Ptolemy: Operations at 21 Lutetia as part of the Rosetta Mission and Future Implications

The Rosetta mission and Ptolemy: Rosetta is the European Space Agency ‘Planetary Cornerstone’ mission intended to solve many of the unanswered questions surrounding the small bodies of the Solar System – the comets, the asteroids and the trans-Neptunians. Launched in March 2004 it is now over halfway through its cruise, leading up to entering orbit around the nucleus of comet 67P/Churyumov-Gerasimenko in mid-2014. To date, this cruise has included three gravitational assist manoeuvres using Earth and one such manoeuvre using the gravity well of Mars, necessary to match the orbit of Rosetta to that of the target comet. In addition, targeted flybys of two asteroids have returned a plethora of data to be compared with the comet observations to come. These flybys were of the 5.3 km diameter E-type asteroid 2867 Steins on September 5th 2008, and a similar 3,162 km flyby of the 100 km diameter asteroid 21 Lutetia on July 10th 2010, the focus of this work.