History-Making Philae Lander Faces ‘Eternal Hibernation’ On Comet

Feb 12, 2016

Photo credit: ESA/Rosetta/Philae/CIVA

By Bill Chappell

Exactly 15 months after it completed a seemingly impossible journey to land on the surface of a comet, the Philae lander now faces “eternal hibernation,” as officials at the European Space Agency say the craft doesn’t get enough sunlight to power its batteries.

“The chances for Philae to contact our team … are unfortunately getting close to zero,” says Stephan Ulamec, Philae project manager at the German Aerospace Center, DLR. He added, “We are not sending commands any more, and it would be very surprising if we were to receive a signal again.”

Philae is the lander from the Rosetta spacecraft, which for months now has been orbiting Comet 67P/Churyumov–Gerasimenko and listening for signs of activity from its companion craft. But after an encouraging period of contact last summer, Philae has been silent since July 9.


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11 comments on “History-Making Philae Lander Faces ‘Eternal Hibernation’ On Comet

  • 2
    Stardusty Psyche says:

    European Space Agency say the craft doesn’t get enough sunlight to power its batteries.

    My immediate reaction to that was “bad engineering”. Incredulously, I asked myself if perhaps ESA was incapable of calculating the solar radiation power available at that distance. I mean, you could create an undergraduate homework assignment to make that calculation.

    I looked for further details and I am sure there is more to the story than engineering incompetence, but I could not find a good explanation for that seemingly lame excuse. Besides, the lander worked for a period of time, so it must have gotten enough power to operate. Blame it on the sun.

    On the bright side following the links took me to a whole series of ESA videos I highly recommend, especially to my American friends. Here in the states we tend to be flooded with all kinds of documentaries about the American space program, so it was fascinating to me to find a video of Soyuz capsule landing on dry land, of all places!
    .youtube.com/watch?v=-l7MM9yoxII

    Here is cool video about space debris with great animation
    youtube.com/watch?v=9cd0-4qOvb0



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  • Stardusty Psyche
    Feb 13, 2016 at 10:34 am

    European Space Agency say the craft doesn’t get enough sunlight to power its batteries.

    My immediate reaction to that was “bad engineering”. Incredulously, I asked myself if perhaps ESA was incapable of calculating the solar radiation power available at that distance.

    The problem was unrelated to engineering calculations of light intensities at various distances from the Sun.

    The probe bounced off a hard surface in the extreme
    ly low gravity of the comet, flew through space recording and transmitting, until it hit a steep rock-face and and dropped into deep shadow at the foot of a cliff on the comet surface.

    Being in deep shadow and with rocks blocking its line to sight transmissions the the mother probe most of the time, the batteries ran down due to lack of sunlight reaching the solar cells to charge them.

    I mean, you could create an undergraduate homework assignment to make that calculation.

    It would be a rather short investigation, as the ESA team already calculated the requirements!

    http://www.bbc.co.uk/news/science-environment-30058176
    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.

    There are comments and links about this on earlier discussions.



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  • 4
    NearlyNakedApe says:

    @alan4discussion-197550

    The probe bounced off a hard surface in the extreme
    ly low gravity of the comet, flew through space recording and transmitting, until it hit a steep rock-face and and dropped into deep shadow at the foot of a cliff on the comet surface.

    Yes and this, it must be said, was the result of Philae’s harpoon malfunctioning. And that, it could be argued, could have been the result of improper or insufficient testing of the harpoon’s propulsive charge mechanism. Had the harpoon worked properly, Philae would have landed in the planned spot and would have gotten plenty of light to recharge its batteries.

    In any project such as this one, one small technical mishap can have far-reaching consequences. When I learned this had happened I must admit I was a bit dismayed because I knew what this meant. I also saw that while the people at CNES were mum about it, the disappointment on their faces was unmistakeable.

    To me, this is indubitable proof that slashing budgets is a HUGE mistake. Sure, testing is expensive but we do it for a good reason. Once that thing is 4 billion kilometers away and lands in a dark hole, there’s nothing anybody can do about it.



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  • NearlyNakedApe
    Feb 13, 2016 at 2:22 pm

    Yes and this, it must be said, was the result of Philae’s harpoon malfunctioning. And that, it could be argued, could have been the result of improper or insufficient testing of the harpoon’s propulsive charge mechanism. Had the harpoon worked properly, Philae would have landed in the planned spot and would have gotten plenty of light to recharge its batteries.

    I’m not sure about this. Essentially the nature of the surface – hardness of the rock etc. of the comet surface, was largely unknown prior to this mission, so the method of anchorage was speculative to a considerable extent.



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  • It looks like the research and data stream will continue – at least until September 2016!

    http://www.bbc.co.uk/news/science-environment-35945644

    Perfectly backlit by our star. This is how Comet 67P was pictured this week by the Rosetta spacecraft.

    The European Space Agency (Esa) probe was a few hundred km “downstream” of all the vapour and dust being vented from the icy dirt-ball.

    Even though the duck-shaped object is heading out of the inner Solar System, it remains classically active.

    Rosetta will continue to study the comet until controllers direct it to make a “landing” in September.

    Mission officials will endeavour to make this touchdown a gentle one, to ensure data is returned for as long as possible. But it will bring the whole venture to an end.

    Rosetta will likely be damaged by the impact and drop all contact with Earth.



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  • It looks like they are trying to get the last scraps of data about the comet, by landing the main probe in addition to the original Philae lander, while it is still possible.

    http://www.bbc.co.uk/news/science-environment-36607608

    The Rosetta probe will be crash-landed on Comet 67P on Friday 30 September, the European Space Agency has confirmed.

    The manoeuvre, which is expected to destroy the satellite, will bring to an end two years of investigations at the 4km-wide icy dirt-ball.

    Flight controllers plan to have the cameras taking and relaying pictures during the final descent.

    Sensors that “sniff” the chemical environment will also be switched on.

    All other instruments will likely be off.

    Flight dynamics experts have still to work out the fine details, but Rosetta will be put into a tight ellipse around the comet and commanded to drop its periapsis (lowest pass) progressively. A final burn will then put the satellite on a collision course with the duck-shaped object.

    Mission managers have previously talked about bringing Rosetta down in a place dubbed “Agilkia” – the location originally chosen to land its surface robot, Philae, in November 2014.

    In the event, Philae bounced a kilometre away, but Agilkia’s relatively flat terrain is an attractive option still, although other targets are being studied.

    Having swept around the Sun last August, Comet 67P is currently on a trajectory that is taking it away from the inner Solar System towards the orbit of Jupiter.

    Today, the probe is nearly half a billion km from the Sun.

    This means the amount of light falling on Rosetta’s solar panels is gradually diminishing; and, as a consequence, it has less power day by day to run its instruments and sub-systems.

    Engineers would soon have to put the satellite into hibernation mode if they wanted to use it long term – during 67P’s next encounter with the Sun in a few years’ time.

    But having already spent 12 years in space, battling huge temperature swings and damaging radiation, not to mention a much-reduced fuel load – there is little confidence Rosetta will still be operable so far into the future.

    The crash-landing on the other hand offers the opportunity to get some very close-in science to complement the more distant remote sensing it has been doing.

    Controllers will try to maintain contact with the satellite for as long as possible during the final descent.



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  • With Rosetta due to end its mission by crashing into the comet on 30th September 2016, this is a nice little bonus near the end of the mission!

    http://www.bbc.co.uk/news/science-environment-37276221

    Philae: Lost comet lander is found

    The little robot is visible in new images downloaded from the Rosetta probe in orbit around the icy dirt-ball 67P/Churyumov-Gerasimenko.

    European Space Agency (Esa) officials say there is no doubt about the identification – “it’s as clear as day”, one told the BBC.

    Philae was dropped on to the comet by Rosetta in 2014 but fell silent 60 hours later when its battery ran flat.

    Although it relayed pictures and data about its location to Earth, the lander’s actual resting place was a mystery.

    It was assumed Philae had bounced into a dark ditch on touchdown – an analysis now borne out by the latest pictures, which were acquired from a distance of 2.7km from the icy body.

    Wait after comet landing ‘bounce’

    The images from Rosetta’s high-resolution Osiris camera were downlinked to Earth late on Sunday night, and have only just been processed.

    Philae is seen wedged against a large over-hang. Its 1m-wide box shape and legs are unmistakable, however.

    Rosetta had previously surveyed this location – dubbed Abydos – without success.

    “Candidate detections” were made but none were very convincing.

    The difference today is a closer-in perspective and a change in the seasons on the comet, which means the hiding place is now better illuminated.

    The discovery comes just a few weeks before controllers plan to crash-land Rosetta itself on to the comet to formally end its mission.

    “With only a month left of the Rosetta mission, we are so happy to have finally imaged Philae, and to see it in such amazing detail,” says Cecilia Tubiana from the Osiris team.



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  • Rosetta has finally ended the data collecting phase of its mission – on timetable!

    http://www.bbc.co.uk/news/science-environment-37520420

    Europe’s Rosetta probe has ended its mission to Comet 67P by crash-landing on to the icy object’s surface.

    Mission control in Darmstadt, Germany, was able to confirm the impact had occurred when radio contact to the ageing spacecraft was lost abruptly.

    The assumption is that the probe would have been damaged beyond use.

    In the hours before the planned collision, Rosetta sent back a host of high-resolution pictures and other measurements of the icy dirt-ball.

    Scientists expect all the data gathered at 67P in the past two years to keep them busy for decades to come.

    Live: Rosetta ends its mission(see link)

    The loss of signal, when it happened, was greeted by muted cheers and handshakes – not too surprising given the bittersweet nature of the occasion.

    Some of the scientists watching on here in Darmstadt have spent the better part of 30 years on this project.

    Throughout Friday morning they had followed every twist and turn as the probe acquired its final observations and aimed for a touchdown spot on the head of the 4km-wide, duck-shaped comet.

    Comet 67P/Churyumov-Gerasimenko is currently heading away from the sun, limiting the solar energy available to Rosetta to operate its systems.

    Rather than put the probe into hibernation or simply let it slowly fade into inactivity, the mission team determined that the venture should try to go out in style.



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  • The analysis of data is still producing new information!

    http://www.bbc.co.uk/news/science-environment-39340800

    The comet visited by the Rosetta spacecraft is constantly being re-shaped, sometimes in dramatic fashion.

    It witnessed the collapse of entire cliffs at two locations on Comet 67P, events that were probably driven by exposure to sunlight.

    The European probe documented the widespread breakdown of materials on the surface during nearly two years orbiting the 4km-wide body.

    Details were presented at the Lunar and Planetary Science Conference (LPSC).

    Rosetta entered orbit around Comet 67P/Churyumov-Gerasimenko, to give its full name, in September 2014.

    The mission enabled researchers to capture multiple images of the comet’s surface features over time, to study how it changed.

    Repeated heating and cooling can tease the surface materials apart, leading to erosion, say the researchers.

    Mohamed El-Marry and colleagues observed cliff collapses at two regions on the comet called Ash and Seth. These collapses occurred as pre-existing fractures gave way, causing sections of material tens of metres long to crumble.

    In 67P’s Khonsu region, a massive boulder was seen to move a distance of 140m. This could have been caused by erosion of the sloped surface the boulder was sitting on, causing it to roll. But the hefty rock could also have been moved by an outburst of dust and gas from within the comet, says the team.



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