Read the full report of last night’s events on Comet 67P/Churyumov-Gerasimenko via the ESA Portal webstory:
Pioneering Philae completes main mission before hibernation
Pioneering Philae completes main mission before hibernation
OSIRIS Image of the Day
View Rosetta’s comet
Where is Rosetta?
Rosetta NOW
Once upon a time…
Rosetta's grand finale
Ambition the film
Click image to watch Ambition
Read Rosetta: the ambition to turn science fiction into science fact
Rosetta Art Tribute
A repository of artistic tributes to the Rosetta mission by artists across the world.
ESA website – images
ESA website – videos
Discussion: 104 comments
Well done Emily for all you efforts during this last few days. I think you should have a little time off now to relax and re-charge as well 🙂
David
Hi Emily, welcome back. First I’d like to say a huge THANK YOU to you, Claudia, Daniel and the rest of the outreach team for doing such a great job over the last few days. Your hard work has made this a memorable experience for so many round the world.
It was sad to see little Philae slowly going under last night, but she has already given us so many wonderful surprises I think we will hear from her again even if she doesn’t have the power to do any more experiments. All we can do now is wait and see what images and data Philae did manage to get, any ROLIS images from during her hops across the surface of 67P will be special. If Holger needs help checking all his images to find Philae, there is a willing band of helpers here who would be more than willing to assist.
No matter what, Philae did an amazing job so far.
Goodnight and wake up soon, Phily!
And to ESA, ASI and everyone involved in this mission, THANK YOU ALL AGAIN for giving my generation its own historical landing experience!
Não teremos fotos coloridas?
ESA implements a proprietary period of 6-12 months for data from Rosetta/Philae.- that includes data from ‘scientific cameras’. They may decide to release these faster, but they don’t have to – so we may have quite a bit of wait time for access to that.
Dear Emily,
please try to find out and report if there are some plans for the lander, once and if it reawakens. Is the mision planing concerning the landers experiments to be continued in a compressed form or is it a higher priority to resettle the lander into a new and obviously better geographic location? Personally im convinced that the lander will wake up again and if its location is known by then it is for sure possible to move it in a planned direction and distance with a few small jumps. the largest of its jumps was 300 to 400 m in altitude and up to a kilometer range lasting for almost 2 hours, if it survived that it is not a risk to make a few 50 meter or shorter jumps in the horizontal projection, and with some luck this would be something that improved the mission success to about 125% from its so far 95%.
Thanks.
Awesome! Greatest invention of the century! Proud of you all on teams! Hope to see the story turning into an educational movie someday! Note: pls add captioning on all of the videos on you tube for hearing impaired viewers.
How far can a electromagnetic / telemetry signal travel in space with the current state-of-art? Are there any limitations for the distance a signal to travel without significant distortion?
Thanx…
NASA is still communicating with the New Horizons spacecraft that is nearing Pluto. Signal takes 4 hours each way.
Well given that NASA is still in touch with the Voyager a spacecraft at a distance of 19 billion km – pretty darn far!
We now need an ESA Rosetta and Philae set from Lego in time for Christmas !
Plus a “comet surface” Lego baseboard to go with it !
Earlier pictures indicates that there might be electric machining that erodes the surface. When the comet approaches sun, this process may increase considerably and that may then increase surface temperature more than increased sunlight can do alone. Therefore recharging batteries may be easier than anticipated even if the solar panels cannot catch good amount of sunlight. So I believe there are much better changes to wake up Philae again than we dare to think.
But this is just optimistic guessing. Today most of astronomy is guessing and wild imagination based on out-dated ideas, more like science fiction than real science. Fortunately we have also real science like this mission. I gladly give my tax money for projets like these as this ultimately helps mankind to evolve and survive. Those who are chasing ghost like dark matter, should acquire funding for their projets from other sources. More real science please. No puring tax money into imaginary black holes.
Electric machining?? Increase in surface temperatures will not increase the amount of energy the solar panels can collect. That’s not science.
Increase in surface temperature means increase in temperature of systems and batteries of Philae as well – meaning the batteries may begin trickle-charging at a certain point. As long as the temperature of the lander is <~-100C (with not enough solar energy input to power the heaters to get it there) Philae remains entirely inert.
The full report says
“The signal was initially intermittent, but quickly stabilised and remained very good until 00:36 GMT / 01:36 CET this morning.
In that time, the lander returned all of its housekeeping data, as well as science data from the targeted instruments, including ROLIS, COSAC, Ptolemy, SD2 and CONSERT. This completed the measurements planned for the final block of experiments on the surface.”
Am I correct in thinking that that includes the results of the MUPUS soil penetrator?
I posted the reply to my own question at the Apod “Asterisk” forum, in the Breaking Science News sub forum’s Rosetta thread.
The simple answer is that the surface of the comet was MUCH harder than anticipated and MOPUS couldn’t penetrate the surface. The hardness is itself a very important discovery.
I would post URLs to this info and to two YouTube videos showing how MOPUS works, but this site doesn’t permit this.
Hi Margarita. That was a problem. We still doesn’t know if material collected before the ‘stuck’, if material sampled back and if material ‘sniffed’ or not. Expected someone informed could say something about it 🙂
As for the URL’s have seen a lot here. Do you refer to policies? They are quite permissive, as long as you don’t publish something ‘others -not being ESA-‘ doesn’t want to. Just add the credits.
Sleep well little space robot…
“Philae’s dream during hibernation: Champi(gn)on!”
Please let me know an email address to send you the photographic illustration.
Thanks + congratulations having come so far.
Frederik
Hi Frederik. Easy to publish to sites like imgur.com, if you want to share with everybody 🙂
Could the batteries recharge later if the shadows change when the comet gets closer to the sun? Or maybe the comet will rotate in relation to the sun… How long will Rosetta remain in orbit?
Hopefully that’s what will happen – as the comet draws closer to the sun, the solar panels can provide more energy. Hopefully the orientation will change to further increase the amount of sunlight falling on the panels, but I think the position of the lander and the cliff it is near is not too well known at this point.
Rosetta’s mission is scheduled to last until
December 2015, but could be extended – it depends on how much propellant is left.
Well done Philae and team.
What happens to Rosetta itself after it chaperones 67P around the Sun? Is it expected to survive the journey? Will it continue in a bounded orbit around the comet as it makes it way outwards again?
Hi Carl. Mission could be extended, a little. Eventually propellant will be depleted.
(There is no such thing as an ‘stable’ comet orbit).
Actual Rosetta wish list:
Pause mission early. Go back to a secure distance (trailing 67P in the same orbit). Wait for the next visit. DO comparative science 😉
What a week! Countless THANKS must go to ESA and all involved!
I would like to write here about something Philae fans might get interested. But before that, I love to make it clear: I have no plan to earn/receive something in the future by writing about this here, including money! And I’m not suggesting to look away from Rosetta/Philae. Totally opposite. Let’s keep watching them until the end of the mission.
I think there is no plan of next #CometLanding mission now, including ones in preparation. But. There is a mission that might looks similar to #CometLanding to some of you. And it’s about to be launched at the end of this month. And more importantly, as far as I have heard. the lander is a kind of little brother or sister of Philae!
https://www.dlr.de/irs/en/desktopdefault.aspx/tabid-7902/13482_read-34316/
https://smsc.cnes.fr/MASCOT/
I am a Japanese. About one week before Rosetta/Philae’s arrival to the comet, I had an occasion to talk directly with two Hayabusa2 mission members, one of them is in a leading role in collaborating with DLR/CNES on MASCOT. Unexpectedly I happened to hear from them that MASCOT is by roughly (I might should say “basically”) the same people as Philae so that when Philae gets busy the MASCOT team becomes busy often. They also told me that MASCOT is the main lander of Hayabusa2, while Hayabusa2 carries Japanese landers, too. (Don’t be confused. Perhaps most informations from Japan may look like explaining as if Japanese lander is the main one.) Thus this is not just another rumour.
But let’s calm down. As you may have seen already in those webpages, MASCOT might not be greater than Philae. But one thing is sure to me: Now MASCOT team must have more confidence, following Philae’s glorious success!
Watching how Rosetta/Philae mission is trying to feed information LIVE to the world, now I would like MASCOT team to do the same. It automatically inspires Japanese side. Hope it ends up with live webcasts from the control room when #AsteroidLanding and sampling operation by the orbiter.
Let’s keep exploring further and further!
Hi Masanori. Will be there, if invitation extended 🙂
You Beauty! You truly are an island in the distant sky for all of us to rejoice and learn from. We are stardust, we are golden (thanks Joni Mitchell & others). I salute you and your creators. Rest well Magic Creature if that is your destiny. I am blessed to be here right now.
A good job all around.
Look at it this way– Philae fared better than the lunar Rangers– they ALL crashed. The lunar Surveyor bounced, but it was under a gravity field many orders of magnitude higher. The Russkies have been to Venus, but Mars has always eluded them. And remember, ESA’s Cassini-Huygens mission has been nothing short of brilliant.
The lander is in hibernation, but even the ROLIS and CIVA images are priceless puzzle-pieces. Not to mention the “other data” collected. And the mission is not finished– we still have Rosetta circling above with many more puzzle-pieces awaiting.
Well done.
–Bill
Indeed well done but remember the Lunar Rangers were supposed to crash-land on the Moon.
Next Philae wish list:
Batteries inside Dewar containers. Titanium made.
Thermo-junction (thermo-pair) active heating/cooling/administering.
Low drain Comm, Comp and Instr able to work batterie – less. All important high drain components should have a low drain back-up.
‘Flying’ frame to gently surface the lander. Shuttle style. At this gravity it’s going to be small.
A small ‘Loran’ radio?
‘Flying’ frame ‘drone multi-helicopter’ style. At least 4 jetting engines, to bring redundancy. (Better a 2 triangles, 6 point star frame).
[and MASCOT teams]
It’s IN a Dewar; it’s space, vacuum! I have no doubt there will be multi layer radiative shielding. But there is always some heat leak via radiation, mechanical supports, wires.
Peltier devices require power. Yes you can get a little more heat than you put in electrically – but only if there is a thermal source for the cold side. There isn’t.
High drain components can’t have low drain backups. They are high drain because that’s essential to do their job. If a low drain backup was available, you’d use it instead, not as a backup. Also one can rarely afford the mass to have backups.
Loran is an old hyperbolic navigation system of no relevance to Philae whatever.
Congratulation ESA on making a great contribution to human ingenuity and knowledge. Bravo ESA!
Congratulations to all the teams involved in this mission. You’ve done a really amazing job so far and I can’t wait for the first results of all the measurements taken and more pictures of course. ;o)
Thank you all.
The command to drill might still be active, so if you cancelled all commands that would use energy – “drilling analyizing etc” the batteries should charge quicker. If they are being drained as fast as its trying to recharge them .. It will never have enough power to perform any tasks. I’m sure its running alot of power draining programs. Just a thought! Should have been monitoring the power usage and battery life/recharge time more closely. The mission and projects are important , but they can’t be done if the equipment is not looked after and given time to replenish its power supply.
Yeah right, I’m sure they didn’t think of that.
Most of us are only humans, KC.
May I add a request, please?
Would you put the TINEE of posting on the blog posts and not just the date? When there are several in a day it can be difficult to read them in sequence.
Thank you!
Oh sorry – I didn’t notice the typo! I intended to write TIME of posting, not TINEE of posting. Don’t know how that happened – I’m gesture typing on a tablet and a bit tired.
You were absolutely brilliant at the Hangout yesterday Lunch Time Emily. 😀 😀 😀
You asked exactly the right questions. I would have loved to participated but was at work, but was given permission to watch live.
I hope we get to see the remaining CIVA and ROLIS imagery soon along with the further NavCam and OSIRIS imagery from Rosetta.
I have heard unofficially that the illumination has improved for Philae, it has doubled to three hours sunlight per comet day following the rise of the lander body and rotation of the solar arrays.
Would not be at all surprised that Philae will come back on at some point. We know that Philae is not damaged and all of the onboard instruments and onboard computer are all in great shape. I think Philae will be back.
Why don’t we call the crater at the top of the ‘head’ Agilkia Crater and get that name fully endorsed ?
Andrew R Brown.
Andrew R Brown.
Wouldn’t Elephantine be a good name for the final landing point. As the Nile jumps from Agilkia at Aswan and flows to the islands of Seheil and Elephantine so could Philae. And it’s a catchy name.
Congratulations for the total success of the mission!
😉 Like that.
from Nîmes, France
i was on twitter last night before going to bed, following Philae’s “last” breath.
i was so happy to see the first acquisition of signal at maybe almost 11 pm o’clock
this last data flow between philae and rosetta is such a fantastic and beautiful end to this part of the adventure.
..it was so awesome watching you and your robots during last days.
thank you so much for sharing !!!!
Rémi
I sincerely hope that it’s only a hibernation and that Philae will actually wake up again with the gently warming rays of Spring sunlight to provide even more information. (Good job we’re all allowed a little poetry…).
Will we receive any information on the preliminary data that was received last night? Did you receive any data to determin if the turn allowed for a greater charge to the battery or was this too close to the end of battery life to receive that information?
If just the ESA policy on the handling of the images were more open, they could harness the power of the community in the search of Philae.
Great comment Nelson. The lack of updates from ESA is incomprehensible. We have been beside them for months following Rosetta and now ESA has gone behind a wal of silence. WE understand the heartbreak of Philae not communicating but so much was achieved. I think we, the fans of Rosetta, are being treated shamefully.
Just a bit of wishful thinking: a thicker coma might do other than block sunlight, it will diffuse sunlight to allow it to enter Philaes “tomb” from more angles and expose more solar panel surface?
I’m 63 years old and these last 4 days were for me the most fantastics until the Apolo flights when I was student.
Congratulations and many thanks to all the team for this great job !
could the orbiter be moved to deflect sunlight onto the lander?
The ability of Philae to spring back to life with a sufficient solar energy charge reminds me of the terrestrial insects that hibernate for years before being triggered back to activity by chemicals drifting in the air.
cicadas? 🙂
Congratulations to all people who took care of the lander for all the time. It was bad luck that all mechanisms that were supposed to keep it landed failed, in the end Philae was saved by its landing gear which dampened most of the impact, and its already spinning out flywheel which kept it straight. Then bad luck struck again and on mostly flat and sunlit surface it managed to fall to a valley with very little sunlight. Yet, the mission control managed to run all experiments and if the drill was successful, then even gather all experimental data planned for the lander. That’s a huge success despite all the bad luck.
I wish you guys some good luck with Philae in coming months, let’s hope it’ll awaken when closer to the Sun and who knows, perhaps you’ll even get it out of that hole and get even more fascinating science measurements of the surface.
Without going into the details, there was fortunately also quite a lot of good luck too after the initial rebound, as mission leaders have since freely admitted…!
How does SD2 distribute comet contents to analytical devices?
Gravity in the neck seems to be close to 0. This could explain why mater escapes from the comet. Does this make sens?
Hi Fernando. At least is an scenario for how small amounts of ‘dust’ are there.
I wish to point out the possibility that the Philae lander and its shadow may be visible to the right of the touchdown mark in the ‘after’ image (to the lower-right or 4:o’clock position) of the large boulder, about 2 boulder-widths away.
Thanks to all mission team for arranging a reunion over 5 billion years in the making! Its an amazing time to be alive.
Moondog says: Machines were mice and men were lions, once upon a time. Now it is the opposite it’s twice upon a time.
Sub-surface beyond 2MPa hard! Guessing ‘core’ material.
question: what I don’t understand is that if philae is only getting 1.5 hours sunshine rather than the projected 6 hours – doesn’t this simply mean it just takes 4 times longer to charge – and that’s all? Or is there an additional problem here?
Jan
Yes, there is.
After its two unscheduled rebounds, Philae probably came to rest against a cliff-face which leaves it in shadow most of the time. No sunlight, no energy to recharge its battery. Does there need to be an additional problem?
Unfortunately, a good portion of these planned 6h would go towards powering the heaters; without these the batteries cannot be charged (if they are frozen, they don’t charge at all.) So, you need a good couple hours of sunlight to break even between what is supplied and what gets expended on just keeping the batteries operational.
The additional problem is that the batteries must be heated before charging or use can take place: not enough sunlight to exceed the theshold of actual charging, when all power must be spend on heat.
Never understood why the design team did not use nuclear power supply instead of batteries.
If they had, we would still have data flow .
Of course there are weight differences, but cant believe(batteries+electronics+cells Vs nuclear generator) would be a substantial weight issue difference, or cost.
NASA has been deploying small packaged nuclear power supplies for decades.
One of the spokesmen already answered that.
It was not politically acceptable to the Europeans.
As usual politics is the enemy of science.
Just because in the lunching site in French Guiana it’s not allowed radioactive material on board missiles 🙁
In the FAQ is written: “ESA has not developed RTG (i.e. nuclear) technology, so the agency decided to develop solar cells that could fill the same function.
Also, it might be related to the fact the German Government is planning to ban nuclear power from their country.
Besides the obvious benefits, like being completely renewable and clean, developing high efficient solar panels compasses a well know feature of the space exploration, which is to bring new technologies as byproduct. In this case specifically, they developed the Low-Intensity-Low-Temperature Sollar Cells.
By the way, this is another accomplishment the project should be awarded: Rosetta is the first mission to fly beyond the asteroid belt powered by sunlight only.
That’s also why it had to enter deep space hibernation which was considered very risky by all (and everyone was genuinely relieved after Rosetta woke up on schedule). And why the mission is bound to end by the end of 2016 when the comet gets too far from the Sun to provide sufficient power for Rosetta.
So yes, it was flying beyond asteroid belt. But it was not able to do much there.
If ESA had some kind of nuclear power in their hands at the time and there was no major problem, we might have been able to watch the comet over its whole orbit or a few. Sure, Rosetta would run out of its fuel eventually but if it stayed in sufficiently low bound orbit it could watch the comet passively for very long time.
Don’t get me wrong, I’m very happy for what was achieved so far and is about to be achieved with Rosetta the way it is, the mission is huge success so far. I’m just not really into glorification of solar power. Like anything else it has its advantages and its drawbacks.
The mission limit is currently set by predicted fuel exhaustion, not by lack of electrical power.
Hibernation was not really that risky; though novel, it was expected to work.
Also by that stage, a Rosetta will probably have pretty much done what it can. It will have accompanied 67P on its approach as it becomes active, and watched as it quiets down. There probably wouldn’t be much more new information to recover.
RTGs are a sensitive issue, the source of the Pu increasingly problematic, with serious concerns about launch accidents etc. ESA’s decision to go another way was perfectly defensible. It’s possible for this mission, but not for out at Jupiter etc.
Congratulations to all the people that made this incredible mission possible !
We’re also grateful towards ESA to share all these great information with us and to give us the ability to follow this “in live + 28min…” !
By the way, farewell Philae and hope to hear you back once !
Thank you for everything. And my sense is that we are lucky for this cliff. Yes, we are in shadow, but we may easily have drifted right off the comet if it weren’t for this nice cliff, stopping us. Thank you, cliff.
What might be the actual reason that the thruster and harpoons failed? Would it be something like radiation / low temps affecting the hardware over time, or some mechanical damage say on takeoff?
In spite of all troubles – it is a fantastic success! Go, ESA, go!
What a fantastic achievement.Congratulations to everyone involved.
Hope to hear from you soon, little Philae.
The last days with you and Rosetta were a great pleasure. And now, sleep well!
The legs of Philae should have been built with joints with ratchets. So, by touching the surface of the comet they would bend and absorb the energy of the landing by the friction of movement of the turnstiles. Thus, the probe would not have bounced out of the planned landing site.
The legs of Philae should have been built with joints with ratchets. So, by touching the surface of the comet they would bend and absorb the energy of the landing by the friction of movement of the ratchets. Thus, the probe would not have bounced out of the planned landing site.
It is perhaps ironic that the parts of Philae that did not work properly were the low tech, long established mechanisms. I believe the harpoons were fired by a small explosive charge similar to Nitrocellulose (Gun Cotton), which has been known and used for well over a century. However its reaction to 10 years in a vacuum and exposure to very low temperatures does not seem to have been well enough understood.
The cold gas jet’s failure to operate is similar, everyone is familiar with Carbon Dioxide fire extinguishers and the cold gas jet, although using Nitrogen, is basically the same technology. The high tech systems had some degree of redundancy built in, the system for ejecting the lander from Rosetta had a mechanical spring to back up the variable drive motors of the main system, for example. A lesson to be learned here perhaps.
As it turns out though the only data missing, is that from the accelerometers in the harpoons. Further science after the initial science package had completed was always conditional on a number of conditions being met during landing. It was always uncertain whether those conditions would be met even if all Philae’s systems had worked.
The forethought and planning that went into this mission has been proven to be exemplary, the ability to overcome problems and adapt to unexpected circumstances is clear evidence of that. The wonder and joy that has been brought by this mission is prompting people to ask when is the next one. This amount of planning does not happen in a few months, let alone the time it takes to travel such huge distances, but there are other exciting non ESA missions to look forward to.
NASA has DAWN’s rendezvous and orbit of Ceres, the largest asteroid in the Asteroid belt. The New Horizons flyby of Pluto and Charon in July next year. Japan has a mission to visit an asteroid and send multiple little landers to visit it, most to take samples to be returned to Earth, which is due for lift off shortly. China is planning a Lunar sample return mission for next year.
Finally one of the best results from this weeks events might well be that it will be easier for NASA to secure the future of OSIRIS REX and its small asteroid capture mission. Although not quite the shock to American pride of the Sputnik and Gagarin missions, note will be made that the Americans are looking decidedly not at the forefront of space exploration, space science or space technology any more.
Does anyone happen to know what the value of g is at the surface of the comet (earth = 9.8m/sec2) I could calculate it from the comet’s known size and a guess at its density, but maybe someone knows an accurate value.
0.98 mm per second squared or 1/10,000 surface gravity on Earth.
Density approx. 0.38 times that of water ice.
Andrew R Brown.
Congratulations for the entire mission crew for the achievement!
Due to the rather strange shape of the comet it seems to me that gravity in the area of the neck must be close to 0. This would be caused by the two main parts pulling in different directions. This could be related with the ejection of material from that area.
You are making a circular thinking here, Fernando.
Robin Sherman, mechanical devices are much more reliable than electronics, especially after more than 10 years of wear in space. Probably the defects in the devices were caused by flaws in electronic controls or software and not on the devices themselves. As you mentioned, ESA used “a mechanical spring to back up the variable drive motors of the main system.” This is a testament to the trustworthiness of these devices.
There have been many failures of mechanical devices in space. There is a considerable issue with things getting stuck do to the vacuum. Lubricants are a big problem as the degasses and contaminate other parts, optics etc.
Of course electronics can fail; so can software. But I don’t think one can make any clear claim about what is more reliable, because there is no clear way to make a meaningful comparison.
Two questions regarding Philae’s ability to recharge: 1. If the comet is rotating, will the sunlight reach the hole Philae is in sufficiently to eventually recharge the lander? 2. Is is possible to reflect sunlight from Rosetta onto the solar panels of Philae to provide solar recharging?
I know logan. I just wanted to stress that in the surface of the comet are different g’s.
Once there, a 0-gravity cleft can keep it’s surfaces dust-free – try this at home 🙂
A great achievemetn for European Solar Agency.
Real science and truly amazing. Keep up the good work. You have proven yourself.
Maybe it’s luck that the module fell into shadow. Will live longer when approaching the sun.
67P never goes close to the sun; perihelion is outside the earth’s orbit.
What you Konstantin is poiting out is exactly what I have been wondering since before the countdown to the landing operation began. Of course the Mission team must have wanted to land on flat area to make Philae sirvive the landing. But what if it would happen to end up at a place with less Sunlight??!! If there are Mission scientist who have wanted to study the comet when the comet gets closer to The Sun after March 2015, this might be rather a favourable situation!
My surprise is that some voices from the Mission team sound like they have confidence in Philae to wake up and study the comet again. Because it means they see their instruments onboard will survive these coming months of cold temperature even though Philae is sleeping (perhaps without heater working).
Bravo little Philae, bravo!! Hope to hear from you again when things “warm up”!
I am 81yrs. of age and marvel at the Skill of all who participated in this wonderful achievement.I hope I will live to learn of all Facts emerging from the Scientific details resulting from info. gleaned so far.I smile(smugly) at the few miserable “Detractors” who would mock the odd Hiccups that to my simple mind were inevitable on such a colossal venture. Press onwards and upwards you Scientists. P,s, I was born in Tipperary–does’nt seem to be so far now!!!!
This is truly a great achievement. So precise. I think this is the most complicated space endevour up to date. NASA could look up to you in many ways.
Although I would recommend to use also some alternative or backup power just in case. Maybe nuclear or other alternative. After all space is full of radiation, it doesnt matter. It would be hard to go any further in space with just solar power.
As for the Philae, maybe you should soak enough power to try to relocate to another spot, if possible.
Keep up the good work and keep heads up high.
A question. Looking far ahead, how long is 67P expected to last intact (with Philae on it)? Could be quite a surprise for some far future explorer (terrestrial, or non). Is there anything on Philae to show where it has come from?
Given the active nature of comets, and the obvious potential for this one to break in two, it’s unlikely an object on the surface will stay there for very long.
Neither is it obvious ‘anyone’ would be likely to find it if it did. You’d go visit planets, not comets.
I wonder if Philae was built to European RoHs compliancy standards. If so, some of its electrical systems may have suffered from ‘Tin Whiskers’ issues, as documented by NASA studies of Pb free Sn based electrical connections. Can anybody confirm if RoHs standards were imposed on the ESA space mission components? They are avoided for NASA hardware due to long term reliability issues. At possible risk would have been the circuits for the landing sequence components which did not appear to have functioned as per plan. Regardless of this, the achievement earned is dramatic, wonderful and well earned. I can hardly wait until the full scope of data collected is made public.