[meteorite-list] Philae Spacecraft Landed 3 Times on Speeding Comet: See Its First Photos

[Ron Baalke]

http://www.space.com/27761-philae-comet-landing-bounces-first-photos.html

Philae Spacecraft Landed 3 Times on Speeding Comet: See Its First Photos
by Miriam Kramer
space.com
November 13, 2014
                             
The European Space Agency's Philae probe landed on the Comet 67P/Churyumov-Gerasimenko 
not once or twice, but three times, when its anchor system failed to fire. 
But despite that, the probe is healthy and beaming back stunning photos 
of its new home.

European Space Agency (ESA) officials still aren't exactly sure where 
the Rosetta spacecraft's lander, called Philae, ended up after bouncing 
on the surface of Comet 67P/C-G twice before finally settling down. At 
the moment, officials think the lander - which was released down to the 
comet from the Rosetta orbiter Wednesday (Nov. 12) - is in a potentially 
precarious position away from its initial touchdown site. The new comet 
surface photos from Philae, released by ESA today, show the lander shadowed 
by what appears to be some kind of cliff.

"It's amazing where we are," Jean-Pierre Bibring, Rosetta mission scientist, 
said during an ESA news conference today (Nov. 13). "We landed...Please 
do not put the emphasis on the failure of the system. It's gorgeous where 
we are." 

The new photos represent the first-ever pictures taken by a probe from 
the surface of a comet. Philae landed on the comet as the icy object, 
the lander and Rosetta were speeding across deep space at more than 11,000 
mph (17,702 k/h).

Philae's harpoon system, meant to fire just after landing, did not deploy 
when Philae got to the comet's surface, and officials with the mission 
are not sure if they want to try re-firing them now. Officials are worried 
that, if the harpoons don't fire properly, they might cause the spacecraft 
to jump again.

Mission controllers now think that Philae could have bounced as far as 
1 kilometer (0.6 miles) into space before making its second landing. The 
spacecraft then bounced away from the surface again on a shorter jump 
before coming to a rest in its current position, officials said today.

Officials are planning on trying to find Philae's spot on the comet's 
surface in images its mothership Rosetta took from the comet's orbit.

One of Philae's three landing legs could be off the surface of the comet, 
so mission operators are still trying to understand exactly how the lander 
is positioned on the comet's surface. ESA officials still aren't sure 
whether Philae's drill instrument (designed to investigate the composition 
of the comet's surface) will work properly in the lander's current position.

"We are also hesitant to, in the next hour or days, to activate the drill 
because drilling without being anchored, and without knowing how you are 
[positioned] on the surface, is dangerous," Stephan Ulamec, Philae lander 
manager at the DLR German Aerospace Center, said during the news conference. 
"We might just tip over our lander."

Scientists also think that the lander is not getting enough sunlight from 
its currently shadowed position, and that could reduce the life of the 
lander on Comet 67P/C-G's surface. Instead of the 6 to 7 hours of sunlight 
expected at the first landing site, Philae is only receiving about 1.5 
hours of sunlight on its solar panels in the new spot, ESA officials said.

But scientists working with the mission are still hopeful.

"Even if we think the mission ends because the first science sequence 
may end, and the batteries are low, the lander is not necessarily dead," 
Ulamec said. It's possible that the lander could go into hibernation mode 
and wake up again when it gets more sunlight, but it's also possible that 
might not happen, he added.

The Rosetta spacecraft and Philae lander arrived at Comet 67P/C-G in August 
2014 after launching to space in 2004. Rosetta is expected to stay with 
the comet, studying it until December 2015.