Philae, Now Idle, Needs Kiss Of Sunlight To Awake

The animated image below provides strong evidence that Philae touched down for the first time almost precisely where intended. The animation comprises images recorded by Rosetta’s navigation camera as the orbiter flew over the (intended) Philae landing site on November 12th. The dark area is probably dust raised by the craft on touchdown. The boulder to the right of the circle is seen in detail in the photo below. Credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

Contact with the Philae lander was lost at 6:36 p.m. (CST) this evening November 14th. Without sunlight to juice up its solar panels and recharge the battery, the craft will remain in “idle mode” – maybe for a long time. All its instruments and most systems on board have been shut down.

“Prior to falling silent, the lander was able to transmit all science data gathered during the First Science Sequence,” says DLR’s Stephan Ulamec, Lander manager. Contrary to earlier reports and initial speculations, Valentina Lommatsch from the German Aerospace Center explained that all three of Philae’s legs are on the ground. But the lander appears to be tipped up at an angle because one of the scenes from the panorama (below) shows mostly sky.

This image was taken by Philae’s down-looking descent ROLIS imager when it was about 131 feet  (40 meters) above the surface of the comet. The surface is covered by dust and debris ranging from millimeter to meter sizes. The large block in the top right corner is 16.4 feet (5 m) in size. In the same corner the structure of the Philae landing gear is visible. Credit: ESA/Rosetta/Philae/ROLIS/DLR

No contact will be possible unless maneuvers by controllers on the ground nudge Philae back into a sunnier spot. On its third and final landing, it unfortunately came to rest in the shadow of one of the comet’s many cliffs.

Jagged cliffs and prominent boulders are visible in this color image taken by OSIRIS, the Rosetta spacecraft’s scientific imaging system, on September 5, 2014 from a distance of 38.5 miles (62 km). Credit: ESA/Rosetta/MPS for OSIRIS team

This evening, mission controllers sent commands to rotate the lander’s main body, to which the solar panels are fixed. This may have exposed more panel area to sunlight, but we won’t know until tomorrow (Nov. 15) at 4 a.m. (CST) when the Rosetta orbiter has another opportunity to listen for Philae’s signal.

Our last panorama from Philae?  This image was taken with the CIVA camera; at center Philae has been added to show how it landed (and took the photos) while on its side. Credit: ESA

The battery was designed to power the probe for about 55 hours. Had Philae landed upright in the targeted region, its solar panels would have been out in the open and soaking up the sunlight needed for multiple recharges. There’s also the possibility that months from now, as seasons progress and solar illumination changes on the comet, the Sun will rise again over the probe.

We may hear from the lander in the coming days or not. But if not, the original plan of gathering as much science as possible in the first two days of landing was for the most part a success.

* UPDATE 7:30 a.m. Nov. 15: Some good news! Rosetta did get back in touch with Philae during the overnight pass. Data was received, but the batteries are expected to be completely drained sometime today.

17 Responses

  1. Troy

    Those color images of the cliffs are simply delicious. The black & white images are so drab, but the color ones I get the feeling of being there. Is it just me or is this comet more dirt than snowball?
    So sad that this will likely be the end of the Philae data set. I’m very doubtful they’ll be able to wake it up in August (!) when the seasons and sunlight changes. They’ve tried to resurrect some Mars probes, electronics are cold hardy but not that cold hardy. Hope I’m wrong on that one. I bet they wish they spent the extra Euros on some RTGs!

  2. Edward O'Reilly

    Not related to Rosetta,but did you notice any auroras in the north Fri night-Sat morning? The aurora oval was displaced pretty far south and,when I went out,noticed a glow in the sky just below the Big Dipper,in the NNE.And this was with some light pollution.

    1. astrobob

      I was out early around 6:30-7 p.m. and then didn’t go out again until around 11 p.m. (CST). Both times I didn’t see any trace of aurora, but it may have been active at other times. The graphs of magnetic activity show that although we didn’t hit the minor storm level overnight, we got close. What time did you see it?

  3. Edward O'Reilly

    Saw it at about 11:30PM Central time Friday night(which was 1:30AM in New Brunswick).The aurora oval was over the far northern part of the province and the solar wind was at around 500. I noticed a distinct glow in the north northeast,not far from the tail star of the Big Dipper. I wasn’t in a particularly dark-skies location,either.

  4. Edward O'Reilly

    As I wasn’t in the countryside(and moon was up),I wasn’t in the best spot to see it;didn’t notice any shafts or pillars of light but there was a distinct glow and it was in the north;so agree that there was probably some minor activity going on.

    1. astrobob

      You can always try to confirm your observation by returning to the area on a night of no aurora to see if the glow might still be there.

  5. Norman Sanker

    Hey Bob, am I correct in assuming that it will be months (if ever) until we have any speculation on how and why the harpoon system failed? Just wondering.

    1. astrobob

      I heard it was because the explosive material used to fire the harpoons did not ignite in the vacuum of space. One thinks that could have been tested beforehand. I caution that this is hearsay – I haven’t heard an official explanation.

          1. Norman Sanker

            Wasn’t there also a system that was supposed to thrust the lander down against the comet’s surface while the feet screwed into the ice? That didn’t work either but seems unrelated to the harpoons. And they didn’t try any last-ditch efforts to knock Philae loose and hope she’d land in some improved position? That might be rash if there is some hope that the comet’s changing position relative to the sun will eventually give the lander more light. It’s possible that ten years in space (not really testable) had some effect on the harpoon charges that neutralized them, even if they were tested and passed before launch. Reminds me a bit of the Hubble Telescope primary mirror fiasco where the testing device had been misassembled and NASA ignored a warning from an amateur telescope maker that the mirror wasn’t quite right. The best laid plans… Norman

          2. astrobob

            Yes, that system failed as well as did the ice screws. Before the batteries went dead they were able to nudge the craft into what they hope will be a better position to catch sunlight in a few months when the Sun’s orientation at the comet will be more favorable at the lander’s location.

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