The European Space Agency’s Rosetta’s lander, Philae, will target Site J, an intriguing region on comet 67P/Churyumov-Gerasimenko that offers unique scientific potential, with hints of activity nearby, and minimum risk to the lander compared to the other candidate sites. The 220-pound (100-kilogram) lander is scheduled to reach the surface on November 11, where it will perform in-depth measurements to characterize the nucleus. Rosetta is an international mission spearheaded by the European Space Agency with support and instruments provided by NASA.
Site J is on the “head” of the comet, an irregular shaped world that is just over 2.5 miles (four kilometers) across at its widest point. The decision to select Site J as the primary site was unanimous. The backup, Site C, is located on the “body” of the comet.
“As we have seen from recent close-up images, the comet is a beautiful but dramatic world – it is scientifically exciting, but its shape makes it operationally challenging,” says Stephan Ulamec, Philae Lander Manager at the German Aerospace Center (DLR) in Cologne. “None of the candidate landing sites met all of the operational criteria at the 100-percent level, but Site J is clearly the best solution.”
A number of critical aspects had to be considered, not least that it had to be possible to identify a safe trajectory for deploying Philae to the surface and that the density of visible hazards in the landing zone should be minimized. Once on the surface, other factors come into play, including the balance of daylight and night-time hours, and the frequency of communications passes with the orbiter.