2014년 11월 17일 월요일

Rosetta Spies Philae's First Precision Comet Landing



As the Philae lander was moments from making its (first) historic touchdown on Comet 67P/Churyumov-Gerasimenko, the orbiting Rosetta spacecraft was overhead with its navigation camera (NAVCAM) trained on the exact spot where Philae was predicted to land. In these two photos of Philae’s landing site — named “Agilkia” — the effects of Philae’s touchdown can be easily seen.
NEWS: Philae to Attempt Risky Comet ‘Hop’ for Survival
In the left photo, 3 minutes and 34 seconds before touchdown when the lander was 250 meters (820 feet) above the comet, the undisturbed landing zone is highlighted in red. In the right image, taken 1 minute and 26 seconds after touchdown, a darkened area within the red circle can be clearly seen. The darkened area is likely dust that was kicked up by the lander’s legs. To emphasize the precision of this first landing, a small green box shows where the lander was calculated to land by mission scientists.
Considering the resolution of these images represent 1.3 meters per pixel, the landing was only around 10 meters from its calculated landing spot — a landing precision that is impressive to say the least!
PHOTOS: Rosetta’s Landing: When Philae Grabbed a Comet
Of course, the lander is not in this shot as, immediately after touchdown, Philae’s anchoring harpoons failed to fire, causing it to bounce off the surface. Though much of the landing impact was absorbed by the landing system, Philae was propelled back into space for a little under two hours until the weak cometary gravity pulled it back down again, causing it to bounce for a second time, approximately 1 kilometer from this initial landing site. The lander touched down a total of three times.
Mission scientists are now scouring other Rosetta NAVCAM images of the comet’s surface to see if they can see where Philae eventually settled, apparently on the slope of a crater rim. They have yet to find the plucky little lander that is collecting as much science before its batteries run dead within the next 24 hours.
READ: What’s next for Philae?
Source: ESA

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