Rosetta mission controllers have made the first call to “Go” for an attempted landing on Comet 67P, the European Space Agency (ESA) announced in a webcast Tuesday.
Scientists say there are still a few more key decisions to take in the coming hours before a planned separation of the landing craft Philae from the mother ship Rosetta on Wednesday.
Hours before separation, Philae’s on-board batteries are prepared and a fly wheel is started to give the probe stability on its journey to the comet surface. Without the gyroscopic effect of the fly wheel there’s a danger that the lander could turn end over end.
To release Philae, wax over a latch is melted and the lander is automatically unscrewed. If it fails there’s a back-up plan. A pyrotechnic charge will fire and push the lander away at just the right speed to set Philae on the right course.
Mission controllers then face a nervous seven-hour wait for Philae to reach the surface. The comet is so far away that a confirmation signal relayed from Rosetta, which remains in orbit around the comet, will take nearly half an hour to reach Earth.
The comet’s gravity is so weak that engineers have come up with ingenious solutions to keep Philae in place. At touchdown two harpoons fire out from the legs, a thruster on top of the craft helps push it to the surface and screws on each of the three feet help attach it to the comet.