ROSETTA In The Year Of The Swing-bys
- Paper number
IAC-07-A3.5.02
- Author
Dr. Paolo Ferri, European Space Agency/ESOC, Germany
- Coauthor
Mr. Andrea Accomazzo, European Space Agency/ESOC, Germany
- Coauthor
Mrs. Elsa Montagnon, European Space Agency/ESOC, Germany
- Coauthor
Mr. Jose Morales, European Space Agency/ESOC, Germany
- Year
2007
- Abstract
The International Rosetta Mission, a cornerstone mission of the European Space Agency Scientific Programme, was launched on 2nd March 2004 on its 10 years journey towards a rendezvous with comet Churyumov-Gerasimenko. Once reached the comet nucleus in summer 2014, Rosetta will orbit it for about 1.5 years down to distances of a few Kilometres and deliver a Lander, named Philae, onto its surface. In the long cruise to its target, Rosetta performs four gravity assist manoeuvres, three times with Earth and once with Mars. After the first successful Earth swing-by in March 2005, the year 2007 started with a highly critical Mars swing-by, carried out in February at a target altitude over the planet’s surface of only 250 Km. This manoeuvre re-oriented the spacecraft trajectory towards the second Earth swing-by, planned for November 2007. In order to optimise fuel consumption the targeting of the Mars swing-by had to be performed with extreme precision, within a few Km from the ideal target. Precise navigation required an intense tracking campaign in the months preceding the closest approach, involving both the ESA and the NASA Deep Space Networks. In addition to the traditional radio frequency tracking and ranging, Delta-DOR techniques were applied throughout the phase. The spacecraft closest approach to Mars occurred on 25th February at 01:58, within about 1 Km from the target. During the swing-by the spacecraft entered the shadow of Mars for 24 minutes. This represented a unique situation for the Rosetta mission. In fact the spacecraft was designed, for an eclipse-free mission, compatible with the original trajectory to comet Wirtanen; however the new mission to comet Churyumov-Gerasimenko, selected in 2003 after a launch postponement of 13 months, had to include an eclipse at Mars. The spacecraft on-board software, and in particular its fault management autonomy, was reconfigured shortly before the eclipse to sustain the temporary loss of sunlight on the solar panels. Also, the power consumption of all on-board systems had to be reduced to the minimum, in order for the essential systems to survive across the eclipse on the available battery power and energy. Although all the scientific instruments had to be switched off during the eclipse period, and notwithstanding an unfavourable geometry of the inbound trajectory, scientific operations were carried out before and after the closest approach to the planet, including Mars and Phobos observations from several of the on-board remote sensing instruments. After the Mars swing-by science operations will continue with a long Jupiter observation campaign, in support of the science observations of New Horizons during its Jupiter swing-by phase. Following a deterministic trajectory correction manoeuvre in April the spacecraft will enter a short passive cruise phase, whilst on ground preparation for the upcoming Earth swing-by will begin. This paper continues the periodic reporting of the operational experience from the Rosetta mission operations. Preparation and execution of the swing-by activities are described. As derived from the lessons learned in this phase, a generic approach to be adopted for planning and execution of planets swing-by phases, including those of future missions like BepiColombo, is presented.
- Abstract document
- Manuscript document
IAC-07-A3.5.02.pdf (🔒 authorized access only).
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