Free Astronomy Magazine September-October 2014

But let’s get back to the approach flight of Rosetta to 67P/Churyumov-Gerasimen- ko. The first three of ten final path cor- rections planned for slowing down and precision steer the probe, were made between 7 May and 4 June 2014, in view of its scheduled rendezvous with the comet. Two other minor corrections were made on 18 June and 2 July. The five re- maining, and even minor, adjustments will be used for setting Rosetta on a pro- visional orbit. Since making that kind of manoeuvres means firing small rockets or thrusters, it is advisable that they last as little as possible, given that the pol- lution caused by their use could con- taminate the envi- ronmental infor- mation collected by the probe, as for example hap- pened at 360,000 km from the tar- get when Rosetta detected along with water vapour released by the comet also a fair amount of hydra- zine exhaust gas SMALL BODIES centre picture, which shows in great detail a seemingly lunar landscape, with several large boulders scat- tered among cra- ters, corrugations and stretches of sand. The left image taken with the WAC, was in- stead shot on 7 August when the probe was just 84 km from the nu- cleus. [ESA/Ro- setta/NAVCAM] mous Rosetta Stone. And what about the com- et's name? As common practice, it is named after its discoverer, in this case the astrono- mers Klim Churyumov and Svetlana Gerasi- menko (the former noticed the presence of the new cometary object on a photographic plate taken by the latter), while 67P, instead, indicates the sequence number in the cata- logue of periodic comets, i.e. those with closed orbit around the Sun. O n the left, a high-resolu- tion shot (2.2 metres/pixel) of 6 August when Rosetta was 120 km away, showing the junction point between the two blocks forming the cometary nu- cleus. The same circumstances apply for this