To start the countdown. The Dawn spacecraft ("Dawn"), NASA will reach the massive asteroid Vesta in less than a year.
"There is nothing more exciting than revealing an alien world, unexplored," says Marc Rayman, chief engineer who is the Dawn mission, the Jet Propulsion Laboratory (JPL). "Vesta" predicts, "will surprise us."
Dawn is scheduled to enter orbit around Vesta in late July 2011. Immediately after it is transmitted to Earth the first high-resolution images, researchers can rapidly combine to produce a film, thus allowing us to follow in the footsteps of Dawn as if we were there.
"seem as if the spacecraft were suspended at a fixed point in space as Vesta rotates underneath it," says Rayman.
Dawn Previous missions have shown us some asteroids, but none as big as this bulky relic, dating back to when the solar system was much younger. With an area of \u200b\u200b564 kilometers and with a body that represents nearly 10% of the entire mass of the asteroid belt, Vesta is, without doubt, a world in itself.
"It's a huge body rocky Earth-like, more like the Moon and Mercury that small pieces of rock that we have explored in the past, "continues Rayman." For example, a large crater at the south pole of Vesta and, within that crater, hosted a mountain that is larger than the asteroid Eros. "
Dawn will orbit Vesta for a year, at which time detailed studies carried out, and thus become the first spacecraft to orbit an body in the asteroid belt. Then, Dawn will leave Vesta behind and head to a second exotic world, the dwarf planet Ceres, but that's another story.
Many scientists believe that Vesta is a protoplanet. The asteroid was in the process of becoming a planet as Jupiter stopped its growth. The gas giant has become so massive that its gravity disrupted asteroid belt material to the extent in which objects were present and could not merge.
"Vesta can teach us much about how the planets formed," says Christopher Russell, University of California at Los Angeles (UCLA), who is principal investigator of the mission. "We have a full team of scientists is looking forward to taking that first look at Vesta."
Dawn will begin its official approach to Vesta, which is also called phase Rayman "oh, this is so cool!" mission in May next year. Unlike most of the orbital insertion, however, it is comparatively simple.
"Maybe this is the first planetary mission that will not cause members of the mission team are biting their nails when the spacecraft is going into orbit around the goal," says Rayman.
The conventional way in which a spacecraft is placed in orbit around a celestial body is accompanied by crucial moments during the which must perform orbital maneuvers with surgical precision. If something goes wrong, the entire mission can be written off. But Dawn, with its soft ion propulsion, is gradually approaching its target in a spiral path, getting closer and closer with every lap.
"The whole plan of propulsion Dawn in its long interplanetary voyage is devoted largely to gradually change the shape of its orbit around the Sun so that, when the spacecraft is in the vicinity of Vesta, its orbit will be very similar to the asteroid. "
With only a slight change of trajectory, the spacecraft will Vesta's gravity to capture it.
"That soft ion momentum is enough to put the spacecraft in orbit. It's like merging with traffic flow on a highway: it only takes a gradual acceleration. Dawn do not even notice the event, but it will put in orbit about his first celestial target. "
Early Dawn orbits are high and there is no hurry, this ship will take several days to complete one revolution around Vesta, at altitudes of about 2,738 kilometers (1,700 miles). After a substantial collection of photographs and data from high altitude, Dawn and will continue propelling a spiral pattern into orbits ever lower, reaching an orbit with an altitude slightly over 161 kilometers (100 miles)-lower than those of satellites orbiting the Earth.
Some parts of the surface are reminiscent of features on the Earth or the Moon, with craters and perhaps even volcanoes.
"Do not expect to see active volcanoes," says Carol Raymond, who is the deputy principal investigator for the mission at JPL, "but there could be ancient features still recognizable volcanic craters."
Meanwhile, "there may be other events that are beyond our imagination, "says Rayman." It will be pure emotion! "
Source: NASA
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