Choice for Philae touchdown site on Rosetta narrows.

Using detailed information collected by ESA’s Rosetta spacecraft during its first two weeks at Comet 67P/Churyumov-Gerasimenko, five locations have been identified as candidate sites to set down the Philae lander in November – the first time a landing on a comet has ever been attempted.

Before arrival, Comet 67P/Churyumov-Gerasimenko had never been seen close up and so the race to find a suitable landing site for the 100 kg lander could only begin when Rosetta rendezvoused with the comet on 6 August.

The landing is expected to take place in mid-November when the comet is about 450 million km from the Sun, before activity on the comet reaches levels that might jeopardise the safe and accurate deployment of Philae to the comet’s surface, and before surface material is modified by this activity.

The comet is on a 6.5-year orbit around the Sun and today is 522 million km from it. At their closest approach on 13 August 2015, just under a year from now, the comet and Rosetta will be 185 million km from the Sun, meaning an eightfold increase in the light received from the Sun.

While Rosetta and its scientific instruments will watch how the comet evolves as heating by the Sun increases, observing how its coma develops and how the surface changes over time, the lander Philae and its instruments will be tasked with making complementary in situ measurements at the comet’s surface.

The lander and orbiter will also work together using the CONSERT experiment to send and detect radio waves through the comet’s interior, in order to characterise its internal structure.