Lander battery voltage falling fast

On board Philae, system voltage has fallen very close to 21.5V; below that, the battery won't last much longer. At this time, there is insufficient sunlight to provide power.



  • Kevin says:

    I'm not familiar with either electronics nor science, but given the fact that Philae has access to merely an hour++ of sunlight per day(?), wouldn't the batteries eventually recharge? Or is the given sunlight not powerful enough to provide power to recharge at all?

    And this may be far out, but is there any way Rosetta can reflect some to Philae?

    Also, congratulations on this amazing achievement!

    • Nick in Wales says:

      That question has been asked before today Kevin, apparently the answer is no, Rosetta is too small, too far away and the solar panels are designed to absorb light not reflect it.

      • Steven says:

        Isn't there anyone down here that can do some reflecting? This is a group effort.

      • Invisible says:

        And even if rosetta's solar panels would reflect enough light, and do this in a focused way (which both isn't the case), targeting the lander would require to tilt them away from the optimal angle for energy production for the orbiter.

      • Les Robinson says:

        Even if they could .... it would help if maybe they knew where Philae was ....

      • Morten Flecks says:

        Do you have anything on Rosetta that you can reprogram to act as a laser? Then you can recharge Rosetta, and beam light down to Philaes solar panels, no need for reflection.

      • Jineesh says:

        Every battery will recharge automatically by the desired climate/ natural. not fully, but for 1 day data transmission/month and so ? there is possibility i think.

    • Peter says:

      I had the same question, it was covered in the press briefing, the answer was really interesting.

      The battery needs to be above 0 degrees C to work, and it is a lot colder than that out there. You can't trickle-charge a frozen battery, so once it stops working and the battery freezes, it won't be able to heat itself up to work again. They said that there might be some hope at perihelion (so maybe the heaters will be the first thing activated if there's enought light?) but it's not good news generally.

      To answer the next question that I had in mind and was also answered: No, the politics (and costs!) of generating and launching plutonium as an RTG or at least a heat source are not an option. For pretty good reasons actually. Not good for Philae, but solid reasons anyway.


      • Guillermo says:

        Which are "the good reason" for not haven´t used a Pu238 heat source ? ( it was used in the smaller Sojurner) ? (In any case my conglatulation for Rosseta-Philae Tean)

        • Amund says:

          I'm sure glad that they don't place a plutonium device on-top of a rocket that might explode somewhere in the atmosphere.
          Never mind that other space orgs do it, I'm happy that ESA doesn't.

    • Jayson T Benedict says:

      Technical it would need a minimum of 2,5 hours of sunlight and then days to recharge,
      It could be done with 1,5 hours, engineers who i work with calculated it, but a lot of experiments need to be posponed then,
      Loading the battery with the hours of sunlight now would take around 3 weeks to load,
      It also depends on the fact that communication has to be restored, a healthcheck is possible, and the software needs to be updated,
      And it depends on the condition of the battery, the enviroment is harsh there, draining a battery constantly is not so good,
      But it can be done for serveral options,
      Best now is to wait and see if it does recharge, contact can be made, see how the little dude is doing in health, and then decide but indeed get some juice in the battery,
      I worked a lot with solarcels and battery's, 1,5 hours is just to low in energy to restore power quick,
      The system even in hybernation does require a minimum of energy too,
      Be i conclude that Phillea is not dead nore the experiment waisted.
      Looking further in time in could get more sunlight, but there needs to be a certain voltage in the battery to maintain its life, so the option of letting it slowly come to live is better then to do to much experiments with to low power for now,

    • Billy says:

      Batteries are too cold when there's no energy to heat them. During exposure to sunlight, the batteries need to be heated to 0 degC before charging can start, and this takes time too.

  • Haring says:

    Any estimate on the time the sun will be rising again of Philae? Hopefully before batteries become to cold...

  • JOHAN says:

    any info about the temperatura around Philae?? All frozen?

  • mim says:

    that's sad :/

  • Kristina says:

    Hope, that at least the captured data is of precious value... Keep the fingers crossed for any contact after few days, when the G67/P approaches to the sun. AND you guys and ladies there, SUCH AN Amazing Work it is not possible to put it in words!!! Brainiacs, MUCH MUCH RESPECT!

  • Jason Barresi says:

    Maybe this is an oversimplification, but... can't the lander be put into a low-power standby mode for a period of time which provides enough sunlight to sufficiently recharge the batteries and then re-approach a solution when the battery has been recharged?

    • Ed Buckley says:

      Jason, they sent that command but according to statements made during todays Google hangout the command never registered for some reason576

  • Jamie Grover says:

    What are the prospects for a greater amount of sunlight illuminating Philae at a later date and allowing it to resume?

    Also, could any of the mechanical instruments like the drill be used to push Philae back off the surface in the hopes that it will land again somewhere better illuminated?

  • Tomb Raider says:

    Second only to my son's birth 26 years ago, this is the greatest event of my life.

    Congratulations to every single person involved in this unbelievably complex and totally successful mission.

    esa, you are the best!

  • John says:

    is there no hope for rejuvenation? perhaps if/when the position changes as it approaches the sun?

  • AuTo says:

    We love you Philae! We all hope you have a pleasant slumber..

  • Henk says:

    Philae is a resounding success. If it fails now it will have done it's job admirably. Well done Philae and esa.

    • Ruslan says:

      This is a huge step in the exploration of outer space. This is a terrific achievement.

  • Mark says:

    Thanks Philae, enjoy the well earned rest 🙂

  • Nick in Wales says:

    I can't believe that I'm sitting here in my study cheering on something that looks like a fridge on legs sitting on a comet 500,000,000Km away! Go Philae!!!

  • steev says:

    We're all confident that Philae will awake as approaches the Sun
    Most experiments have given results look, sniff, listen just touch and taste is so close
    How long can Rosetta keep transmitting?
    [should have used Duracell 🙂 ]
    Every respect for past a present Engineers - each as individuals
    It's amazing what you can when you TRY

  • Dan Khan says:

    Thanks for the great, actually incredible mission so far ... Let's pray for a miracle to keep it going.

    I'm an engineer and am in awe of what the human mind and hand can create from sheer will power. Let's collectively send our best thoughts to our little friend Philae for a job well done and to help him get out of a tricky situation.

  • simon frederik says:

    If the life of Philae will end soon , then turn on the Surrey Momentum Wheel and let Philae make just 1 little hop using the harpoon , drill or whatever can be used .

  • Fintan Sheerin says:

    It has been truly amazing! I haven't felt this buzz about space science for years (decades?). Just fabulous. Thanks to you guys for doing what you do. Feeling a bit sad though 🙁

  • grecodan says:

    Even if Philae were to run out of power this instant, I'd say it's mission was hugely successful. Close-up pictures and LANDING on a freakin' comet!!

  • Nick in Wales says:

    i wonder if the 35 degree turn has done enough to catch some more rays? I understand perihelion for 67P is about 1AU so hopefully our little hero will wakeup again somewhere around then and maybe have another bounce!

    "Now cracks a noble heart. Good night sweet prince:
    And flights of angels sing thee to thy rest!."

  • frog says:

    little hero!

  • GK says:

    I believe that the electronics onboard Philae require a certain temperature to function (all electronics do). I would guess that the battery in Philae also runs a small heater that warms the components to minimum operating temperature. Without sufficient power to run the heater, the electronics start to fail. Philae can't start back up again, even with a charged battery from the solar panels, because the circuitry is too cold to tell it to start back up again.

    • Robin Sherman says:

      It is to be hoped that the few watts the solar panels generate will be enough to keep Philae ticking over, its just not enough to warm the battery up enough to start charging again.

    • bngtlrs says:

      Wouldn't more intense sunlight heat the whole lander and with it the battery and electronics? Perhaps that would be enough to get Philae operational again even after a long sleep phase.

    • vince31 says:

      wont Philiae heat up sufficiently of its own accord to power up/recharge when in closer proximity to the sun around perihelion?

  • John says:

    Come on Philae! You can do it!!

  • Tanja says:

    You guys have done such an amazing job, words can't even describe it. Congratulation! Hope to hear about today's data that was received once you all got some rest. ESA rocks!

  • Suzanne says:

    I feel like my best friend is seriously ill.

  • Brian Ingram says:

    Was this an expected event?

  • Mario Antonio Zavala Lamtenzan says:

    I guess that comet rotating it´s to fast, and does fast rotation are generating intermitent light reception from the sun ( a like to turn on and turn off switch, or at the change between DAY and NIGHT )
    by these reason it´s not posible to the solar panels receive a full sun light to permit the FULL CHARGE BATTERIES, one solution it´s permit to expose out from the comet rotating to PHILAE.

  • Robin Sherman says:

    What a sad end for brave little Philae. Not only did she give us all the science, but extra information about different sites on 67P and possibly some wonderful pictures from ROLIS during her flyby at less than 1Km height. She found some serious rocks to look at all by herself the ones the scientist wouldn't let her visit and gave us all the thrills and excitement of this epic adventure to boot.

    Next year in true Hollywood fashion we can look forward to "Return of the Lander" if she can get enough sunlight. Being hidden in her little nook she may avoid the worst excesses of the increase in cometary activity, there may be extra light energy from the reflected light from the coma.

    Until the next time, our little robot superhero, sleep well. We look forward to your holiday snaps and the amazing stories all your instruments have to tell. Now Rosetta can find you she will keep watch and listen for your waking.

  • Rune says:


    (Power up flywheel / shoot harpoon(s) / make something fall off? )


    Tx Philae!

    And tx ESA!

  • Heiko says:

    Thank you ESA! My absolute respect to this achievement, to all those who were and are part of it.

    When I saw Ambition - The film I thought it was a little bit oversubscribed but at least when watching your live stream, feeling the excitement and tension about what to come I suddenly know: It are the greats things that you did and do that keeps mankind's heart beating. Rosetta/Philae at least is exactly what the short movie shows: Show what's possible, learning about ourself and reaching for more. Rosetta/Philae are somehow the first step to know how to make it: Water!

    Regardless was any press may say: For me your mission is a great success.

    Again thank you an my deep respect

  • Mike McCarthy says:

    I truly amazing and successful adventure. Most objectives have been achieved with such a professional execution.
    A mission 25 years in the planning, a lifetime for some, that has captured the imagination of the young and rekindled the appetite of those of us that remember the manned missions of the past.
    An unbelievable success, congratulations to all of the mission teams.

  • Eric Yang says:

    I dont know if it is possible. It seem the battery in Philae is going to dead. Before system out of control. Can just let Philae go sleep and wait until 2015.8 or 9. That time the distance from sun will be reduce to around 186 million km and now is 44x million km.

  • 1) CPU (and / or orther peripherals) goes to sleep mode when charging. For Example: ATMEGA328p Active Mode 2mA Power-save Mode: 0.75 µA (Including 32 kHz RTC)

    2) CPU run on slow speed for longest battery life.

    I am using this solutions on my electronic projects.

  • Heiko says:

    When I first saw Ambition - The Film I thought it is a really great movie but a little oversubscribed. Following your life stream from 11 to 12-Nov-2014, seeing you in the ESOC which all your heart to the mission I realized: Rosetta/Philae is exactly what the little movie shows: How to begin to get knowledge about ourself, showing what's possible until one day we can do it: Water!

    Thank you ESA! May deep respect to all of you working on this absolute fascinating mission of exploration, it has made me goose flesh and water in my eyes.


    • Nick in Wales says:

      Good comment Heiko, if mankind is to have a long term future we no alternative but to become a spacefaring species and culture. The pace of discovery in astronomy these days is astonishing, from exo-planets to dark energy and now to sniffing comets. Rosetta and Philae have together shown what we in Europe can do, Curiosity is a stunning technical triumph by NASA, Jade Rabbit was China's first step to a new man on the moon and India has joined the interplanetary club. It's all so exciting!

  • john from Poland says:

    If I were on theirs place I would do everything what is possible to move Philae from that position. Truly I don't belive that it will be able to comunicate with rosetta more time in few months from recharged battery. Comets orbit is not so close to sun (almost same as Earth), so sunlight won't be extremly high. They probably just calculated how much energy thay can get. I suspect that this horrible place where it landed will never allow to get enought energy to work. They have two options:
    1. Less risk but more patience - wait until sun will be closer and maybe it will fix situation,
    2. More risk (I would prefer) to try eject Philae and wait for its repositioning and recharging (from better place). There is almost no gravity so a bit thrust could move it far away and fix problem.
    Option 1 has one more disadvantage: it can happen that Philae will never more link radio.
    Always is better to do something risky and to win triumphantly or gone than do nothing and slowly defeating.

  • Jamie Grover says:

    Communication has now shut down and Philae is in idle mode, so there is no more possibility of using an instrument to try to float it again. I understand that despite worries about needing to keep electronics warm, Philae is apparently now in an idle mode (heater on or not?), and there is some possibility it will be able to wake at a later date. At that point, if it happens, should they choose to try to pop it free, or use the available energy for a deeper drill sample or something like that?

  • April says:

    I am blown away by what you have achieved and actually shed a tear watching.....the whole mission is mindblowingl!

    Even if Philae can do no more Rosetta remains.

    What saddens me is how little coverage this gets from the mainstream media who would rather cover war than the peaceful cooperation of brilliant human beings.

    YOU guys are my heroes

  • marco says:

    Hi - To answer many questions at once regarding eventual recharging. There are two related factors - battery temperature and total wattage from the solar panels. To charge the batteries at all, the temperature of the battery needs to be above freezing (0 degrees C). Power directly from the solar panels gets routed to the battery heater first until that happens. After that, excess wattage can charge the battery. Both expected temperature and wattage are below required levels to enable any charging at all. This should improve over time however, and when it does, Philae will wake up. Best guess is not for another couple of months, although Rosetta will try most days, as there is slim chance that the actual situation may become suddenly much better.

  • Alun Hoskins says:

    An awesome job, well done. I haven't been so excited about a space project since watching the first moon landing as it happened on TV. In my book, this is up there with that event. Sleep tight little Philae.

  • ststeve11 says:

    In the briefing during the Google Hangout there was a description of the exact percentages of light each panel got. Any new data, new percentages after the lander adjusted its position?

  • Arthur says:

    "Always is better to do something risky and to win triumphantly or gone than do nothing and slowly defeating." I agree with John from Poland. They should have tried to move it.

  • Paolo says:

    Many thanks to ESA team for the incredibile task! We hope that Philae's solar panel will be soon recharged by sunlight (finger crossed)

  • Johan Prins says:

    Yes. The secondary battery, and it's solar charging, were a "plan B" giving more time for measurements, but only if.. the landing site would be illuminated well enough. The choice of the landing site having finally been made by rolling a dice, The mission was still a "lucky strike". The lander could have been upside down, or otherwise unable to work / communicate. Now my question: why is there never a configuration that allows to run part of the systems right off the solar panels, as it happens only by long-term dead battery disconnect on ships like Amsat oscar 7 or ISEE-3.?

  • Frannie Brennan says:

    This has been absolutely spellbinding... every single second of it. What an epic journey. Truly the stuff of legend! Huge congrats to all concerned. You have captivated us all x

  • 1. Idea:
    Philiae has at rocket in the top and the legs act like springs. Is it possible to burn the rocket for a few seconds and make Philae jump of P67 and land in another spot?
    2. Idea:
    is it possible to bring Rosetta close to Philae and blow on it using the "fly" rocket?
    3. Idea:
    Is it possible to heat up the surface under Philae, using some of the gear inside Philae and create a geyser, that will lift it off P67, so it lands somewhere else?
    4. Idea:
    If Rosetta has a reflective surface, is it possible to position Rosetta near Philae, so that it reflects sun light onto Philaes sun panels, so that the production improves.

  • Roland says:

    Das Landemodul braucht dringend mehr Licht.
    Könnten nicht die Solarmodule von Rosetta als Spiegel benützt werden ?

  • Elly says:

    Can someone explain how Rosetta is able travel at the same speed as the comet?

  • Steve says:

    Who made the harpoons and thruster? I will avoid their products in future!

  • Robert S says:

    One subject that hasn't been raised is how the illumination of Philae's panels (1.5 hrs per day before the final attempt to change attitude and rotation) could change with the "seasons" as P67 makes it around the sun?

    Congratulations to the team. It's been wonderful and inspiring to watch. Absutley amazing!

  • Jorge Plaja says:

    With its batteries depleted and not enough sunlight available to recharge I wonder if there's any thing that could be done to reactivate those batteries.
    Could it be posible to place Rosetta on a geostationary orbit around 67P and perhaps reflect some sunlight towards the Philae Lander.
    I know this is a crazy suggestion because the surface of Rosetta may not reflect light but much to the contrary in its own benefit, but...
    Otherwise we're facing a long silence until the landing area gets enough sun exposure.

  • Cometstalker says:

    The amount of radiation from the sun the comet gets right now is about 144 W/m2 and this will increase to a maximum of 870 W/m2. That is about 6 times more than now and should be enough to recharge, wakeup and continue. Hopefully this time the power will be used to improve its geographic situation. After all its worth a lot to reach a sunny spot once again leaving the sun.

  • Albert Wang says:

    Philae has done a great job already. Even if the battery is frozen, Phalie is just sleeping on 67P, right? WHEN IS 67P COMING AGAIN? With the technology advancing, and what we learned in this Rosetta Mission, wouldn't it be worth having another mission to land on 67P again? and of course to retrieve Philae...

  • Damian says:

    No matter what this can only be Hailed as a success . Truly remarkable that mankind can achieve so much all working together .
    With all the conspiracy theory's out there only 1 is fact - We did it 🙂
    Who knows 67p could fix the problems for us as it travels some unique solar storm turning it into a solar conductor and zap large static charge or singing change in gravity working in our favour 🙂
    What ever happens its truly truly a wonder to watch , listen and follow . Thank you

  • Víctor says:

    Does Philae tried to change a little bit his position in order to reach some sun light?
    if is not possible, how many times do you think Philae will still going on before his batteries will be finished?

  • Bridenne says:

    What about using Rosetta solar panels (65 m of solar panels) to reflect sun light to Philae? On earth we can observe the sun light reflected by the Iridium satellites. If we could guide Rosetta to light up Philae with its solar panel would it enough energy on Philae solar panels?

  • Erik Nielsen says:

    Can't you place the mothership, so the light from the Sun will be reflectet to Philae???

    The light flashes from passing sattelites looks very dense seeen from here.

    Erik Nielsen.

  • Greg says:

    I can't understand one thing. Is there no backup power source? No backup battery? WTF!?

  • Marcos says:

    First of all, I want to congratulate the team that made this remarkable success possible. I cannot help to feel a bit sad, since my expectatios were to see the information from Philae in the next months, and all the exciting things this could potentially discover. I have had a thought running thru my mind the last couple days. Could have been possible that ESA would have fit a nuclear battery into Philae´s body to deal with this type of contingency situation that is now happening, with low solar exposure onto the pannels?.

  • Stefan says:

    Solar panels are designed to collect, not to reflect sunlight. Additionally with only a little reflected spot of rosetta´s panels you exactly need to know where Philae is located to hit him.

    Solarzellen sind zum Sammeln, nicht zum Reflektieren von Sonnenlicht konzipiert. Außerdem müsste Philae´s Position genau bekannt sein, um die kleine Reflektion genau auf ihn zu lenken.

  • Emiraga says:

    Congratulations to European Solar Agency.
    ESA lived up to the name it carries.

  • Jojo Balagtas says:

    I think that is too far too get light power from the sun

  • Jojo Balagtas says:

    I think when Philae bounced.... It goes to a not good and unbetterrer (hehehe! Dont know to that) landing place. Hmmmmm.....?

  • BetterApproach says:

    If NASA design the Curiosity similar to the Philae then the Curiosity must land like a asteroid on Mars!

    • InSearchingForBetterApproach says:

      If NASA designed the Curiosity with a landing method similar to the Philae of ESA! then the Curiosity must land like an asteroid on Mars!
      In this situation, ESA must design a next comet-lander with an autonomous soft-landing mechanism! instead of use a traditional way of hard-landing scheme of natural way of all asteroids in the universe !
      A good and safe landing scheme such as: "autonomously soft-landing method" is a must for all future landers of ESA or NASA or others! (ImpeccableVision)

  • InSearchingForBetterApproach says:

    In other words, the EAS should incorporate to each foot of the lander (Philae) a self-deployable computer-controlled electric Drill-like Lander-Foot "fastener" (LFF)! and the Drill-bit of each LFF should include a hardened, pointy conical shape with a similar masonry drill bit, in order to allow 3 drilling apparatuses of 3 feet of the LFF to drill as quickly and deeply as possible at the same time if possible. This approach is to arm 3 feet of the lander with 3 individual drilling instruments and they automatically self-deploy as soon as their proximity sensors been activated! Good Luck to the next lander!

  • InSearchingForBetterApproach says:

    Rosetta if has a light reflector mirror and controlled by a controller to redirect the sunlight to the Philae's solar panels as I can conceive then in this case, the Philae can receive sunlight artificially done by the Rosetta automatically to charge its batteries banks! (This is a THD's Concept, conceived by me)
    Next time this TDH's concept should be evaluated to possibly incorporated into a next lander's delivery system or Rosetta-2, etc..

  • InSearchingForBetterApproach says:

    Another approach is to equip the lander with retro-rockets system, to slowly let the lander touches the comet soil and 3 Fastening units at 3 contacting feet or foots of the suspension landing legs of the lander will finally be deployed to anchor 3 touching-down feet to the comet soil for securing the lander to the comet and this secured fastening mechanism can prevent the lander from being thrown out into the space while the comet is rotating and moving!

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