Reading up on the Rosetta mission.
Golly.
What makes the Rosetta mission so special?
Rosetta will be undertaking several ‘firsts’ in space exploration.It will be the first mission to orbit and land on a comet. That makes Rosetta one of the most complex and ambitious missions ever undertaken. Scientists had to plan in advance, in the greatest possible detail, a ten year trip through the Solar System. Approaching, orbiting, and landing on a comet require delicate and spectacular manoeuvres. The comet, 67P/Churyumov-Gerasimenko, is a relatively small object, about 4 kilometres in diameter, moving at a speed as great as 135,000 kilometres per hour.
And doing that very very very far away.
How did Rosetta reach comet 67P/Churyumov-Gerasimenko, and how long did it take?
Comet 67P/Churyumov-Gerasimenko loops around the Sun between the orbits of Jupiter and Earth, that is, between about 800 million and 186 million kilometres from the Sun. But rendezvousing with the comet required travelling a cumulative distance of over 6.4 billion kilometres. As no launcher was capable of directly injecting Rosetta into such an orbit, gravity assists were needed from four planetary flybys – one of Mars (2007) and three of Earth (2005, 2007 and 2009) – a long circuitous trip that took ten years to complete.
Golly.
But – it may not last as long as they’d hoped. It’s in a shadow so its battery isn’t going to last long because it can’t be recharged by the sun. So the scientists are working fast to grab what they can.
Yes, this whole thing has been such an amazing story! And now it’s balancing on two of its three feet, apparently. Floating on the surface, as it were. It’s wonderful what they’ve been able to achieve.
It does get some 1.5 hours of sunlight, I gather, so, who knows, it may last a bit past Friday. I would think if it looks hopeless, they might as well try a maneuver that would hop it to somewhere else. If it lands badly, they’d be no worse off in that case, and if it lands well, the rest of the mission might be rescued.
I think they are planning a hail Mary of some kind, while working fast on the top priority stuff first.
A little clarification may be in order: Rosetta, the main spacecraft, is not in jeopardy. Concern is for the Philae lander, which due to a couple of systems failures bounced about a kilometer from the preferred landing spot into a dark corner.
Oh, right – that’s what I meant. I guess I was thinking “it”=Rosetta=the whole project including Philae.
Bouncing one kilometer on a body four kilometers in diameter would be like bouncing from Ecuador to the North (or South) Pole on Earth. Amazing Philae didn’t fly off into space again, or go into orbit around the comet.
Pierce R Butler @5:
Sorta. Here’s Emily Lakdawala on Philae’s trajectory:
So it basically hit like a semi-deflated ball dropped vertically, exhausting a fair bit of energy on impact (Lakdawala says it went from 1m/s before first impact to 38cm/s after) and ensuring it wouldn’t pop back up to the same height as dropped. In fact, the team has wildly conflicting ideas about where it could be, consistent with a near-vertical hit:
There is one complicating factor, though (hence “sorta”); had it hit at a funny angle on something hard, Philae may have behaved more like a super-ball and shot off at a crazy angle with almost all the gravitational energy it had. That could have put it in or beyond orbit. It’s not likely, but then again neither was hitting too softly to trigger the harpoons.
Also, I heartily endorse Emily Lakdawala’s Twitter feed for the latest news; she’s not only on-site for the press conferences, she’s a member of the Planetary Society.
This video from August is fascinating, to see how the spacecraft used gravity to slingshot out to the comet’s orbit, then spent the last few months working its way around the comet in triangles before sending the lander down. Just getting there was more elaborate that I could imagine.
I find parallel parking a challenge.
Don’t forget Rosetta itself, which will be keeping tabs on the comet as it warms up. It’s already visited a couple of asteroids and a planet. Even without the lander this mission would be staggering.
According to one expert on the BBC this morning, the main scientific mission can be completed using a 60-hour battery (which was always the plan).
The solar battery is simply the cherry on the cake which will alow the mission to be extended if possible.
Of course, if they do attempt to reposition the probe, they will have to do so within the lifetime of the conventional battery system.
There is a live hangout update starting any second.
http://www.theguardian.com/science/across-the-universe/live/2014/nov/14/rosetta-mission-philaes-third-day-on-comet-as-it-happens
Worth repeating. It’s an awesome achievement.