Anticipation is intense as the Philae lander free-falls to the surface of Comet Churyumov-Gerasimenko this morning. The final “Go” for separation from the Rosetta spacecraft was given around 2:30 a.m.; Philae’s now well on its way to Agilkia, the target landing site atop the 67P/C-G’s largerEverything is running smoothly except for one potential problem. During checks on the lander’s health, it was discovered that the active descent system, which provides a thrust to avoid rebound at the moment of touchdown, can’t be activated.
At touchdown, as Philae anchors itself to the comet with harpoons and ice screws on each of its legs, the thruster on top of the lander is supposed to push it down to counteract the force of the harpoon firing in the opposite direction.
“The cold gas thruster on top of the lander does not appear to be working so we will have to rely fully on the harpoons at touchdown,”says Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Center.
Philae is on target to land on the comet around 9:37 a.m. CST (15:37 UT). Confirmation of touchdown will take about 28 minutes as the signal, traveling at the speed of light, works its way back on Earth. As Philae floats down to the comet it not only has to deal with the 67P/C-G’s gravity but also the cloud of dust and ice grains escaping from the surface. Check back for regular updates and photos!