Free Astronomy Magazine September-October 2014

SMALL BODIES mum speed of 55,000 km/h and enter into an orbit similar to that of 67P/Churyumov- Gerasimenko –a fundamental requirement for an approach at a relative low speed. All that necessary “wandering around” in the solar system ended up in a long journey that put 6.4 billion km on the probe's clock, hence about 6 billion km more than the dis- tance of the comet from Earth on the day of the rendezvous between the two players. But there was no alternative, in having to reach the cometary nucleus at a relative speed sufficiently low (about 1 metre per sec- ond) to gravitationally bind the probe to it –primary objective of the mission. However long Rosetta’s journey may have been, it O ne of the first images of the comet cap- tured by Rosetta on 28 June 2014, from a distance of 86,000 km. About a month later, on 25 July, the OSIRIS wide- angle camera re- corded a weak coma (top right). On the side, a col- lage showing the size of the nu- cleus compared to the coma and the increase of the morpholog- ical details be- tween 25 July (3000 km away) and 31 July (1327 km away). [ESA/ Rosetta/NAVCAM/ OSIRIS/MPS/UPD/L AM/IAA/SSO/INTA/ UPM/DASP/IDA, M. Di Lorenzo/ Ken Kremer]