Philae isn’t dead:, just sleeping (?)

November 15, 2014 • 2:27 pm

Well, our optimism about the comet probe Philae was premature, but it wasn’t a total loss. Although it failed to “harpoon” itself to the comet, Philae did land after a couple of bounces and sent out some data. Sadly, its solar battery wasn’t able to keep it going since it was stuck on a dark part of the comet, and for some reason the Europeans who launched it weren’t allowed to use nuclear batteries, which, I’m told, would have been sending out data even now. (I may be wrong here, but I’m just saying. . .).

As the BBC reports:

The Philae lander on the distant comet 67P has sent another stream of data back to Earth before losing power.

The little probe delivered everything expected from it, just as its failing battery dropped it into standby mode.

Philae is pressed up against a cliff. Deep shadows mean it cannot now get enough light on to its solar panels to recharge its systems.

The European Space Agency (Esa) fears this contact may have been the robot’s last – certainly for a while.

A tweet from the official Philae lander account said: “I’ll tell you more about my new home, comet 67P soon… zzzzz.”

Here’s the tweet:

Screen Shot 2014-11-15 at 1.23.53 PM

The European Space Agency (ESA) says it may be able to reactivate the probe’s solar panels, but it sounds dicey, and they may be trying to keep us optimistic:

The next opportunity to talk to Philae was set to begin at around 10:00 GMT (11:00 CET), when the orbiting Rosetta satellite – which delivered it to the 4km-wide “ice mountain” – was due to come over the horizon.

But with only 1.5 hours of sunshine falling on the robot during the comet’s 12-hour day, it seems doubtful the battery will have recovered enough performance to complete the radio link.

Engineers did manage to maximise the possibility of it happening, though, by sending a command to reorientate the lander.

This involved raising Philae by 4cm and rotating its main housing by 35%. This will ensure the largest solar panel catches the most light.

And there may also be more light for the solar batteries as the host comet approaches the Sun. The ESA is also saying that they still got a lot of important data despite the poor landing location, but we have yet to see what that data show. This may be a case of making a virtue of necessity. Nevertheless, we do have some spectacular photos, and it was still a stupendous achievement to get the probe on the comet in the first place.

The sad thing is that many of us came to think of Philae as alive, an anthropomorphism encouraged by the ESA (and xkcd), so now we’ll have to undergo a period of mourning as the little thing fades away, perhaps for good.

Now—what about those nuclear batteries?

 

69 thoughts on “Philae isn’t dead:, just sleeping (?)”

  2. It’s been a tremendous achievement – the fact of landing on a comet for the first time ever. Even the journey to it was a fantastic tour de force, because of the complexity of the orbit and the planetary encounters needed to get Rosetta into the right trajectory for the encounter. Just amazing.

    1. The first phase of the Rosetta mission, that is getting the spacecraft to enter the comet’s orbit was science at its best. Nothing short of spectacular.

      1. True. And it is nice to contemplate that this is probably just the first in a long series of explorations which can capitalize on the momentum of Rosetta’s success.

  3. I think the decision to upset escolar panels was made to try out the ne technology. From here:

    Solar technology will have played an important role in delivering new discoveries and reaching new limits. It remains to be seen whether solar developments on Earth’s surface, through its vast spread of solar power, or the knowledge gained from the outer parts of space system, transform our world faster.

  4. It’s ironic that harpoons, some of the earliest human tools, were the failure mode. You’d think that in 35,000 years more-or-less we would have perfected the art of harpooning, which is just like spearing but in the water, or in this case on a comet. The Romans were spearing experts! Spearing (and hence harpooning) technology has been stagnant since the suicidal bayonet charges in The Great War. Have we become complacent in the modern era, where harpoons have limited application or appeal? (Compared to a smartphone, for example.) Clearly, we need to invest much more in harpoon science and technology.

    2. Actually, out of 5-6 anchoring devices 3 failed, the harpoons and the top thruster. Any one of these would have prevented the bounce I take it (because the thruster would have worked against both the bounce and the harpoon’s momenta).

      The landing gear screws worked, but they relied on the other three devices to get anchor grip. (I’m hazy if there were 2 or 3; certainly there were 3 legs and 3 foot pads; but the mission was mass limited so maybe they opted for 2.)

      1. I wonder what would have happened if the harpoons fired correctly but failed to penetrate the comet’s surface…

        1. I wondered likewise. How would a harpoon penetrate a chunk of crystalline mineral anyway? It seems they were presuming a favorable surface structure.

    3. About the failing top thruster. You would have thought its nitrogen had leaked away after 10 years.

      But no. I hear the heater that was to remove its wax sealing didn’t work.

      Wax sealings are thousands of years old technology too…

    4. To be honest, when I was watching the videos of the development process, I was thinking more of the ice-climbing tool called a “

      http://dmmclimbing.com/products/deadman/

      ” (and their little cousins, deadboys). A properly seated deadman can take several tonnes of load – you need that 4mm/ 5 tonne SWL wire.

  5. Nevertheless, we do have some spectacular photos, and it was still a stupendous achievement to get the probe on the comet in the first place.

    It’s amazing. Even though it’s been some time since we’ve been able to land men on the moon, and have robots on the surface of Venus, Mars, and Titan, I’m awestruck by this simple fact:

    Philae is nowhere on Earth.

  6. many of us came to think of Philae as alive

    My seven-year-old daughter was that “our” robot on Mars will never be coming home.

    Philae’s slimly-possibly-temporary shutdown does feel sadder for the lander having been given a cutesie personality, but the fun of the spunky little guy tweeting his wonder and excitement was worth it and so much fun while it lasted. I will remember that – and xkcd’s realtime cartoons – very, very fondly.

      1. That one was malevolent, though.

        My boss, whose name is Dave, and is obviously a closet Star Wars fan, pinned up by his desk

        “Do, or do not. There is no try”.

        I couldn’t resist, I pinned up below it
        “I’m sorry Dave, I’m afraid I can’t do that.”

        It’s still there…

  8. And regarding the non-use of nuclear batteries, I was a little surprised when I heard, since I know a little Reused Soviet plutonium is keeping the Mars rover warm and charged-up. A billion euros and a decade-plus investment of labor might have justified a teeny bit of non-greenness I might think. I wonder if there is an ESA engineer or two with a little bit of bittersweet I-told-you-so going on. I hope not; that would be a real bummer.

    1. I think the risk was on launch. If an explosion happens the nuke stuff might be scattered about randomly over neighborhoods. An understandable worry I suppose, but regrettable that a method could not be found to safely use the easy form of power.
      I was also thinking…why not use a form of distributed solar panel thrown off by the lander that would fling collector chips connected with fine wires, like a fishing net, over a larger area of the comet? Wait. I’m not an engineer. What do I know?

      1. a form of distributed solar panel thrown off by the lander that would fling collector chips connected with fine wires, like a fishing net, over a larger area of the comet? Wait. I’m not an engineer. What do I know?

        Tangling.
        If It’d be a pig to set up so that it wouldn’t be able to tangle the cables. Could you do it as a network? A mesh of cables and nodes? That would also settle the question of preventing the solar cells from settling wrong-way up.
        Or would streaming a sequence of cells from the lander as it’s descending possibly have worked better? Would have potentially provided some more anchoring forces, but at the risk of a harder impact on surface.

        1. In my version Philae would descend with a significant rotation in the horizontal plain and gradually let out the net from the bottom edges. The net would flair out as a skirt from a spinning dancer. When its close enough, Philae separates and lets the spinning net land first.
          The streaming sequence of cells is also a nice idea.
          I also wonder if a film of glue on the contact points could be used to prevent bouncing?

    2. Concerning nuclear RTGs, I had the same thought until I did some research. The likely weight of an RTG (radioisotope thermoelectric generator) 10+ years ago, or even now (see Wikipedia) probably eliminated it as a choice. It alone would have weighed about twice as much as the total science package on Philae.

      1. I was wondering the exact same thing, was it nuclear fear or just weight practicality. Of course, like mentioned in other posts, the power issue is a tertiary problem. The bigger issue is in fact the failure of the downward thrusters followed by the failure of the harpoons. As the landing was pretty much spot-on, the proper functioning of one or both of these landing devices would have rendered the power system a moot issue, as the lander would have landed rather than gone for a bounce or two. It’s still a success, success with an asterisk perhaps, but these failures will lead to better missions in the future and I’ve enjoyed the drama immensely.

        1. The failures are minimal if they get the data. It turns out that the harpoons used small nitrocellulose charges for firing. Recent research (that maybe should have been done before the decision to go with the ancient technology of gun cotton was made?) shows that nitrocellulose reaction in vacuum is VERY inefficient.

          This is not to imply that the chasing down of the comet, and landing of Philae on it wasn’t one of the greatest accomplishments of the 21st Century to date.

          1. Bloody typical humans. They travel millions of miles across space to rendezvous with a comet which has itself travelled billions of miles and the first think they can think of to do is shoot it.

            😉

        2. I think it was a singular downward thruster. That is the description in the articles.

        3. As the landing was pretty much spot-on, the proper functioning of one or both of these landing devices would have rendered the power system a moot issue

          Since before landing we did not have any data points about the physical properties of cometary surfaces, it is hard to know exactly why these systems did not perform as intended. There may be more data in the dumps which is relevant, but if your remember back to the Huygens landing on Titan, it took some days before enough analytical work could be done to come up with the “creme brulee” model.

    3. The reason is orbit. If closer than Saturn to the sun, no mission would use nuclear batteries (unless it lands on planet).

      RTG and ASRGs(*) require Pu238 right now. Maybe later Sr90 (more noisy radiation for instruments on board), but if it is Pu238, in America that means a signature from the President of the United States. In Russia (ca. 2008) there was only 20 kg of it, though ESA may have made the case to turn more on.

      Nuclear fear is not warranted in the case of launch catastrophe.

      (*) http://en.wikipedia.org/wiki/Advanced_Stirling_radioisotope_generator

      1. The politics aside, when this craft was constructed 20-10 years ago, there wasn’t photovoltaics capable of being outside of Mars orbit. There are crafts that use them for Jupiter now, and are cheaper for it.

        I haven’t heard that photovoltaics would be capable for Saturn in a feasible way (sufficiently small and non-costly panels). Nice, if it can be done.

        I doubt Sr90 can be used for mass limited spacecrafts. Pu238 decay chain mostly generate easily stoppable alpha particles IIRC, so don’t need much shielding mass. Sr90 decay chain radiates betas and gammas, I hear, so it would be a much more massive packet in order to protect the electronics of the craft.

        Presumably it would take a whole new launch technology besides chemical to make Sr90 a feasible technology.

        By the way, the ASG work has been shelved. US is now too poor to invest in future economical gains. :-/

        1. My mistake: “there wasn’t photovoltaics capable of being outside of Mars orbit.”

          _Much_ outside, seeing that there is where Philae and Rosetta is. I dunno if they were ready to use them for Jupiter though. Maybe they were stretching the then technology as it was.

          1. Missions to Jupiter also generally are not designed to last long: almost exclusively due to the massive radiation doses crafts must endure inside the Jovian radiation belts. JUNO, I think, has inch thick walls of Ti surrounding critical electronics.

          2. Woe be unto the astronauts venturing to that part of the Solar system. They would probably be more vulnerable than the electronics.

          3. Radiation throughout the Solar system is a big issue in human mission planning. What we’re going to do about it, apart from mass, is another thing.

          1. Not relevant : the “European” part of “European Space Agency” doesn’t include much US contribution.

        1. I am not sure they have purified their ‘reserves’ or ‘waste’. Anyhow, Pu238 is a very different animal than Pu239, and not so horrible.

    4. It is not limited to this mission. For political reasons, Europe hasn’t developed RTGs (AFAIK).

    5. it’s suspicious that the European Space Agency is not answering the question about nuclear batteries. It makes it look very much like they were just being politically correct instead of being scientific. The politically correct people that did not want nuclear batteries should be fired. They are not scientists and they never belonged as part of this mission. the fact that they will not answer this question suggests that this is the answer

  9. I think that on balance this is a great achievement, and the ESA should be proud. Of course, assessments of design are being done, and I expect they are looking at the virtues of small sources of nuclear power for deep space missions.
    I had been hearing that Philae managed to drill a sample. I would love to hear about the results, if true. I wanna hear that it found gobs of amino acids, but I will gladly take whatever it finds.

    1. I hear the drill cycle has been finished. But I haven’t seen anyone claiming it did reach the comet surface from Philae’s tilted position.

      [Confusingly, there is also a thermal probe “drill” (or two, I think it had a backup/2nd probe) which was activated earlier. That probe had a capability to work its way in regardless, and one can hope the sample drill can do it too.]

  10. The sad thing is that many of us came to think of Philae as alive, an anthropomorphism encouraged by the ESA (and xkcd), so now we’ll have to undergo a period of mourning as the little thing fades away, perhaps for good.

    I’ve wondered about the extent to which our current propensity to personify spacecraft dates to the movie Wall∙E. Opportunity and Spirit had been on Mars a number of years when that movie came out. It’d be interesting to see whether journalists were more inclined to treat the probes as agents after 2008.

  11. Reminds me of the 1998 movie “The Brave Little Toaster Goes to Mars”…or, in this case, the brave little washing machine. Sleep well, Philae 🙂

  12. It is truly an incredible achievement to have landed on the comet.

    However, I’m still feeling crushed by the current technical failures. Just thinking of the effort, money and especially time it took to get there. So close….

    1. 80 -100 % of the primary mission was achieved, more likely 100 %.

      Yes, it sounds like a Philaic defeat. =D

      1. I don’t think they were able to send back the data from the drilling experiment which was the centerpiece of the mission, before the lander ran out of its battery.

    2. Same here. After the critical failure of its ALL onboard systems designed to attach the lander to the comet, Philae bounced as high as 1 kilometer from the surface, and that means it could have landed anywhere on the *constantly moving* target. In the worst case scenario it could have crashed on the comet’s steep hills.

      I wonder how close the lander actually was to escaping the comet’s ultra-weak gravity (100,000 lower than that of our planet) after the bounce……

  13. The European Space Agency (ESA) says it may be able to reactivate the probe’s solar panels…

    There’s a simple solution: move the sun. Does someone have Bruce Willis’ number?

  14. Re: nucular power – the main thing to keep in mind is what the lander was designed for and then work your way back.

    ESA wanted to get X data from the surface of the comet, for which they had Y budget and a Z launch mass.

    The scientists figured they could get most if not all of that data in an approx 60 hour (IIRC) time window of a lander on the surface. So Philae was designed with a simple, 60-hour battery.

    Only later, when the probe was already pretty much designed, the scientists found a way to stick some solar panels on to try to extend its life.

    Adding a nuclear battery by this time would have not only required a total redesign (for which i doubt there was time or money), but also would have added almost nothing to its scientific capabilities.

  15. “This parrot is resting. He has ceased to be awake.”

    It is frustrating to not now know if the drill did sample the comet or if the vital volatile experiments CASAC and especially Ptolemy (the isotope experiment) sampled that or at least the ambient sufficiently.

    Or if all the data made it to Rosetta, but that point seems now to have been laid at rest in the BBC/ESA reporting (IIRC), they got ‘every bit and byte’.

    Now—what about those nuclear batteries?

    The primary reason why ESA crafts have no nuclear batteries (but experiment/heater radioactives if necessary, I would guess) is political.

    Did you really think a cooperative of nations could agree to use nuclear power then (20-10 years ago, when the craft was constructed) or now (Fukushima)?

    But it couldn’t have been used by Rosetta anyway. The mission was extremely mass limited by the then launcher, which is why it took 10 years of travel, a martian gravity assist, and an unprecendented long power down period (30+ months!) to make the trip.

    The lander had to forgo luxuries like steering thrusters and was instead thrown to the target ellipse (with 10 m precision!).

    The battery capacity was evidently designed after the mission criteria of powering all the experiments for the primary mission and not a Wh more.

    Besides, there is the cost factor already mentioned.

    1. To be more precise on the battery mass:

      The lander masses 98 kg. The power system masses 12 kg! [ http://en.wikipedia.org/wiki/Philae_(spacecraft) ]

      The least massive RTGs ever devised masses 2-12 kg [SNAP devices; http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#Space ] and are no longer made. Besides, the 2 kg version output was 2.5 W, so it would have needed an auxiliary storage battery and a lot of patience to power even one experiment at a time.

    3. It is insane that people equate radiation disasters like Fukushima with research into backpack sized power supplies that can output only enough energy for a few laptops.

      1. My current laptop is around 80W running ; Philae’s computer about 3W. That’s down there with some of the Raspberry Pi models. In a radiation-hardened sort of way.

    4. The battery capacity was evidently designed after the mission criteria of powering all the experiments for the primary mission and not a Wh more.

      Would have been really awkward. IIRC from one of the press conferences, the computer needs about 5W to boot and 3 or so to run. So the intermediate batteries would have been working really hard.

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