be straight?
– the direction change after the first impact is quite dramatic. Ok, this can be due to the terrain and comet rotation, but can we check this from the pictures?
– does anybody knows how the comet rotation is, in relation to these pictures?
I got a couple more but I stop now because I start to feel stupid and nobody likes to feel like this. I’m no exception:-).
What we really need is a complementary animation of this show, just as those nice orbit animations that we got from this mission prior to the first landing, only a bit zoomed in to catch the excitement. Hope for the best, after all nobody ever had a jumper in space before.
Inspired by your question about the terrain Steven I set about trying to see if that might be the case (see earlier post). No need to feel awkward, none of us are finding it easy to understand this crazy place and how it all works, including the folks at ESA.
The comets rotation whilst Philae was travelling between touchdowns has been mentioned a lot. If you jump in the air on Earth for one second, the Earth’s surface in theory moves underneath you. The surface of the Earth at the equator moves at roughly 1670 Kmph so you should land 463 metres away., but you don’t. You are gravitationally bound to the surface of the Earth. The higher you jump the less the strength of this binding. It has been calculated that a pole vaulter does travel a measurable distance relative to the surface when completing a 6m vault.
The gravity on 67P is very weak, one ten thousandth of Earth, but Philae would still experience the same type of gravitational effect since she did not reach orbital velocity. The precise amount the comet’s rotation affects the distance she travelled would depend upon, the local gravity direction and strength, the velocity (speed and angle) she left the surface and her mass. The only thing any of us amateurs know for sure is Philae’s mass, all else is conjecture, which is why this is fun, our prognostications are of no consequence.
Sorry but I see a problem. One second before jumping on the earthyou have exactly the same velocity vector as the small piece of land beneath your feet.
Thi is hugely different from having two objects colliding like Philae and 67P.
In conclusion, rotation has absolutely to be considered in the calculation.
If precision ballistics are a matter like shoting a with sniper rifle or a canon here on almost flat earth, with its low rotation, high gravity, and short time of flight the Coriolis force is to be taken into concern. Google for this and check the complexity of it.
On the smal comet with the low and fuzy gravity plus the two hour time of the debounce and the fast comet rotation the ballistic calculation is extremely complex and so far not even ESA has presented an estimate of its supposed new landing position. Its somewhere in the neck region for sure and in a area where the sun does not shine to well.
Landing on the same spot when making a little jump on earth, has little to do with gravitation; it’s a matter of relative speed. Indeed jumping vertivally at near sphere radius (or some 8000 meters) would result differently. Jumping high at an angle on a rotating object: even more calculus.
Maybe these videos could help https://www.youtube.com/watch?v=wlcv6tZ9TII https://www.youtube.com/watch?v=4a3eY5siRRk about comet rotation
Thank you for your replies. I still don’t get where you find all this information. Very nice animation of the deployment. And together with an extra blog from Daniel about the perspective I understand the pictures better.
I’m flabbergasted about the resolution of some pictures. How is it possible to see the lander with tripod and hint of rotation. I didn’t think the pixel resolution was high enough. Great job.
What year is it in that comet realm? Above Karman line, it cannot still be 2014 and we all know it. What year Philae landed on the comet? Can we just will the comet towards the sun to recharge the battery. Why Philae took so long to get there? What would Carl Sagan say? I know he sent an
awareness box up there ! Is it atonement for Philae?
The essential information in these super images is that the trajectory of Philae was captured in pre and post landing. The rest is FYZY LOGIC. The comet moved and rosetta moved so the only correct combination is the touchdown #1 stamp mark and time stamp 15:34 concerning its relative positions, for the rest the projection gets fuzy.
The surprise is the flat debounce trajectory and relative high velocity that took Philae into random walk for at least a mile. With this the flight dynamic team for sure can estimate the new landing spot. With my wild guess i will join the neck region believers. the new name might be “Carpe Jugulum”.
This actually turned out to be an amazing story just as exiting as the initial landing. Congratulation to invite Murphy to the mission command team;)
I am a bit puzzled because the comet is known not to be rotating regularly, but rather tumbling. Then I doubt that defining geographical coordinates based on rotation would be unambiguous. Maybe the coordinates are a convention based on a set of landmarks on its surface? I like the reply from Jason above “it’s a rubber duck”. Who can help and clarify?
Given that the lander is now useless in its current location (due to shading from sunlight), if the comet’s movement/rotation should give the lander a brief bit of light, sufficient to wake briefly, I wonder if it would be worth trying some maneuver to prompt another bounce/lift-off (i.e. using the drill not to drill, but to push off) in hopes it might drift and re-land in a better location?
Well done.. love you Philae. Awesome work Rosetta.
The images of 15:43 shows that Philae bounced back so high and far in just that minute. Pls answer esa.
@seema, I am not with ESA, but I think that Horacio Salazar answered your question. His comment is in answer to @doekia (t=17/11/2014 at 20:23). He said, “It’s all right. Philae had its first touchdown at 15:34. The picture at 15:43 was taken [at nine] minutes after that [touchdown]. That’s why in that inset you can only see the footprint of the craft…”
I doctored up this image to showing the direction Philae went after its first touchdown:
https://imgur.com/f1QKIAe
It’s based on one of the images Bill linked above, which shows an estimate of where Philae may have landed based on early information–that it went about a kilometer and ended up in the far side of the crater adjacent to the point of first contact.
It’s now clear that Philae went both quite a bit further and in a different direction than that initial estimate.
Interesting!
That’s a totally different scenario, Flug. Hope someone else work on it.
Guess Rosetta is really sorry she didn’t bring a large mirror with her on the journey. Then she could have reflected sunlight onto her travelling companion.
Jörg wrote: v = d/t = 0,3635 m/s
Assuming that is the horizontal velocity and assuming the team’s estimate that the lander would have absorbed about 2/3 of the 1 m/s vertical velocity, leaving 1/3 m/s as the vertical velocity of the lander after it rebounded, that gives us an interesting situation:
Given 0.3635 v_horizontal and 0.3333 v_vertical gives an overall velocity of 0.491 m/s
That is MIGHTY close to the estimated escape velocity of 0.5 m/s.
If that proves to be the case, the question of whether Philae was going to land a second time may have been far more touch-and-go that we originally imagined!
Is the speed determined for the drifting Philae (after touchdown) relative to the comet’s surface, or the raw speed independent of the comet’s rotational speed? If it is the former, then it means that over the 2 hours of the jumping phase, Philae would have moved a total of 3.6 km over the comet’s surface, which is 1 km over the width of the smaller lobe! That means it would have fallen off the edge of the lobe into the path of the larger lobe. Since that obviously did not happen, my calculations allow for only a relative speed to the comet’s surface of 0.14 m/s, not 0.5 m/s, given that Philae only travelled 1 km during the jumps. Why the discrepancy?
Also, if the large insets are indeed 17 x 17 m, then I calculate that from touchdown, Philae had moved 180 m to the east by the time of the 15:43 exposure — this means a speed of 0.25 m/s, more in line with my calculation of 0.14 m/s, relative to the comet’s surface. How did they arrive at 0.5 m/s for the speed? That calculation must have been erroneous.
While Europe is sleeping (past midnight MET), I am solving my own puzzle with Philae. Looking at an animation of the landing from the Rosetta Twitter site >> https://www.youtube.com/watch?v=4a3eY5siRRk&feature=youtu.be << I came upon the discovery that 67P may have been rotating *in the same direction* as the horizontal vector of movement for Philae after the first touchdown. If 0.5 m/s is the correct raw speed of Philae after touchdown #1, and my calculation of the comet's rotation (0.35 m/s at the surface) is correct, then the relative speed of Philae to the comet surface is 0.15 m/s, which is exactly what is required for Philae to have travelled ~1 km on the comet's surface over the course of its jumps. Problem solved?
An alternative way to put something to the ground would be to park the orbiter a bit outside the geostationary orbit and eject the lander to the surface hanging on a thin line and when over an interesting spot release this line.
Not physical:
at nucleus-stationnary orbit (which may not exist, check for discussion about it on previous posts) vertical acceleration is 0 (so called microgravity environment).
At the nadir vertical acceleration=1G (comet’s G = +/-0.0001 m/s² )
in between a lander trying to orbit the nucleus at an intermediate rate playing the yo-yo with its tug-line… not a very safe situation for both the “lander” and the orbiter 😆
Gradient stabilizing for satellite involve a rigid boom, not necessary very efficient to deposit a lander on the ground… (let alone the fact I am not sure the gradient around the nucleus is as smooth as our regular shaped Earth’s)
The geostationary radius is with the mass given and the period given as well, about 3200 m. its fairly stable once the spot is reached over the equator and only a few kilometre above surface. The solar wind and dust ist easy to compensate for as it was done at the orbit at 10km distance that we once had. Its just an idea and most likely a future mission will be a lander that has some propulsion to be able to move about. The jumper and a few thrusters would be a perfect combination. Lets see when NASA make their sample return mission to an asteroid.
Whoa!!!
Hasn’t anybody else noticed the strangely regular, artificial looking, structure to the left of Philae as she exits the frame top-right?
That would be a target to land on!
Removing tongue from cheek – Well done ESA!
did Philae land at an angle?
Did you remark a strange behaviour? The landing speed was about 1m/s. After first touchdown it was 0.5m/s. The duration beetween first and second touchdown was 1h51m but between second and final only 7 minutes. Why during the second touchdown philae lost so much velocity, far much more than during first one?
I wonder why creators did not want to use a radio isotope generator on Philae at lease. These batteries can give energy for 10 -15 years. These are even used on earth’s remote areas. And there were similar batteries on Pioneer space crafts, and still working in their 4th decade billions of miles away from sun.
With your findings about Philae from Rosetta’s camera I assume the scientists in ESA know where Philae finally landed. Is there a possibility that you sand comnand to Rosetta to stay in view with lander’s final landing point so when sun shines(1 hour 30 minutes in comet’s approx.12 hour of rotation period) on Philae, Rosetta can take pictures of Philae and his final touchdown on comet Churiomov- Gerasaminko.
Has anyone else seen the nice diagram showing the rebounding sequence of our beloved little Philae, complete with altitude and traveling speed information at a given time _after_ the 1st touch down? It showed clearly that during the 1st “hop”, Philae was drifting at 0.285 m/s for 112.25 minutes, then the 2nd “hop” occurred, with Philae drifting further away at 0.019 m/s for another 9.405
minutes…
Searched wide and beyond but I’m unable to find it anywhere. I remember it was shown during one the webcasts but I cannot find a static version anywhere.
I wonder… Were those indicated traveling speeds the resulting “linear/horizontal” drift speed during each “hop”? If that’s the case, then all the calculation about the actual distance traveled by Philae toward its final touchdown spot above are off by at least half a kilometer…
No offense intended, I’m just trying to understand as much as anyone else. Cheers!
1st hop 0.285*112.25*60 = 1919.460
2nd hop 0.019*60*(120.5-112.25) = 9.405
distance traveled from touchdown = 9.405+1919.460
—
1928.865 meters away from initial touchdown.
Sigh! I’m fully aware that this is another wild guess… But I cannot set my mind at ease, thinking that that good Philae system is stranded in the dark, cold, shadows of a dirty, smelly, unfriendly but so much fascinating chunk of primordial… Dust and Ice?
You should consider that the accuracy of your calculation has and input error of some % on top of other uncertainties that in best case will give you a total error of at leas t 10% and due to this you might adapt your figures to not show a millimetre precision. Better say 1.9 km +/- 0.2 km.
Cheers! Omero 🙂
Why did Philae change direction after the second landing? Perhaps because of the surface angle or because it was still rotating? I see only two distinct spots where legs seem to have hit the ground.
Yes, Y rotation and, take a close look at photo #2, X rotation as well, which is far more disturbing.
Someone else already pointed out, and I tend to agree: Philae landed either on its back, top down, legs up, or sideways, and that’s the reason the harpoons did not fire.
Most probably the answer is no:
according to the timing of the radio link windows with the orbiter, the Z axis of the lander at its final position is very close to the one expected at the first touchdown (more or less normal to the surface at target).
The lander was stabilized by its réaction wheel, and even though it was powered off after what the lander computer took for a “landing” (the first touchdown) it most probably stabilized the lander Z-axis during the next couple of hours allowing a final landing with the same orientation in space… but not w.r.t. the local topology 😉 at a 1km distance on a 4 km diameter world the local vertical is significantly different (even worse on the smaller lobe of a rubber-duck shaped nucleus).
For the aspect change of the lander, do not forgot that the orbiter was also moving with respect to the lander… according to the CIVA panoramic images, the lander still has three feets as of today 😉
Conclusion: Z rotation = yes (slow and most likely intended)
X and Y rotations simply rotation of the viewpoint due to the escape trajectory of the orbiter.
2558
Oups, the CAPTCHA made an unexpected landing at the bottom of my post 😆
My thoughts exactly.
I’m also contemplating precession due to changing gravitational vector. Not during drop but during hop. Not that it matters much, just for sports.
QUESTION, Would an hour a day of sunlight accumulate over a period of days enough to charge the batteries>
The batteries need to be warmed up to 0c before they can start charging. eSA did not disclose specific times, but If they assumed 6-7 hours of sunlight, one could assume at least 3-4 hours to warm the batteries, and another 3-4 to charge them. Total speculation on my part. eSA should provide specifics. Question for ESA: of the 6-7 hours of sunlight expected, how many hours were needed to warm the batteries before they could start charging?
Question Would an hour of sunlight a day accumulate enough to charge the batteries?
During Philae design (~ 15 years ago), I believe, were many many scenarios and simulations. I am curious if the scenario that the harpoons will not deploy, was simulated. Just as a lesson to learn for future space missions.
However, everything is amazing about this mission, good luck to all esa team!
One additional consideration: ESA reported that Philae touched the surface at 15:34, 17:25 and 17:32 GMT, so the first jump tooked 111 minutes and the second only 7 minutes.
Since the the harpoons was never fired, is it possible that after that 111 min it didn’t landed but hitted a rock loosing it’s kinetic energy and falling near it ?
This could be confirmed by the current position near a rock.
I fully agree, Roberto. I have myself been thinking this is the most likely scenario:
On its first rebound, Philae gained sufficient altitude to be able to clear any obstacles (large boulders, cliffs, crater-walls, rock-faces) on its “flight-path”. The second touch-down point, however, then occurred too close (100-200 metres, for example) to something like a cliff-face for Philae to be able to clear it. After gently colliding with the cliff, Philae fell/slid/tumbled down to the base of it and came to rest in the sideways down position we can infer from the photo it sent back of that rock: https://blogs.esa.int/rosetta/2014/11/13/welcome-to-a-comet/.
It is probably stuck in one of those piles of boulders we can see at the base of virtually every cliff-face on the comet, in the shadow of the cliff itself.
Hi Roberto. It is obvious that some matter ‘cached’ most of the kinetic energy in the 2nd jump 🙂
….and disappears into comet’s black hole…. jeje
This is all so exciting and I love the brain power and collaboration… but for those of us a step behind the physics involved…. Can someone summarize in plain English what we know and what we do not know about the lander after it touched down? I.e. if based on the data and imagery available… we were to recount the events… what is the last known fact about its speed, direction of travel, the last reported or perceived physical integrity of the vehicle, what did the last self report say after harpoons failed to deploy.. at what point do we transition from verifiable facts to theorizing what happened next?
I have read that the bounce occured because the surface beneath the dust was harder than expected – as hard as rock so the harpoons and screws could not get any purchase. This sounds to me like solid ice. Ice has a much higher density than snow as it is a crystaline substance. Thus the comet in general should be heavier than thought.
Obviously due to the odd shape of the comet such measurements are hard, has a higher mass been detected through any gravity measurements made by Rosetta?
Steve, one thing is to deploy the harpoons and not be able to stick to the ground, quite another thing is not to fire the harpoons at all. From what I read on previous posts and ESA press releases the harpoons did NOT fire at all, so they didn’t even try to hook up to the ground. The same thing for the top jet pushing down and feet drills. I think we might have a single point of failure here: The sensors that detect touch down, or a common trigger device that was suppose to fire all 3 processes. Just guessing here… as everybody else…
It wasn’t ice, it was, beneath the dust layer, the rock we see everywhere on the comet’s surface. That’s indeed why the harpoons couldn’t get a hold on it.
Dear Flight Dynamics,
First, all honor to you for your Agilkia targeting!
If you are looking in on this blog. you have seen that many people are trying their hand at following Philae’s leap and skip with only scraps of information. As a result, they’re spending lots of time in probably fruitless speculation. Please don’t let them flounder so.
If you have an interest in crowd-sourcing the search and getting useful hypotheses from the public, I think it would help if you would share more specific details based on the knowledge you already have. It would therefore be great if Your Team would post a well-thought-out page or two of calculations showing (say, at the Physics 101 level or so) what your current best approximation is of the arithmetic showing what you think has happened. These would be really fun to read even if you don’t much need the public’s help and advice to find your intrepid explorer.
(A manipulable 3-D model of the comet, showing its rotation, its rough gravitational field contours and including the putative Philae trajectory, would be wonderful to see as well. The bloggers would eat it up.)
@seema : No! Philae touched down at “touchdown point” at 15:34. At 15:43 it was airborne near that huge rock (the last pic) and at THAT time the pic of “touchdown point” was taken which shows only dust trails. So, in short Philae took 9 mins to move from “touchdown point” to besides that huge rock….
From the Geomorph map you provided, the lander would have initially bounced from a plumed area, then bounced just before or on the ridge (light toned effusive deposit), and finally falling into the crater south of the primary landing site.
More speculation on my part, but the indentation at the primary landing site appears as though the main body of Philae bounced onto the material in the plumed area, i.e., the landing gear dug deep into the soft material and didn’t arrest the lander until the bottom of the main body compressed the material and then bounced towards the crater.
Interesting. Foam/dust like surface… perhaps not dense enough to trigger the landing sensors… hence the feet structure only absorbed 4 cm of downforce… hummm… good call Maurice…
From this new fantastic pictures we can do another estimation. By using the 17 meters reference we can estimate the distance between the picture taken at 15:35 and the picture at 15:43 at about 197.4 meters in 480 seconds. That gives as a higher speed than before: 41.1 cm/s.
Which would make the total distance of the first bounce at 2739 meters. Much farther than my previous 2200 estimation. That is larger than the size of the small lobe (2.5km).
https://pbs.twimg.com/media/B2tGoYqIIAAgwjj.jpg:large
Hi.
I think the 17x17m scale of the images only applies to the inset images, not the background images.
I posted my basic attempt to find Philae above. Although my montage is pretty crude, I’m certain Philae ended near the edge of the “crater”.
You maybe right. I recalculated the speed using the 28cm per pixel instead and is a little bit slower but not much. Instead of 2739 m the distance travelled would be about 2500 m.
The end result is the same: Philae probably landed on the neck or even the underside of the small lobe.
I hope they can find it.
I think it is also important to calculate for the changes to image scale the further you move from the counterpoint of the image.
Variations in Philae’s velocity during the bounce, and 67P dimensions / orbit etc… will also be important. Of course, no one apart from ESA have access to that data..
I’m not saying you’re wrong or I’m right – it will be very interesting to see were Philae ended up – but it is great fun trying to work it out (with the little info we have).
It’s in the dark (most of the time), so obviously we can’t see it, especially on a limited number of photos! Radio/radar location will eventually locate it.
Wow! It looks so strange! The most jagged rock surfaces and yet ‘sand dunes’ everywhere, almost on parade lines! Craters and rocks, boulders and pebbles like from a river bed! It seems to be dissolving! Layers like a banana split! Vanilla on Chocolate on Strawberry with syrup and pineapple chunks! It’s dissolving with each dune not windblown but created in situ! The texture of those rock is new. Its a stranger. Never seen before.
Are we certain all Comets are from our Solar System? Could it be from deep Space and maybe 4 billion years old?
I must assume that the lander guidance was to detect a large patch of anything that maintained its color, because this would be a smooth patch with no hills or crags to get next to. I hope she gets some light on the other side of the Sun. Thanks ESA. HD pics are everything to me. Thank you!
I just wondered if Philae hitting the comet might have altered the comet’s trajectory…
Sure it has. The momentum of Philae before touchdowm was about 200kg * 1 m/s. Assuming that the whole comet has now the same momentum, we can calculate it’s additional velocity vector:
v = 200 kg m s^-1 / 1e13 kg = 2e-11 m^/s
That’s 1.7 µm per day or 0.6 mm per year..
I don’t think it had enough energy and mass to alter the trajectory. If you think like that, then you could also think that having Rosetta orbiting him would also alter the trajectory a bit.
Just not enough mass to do anything IMHO.
Uh, yes it has… By a tiny, tiny, tiny, tiny amount 🙂
Perhaps this is an opportunity for Philae. ‘When’ it comes out of shade it’s landing site could be an Aladin’s cave of discovery.
Great, truthful comment, that site sure will be 😀
Let’s hope that Philae does awaken under improved solar angles later on.
Andrew R Brown.
Another approach is to use a rotational frame of refernce. If we use a horizontal velocity of 0.38 m/s, and assume the lander is 2000 metres above the centre of mass,, the the rotational velocity is about 0.00019 radians per sec. the lander will travel about 1.27 radians in 6660 seconds or about 72 degrees. So I agree with Michael Koch, and others – it is in the neck.
A better solution requires orbital mechanics simulations, eg:
https://www.wired.com/2014/11/modeling-philaes-double-bounce-comet-landing/
That is the most sensible approach.
I used it with slightly different numbers, here:
https://pbs.twimg.com/media/B2tGoYqIIAAgwjj.jpg:large
The angle depicted is 1.3695 radians:
The Philae is probably in the neck but it may also have fallen on the underside of the small lobe (or ‘head’).
Thanks Amieres,
There is not enough reliable data in the public domain to simulate where Philae has bounced, although it’s hard to see how it could still be on the head of the small lobe, and the bounce was not long enough for it to be on the head of the large lobe.
Emily Lakdawalla of the Planetary Society did a detailed analysis of the approach and bounce using alitude, latitude and longitude data:
https://www.planetary.org/blogs/emily-lakdawalla/2014/11171502-rosetta-imaged-philae-during.html
The data were then corrected:
https://www.unmannedspaceflight.com/index.php?s=9f2bd17571a6d254f869e21a71f0c5f7&showtopic=7896&st=705&p=215462&#entry215475
But these numbers suggest the Philae was moving almost due north at landing:
https://www.unmannedspaceflight.com/index.php?act=attach&type=post&id=34338
Which doesn’t seem agree with the landing pictures and the known orientation of the comet:
https://planetary.s3.amazonaws.com/assets/images/9-small-bodies/2014/20141117_Comet_on_14_September_2014_-_NavCam_annotated_postlanding.jpg
Sigh!
Perhaps would it be interesting to investigate a lot on the scar of te touchdown: If the touchdown insert are at the same scale that the other inserts, clearly the touchdown created what look like three depressions that span an area much wider than the spacing of the lander legs. Perhaps the surface is covered with hard refractory plates over a lacunary low density underground and the lander bounced on a plate slightly larger than itself and made the surface around the plate to collapse.
When we see the image of the “boulder” that shadows the lander on the top left image of the CIVA panorama, it looks like a relatively flat stone standing vertically (w.r.t. lander 😉 ) .
Anyhow, when the orbiter will make its planed low altitude flybyes it would be interesting to try obtaining high resolution OSIRIS images of the touchdown area to compare with the lander ROLIS image (which shows the area seconds before impact). This could provide precious information of the subsurface nature of the nucleus.
Daniel’s right! it is essential to take into account the outlook for the feedback.
And also consider that there is all in rotation and movement and perhaps in oscillation, for which the perspective may change from frame to frame.
To confirm this, the sequence of descent is not a straight line: if we draw a straight line from the square 15:14 to 15:19 , from 15:19 to 15:23 and then from 15:23 to a landing site number 1, in the end we built a parabolic path.
Again due to the perspective and the rotation, the square 15:43 shows the Lander projected in the dark but he may also be actually on the perpendicular of the first impact (or ridiculously to left, if the speed of rotation of the comet is sufficient to exceed that of horizontal displacement of the Lander).
Also because the first bounce was definitely more in height that long.
Another contribution:
photographically investigate to find Philae is not impossible, lit areas reflect some of the light and allow you to take pictures even in dark areas.
This I learned photographing the Moon.
Let’s say increasing by about 7 X exposure times (or aperture or ISO) will saturate the area illuminated by the Sun and you can see the shaded areas.
Unless Philae is not in the shade even with respect to the reflected light. . . Murphy signed 🙂
That braided feature you talked about at the bottom has a clear shadow! My theory is some sort of damage,
Viewing the trajectory of the probe in these pictures and seeing first touchdown picture is easy to deduce where the probe has fallen … unfortunately. Look to the right of the first touchdown picture.
I sincerely hope that this will be the end of the ridiculous notion of comets as ‘ice mountains’ or snowballs. Comets are made of rock, as has already been established by previous spacecraft encounters.
Afraid not, density is far, far too low. Also this is a comet, not an asteroid.
The distinction between comets and asteroids has yet to be established. The Centaurs tend to prove that it doesn’t exist, except in terms of their degree of deviation from a more or less circular solar orbit.
NASA itself says so: https://www.jpl.nasa.gov/news/news.php?release=2013-234
Bloggers blog, and Flight Dynamics do their thing. Having read all the comments I conclude: let’s keep it that way 🙂 having said that I recommend watching the lander deployment video. There is some complex relative movement and gravitation going on, and by that I don’t even consider the irregular shape. As far as I can see, most of the simplified calculations here omit the rotation part of the comets movement. Simply extrapolating from relative speed through 1:50 produces a substantial overestimation of distance traveled measured as distance across the surface of 67p.
When Philae continues the path of which we see the beginning here, it (sorry: “he”) moves farther away from 67p and approaches a geostationary orbit, but doesn’t quite get there, and then begins a descent, with a decreasing speed relative to surface. Impact no.2 has a lot more unknown variables, among them slope, angle, inclination, relative speed, mechanical properties of the surface. Whatever was the scenario it resulted in the much shorter last flight, which might have been a ‘descent’ down a slope or “well”.
Without any proof, only trying to use common sense, I would say that with less than 7 minutes since the 2nd hit the probe was still ascending from the bounce and hit a wall of a crater or alike (cliff) and started falling/rolling down to the bottom of the cliff.
Having take over an hour or so to do the first bounce, I don’t believe it would take just 7 minutes or airborn time in the second bounce. Surely it hit something.
All in all, I think it was a miracle and a tribute to the team who built the Philae, to have it endure such hard treatment and still be able to perform scientific tasks in its labs and send back the results.
What a marevelous work they done. Brave Philae.
That will be 67p-stationary instead of geostationary – doesn’t make it anyhow.
Hi Jacob: “…which might have been a ‘descent’ down a slope or “well”.
According to its trajectory, not to local gravity 🙂
This 2nd impact is 100kg at the speed of a man walking. Really nothing, from human perspective, to little from Rosetta perspective. Not even sure if they are still looking for or just waiting for spring time. Sooner or later a bright pixel is going to appear in the suspicious zone. Think location is important for the radio tomography.
look to this nice infographig about the bounce and landing of philae
https://aliveuniverseimages.com/images/articoli/2014/infografica.jpg
@EsaTeam : when some update??? we have payed tickets need some update!!! 😀
Indeed nice. Where did you find this?
And why doesn’t he bounce straight up?
Would it be possible to publish a higher resolution photograph of the inset taken at 15:43 ?
What a magnificent picture that is !!
I believe that’s native resolution. Does your camera do portraits at 20+ km distance?
This projekt is fascinating, and grandiose: congratulations to all involved.
I am puzzled by the change in direction of Philae after the first contact with the surface of the comet.
The impression I receive is that of a ball having received a kick from the side. I imagine the comet as a football player, it surface as a foot, spinning around ist center of gravity . Assuming a distance from the center of gravity of 1 Km, the surface would have a linear speed of 0,13 m/s . If the published images show the axis of rotation vertically,, and the comet rotates from left to right, then Philae by attempting to land, has tried to “stop” a certain amount of comet material several times larger than itself. As a reaction Philae could have received an acceleration several times higher than this speed.
e.g Philae = 100 Kg, ; impacted material (dust, rocks, ..) mass = 300 Kg. Speed received = 3 x 13 cm/s = 39 cm/s.
Is this hypothesis sensible?
right. we have a touchdown. a picture with an estimated shadow projection on the terrain they geomapped. hence an approximated height resulting in a fly vector with a timely length for the speed they have and the direction pictured. a bit of reversing projection of rosettas location for that and you could have something. as posted – an approximation. the flight is vacuum. no brakes. the comet rotates. rosetta moves. making it difficult. i’d not even know what to base the calculation on. nothing is fixed. it’s a flux balance equation. you gotta shape it into a fixed location. what is also unknown is the gravity. this is the space guy’s thingy. they know the characterisitcs of that comet. magnetics and all that. i dunno how’d that bend the flight curve. the only thing known is the timely lenght of the curve to second touchdown.
when they get a chance they gonna measure aka triangulate the location anyway. they just need the battery to charge for the ping. i’m sure they’ll find it.
Perhaps I’m out of my field (SURE) and I missunderstood many things but… let’s go:
I’m reading distances about 2 km in the second flight after “main” bounce… and farest, i disagree.
I’ll put easy: Philae’s trajectory after bounce is nearly vertical and something, terrain or lander axis position, induces on little inclination, BUT the main inclinatión became from Chury’s rotation movement in that ¿111?min flight.
You’re putting the distance over flatest trajectory I pressume..
I’m sure Philae is into B zone, not beyond; and perhaps closer to first bounce that we presume…
Yes, of course it will be an Ikea commercial very similar to the little lamp in a rain storm all by its’ self without anyone caring at all, oh, that poor little lamp.
Although Philae “weights” only 1 g, it still has an inertial mass of 100 kg. But it did an incredible change of direction after the first touchdown!! How is this possible?
Is it possible that one of the legs has been broken after the first touchdown? the snapshot after the first touchdown does not show cleasrly three legs. It may be due to the orientation of Philae, but after the great change in direction in the first touchdown and after hearing that after the final touchdown it seems that one of the legs is not on the ground, perhaps it’s broken, bent, etc…
Looking at the one pict that amieres posted https://pbs.twimg.com/media/B2tGoYqIIAAgwjj.jpg:large showing the trajectory line curving behind the small lobe – I wonder if the CONSERT data is actually correct – except Philea is behind the lobe in that diamond area – need a 3D model to superimpose the CONSERT diamond on the back side of the small lobe and the adjacent side on the larger lobe – it may be well in those small well-defined areas.
That is an intriguing possibility.
Was watching at an age of 6 the moon landing live and now beeing even more fascinated by the successful Rosetta/Philae mission.
BTW: Any idea, what *caused the kink towards south* (right) after Philea`s 1st touchdown (descending in NE direction)?
I would think the angle on the surface is slightly slanted in that direction
So fascinating topic.
I wonder if we could envisage upload a blinking sequence of the arrays of ROLIS instrument that is incorporating four independent light emitting diodes (LEDs) irradiating through the visible and near IR.
https://www.dlr.de/rb/en/desktopdefault.aspx/tabid-4538/7439_read-11269/
ROLIS is oriented in a downward-direction but the light would maybe reflected by surface of comet and perceived by Rosetta’s navigation camera in a so dark environment. It could be done only when Philae’s battery will be reloaded.
FYI after the discussion here yesterday I got messing around with the Rosetta/Philae/Comet 67P simulation in Orbiter Space Flight Simulator.
You might be interested in taking a look at the results. It has three interesting results:
– A pretty good indication of where Philae landed (near the top of the giant cliff/hill on the far side of the neck)
– Comet 67P 3-D mesh imported into Orbiter, which gives a nice way of visualizing Philae’s movements against a pretty realistic background.
– View of what the Philae first bounce looked like (pretty much, MUST have looked like given the parameters outlined on this page) from the point of view of Philae and also an external point of view
Take a look here:
https://www.youtube.com/watch?v=0Gsn3KTszqQ
Couple more quick simulation runs here:
https://www.youtube.com/watch?v=0Gsn3KTszqQ
https://www.youtube.com/watch?v=MWYnkFsNCK4
One more followup – this image has the likely landing zone well illuminated https://www.esa.int/spaceinimages/Images/2014/11/Rosetta_at_Comet_landscape
I would be in a line close to the top – maybe bouncing at the end of the neck into the large lobed crater area or just hitting a crater wall and falling down. There are really only a small number of shadowed areas here so it should be easy to narrow down with a few OSIRIUS shots. I’d put my money on being in one of these 3 craters show in closeup https://www.esa.int/spaceinimages/Images/2014/11/NAVCAM_top_10_at_10_km_7 and are right in the target area at the base of the large lobe (top of previous image).
hi,
nice picture, even it’s processed by technology like MPEG with gray level 🙂
Dear ESA people, just for our childish fun, can you share each single picture that is composing the above mosaic?
And… don’t you have any picture taken at 15:28 (before TD) and 15.38 (after TD)?
🙂
It is odd that the down-thruster, harpoons and screws all failed to deploy. I can’t imagine these were all programmed to operate in serial?
And it will be interesting to see if there is a parallel here to the 1998 Mars Polar lander that crashed on impact due to poor design of sensors in the landing gear. In that case, the retro rockets caused the landers legs to flex upon firing, triggering the sensor indicating that it was on the surface, cutting the main engine too early and crashing at high velocity.
This case appears to be the opposite. A lander with the relative weight of a feather lands on a sandy surface, without the expected force of the down-thruster and does not trigger the landing sensors to deploy the harpoons or screws.
Somehow, however, it had enough impact to bounce 1 km back into space. I guess a feather, bouncing off another feather could travel 1 km, in space.
So far no result from the flight dynamics meaning this is a really hard nut to crack. I tried myself and gave up quite early realising that the input data is too crippled to make a proper calculation. An estimation is that the track is about a third twist of a clockwise corkscrew staring at the skull of the duck and ending at its neck. It fell deeper then it raised and the second rebound was as soft as the final place is hard.
If Philae flew 1km SE, then is located at this point.
https://s26.postimg.org/rtylcymnd/philae_site.png
Maybe the human race’s finest young brains will conduct enough lightning speed nano experiments to gain control of the infant maglev technology, and produce a lifeguard experimental craft that could use the cold of space to create wormhole speed and rescue Philae. Maybe they could get to the comet yesterday; to help salvage this extraordinary accomplishment and even continue on, to discover new and more exciting answers!
Worth to mention this mission “replay” using SPICE data + animated model …
Big five to Brian
https://www.youtube.com/watch?v=qjI7Oerg48I&feature=youtu.be
Excellent work from Brian.
It seems to suggest that Philae’s ground tracking prior to touchdown would be opposite to the direction of rotation (westerly), rather than in the direction of rotation (easterly, or specifically north-easterly).
One last followup from my other 2 posts – I found a better shot of the likely landing zone from another perspective that has the bounce trajectory in the plane of the picture and is well illuminated. I roughly drew 2 possible bounce / orbit ellipses (out of a large family above and below) and a possible 2nd bounce concept (red lines) to land at the middle/base of the large craters on the large lobe https://s28.postimg.org/57dnve0hp/Comet_on_19_September_2014_Nav_Cam_annotated2.jpg
I think because the velocity was so high the lander was basically in orbit relative to the small lobe about the central CG point which is in edge of the large lobe. Philea just ran into the large lobe which got in the way of an otherwise nice orbit.
I insist, do not be fooled by perspective: my theory is
https://domelune.com/photos/PhilaeTD5pro.jpg (Photo copyright ESA)
I transferred to the ground the positions of the Lander before and after the impact.
Add to this the rotation of the comet and other minor variables.
That makes sense Marco, the perspective can throw us of .
I´m not a scientist and don´t have the information on the rotation of 67P, but I can see what you´re implying.
Wow… so close to having the perfect spot, if it didn’t bounce a second time, Philae would probably have plenty of battery power right now. It’s really a shame, they put Philae right where it needed to be, but without the harpoons deploying it bounced to a spot where we have to wait and hope it gets enough sunlight in the future to start doing more science.
On unmannedspaceflight.com, user Malmer posted a really interesting simulation of the bounce to second touchdown, which he made using a gravity simulator based on a model of the comet body, plus some assumptions, etc. Quite interesting:
https://www.youtube.com/watch?v=WF3anN_A1mw
His comments about the simulation are here:
https://www.unmannedspaceflight.com/index.php?showtopic=7896&st=749
Just a thought for everyone who tries to calculate Philae’s trajectory from these photos:
Rosetta was moving as these amazing images were taken, hence they are seen from different angles. For this montage the background (comet surface) of the different photos was matched and philae, being at some height above the surface, was obviously not were we see it. (depending on it’s vertical distance from the comet ans rosetta’s position)
I want to add this is an absolutely breathtaking mission and the esa people do an amazing job. keep going!
ESA is now analysing data gathered from where Philae ended up: see the latest posting. This will help locate it. As WE can’t map the first hop, speculation on the nature of the second seems pointless. It does appear however that Philae is very mechanically robust relative to its low gravity environment as most of the experiments appeared to function correctly and send back data from the final site.
Let’s not forget the on board software shutdown the gyro’s automatically upon detecting a landing event. Then it bounced and then went into a unspecified roll and pitch (depending on your orientation) maneuver.
This really hurt at the second landing where enough time had elapsed too really get things spinning. Hence the direction after the second bounce err… landing.
Can’t see the lander orientation from the 15:43 image.
Just my 2-cents.
Jack what do you think of the ESA quote proclaiming “…the [Philae] lander achieved the first-ever controlled touchdown on a comet nucleus.”, but the facts were that the lander suffered two major failures to its surface landing system. The first happening before the lander was even released from Rosetta, the cold gas jet thrusters that fire upon contact with the comet’s surface to help secure the lander failed to prime and start-up. This left only the Harpoon system to secure the lander, and then once this had failed to operate as well, there was nothing left to keep Philae in-place where it had touched down, rather away it went on an uncontrolled two and half hour bounce across the comet’s surface. At the exact moment when the Control Center members were ecstatically celebrating the success of their lander’s “controlled touchdown”, Philae was in the midst of its now famous double-bounce maneuver that resembled more of a “crash” and less of the publicized “controlled” landing.
REALLY REALLY MAGNIFICENT! Amazing! It’s UNBELIEVABLE!!!! Cheer up all of you guys from ESA. It’s completely out of imagination to land a probe on a moving object without any motivations. Waiting for TEN years!!! What a huge calculations!!! OMG!!!
How about putting Rosetta in close orbit above Philae reflecting sunlight of its collectors for a period of time. Or would this deplete the batteries of Rosetta to fast?
how lucky on the 2nd and 3rd bunch…..woah!
The big picture above shows the Philae lander at 4 positions , from 15:14 h to 15.43 h . Several insets (zoomed in pictures ) are also used . Correct me if I’m wrong but I guess that the big picture must be a processed (assembled) picture . Otherwise I can not imagine how Philae shows up at 4 locations in one pictiure .
I’m curious to hear if there are pictures available AFTER 15:43 h .
First of all thanks to share this knowledge with us this is really informatory knowledge. The picture shows the 4 location that is 15:14 , 15:19,15:23 are used. please share with me more knowledge about this.
Breaking news 14.6.215, its alive. signals been received at mission control