Yesterday the European Space Agency made history by completing the first soft landing on a comet. The Rosetta mission successfully dropped the lander Philae onto Comet 67P/Churyumov-Gerasimenko, and it has already sent back data and photos.
But the landing was not as soft as scientists were expecting: After the failure of Philae’s thrusters and harpoons, which would have anchored the lander to the surface, the lander seems to have bounced to a height of about half a mile. After a second, smaller bounce, it settled down on an unknown site likely half a mile away from its intended target. This region is a jagged landscape near what appears to be a steep cliff.
I’m in the shadow of a cliff on #67P. Where exactly? That’s what my team is in the process of finding out! #CometLanding
— Philae Lander (@Philae2014) November 13, 2020
Ulamec: @Philae2014 thought to be in blue area, 1st touchdown close to planned landing site (in red) #CometLanding pic.twitter.com/3TjkChhKoX
— ESA (@esa) November 13, 2020
Because of the shadow from the cliff, the lander is only getting a few hours of sunlight per day. That’s a problem, since it’s 60-hour battery needs to recharge via solar panels.
One of Philae’s feet is not touching the surface of the comet, and the other two have not screwed in. This means the lander is not anchored, and probably will not be able to drill into the comet’s soil without causing damage to the probe. If mission control tries to deploy the harpoon anchors now, it might send the lander flying into space again.
BBC reports that the ESA may try to move the lander to a new location.
The $1.4 billion Rosetta mission traveled 10-years and 4 billion miles to reach the comet. By studying its dust, gas, and ice content, the mission hopes to learn about the conditions of the early solar system and whether comets could have carried molecules that helped life on Earth develop.
Despite the unexpected circumstances, ESA is optimistic that the mission will still return valuable science.