The Rosetta probe was launched in 2004 by the European Space Agency to chase and ultimately rendezvous with the Churyumov-Gerasimenko Comet also known as Comet 67P. It is nearing the end of its journey and should reach Comet 67P this week.
Comets are small icy bodies that travel in a variety of orbits that them from the outer reaches of the solar system to near the sun. As they approach the inner solar system, the heat of the sun causes them to spew out gas and steam. If they are large enough, they can been seen from Earth without a telescope. In some cases, the out gassing creates a long tail that is also visible from the Earth. The human race has been observing and record the passage of comets for thousands of years. Comets were believe to be harbingers of disaster. It is thought that much of the water on Earth may have been brought by comets which could also have brought organic molecules that made life possible.
The Rosetta mission is named for the Rosetta Stone which was found on the island of Philae in the Nile River. It contained a royal decree that was written in three languages. The Stone made it possible to decipher Egyptian hieroglyphics. It is hoped that the Rosetta mission will enable the "deciphering" of the history of the solar system since its formation. The spacecraft is carrying thirteen thousand pages of text in twelve hundred languages etched in a nickel alloy disk.
The spacecraft has two main components. The Rosetta space probe orbiter has twelve instruments aboard. The Philae robotic lander has an additional nine instruments. The obiter is intended to orbit the comet for seventeen months and it will conduct the "most detailed study of a comet that has ever been attempted." The spacecraft is powered by solar cell panels and has ten nozzles for directing propellant during manoeuvres. When Rosetta reached the comet, Philae will be launched to land on the comet.
The Rosetta mission includes the following instruments:
ALICE is an ultraviolet imaging spectroscope which will look at the noble gas content of the comet nucleus,
OSIRIS is an optical, spectroscopic, and infrared remote imaging system which will take pictures of the comet in different wavelengths.
VIRTIS is a visible and infrared thermal imaging spectrometer which will look for molecular spectra in the gas surrounding the comet.
MIRO is a microwave instrument which will look for microwave emissions from volatiles such as water, ammonia and carbon dioxide.
CONSERT is a device for comet nuclear sounding by radiowave transmission which will probe the deep interior of the comet with radar.
RSI is a device for radio science investigation which will use the communication system of the orbiter to probe the comet nucleus and the gas around the comet.
ROSIA is a spectrometer for ion and neutral analysis.
MIDAS is a micro-imaging dust analysis system which will analyze dust particles that are deposited on a silicon plate.
COSIMA cometary secondary ion mass analyzer will also analyze the dust particles.
GIADA is a grain impact analyzer and dust accumulator that will detect the cross-section, momentum, speed and mass of every grain of dust that enters the instrument.
Rosetta and Philae will search for complex organic compounds composed of carbon, hydrogen, oxygen and nitrogen. They will also search for organic molecules such as nucleic acids and amino acids.
The Rosetta probe: