Programme will include new Dawn asteroid exploration craft and further telescopic planet-location efforts

NASA has selected two new missions costing $299 million each: an asteroid explorer called Dawn and the planet-hunting Kepler telescope, for its Discovery programme to be launched in 2006.


Dawn will conduct a nine-year journey to the solar system's two largest asteroids, Ceres and Vesta, in the main belt between Mars and Jupiter. Vesta is thought to be a dry body of basaltic lava flows, while Ceres - the largest asteroid and the first to be discovered - is believed to have a primitive surface, water-bearing minerals, frost and a weak atmosphere. Dawn will orbit each asteroid, coming to within 100km (60 miles) of each. Spacecraft for the Jet Propulsion Laboratory- (JPL) led mission will be developed by Orbital Sciences.

The Kepler telescope will search for planets by looking for periodic dimming of stellar discs, which indicates the transit of a planet across the disc.

The signature of any dimming will indicate a planet's size and orbit. The telescope, which will be built by Ball Aerospace & Technologies, will be directed continuously at a region of space containing 100,000 stars. Telescopic observations have so far detected around 80 Jupiter-sized planets outside our solar system.

Previous Discovery programmes include the NEAR Shoemaker mission to the asteroid Eros, the Mars Pathfinder and the Lunar Prospector. Current Discovery craft are Genesis and Stardust - interplanetary material collectors, which will be followed by the comet-explorer Contour this year and Mercury- orbiter Messenger in 2004.

Meanwhile, NASA is developing prototypes of small All-Terrain Explorer Mars rovers which can drive up steep hills and descend almost vertical cliffs, as part of plans to examine the potential water outflows near cliff edges seen in images taken by the Mars Global Surveyor. The JPL has so far demonstrated a vehicle that can traverse slopes of up to 50º.

Source: Flight International