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I'm confused, if after the first contact the lander expected to be stationary but was actually moving 20cm/s away from the comet, how is the lander still on the
by macrael 12y ago
I'm confused, if after the first contact the lander expected to be stationary but was actually moving 20cm/s away from the comet, how is the lander still on the comet? 20cm/s seems like it would take it off into space pretty quickly. How does a lander "bounce" on a comet without an appreciable gravity, wouldn't it only bounce once?
- acqq 12y agohttp://blogs.esa.int/rosetta/2014/11/14/three-touchdowns-for-rosettas_lander/ http://blogs.esa.int/rosetta/2014/11/14/three-touchdowns-for... "But then the lander lifted from the surface again – for 1 hour 50 minutes. During that time, it travelled about 1 km at a speed of 38 cm/s. It then made a smaller second hop, travelling at about 3 cm/s, and landing in its final resting place seven minutes later." It's not that its direction was directly away from the comet. It's that it's estimated that it slowly moved during almost 2 hours. The sensors detected landing once then almost 2 hours later again. The speed is an estimate, but it's reasonable. Also note the shape of the comet, it isn't spherical.
- dllthomas 12y agoThe mass of comet seems[1] to be about 10^13 kg. If my math is right[2], I think that puts escape velocity above 20cm/s out to about 33 kilometers. [1] http://en.wikipedia.org/wiki/67P/Churyumov%E2%80%93Gerasimenko http://en.wikipedia.org/wiki/67P/Churyumov%E2%80%93Gerasimen... [2] http://www.wolframalpha.com/input/?i=%282+G+%2810^13+kg%29%29%2F%2820+cm%2Fs%29^2 http://www.wolframalpha.com/input/?i=%282+G+%2810^13+kg%29%2...
- mikeash 12y agoEscape velocity from the comet's surface is about 1m/s. 20cm/s would not send the lander away forever.