Dawn Space craft enters in approach phase towards dwarf Planet "Ceres"

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NASA's Dawn spacecraft has begun approach phase in which it will continue to close in on Ceres, a Texas-sized dwarf planet never previously visited by a spacecraft. Dawn launched in 2007 and is planned to go into Ceres orbit in March 2015.

Dawn just arose from solar conjunction, in which the spacecraft is on the opposite side of the sun, restricting communication with antennas on Earth. Now that Dawn can consistently communicate with Earth again, mission organizers have programmed the manoeuvres necessary for the next stage of the engagement, which they label the Ceres approach phase. Dawn is at present 400,000 miles (640,000 kilometers) from Ceres, going in at around 450 miles per hour (725 kilometers per hour).


The spacecraft's arrival at Ceres will mark the first time that a space probe has ever orbited two solar system objectives. Dawn formerly studied the protoplanet “Vesta” for 14 months, from 2011 to 2012, taking thorough images and data about that body.

"Ceres is practically a complete secret to us," said Christopher Russell, principal researcher for the Dawn mission, established at the University of California, Los Angeles. "Ceres, contraty to Vesta, has no meteorites associated to it to help disclose its secrets. All we can expect with confidence is that we will be astonished."

The two planetary bodies are supposed to be dissimilar in a few significant ways. Ceres may have come into being later than Vesta, and with a cooler centre. Present evidence proposes that Vesta only reserved a small amount of water as it formed earlier, when radioactive substances were plentiful, which would have yield more heat. Ceres, in on the other hand, has a thick ice mantle and may even have an ocean underneath its icy surface.

Ceres, with an regular diameter of 590 miles (950 kilometers), is also the biggest body in the asteroid belt, the belt of solar system real estate among Mars and Jupiter. By assessment, Vesta has an average diameter of 326 miles (525 kilometers), and is the second most gigantic body in the same asteroid belt.

The spacecraft uses ion thrust to traverse space far more proficiently than if it used chemical propulsion. In an ion thrust engine, an electrical charge is applied to xenon gas, and charged metal grids accelerate the xenon particles out of the thruster. These particles repulse on the thruster as they exit, creating a reaction force that drives the spacecraft. Dawn has now accomplished five years of accumulated thrust time, far more than any other spacecraft.

"Orbiting both Vesta and Ceres would be truly unbearable with orthodox propulsion. Thanks to ion propulsion, we're about to make history as the first spaceship ever to orbit two unfamiliar alien worlds," said Marc Rayman, Dawn's chief engineer and mission director, established at NASA's Jet Propulsion Laboratory in Pasadena, California.


The next couple of months will provide continually refining views of Ceres, prior to Dawn's arrival. By the end of January, the spacecraft's pictures and other data will be the best ever taken of the dwarf planet.

Astrophysics

Space Exploration

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