The Rosetta mission, approved by the European Space Agency (ESA) in 1993 and launched in March 2004, is one of the most ambitious endeavors of European spaceflight. On its way to comet 67 P/Churyumov-Gerasimenko the space probe has already (Sept. 2008) flown by the main-belt asteroid Steins and is due to fly by another main-belt asteroid, Lutetia, in July 2010. In both cases the Rosetta observations provide information on size, shape and surface chemical composition. After more than 10 years travel time with 4 swing-by maneuvers Rosetta will reach comet 67 P/Churyumov-Gerasimenko in 2014. Rosetta will rendezvous with the comet at a distance of about 3 astronomical units from the Sun. The first measurements will help to identify a place suitable for landing; then Philae, the lander module, will be released from the orbiter and descend to the comet’s surface.
Both modules will stay with the comet on its several month-long journey to perihelion, the comet’s closest point to the Sun. The instruments will precisely monitor how the formerly cold and inactive chunk of dust and ice “awakes” under the influence of the increasing solar heat flux.
The ESA mission takes its name from the Egyptian town of Rashid, or Rosetta, where archeologists in 1799 found a stone with ancient hieroglyphic inscriptions in three different languages. With the help of inscriptions found on an obelisk from the town of Philae, archeologists were able to decipher the enigmatic hieroglyphs. Cometary scientists are hoping for similarly fundamental insights from the investigation of Churyumov-Gerasimenko by means of the Rosetta and Philae space probes. In contrast to planets, moons and asteroids, comets spend most of their existence in the cold outer parts of the planetary system. Therefore they may still contain original matter preserved in a frozen state from the time of formation of the planets.
Rosetta, with 10 experiments onboard the orbiter and 10 experiments onboard the lander, will investigate the comet’s nucleus in detail. The main objectives of the mission are:
- The global characterization of the comet’s nucleus and the surface topography.
- The characterization of the chemical, mineralogical, and isotopic compositions.
- To derive the physical properties of the comet’s nucleus, such as internal structure, and investigate thermal, electrical and magnetic properties.
- To monitor the development of cometary activity as the comet approaches perihelion.
With the help of the data collected scientists will gain insight into the formation of the solar system and, possibly, the development of life.
The German Aerospace Center is heavily involved in the landing module Philae. Scientists in the Asteroids and Comets Department are responsible for the ROLIS, MUPUS, SESAME experiments and are involved in four further experiments.