The European Space Agency has unveiled the primary landing site for the Rosetta spacecraft’s 100kg lander, Philae, on comet 67P/Churyumov-Gerasimenko on 11 November.
The site, designated as Site J, the centre of which is indicated by the cross in this OSIRIS narrow-angle image.
The ESA said the site offers the minimum risk to the lander and is also scientifically interesting, with signs of activity nearby.
Most of the slopes at the site are less than 30°, reducing the chances of Philae toppling over during touchdown. It also appears to have relatively few boulders and receives sufficient daily sunlight to recharge Philae’s batteries.
Site J, Philae’s primary landing site. The centre is marked by the cross in this OSIRIS narrow-angle image. [Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA].
A context image of Comet 67P/Churyumov–Gerasimenko with the original five candidate landing sites for Rosetta’s lander Philae, and with the backup, Site C, indicated. [Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA].
The ESA said choosing the site was not easy:
“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 DLR German Aerospace Center.
“None of the candidate landing sites met all of the operational criteria at the 100% level, but Site J is clearly the best solution.”
“We will make the first ever in situ analysis of a comet at this site, giving us an unparalleled insight into the composition, structure and evolution of a comet,” says Jean-Pierre Bibring, a lead lander scientist and principal investigator of the CIVA instrument at the IAS in Orsay, France.
A detailed operational timeline will now be prepared to determine the precise approach trajectory of Rosetta in order to deliver Philae to Site J. The landing must take place before mid-November, as the comet is predicted to grow more active as it moves closer to the Sun.
The gravitational field of the comet has a force 100,000 times less than that on Earth, meaning Philae will weigh only one gram on the surface. It will anchor itself to the surface using harpoons and ice screws.