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SYFY WIRE Bad Astronomy

Quick Philae Update

By Phil Plait

There’s more news this morning about Philae, the European Space Agency lander that is on the surface of the comet 67P/Churyumov-Gerasimenko. Recap: It set down on the comet yesterday, but the harpoons didn’t deploy. It bounced, twice, and came to rest a kilometer or so from the desired landing site. It’s not known precisely where it is, and it’s too small for the Rosetta spacecraft, still orbiting the comet, to easily find it.

Update, Nov. 14, 2014 at 18:00 UTC: The ESA Rosetta blog has posted an update, which has information about what the instruments on Philae have been doing so far.

Philae came to a rest on its side, unfortunately in a hole or an area surrounded by tall outcroppings. Because of this it’s not getting enough sunlight for its solar power cells to keep it charged. It has two batteries, but the instruments are using up that power rapidly. If nothing is done, it will run out of power soon.

If it does run out of power, all is not necessarily lost; as the comet nears the Sun the cells may receive enough charge to turn the lander back on. This is speculative, though.

The good news is the lander is working and taking data; dozens of high-res photos have been taken, for example, and are waiting to be transmitted up to Rosetta so they can be sent back to Earth. Contact between Rosetta and Philae is intermittent as the orbiter moves around the comet and the line of sight clears to the lander. The next good pass should be today around 21:00–23:00 UTC (16:00–18:00 Eastern).

I wondered yesterday if outgassing from the comet could dislodge Philae, but apparently it’s too dense for that to happen. One idea engineers are looking into is turning on the lander’s flywheel (a heavy, rapidly rotating disk that is used to rotate the lander)—Lander Manager Stephan Ulamec calls it “a very attractive idea”—which might provide enough torque to get Philae upright. There may not be enough power to spin it up though.*

I get the impression that, of course, people on the Philae team are disappointed at what happened, but are still really happy that it worked at all and got as far as it did. I keep hearing comments that anything they get now is “cream on top” of the amazing data they’ve already received. In other words, this mission was a success!

Let’s hope that the success it’s had so far is just the beginning, and not the end. And remember: Rosetta is still orbiting and going strong. That part of the mission has many months of discovery ahead of it.

*Correction, Nov. 14, 2014: This post originally misspelled the first name of Stephan Ulamec.

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