During the mid 1980s media and scientific hype on the Halley Comet, a number of international space probes were sent to explore the cometary phenomena, most prominent among them being ESA's highly successful Giotto. After the probes returned a treasure throw of valuable scientific information it was becoming obvious that follow-ones were needed that would shed more light on the complex cometary composition and resolve the newly opened questions.
It was originally to have been launched on January 12, 2003 to rendezvous with the comet46P/Wirtanen in 2011. However this plan was abandoned after an Ariane 5 failure on December 11, 2002. A new plan was formed to target the comet 67P/Churyumov-Gerasimenko with launch on February 26, 2004 and rendezvous in 2014. After two cancelled launch attempts, Rosetta was launched on March 2, 2004 at 7:17 GMT. Besides the changes made to launch time and target, the mission profile remains almost identical. As before, the Rosetta craft will enter a very slow orbit around the comet and gradually slow down in preparation for releasing a lander that will make contact with the comet itself. The lander, named "Philae", will approach 67P/Churyumov-Gerasimenko at relative speed around 1 m/s and on contact with the surface, two harpoons will be fired into the comet to prevent the lander from bouncing off. Additional drills are used to further secure the lander on the comet.
Once attached to the comet, the lander will begin its science mission:
Characterisation of the nucleus
Determination of the chemical compounds present
Study comet activities and developments over time
The exact surface layout of the comet is currently unknown and the orbiter has been built to map this before detaching the lander. It is anticipated that a suitable landing site can be found, although few specific details exist regarding the surface.
The probe is named after the Rosetta Stone, as it is hoped the mission too will unlock the secrets of how our universe looked before planets formed. The lander is named after the Nile island Philae, where an obelisk was found that helped decipher the Rosetta Stone.
Planned mission timeline
This is the planned timeline for the mission after its launch:
ESA's Rosetta mission is successfully launched at 07:17 GMT (08:17 Central European Time). File:KOU01-182614-pih L.jpgLaunch of Rosetta The launcher successfully placed its upper stage and payload into an eccentric coast orbit (200 x 4000 km). About two hours later, at 09:14 GMT, the upper stage ignited its own engine to reach an escape velocity in order to leave the Earth’s gravity field and enter heliocentric orbit. The Rosetta probe was released 18 minutes later. ESA’s Operations Centre (ESOC) in Darmstadt, Germany, established contact with the probe shortly after that.
The first and most important deep space maneuver was successfully executed and brings the space craft on its correct course, with a reported accuracy of 0.05 %.
Reference
"Comet chaser has new quarry", BBC News Online, March 7, 2003; [1]
