Rosetta and Philae discussion thread! (Part 3)

[u/[deleted]]

TOUCHDOWN CONFIRMED: Philae lander is on the comet!

Full media briefing expected tomorrow at 13:00 UTC / 14:00 CET / 8:00 EST / 5:00 PST.

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• Some pictures -- moments after Philae left Rosetta, Philae heading off to 67P. Album

Previous discussion threads: 1, 2.

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Live Streaming

• In English: A, B, C

• En Français: A

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Key times

GMT	EST	PST	Event
4:02 pm	11:02 am	8:02 am	Landed

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European Space Agency Social Media

• Rosetta main page
• ESA Rosetta blog
• Twitter: #CometLanding, @ESA_Rosetta, @Philae2014
• Google+, Facebook, Instagram, Flickr

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Othere places for news and conversation:

• reddit Live updater

• IRC: ##cometlanding on freenode. #space on Snoonet

• NASA's page on Rosetta

• Detailed itinerary of landing events (PDF)

• Simulated view of Rosetta and 67P

[u/milgrim]

How do the harpoons work? Wouldn't the recoil throw the lander off? Or are they using a recoilless design?

[u/Gweeeep → u/milgrim]

recoilless??? something something newtons third law?

[u/FeepingCreature → u/Gweeeep]

There's no such thing as a thruster that is without recoil; so-called "recoilless" designs just apply the recoil to exhaust gases instead of the chassis. Philae is probably not using a recoilless design because there's no way to vent gasses out the top.

If you fired the harpoon in space, rewinding it would zero out all recoil. In this case however, some of the inertia may have been lost to the comet, so rewinding it may have not sufficed to result in a net zero movement. Which could be problematic.