Philae Idled, Batteries Drained; Needs Luck, Sunshine to Awake

Contact with the Philae lander was lost at 6:36 p.m. (CST) this evening, November 14th, before the normal loss of signal when Rosetta orbits below the lander’s horizon. Without sunlight to juice up its solar panels and recharge the its batteries, 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. All of the science instruments were deployed, including the instruments that required mechanical movement, such as APXS, MUPUS, and the drill, which is designed to deliver samples to the PTOLEMY and COSAC instruments inside the lander.

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. Contrary to earlier reports (or 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.

Jagged cliffs and prominent boulders are visible in this photo taken by OSIRIS on September 5, 2014 from a distance of 38.5 miles (62 km) and processed/colorized by Marco Faccin and Elisabetta Bonora. 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 Saturday morning (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 its orientation on the surface. Credit: ESA

The batteries were 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 illumination changes on the comet, that the Sun will rise again over the probe.

We may hear from the lander again or not. But if not, all the science instruments were deployed in the first two days of landing and data has been received.

* Update 7 a.m. (CST) November 15: A bit of good news! Rosetta has regained contact with Philae during the overnight communication pass, confirming that the lander still has power. The bad news is that the batteries will be completely drained sometime today.

Deputy flight director Elsa Montagnon watches data flow from Philae on the surface of comet 67P/C-G Credit: ESA
Science data transmitted by Philae on November 14th. Credit: ESA
Bob King

I'm a long-time amateur astronomer and member of the American Association of Variable Star Observers (AAVSO). My observing passions include everything from auroras to Z Cam stars. I also write a daily astronomy blog called Astro Bob. My new book, "Wonders of the Night Sky You Must See Before You Die", a bucket list of essential sky sights, will publish in April. It's currently available for pre-order at Amazon and BN.

View Comments

  • Thank you Bobfor the release of those scarce ESA pics! I'm just amazed at what we are witnessing
    Philae accomplished all its goals, all the science in ! Can't wait to hear the next press conference (any idea of when that'll take place?). And I agree with the prospect that the little guy will wake up as "Chury-Ger 67P"'s attitude will change as it rounds the Sun. Plus Rosetta is healthy and the show has just begun!
    I must add: Way to "GIF" :)

    • Agreed coverage has been awesome Bob. Fingers crossed that the sun evaporates that shady mountain into oblivion.

  • You're welcome BC! I can't find when the next press conference might be. Maybe if they succeed in moving the probe back into sunlight overnight, we'll hear about it.

  • Will Philae 'wake up and smell the coffee' when the comet's orbit processes some sunlight? We can only hope! Remember when the 'Jade Rabbit' was written off and considered dead, only to be revived when the lunar night ended?

    The ESA's proprietary information rules SHOULD be bent to at least show SOME of the high res. images... sheesh.

    • Dilo,
      Thanks for heads up. I came across this as a straight OSIRIS color image according to captions/images that came up in several different searches. I assumed it was correct because OSIRIS has taken color photos of the comet. I will update.

  • As I understand it, the batteries on Philae need to be heated to 0C before they can charge, so Philae needs to spend some of its illuminated time heating the battery before it can accumulate energy.

    As the comet nears the sun, prospects will improve for two reasons: first, more intense sunlight will provide more power to the panels Second, more sunlight means warmer Philae, so the batteries might not need to be heated for as long before they hit 0C, so more time for charging.

    There's also a chance that Philae could shift its position slightly in the coming months because it is not anchored firmly to the comet. IIUC its current position could hardly be any worse, so any change in position is likely to be an improvement. We may still see the little guy wake up. Fingers crossed.

    • Good question! It appears to have recorded the touchdown and should be able to image the lander once it can find it. The OSIRIS camera on Rosetta has a resolution of 5cm (2 inches) per pixel and Philae's about a meter across, so yes, it would seem so.

      • Thank you for the information, Mr. King. That would be more "cool" imagery on top of the spectacular images we have already seen. As a geologist and an armchair astronomer, the pictures have been breath-taking. The mission is a success in my book, despite the setbacks.

        • Orrery 66,
          I agree! We'll be at the comet for many months still, so lots of discoveries lie ahead. It should also be interesting when all the science that Philae gathered on the surface is shared. I'm especially interested in the soundings that will reveal 67P/C-G's internal structure as well as what they found in their sample analysis.

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