The Absolute Cosmos: Scientists reveal Philae comet lander’s 2nd touchdown in Skull-Top Ridge
Astronomers have located the second place where European Space Agency’s (ESA) Philae lander touched down on comet 67P/Churyumov-Gerasimenko, six years ago.
Philae lander was the part of Rosetta spacecraft until it got separated from the spacecraft on 12th November 2014 and made the first ever soft landing on the surface of four kilometres wide comet.
The robotic Philae lander somehow managed to touched down on the comet, but the landing didn’t go as was expected. Philae’s anchoring harpoons failed to deploy properly and the lander bounced off comet in two separate places.
It finally got settled in dark cave like structure two hours after first touching the surface. Comet 67P’s gravity is fifty thousand times weaker than that of our Earth, so objects that bounce there tend to stay up for a while.
The lander was not able to get enough sunlight in its final resting place, as a result its secondary battery didn’t get recharge required to function. It could only gathered scientific data for few days, yet it helped astronomers to better understand comet 67P.
The mission team was quick to locate the Lander’s first touch down site in images taken by Rosetta spacecraft, which began orbiting the comet in August 2014. After rigorous imagery search, the lander was found in September 2016, but its second touch down location remained unclear.
According to ESA astronomers, finding the location of final touch down was of great importance as the Philae sensors suggested that it had dug into the surface, probably revealing the billions of years old ice hidden below.
But now according to a new study, a team led by astronomer O’Rourke has been able to locate the second touchdown site. The site is located in a region that has been nicknamed “skull top ridge”.
The study reports that the second touchdown site lies just thirty meters from lander’s final resting place. As per team the lander almost spent two minutes at the second touchdown site, striking the surface for at least four different times in the process.
These impacts excavated the bright material that according to scientists is water ice. The newly unearthed material appeared different from the rest of the comet’s surface, which has been subjected to harsh space environment conditions.
One of the impacts scooped a twenty five centimetres deep dent into a comet ice boulder. Scientists further computed a porosity of seventy five percent for this boulder. The calculation is consistent with the porosity value on entire comet.
Neither Philae lander nor Rosetta spacecraft is operational today.