See The Vesta’s Spacecraft Dawn’s detailed

Tuesday, August 2nd 2011. | Science News

A spacecraft from Earth named Dawn has snapped the first detailed images of the asteroid Vesta, revealing mysterious cratered tracks on its surface that show how the “protoplanet” must have been battered by some other unknown asteroid during the chaos of its formation at the beginning of the solar system.

The spacecraft has just swung into a yearlong orbit around Vesta, seeking clues to an era when all the planets, including Earth, were forming some 4 1/2 billion years ago. The images are extraordinarily detailed, revealing mountains, craters, cracks and broad stony plains. The pictures were the first ever to bring such focus to an object in the distant asteroid belt where hundreds of rocky objects are all flying between the orbits of Mars and Jupiter.

“We did not imagine the details of what we’re already seeing,” said Chris Russell, a UCLA physicist and the project’s chief scientist, during a news conference Monday at NASA’s Jet Propulsion Laboratory in Pasadena.

“It’s a great revelation into the building blocks of the solar system – a beautiful and exciting small world, sitting there in the middle of the asteroid belt.” Vesta, often called a “protoplanet,” is 330 miles in diameter and is the second-largest asteroid in the belt behind Ceres, 590 miles across and officially known as a “dwarf planet.”

The Dawn spacecraft was about 3,200 miles from Vesta, and both are about 114 million miles from Earth; but Dawn will fly in increasingly lower orbits during its yearlong mission to the asteroid. Eventually it will gather images from less than 125 miles above the asteroid. From the images, taken both by the spacecraft’s framing camera and its infrared spectrometer, the scientists will be able to identify the minerals and chemical molecules of Vesta’s surface, Russell said. The images will also show details of landslide debris inside the scores of deep craters that pock the asteroid’s northern hemisphere craters, he said.

Vesta is marked by a truly enormous crater gouged deeply from its southern hemisphere, and along the asteroid’s equator Russell and his colleagues have observed a curious set of slim parallel tracks, looking as if some glancing blow had gouged them. The researchers wonder if perhaps the tracks were caused by the same object that battered Vesta’s southern half long ago. “It must have been some fantastic impact that caused the asteroid’s tectonic features,” Russell said.

The images of Vesta’s surface are revealing the nature of the asteroid as it must have been 5 million years after it first formed, Russell said. Probably 4.65 billion years ago, he said, a distant exploding star called a supernova must have irradiated the newborn asteroid and melted its rock material to differentiate it into the crust and iron core that mark its existence today. When its mission circling Vesta is complete, Dawn will fly across 900 million miles of space to the asteroid Ceres, where it will spend another year.

The project is one of NASA’s origins missions – designed, as the space agency says, ” to look far into the universe, back toward the beginning of time, to see galaxies forming, or by looking very close to home, searching for planetary systems like our own.”

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