The lander Philae, currently attached to the European Space Agency spacecraft Rosetta, will make its descent towards the surface of the nucleus of Comet 67P/Churyumov-Gerasimenko in early November. Five potential landing sites have now been selected, based on information collected during the first two weeks of observation from a distance of roughly 100 kilometers. This selection is based on flight dynamics constraints (both for orbiter and lander), communication opportunities (between Rosetta and Philae), illumination conditions (battery charging, overheating), surface characteristics (we do not want to land in pits, on boulders, on steep slopes or rough terrain), and last but not least – scientific relevance.
Overview of the nucleus of Comet 67P/Churyumov-Gerasimenko and location of the five potential landing sites. The nucleus is about 4 kilometers across. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
The potential landing sites have been labeled A, B, C, I, and J. Two of the sites, A and C, are located on the larger of the two lobes. The other three, B, I and J, are located on the smaller lobe. The labeling does not reflect any particular order of importance at this stage. The task now is to study the five sites in more detail, as Rosetta gradually approaches to within 30 kilometers of the nucleus. A decision on a primary landing site, as well as a backup, will be made on September 14. Whether to go for the primary or the secondary site will be determined whilst moving to within 20 kilometers of the nucleus, and a final decision will be made on October 14, roughly a month before the actual landing.
As a comet scientist, deeply involved in the Rosetta mission, this is a time of adventure, fascination, and the sense of discovery of something fundamentally important about our Solar System – but it also means long working hours, and not too much sleep. Which is why I have not been able to update this blog as often as I would like to – but with images like these, who can complain!
Site A is located on the larger lobe, with a good view of the smaller lobe. The terrain between the two lobes is likely the source of some outgassing. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Site B, within the crater-like structure on the smaller lobe, has a flat terrain and is thus considered relatively safe for landing. However, boulders and illumination conditions may pose a problem. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Site C is located on the larger lobe and is well illuminated but rich in surface features that potentially can make a landing risky. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Site I is a relatively flat area on the smaller lobe, but higher-resolution imaging is needed to assess the extent of the rough terrain. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Site J is similar to site I, and also on the smaller lobe, offering interesting surface features and good illumination. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
The scientific imaging system OSIRIS was built by a consortium led by the Max Planck Institute for Solar System Research (Germany) in collaboration with CISAS, University of Padova (Italy), the Laboratoire d’Astrophysique de Marseille (France), the Instituto de Astrofísica de Andalucia, CSIC (Spain), the Scientific Support Office of the European Space Agency (The Netherlands), the Instituto Nacional de Técnica Aeroespacial (Spain), the Universidad Politéchnica de Madrid (Spain), the Department of Physics and Astronomy of Uppsala University (Sweden), and the Institute of Computer and Network Engineering of the TU Braunschweig (Germany). OSIRIS was financially supported by the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), and Sweden (SNSB) and the ESA Technical Directorate.