As more details emerge regarding Philae's historic landing on a comet, mission managers are realizing just how lucky they are to have completed such a feat.
According to a new post on the European Space Agency's (ESA) Rosetta Blog, the lander bounced on the surface of Comet 67P several times. The analysis made the landing seem more like collision than anything else.
Hans-Ulrich Auster, from the Technische Universität Braunschweig, Germany, serves as a co-principal investigator on the Rosetta Lander Magnetometer and Plasma Monitor (ROMAP). He said the ROMAP has allowed Rosetta mission managers to get a better play-by-play of what happened in deep space on Nov. 12.
"Any motion of Philae in a magnetic field - even if it is small - can be seen by field changes in the measured magnetic field direction," he said in the blog post.
At the time of the detachment, Philae was rotating approximately once per five minutes. After seven hours of descending on the comet, Philae touched down on the comet but bounced off the surface, increasing its rotation rate to about 13 seconds per spin. Then it apparently grazed a crater on the comet, slowing the rotation a bit before the probe eventually found its landing spot.
But where Philae landed was not where the ESA had intended and the probe was stuck in the shadow of a cliff. It has been in hibernation mode since the cliff is blocking its solar panels access to sunlight.
Still, the new developments may have mission managers feeling fortunate.
"It was not a touchdown like the first one, because there was no signature of a vertical deceleration due to a slight dipping of our magnetometer boom as measured during the first and also the final touchdown," Hans-Ulrich said. "We think that Philae probably touched a surface with one leg only - perhaps grazing a crater rim - and after that the lander was tumbling. We did not see a simple rotation about the lander's z-axis anymore, it was a much more complex motion with a strong signal in the magnetic field measurement."
