How (and where) is Philae?

The current status of Rosetta’s lander Philae was discussed live during a Google Hangout this afternoon, together with scientists and engineers from the mission teams at ESA and partner agencies. The teams are very happy about the lander and the successful functioning of all instruments that were operated so far.

Philae's instruments. Credit: ESA/ATG medialab

Philae’s instruments. Credit: ESA/ATG medialab

As reported by Stefan Ulamec, the lander manager from DLR, last night a sequence of commands to operate a number of instruments was uploaded to the lander. The resulting data were downlinked earlier today and the scientists are currently analysing them and trying to figure out what they mean.

One of the instruments that was activated during this sequence is MUPUS, the MUlti-PUrpose Sensors for Surface and Sub-Surface Science, which has hopefully penetrated and hammered into the surface of the comet to test its thermal and mechanical properties.

Another instrument that was deployed during this sequence is APXS, the Alpha Proton X-ray Spectrometer, to probe the elemental composition of the comet’s surface.

They also conducted new measurements with CONSERT (COmet Nucleus Sounding Experiment by Radio-wave Transmission), an instrument that is operated both on the lander and the orbiter. The CONSERT data will be used to get a better estimate of the lander’s position, which has not been extactly identified yet.

The search for Philae is on, using not only CONSERT data, but also imagery from Rosetta – both from the OSIRIS imaging system and the navigation camera (NavCam) – as well as the data collected locally by the lander.


Looking for Philae using OSIRIS images from Rosetta. The red cross marks the first touchdown point. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

Holger Sierks, Principal investigator of OSIRIS, mentioned that images taken after touchdown are still to be downlinked; as soon as the images become available to the team, they will try to locate not only the lander’s current position but also its bouncing trajectory after the first touchdown. Meanwhile, they are continuing to image the surface of the comet with OSIRIS.

Another instrument that was operated on the lander is SD2, the sampling, drilling and distribution (SD2) subsystem, which was activated and started drilling. Philippe Gaudon, manager of Philae’s Science, Operations and Navigation Centre (SONC) at CNES, Toulouse, explained that the mechanism was working well, as they saw the drill go 25 cm below its base plate.

Shortly after, however, the link with Philae was lost – as expected, since the lander had moved below the horizon from Rosetta – so the results of this first drilling session should be available in the evening.

If successful, the first sample collected by the drill is scheduled to be fed to COSAC, the COmetary SAmpling and Composition experiment that will analyse the cometary material looking for organic compounds and measuring the chirality of the molecules.

A crucial uncertainty at the moment is the duration of the primary battery, which may run out before the end of this final block of the first science sequence. As explained by Valentina Lommatsch from the Lander Control Center at DLR, simulations that were run last night indicate that the battery might still have around 100 Wh left, which may be just enough to complete the sequence and relay back the data if the temperature of the battery does not decrease. The outcome will be known for sure only late this evening.


First comet panoramic on the surface of 67P/C-G, with an indication of the lander orientation superimposed on top of it. Credit: ESA/Rosetta/Philae/CIVA

As for the position of the lander, Valentina Lommatsch explained that all three of Philae’s legs are on the ground, but the sunlight received at the solar panels is very low, which is likely due to the local topography of the site of final touchdown. As reported by Stefan Ulemec, one of the panels is receiving sunlight for about one hour and twenty minutes and two more panels for about twenty-thirty minutes every comet day (which lasts 12.4 hours). They also confirmed that the lander has not moved since the third touchdown, after which the first CIVA-P panorama was taken.

The orbiter is doing great by the way, as reported by Andrea Accomazzo, ESA Rosetta Flight Director at ESOC. The team had to manoeuvre Rosetta to keep visibility with the location on the comet where Philae is, and the signal received from the lander is very stable. Of course, everyone is looking forward to finding its exact location on the comet’s surface and, most importantly, to hearing back from Philae tonight.

Matt Taylor, Rosetta project scientist at ESA, mentioned that both orbiter and lander have been performing outstanding measurements so far, at the very cutting edge of science. Everyone’s looking forward to the first scientific results, which will be presented next month at the Planetary Sciences Section of the American Geophysical Union.

Looking forward to the scientific output of the mission are also the two guests who joined the Google Hangout from the United States, Jeff Grossman and Gordon Johnston from the OSIRIS-REx Program at NASA, who are eagerly learning from Rosetta in sight of their coming asteroid study and sample return mission, planned to launch in a couple of years.

But for the moment, all eyes are turned on Philae: both on the short term, waiting to get the signal back from the lander tonight, and on the longer term. Even if its current location does not offer optimal exposure to sunlight to fully recharge the secondary batteries, it is possible that, as the comet approaches to the Sun, the illumination will increase and Philae will once more wake up and talk to us.



  • MacMan says:

    That is fantastic news

  • Jeb says:

    It would be nice in the “looking for Philae” image if you indicate the direction(if you know) that Philae went after the first touchdown.Keep up the excellent work ESA!

    • Roger Keulen says:

      They still don’t know. Watch the G+ Hangout at Youtube and watch for “Holger Sierks”… He will explain. URL =

    • john spiegel says:

      ESA if you look at your photo with the red circle and then treating it like a clock go to the 2 o’clock position. Now using a ruler on that image at a 2 o’clock angle go over 1″ 1/4 and look at that white image with the drill housing sticking out of it. What ever that is it is at an angle and has something propping it up away from the sunlight

  • Ron Wilcox says:

    Nicely done article. A much needed update for those thirsty for info.

  • eSpace says:

    Thanks for the update, Claudia. Is it possible to put Philae into hibernation for several days as the secondary battery recharges, conducting the science program only every 4th or 5th day? Hang in there Philae!!

    • David Smith says:

      From watching the hang-out, it appears that the battery needs to be warmed up to 0 degrees celsius before it can be charged. This takes more energy than the subsequent charge would add back (because of the limited time that sunlight is falling onto the solar panels). So, unfortunately, it’s going to take an increase in the solar power available before charging is going to add more energy that it consumes – either more sunlight (by turning more/larger solar panels towards the sun) or later in mission (when the comet, et al, will be closer to the Sun).

      But I could have misunderstood…

  • Margarita says:

    Thanks for this excellent synopsis, Claudia.

    Is it possible to use this forum to pass on my deep thanks to all the Rosetta team for their tireless and incredible work? I’d especially like to highlight Matt Taylor, and note my appreciation and admiration of him, both as a scientist and in his public presentation.

    I made a related comment on the YouTube broadcast of this hangout and I see that several people have agreed with my post.

  • Ryan Green says:

    You will forgive my ignorance on the topic, I am sure such things have and are still being discussed at the ESA; furthermore, I am but a filmmaker from Los Angeles, in no wise qualified to have a voice in such important conversations. However I cannot help but think of how we in the film industry solve the problem of objects falling into deep shadow when abundant sunlight is available nearby – mirrors. Would it be possible to use Rosetta’s vast solar panels to not just absorb the sunlight for itself, but also to reflect it to hit Philae’s panels as well? I’m sure some complicated math would be involved, but I would think that the hardest part is over on the front, getting Rosetta to the comet in the first place!

    • Pete Lefis says:

      This actually appears to be popular idea, as myself have been thinking about it. Someone already has put this question during afternoons Google Hangout session. The scientists answered this is nearly impossible, given that the solar panels even cannot provide enough sunlight to comet’s surface at all.

    • eMGieBe says:

      Ryan, unfortunatelly, the idea is only good on film, not in real life. Mirros are effective in reflecting light from a meter or two… maybe 10 meters. Unfortunatelly, Rosetta is miles away. If the pannels were positioned to reflect the sunlight towards Philae, from the comet it would be visible just as a faint dot in the sky. On earth we can see “iridium flares” that work the same way – their sollar pannels reflect light towards Earth, but the light is visible only as a small dott – the ground doesn’t become visibli brighter.

      So, sadly, if Philae has landed in a hole, that’s very unfortunate. It was designed to land on an open space… the first panorama was supposed to look a lot diffrent – we should see quite far in every direction… and it would be easier to coduct the scientific experiments.

      Let’s hope Philae sends as much data as possible, during the three days of primary battery life…

  • Guillermo says:

    Keep up the amazing work! I’m eager to see the scientific results.

  • Ncrab says:

    When the sailor is lost, he looks to the sky. Any chance that the circles shown in this image may be stars (out of focus)?


  • Gustavo Durañona says:

    Extraordinario logro para la humanidad !!! Felicitaciones desde Uruguay

  • Ian Stirling says:

    Assuming for the moment that the lander stays where it is.
    Some time in the near future, the sunlight onto the panels will increase again.
    Is there anything tn the lander that certainly won’t survive an extended period at ~-150C or so without heaters?

  • I am proud of the achievements of human thought.
    I support the site on Robotics and posted on its website information on the beautiful space robots Rosetta and Philae, which work in tandem
    I would like to have a video taken during the landing and the surface of the comet.
    Good luck!

  • mauricio says:

    based on information at hand before make the Go/NoGo decision

    ‘the thrust’ of the active descent system would have avoided the bounce, right?

  • Indira Montejo Lamas says:

    You guys are awsome.’

  • Bersan says:

    Could You add the Time when posting blog. Thanks

  • Vicenç Moliné says:

    I hope everything went as planned but this intrigue is far more amazing than a “perfect” landing.

    Great job and keep working like that, both scientifically and communicative!

  • Peter says:

    Congratulations very exciting

  • Harald says:

    Hang on buddy

  • Derek Storkey says:

    Perhaps when you know where it is, you could use something on Rosetta to reflect sunlight onto Philae.

  • Mark Lynass says:

    I just want to thank you for providing us this information and for the rapid communication of the conclusions drawn from the data you are receiving. Keep up the great work and the best of luck for finding Philae!

  • Emilio says:

    Good job forvall of you. Everybody has to be astonished forma the good approach and landing but above al fir the data to cine un the following days. It ir the best point of departure forma the future. Thanks206

  • Marc Couprie says:

    Let’s hope the CONSERT experiment will shed more light on the exact whereabouts of Philae…
    And of course let’s hope Philae will stay tuned and powered!

  • Sherlock says:

    Great site and thank you for what is proving to be an unbelievable experience

  • Brigid says:

    Next to landing on the moon – this is the most exciting space event I have witnessed in my lifetime!
    Thank You ESA

    • Haring says:

      I think the same!
      Many congratulations and thanks for the exceptional adventure!!!

    • Garrettt says:

      I agree, this is a magnificent achievement indeed!
      Another totally amazing First. Thanks to everyone involved!!

  • Allan Meyer says:

    Wunderbar, ausgezeichnet, absolutely astounding. A historic event on par or even more significant than other landings (Moon, Mars, Titan), especially with the challenging situation.

    Email exchange with my daughter (Alaska seismology field tech):

    > Nail-biting!! If it were my choice, I wouldn’t move the lander and instead allow it to enter hibernation mode. The article says the lander needs six to seven hours of sunlight to charge its batteries, but in its current spot will only receive 1.5. So long as their power switching equipment is robust, that means they could gather data every 4 days or so.
    > My work has to make sacrifices like this at some of our winter-battered seismic sites – 1/4 of the desired data is still precious data. Sometimes we have the option to try something that MIGHT work to improve the datastream, but if it means very possibly losing all data until we can visit the site next summer, we don’t attempt the change.
    Good conservative advice, but you all have several sites, providing some redundancy. Not to add to the drama, but imagine you had only one site, and it took 10 years and $2 billion to set it up …

    The article doesn’t mention it, but you may be right that hibernating there may be what they should do. If the lander can survive the cold, as the comet gets closer to the Sun it may get more sunlight on the panels and get “thawed out” enough to resume its work. The other unknown is how much it may be affected (moved, blown away) by the jets of evaporating gas that produce the comet’s tail when it’s close to the Sun, but that always was going to be part of the game.

    • Ted says:

      We’re all making suggestions on how to save Philae, most of which the planners evaluated and modeled years ago. The problem with the hibernation time-sharing idea is that, as Valentina Lommatsch pointed out in the Google Meetup, much of the power budget must be used to heat the batteries before they can be charged, and 1 hour 20 minutes of partial light isn’t enough, at least at this distance from the sun. After the other managers’ comments seemed to hold out some hope, her clear explanation spelled out how dire the situation really is.

  • Antonio says:

    We have been lucky after all. Philae could have got crashed against the comet surface. Or suffered strong damage when landing. And nothing of that kind seems to have happened. Almost all systems are operating reasonably well and communications with Rosetta seem to work properly. The recharge of the batteries is essential. Let’s cross fingers about that!

  • Roland Buehl says:

    I wish Philae Good Luck regarding the sunlight. And you: Congratulations regarding the landing and your great success!

  • Josh says:

    So is this really just an excuse to see if we can blow it up or change it’s orbit. Would ‘anyone’ even know if this comet were, say, headed toward Earth?

    • Ted says:

      Your posting isn’t very clear, but to answer your question: The Rosetta planners have to know the comet’s orbit very precisely to plan this mission in the first place. Knowing the orbit, we know that this comet has no chance of hitting Earth. The comet’s orbit doesn’t even cross Earth’s. See, for instance, .

    • Robin says:

      That is very unlikely. The comet’s closest approach to the Sun which will happen around 2015, will not intersect with Earth. Earth will follow it behind.

  • Adrian says:

    Thank you, really excellent blog, and nice to have the acronyms explained/realised.

    I’d like to work for ESA…. we could map the solar system and make it into a virtual 3D world, that we could walk around!!! We should right now be walking around a virtual Martian landscape.

  • Bill (William) Grenoble says:

    WOW! Science is accelerating. I graduated as an Electrical Engineer in 1964. I bought my first transistors in 1950) I have studied more since I was in school than when I was a student.
    Look at what your robots are doing. A manned mission would not be possible.
    There has been some chatter about the leg spikes not penetrating. There is no wind up there, is there concern that the comet outgasing will blow the lander off?
    Congratulations You’all!
    Bill Grenoble
    Accokeek Maryland USA
    (17 miles due south of the White House)

  • Alex Bechini says:

    So… great failure. The lander rebounded three times, ended in a canyon, no sunlight, no batteries, everything’s over.
    Didn’t grasp his legs to the surface, so if he tries to drill, the pressure on the ground will be greater then his weight, so he’ll be pushed away.
    I know this project was originated 20 years ago, old technologies but the money spent would be good even today

    • Canada - A Bit of Europe on the Other Side says:

      So… A Great Success.

      Perhaps a lighter view would be helpful, with apologies to George, and more appropriately Cosmo.

      At that moment, ESA became the world’s greatest Marine Biologist.

      A hole in one, on a target moving 40,000 km/hr, on a hole with multiple doglegs and more than its share of traps. Wonder what par should have been?

      ESA, you have transported us further than most can dream. Well done.

  • suresh parikh says:

    I am curious to know the data every minute.Science has done a great job for mankind compared to religious mined people.I remind of the days 0f Galileo, Bruno and others

  • Alex Bechini says:

    They don’t know where the darn thing is, all they know is that he can’t get sunlight, no batteries, everything’s over.

    • Margarita says:

      I’ve heard of the difference between people who see a glass as either half full or half empty, but it is curious to read comments that, seeing a glass that is 3/4 or more full, declare that it is empty.

    • THOMAS says:

      During its 2-3 days of activity on the comet, Philae managed to complete its primary scientific sequence and transmit all the acquired data back to Earth. In other words, it achieved a very large part of its mission target.

      It no doubt even acquired a considerable amount of bonus data during that 2-hour long lateral hop after the first rebound (concerning electromagnetic and plasma conditions close to the comet’s surface, in particular) which was not at all planned initially.

      I consider the Philae part of the mission to have been a brilliant success too (and it may not be over).

      Just can’t wait for the acquired data to be analyzed for public release (especially the CONSERT findings on the internal makeup of the core).

  • jeff says:

    Th I s is such a historic feat! I wish there were just more coverage.
    i wonder if NASA had been involved in the lander ops, wouod they had solved the harpoon problem? Ij just seems that NASA , was always good at backups to there backups, as x well as fixing problems

  • Jacint says:

    But… in the image of Osiris you’re sharing doesn’t appers the searching zone. Blue square. 🙁

  • chris brown says:

    What are the chances that Philae could be shut down until later in the comets orbit and restrted when there is better illumination?

  • andini says:

    Good info blog, thanks. I like to think that we may have just posted and deep frozen a little organic material ourselfs. Might start a primevil soup long after we are gone. Got to love space stuff !

  • Theo van Dooren says:


  • Leonardo Caponi says:

    I am not a specialist, but why no use Rosetta in slow and controlated auto rotation, using it directional radio antena, emiting a byte-word and a timestamp continuosly in low potency. Philae, at the same time, receive data from Rosetta, record it and when finish the search send all the data to Earth via Rosetta. Then, ESA calculates the BER (bit error) of each packet received by Philae and can calculate the orientation of Rosetta (like a marine direction-finder). With this method ESA will can determine a line in the surface of the comet when Philae landed. Modifying the Rosetta orbit a little and repeating the measurements, ESA will obtain another line. Where the lines intersect is Philae!!
    Sorry if my suggestion is naive. 🙂
    Congratulations ESA team!

  • dario says:

    Congratulations to all you for the fantastic job and for this unbelilievable experience: i wish you a great success and …GOOOO PHILAE re-charge yourself quickly and start drilling ….. Mandi dal Friul

  • vayenn says:

    Maybe Philae just found a safer place for hotter days to come.

  • BVE says:

    A possible shape as Philae is at 194 x 550 pixel in the high resolution version of above pic, about 500 meter NW of landing site. You need a high res monitor to see shape and relative position . Looks like one side leans against a rock, one side looking towards a flat area and one side looking towards opne space, just as ESA thinks it is postioned. There is no other shape or color in the entire picture.

    Have a look and see what you think.


  • Reg says:

    Is it possible that Philea is not on the surface, but pressed up against a cliff, well above the surface? This could have happened if the rotation of 67/P brought the cliff face to Philea before it decended back the surface. That would explain the appearance of being on its side; it could actually be still right side up, with one leg dangling in “mid-air.”

  • Abid Hussain says:

    Philae we know night is cold and long,
    but you are brave and strong.

    So sit tight, stay awake,
    and lets hope harpoon wax seals break.

    Anchor yourself to strange lands,
    and send us data of spectral bands.

    Please remember not to sleep,
    sunshine is on the way to make you beep.

  • Jim says:

    Truely amazing project. An absolute sucess as far as I can see.
    Maybe Philea is stuck in a hole and maybe that is the only reason it is still there and able to carry on. Perhaps this is my “half full” explanation, perhaps it was more luck than could have been hoped for, but either way I am in absolute awe of all those involved since its original conception.

  • Vincent says:

    MUPUS digs sideways to get sample?

    Info that Philae is on two rather than three feet on ground false? 3 in blog.

    Is ice on comets grey? Is loose ice called dust?

    Is gravity stronger on side of Cliff?? making Philae orient itself sideways thinking it being pulled down?

    Ohhh I give up.

  • Matthias says:

    great news, pity with the solar panels.

    why not ask Rosetta to fold out a giant lens / mirror system and beam some extra sunlight down to the lander panels….


    fingers crossed

  • Diane says:

    Don’t you think a geyser of gas, while the comet will approach the sun, can make Philae jump at a more sunny place in some days or months ?

  • I. Newton says:

    Assuming that the local gravity at the comet is 0.000001*g (as stated by the Rosetta lead scientist) and the height of the first rebounce of the Philae lander was estimated to be 1000 meters, it can be calculated that Philae rebounced with a velocity of 0.45 meters/second. This is surprisingly high, given that the landing gear was designed to absorb most of the lander kinetic energy at touch down.

  • murat says:

    it is obviously shown that, target landing point of Philaes was not chosen correctly. As shown in rosettas navcam you should target a landing point with low sun shade density. The deep sun shade densities of your targetted point is highly risky area;. Such a target point decision resulted a partially useless Project results

  • Moondog says:

    Moondog says: Machines were mice and Men were lions, once upon a time. Now it is the opposite, it’s twice upon a time.

  • ross says:

    can rosettas’ solar panels be positioned to reflect the sun onto philaes’ solar panels?

  • Clive says:

    Have the team considered releasing large-scale photos to this site for us followers to go over in the hope we might spot something? The more of us to help, the better?

  • Christof Baer says:

    The mission and the achievements are incredible and fascinating. Too bad your webpage is a disaster!

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