The Rosetta probe will descend into a place of pristine material in the comet 

On November 11, for the first time a spacecraft will land on the surface of a comet nucleus, 67P / Churyumov-Gerasimenko. The Philae, that will coupled to the spacecraft europeaRosetta, is making a risky maneuver that will last about seven hours, culminating with the appliance 100 kilos nailed down with harpoons, for attachment to a body of low gravity. Scientists and engineers have chosen the mission this weekend the place, called J, for the descent from five options that were shortlisted, combining scientific interest to the technical and safety requirements of the probe. "The site offers the opportunity to explore pristine material characterize the properties of the nucleus [comment] and study the processes of their business," said Jean Pierre Bibring, one of the leaders of the mission.

The J place (the name corresponds to the order of the first list was made of possible point drop) is in what has been called the head of the comet, shaped with two lobes, like a rubber duck, has surprised when scientists were able to get a closer look at Rosetta and send images of the celestial object four kilometers in maximum diameter. As a backup location, experts have chosen the C lobe is called the body of 67P / Churyumov-Gerasimenko.
Illustration of `Philae' lander on the surface of the comet 67P / Churyumov-Gerasimenko. / ESA / AOES MEDIALAB
"From what we have seen in recent close images, the comet is a nice but dramatic world; is scientifically exciting, but its shape makes operations there be a real challenge, "said Stephan Umalec, head of Philae module, a statement from the European Space Agency (ESA). "None of the candidate landing sites meets all operational criteria 100%, but the J is clearly the best solution."
Most outstanding in place J are not too pronounced, reducing the risk that the probe tip on landing, and get enough light from the sun to recharge the batteries. "No one has tried before landing on a comet, so it's a real challenge," says Fred Jansen, head of the ESA mission whose cost amounts to 1,300 million euros each. "The complicated double structure of [67P / Churyumov-Gerasimenko] has had a considerable impact on the overall risk of landing, but they are risks worth taking."

The experts, who last weekend met at the French Space Agency (CNES) to study the five possible landing sites that were the final candidates have had to evaluate and weigh the one hand, the scientific interest of each site and secondly, the amount of visible, besides the orbital dynamics obstacle to reach the ground and the positions of the probe and the vessel downward. Also keep in mind the hours of daylight and the right position to ensure smooth communications with Rosetta Philae, which will be circling the comet, and this Earth.Landing site (marked with a cross) of Philae probe into the comet's surface. / ESA / ROSETTA / OSIRIS TEAM FOR MPS MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA.

"Any site of this comet has a very large interest for scientists," said El Pais, Laurence O'Rourke, one of the coordinators of Rosetta science operations. "But the site chosen J is interesting, first, because scientists have seen that there is some activity in one of the small nearby craters, which means that while it is less than what we see in the neck of the comet landed if there we will see that activity closely, about 500 meters away, "he explains. "Second, J is the best place for Consert radar instrument, which has a part in Rosetta and Philae other," he continues. "Third, and very importantly, the Philae lander will use the main battery for the landing and the early days of scientific activity (the decline will last seven hours), but the lighting of the Sun in J means that there are opportunities to continue work longer using the secondary battery receiving the charge from the solar panels, "adds O'Rourke.
The selection of suitable landing sites has been done in a few weeks, since until the Rosetta was not bringing enough to 67P / Churyumov-Gerasimenko to take good pictures and data, not enough information to determine in advance the place landing. J point selection will be confirmed within 10 days, when you have made more path analysis

La Rosetta, which left Earth in March 2004, has been doing some complex maneuvers to approach the surface of the celestial object, since he arrived on 6 August, and is now about 30 miles. By going closer to the Sun, the comet 67P / Churyumov-Gerasimenko is gaining activity.

On November 11, the Philae must execute the landing on a comet ever attempted before. With all the commands from the control center and stored on your computer, perform a passive descent, taking pictures, since it disengages from the Rosetta to the chosen area, predetermined as an ellipse of a few hundred meters, says ESA . Upon arrival you will use harpoons to engage the ground and avoid bounced out (given the low mass of the comet, its gravity does not catch on the floor).

Its first task will be to make a panoramic image and send it to Earth for scientists and engineers to determine their location and orientation. Then, if all goes well, it will start itself scientific phase of Philae, analyzing plasma and magnetic environment, measuring temperatures and drilling on the floor to take samples analyzed in the laboratory aboard. ] An experiment emitting radio waves toward the ship Rosettapermitirá know the internal structure of the comet.

By : Miriam Herbada