Farewell, silent Philae

Tomorrow, 27 July 2016 at 09:00 UTC / 11:00 CEST, the Electrical Support System Processor Unit (ESS) on Rosetta will be switched off. The ESS is the interface used for communications between Rosetta and the lander, Philae, which has remained silent since 9 July 2015.

Switching off the ESS is part of the preparations for Rosetta’s end of mission. By the end of July 2016, the spacecraft will be some 520 million km from the Sun, and will start facing a significant loss of power – about 4W per day. In order to continue scientific operations over the next two months and to maximise their return, it became necessary to start reducing the power consumed by the non-essential payload components on board.

No signal has been received by Rosetta from Philae since last July and earlier this year the lander was considered to be in a state of eternal hibernation. In spite of this, the ESS was kept on until now in the unlikely chance that Philae would re-gain contact. Although Rosetta has reached altitudes well below 10 km over the surface of Comet 67P/Churyumov-Gerasimenko, however, no signal from the lander was received since July 2015.

The decision was taken by the mission manager and will be implemented by the Rosetta Mission Operations Centre, in coordination with the DLR Lander Control Center and the Rosetta Science Ground Segment.



  • A.Cooper says:

    Hi Claudia

    If the power loss is 4 watts per day, could you tell us from what baseline that is? I would have thought it’s a few hundred watts, perhaps. This would mean that a diminution of 4 watts per day isn’t quite as bad as it might sound but yes, building up to around 240 watts by the time of the landing (ignoring the 1/r^2 factor for sunlight reduction on the panels).

    • Harvey says:

      Wiki gives 850 watts at 3.4au
      Currently, from the ESA web site, at 3.47AU from the sun.
      So that gives about 816W, but there may be some degradation of the solar cells by now?

      • Harvey says:

        Ah, they are indeed special cells:
        “In practice however, in low solar intensities with temperatures dropping below –100°C, standard solar arrays show worse-than-expected performance due to unpredictable degradation of individual cells. To overcome this problem, the LLIT (Low Intensity Low Temperature) specific solar cell technology was developed. The resulting single-junction silicon cells are flying on ESA’s Rosetta comet chaser, which is venturing three times further from the Sun than Earth.”

  • Daniel from Germany says:

    Farewell Rosetta and Philae! ;-( You had made a long journey and had been a milestone for all of us excited of this mission. Farewell! You will not be forgotten! 🙂

  • logan says:

    …whispering farewell.

    We’ll be back.

  • Su says:

    Makes me sad, both Rosetta and Philae came so much to life through the years thanks to the cute twitter communication^^ So it makes me happy Rosetta will join the Little sleeping one at last (even if it is childish lol). Thanks for having us on you awesome adventure!

  • S odwyer says:

    philae will be back in star trek 25

  • Bas says:

    So, sticked to 67P, when can we expect you back in our solar system?

    • Harvey says:

      It never leaves it.
      The orbital period is 6.44 years, and aphelion 5.6829 AU (850,150,000 km).

      • Lucas says:

        So is there any possibility Philae could be back in few years IF we would be still listening?

  • John Hartington says:

    See you Rosetta,,, job accomplished and well done until we meet again

  • Vik says:

    Good Bye and God speed into the unknown!!
    – Wishes from India

  • Jean Stocks says:

    Goodbye! Don’t be sad.

  • Kevin Dennis says:

    Philae and Rosetta, thank you. You will be on an eternal patrol long after all of us have turned into dust.

    I will always remember the history you made.

  • Ron McGinty says:

    Any sailor (be he on seas or the cosmos) would tell you always carry more than one anchor! was exciting to watch it all unfold. Great team and great results..That”s why science is characterized as Trial & Error NOT Trial & Success.
    “Far better it is to dare mighty things, to win glorious triumphs, even though checkered by failure…than to rank with those poor spirits who neither enjoy or suffer much, because they live in a grey twilight that knows not victory or defeat.” ~ Theodore Roosevelt

  • shane says:

    Oh Man, I’m bummed out to hear this, but hey one day it just might come back to life, I mean after all, if it was all that gone and lost, why would you even worry about powering it down!? The end means just that, unless somehow that comet will be back ,which it will, an it just may go near other sun’s to gain power, if left on, so what would it hurt, either way.. hmmm? but whatever we wont know anything in our life time, meaning the living generation now, sigh~~~

    • Harvey says:

      Shane. The unit being turned off is on Rosetta, which now needs the power for its other instruments. Not least probably for heaters – it’s cold out there! I suspect it had just been left on because there was no shortage of power until now, on a ‘well we might as well’ basis, and that in reality there is no concern about turning it off.
      Since Philae has not been located it is probably under dust and debris now, and in any case far too cold to function. It’s been clear for a long times that the chances of hearing from Philae again were remote in the extreme.
      The comet’s period is quite short BTW, 6.44 years, so it will be back; but Rosetta and Philae will not be ‘alive’ to report on that.

  • Angelo says:

    Goodbye little robot, a beautiful representative of human genius

  • Luigi says:

    Did you ever managed to figure out the exact position of philae? Do you have plans to take some close-up pictures of the area where you think it is, or it’s now shrouded in perpetual darkness?

  • Steve says:

    Hi. Will any attempt be made to use Osiris to take an image of the final resting place of Philae at close range?

  • luigi says:

    Thank you Philae, thank you! And thank you to all men that put you in space!

  • delcan says:

    farewell. slán agus beannacht in Irish Gaelic.

  • Vinciane says:

    Ce fut une belle aventure

  • Gil Seda says:

    Wow I have seen the man landing on the moon, Space Shuttle etc. and now it’s time to say good bye to our little Robots Philae and Rosetta. Thanks for all the Pictures and Data that you provided, you guys can rest now, job well done!

  • logan says:

    Only because is a niche, it has the right view of the then neck jetting, and where initially believed it had fallen down:

    Pixel 1562,1037 of 20160114171626_F100


  • Peter Lindsay says:

    Since this may be the last post regarding Philae I’d better put my oar in now. The Rosetta mission has been a fabulous success of vision, design and execution.

    However, “brave little Philae” had a very nasty cold. The landing team placed her precisely at the planned position but she failed to attach and crashed somewhere unknown. Philae’s ability to complete most of her mission was a matter of extraordinary good luck and brilliant handling by her control team.

    As a long retired designer of electronic circuits I have a keen interest in the analysis of failure. Not because I want someone to blame ( please don’t do that ) but because the lives of future astronauts and, more mundanely, the lives of our grandchildren in driverless vehicles are possibly at stake.

    Mistakes are not sins but failure to learn from them or help others to do so, could well be blameworthy. Please let us know the latest analysis. My own suspicion is that the failures to prime the thruster prior to launch and to fire the harpoons on touchdown are somehow related. Perhaps the go/no go decision was unfortunate.

    It seems to me that in the early days OSIRIS suffered a PR headache by refusing to let us look at any of their prizes. Their latest image of the day series has been a great delight and PR success. The capture of Philae’s final position would be a real Gold Medal.

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