WASHINGTON, Sept 27: The US space agency NASA on Thursday launched the space probe Dawn on its eight-year mission to unlock the secrets of the solar system by studying the two largest asteroids orbiting the sun.
The unmanned spacecraft successfully lifted off from Cape Canaveral, Florida and began its 1.7 billion mile journey to Ceres and Vesta in the asteroid belt between Mars and Jupiter.Dawn’s long-haul to Vesta is expected to take four years, as NASA anticipates its arrival in orbit around Vesta in October 2011.
The probe will proceed to Ceres in May 2012 and then begin orbiting Ceres in February 2015 -- traveling a total distance of 3.1 billion miles.
The deep-space explorer, measuring 1.64 meters long and 1.27 meters wide, aims to provide a better understanding of the building blocks that formed the terrestrial planets and how the two “protoplanets” followed different evolutionary paths.
Dawn’s mission is to learn about the first moments of the solar system’s creation 4.6 billion years ago by gathering information about Ceres and Vesta, including what kinds of elements form such terrestrial planets, among them Earth, Mars and Mercury.It also plans to explain why and how Vesta and Ceres followed a different evolutionary and formative path, particularly the role that water may have played in their development.
“By using the same set of instruments at two separate destinations, scientists can more accurately formulate comparisons and contrasts,” NASA said.
“Dawn’s science instrument suite will measure shape, surface topography and tectonic history, elemental and mineral composition as well as seek out water-bearing minerals.” The spacecraft is equipped with innovative ion propulsion engines, which consume relatively little fuel and only accelerate at a gradual pace. The engines use an electrical charge to accelerate ions from xenon fuel.Dawn is also carrying a high-definition camera and two spectrometers.
Ceres, discovered in 1801, has a spherical shape and a diameter of about 596 miles. Scientists believe it may have a layer of thick ice under its crust, covering a rocky core.
Ceres was classified in 2006 as a “dwarf planet,” according to a new definition by astronomers to describe asteroids in the solar system.
The decision by the International Astronomical Union was the result of a debate about the status of Pluto, which is now classified as a dwarf planet along with Ceres and another celestial body, Eris.
Vesta, discovered in 1807, is smaller than Ceres but the third largest asteroid in the solar system. With a diameter of 520 km, Vesta has a rocky surface without a trace of water and a hot interior.
Scientists are especially interested in the enormous crater on the south pole of Vesta, 460 kilometres wide and 13km deep, which is believed to be the result of a major collision.—AFP