The European Space Agency (ESA) has successfully completed its first ever attempt by launching Rosetta spacecraft in 2004 with an ultimate goal to make it orbit around the comet, dubbed "67P/Churyumov-Gerasimenko" after a long chase of over 6.4 billion kilometers (4 billion miles). Now the top priority for the science and engineering team leading Rosetta is to control and mange the landing of Philae (a lander that Rosetta is carrying) on the comet's surface.

The 100-kilogram Rosetta lander, which is equipped with 10 science instruments, is provided by a European association under the leadership of the German Aerospace Research Institute (DLR). Other members of the consortium are ESA and institutes from Austria, Finland, France, Hungary, Ireland, Italy and the UK.

Philae's history-making landing on comet 67P is currently scheduled around November 11. So far, Rosetta mission has selected five landing sites for its Philae lander.

ESA said, "The site must balance the technical needs of the orbiter and lander during all phases of the separation, descent, and landing, and during operations on the surface with the scientific requirements of the 10 instruments on board Philae".

The lander has been commanded to self-eject from the main spacecraft and unfold its three legs, ready for a gentle touchdown at the end of the ballistic descent.

Immediately after touchdown, a harpoon will be fired to anchor the lander to the ground and prevent its escape from the comet's extremely weak gravity.

Philae will collect stereo and panoramic images and also drill 23 centimeters into and sample its incredibly varied surface. After analyzing, it will transmit data about the comet's composition.

Rosetta also will be the first spacecraft to witness at close proximity how a comet changes as it is subjected to the increasing intensity of the sun's radiation. Observations and data collected by Philae after analyzing the comets' surface will help scientists learn more about the origin and evolution of our solar system.