Odd asteroid much bigger on camera
By Richard Stenger
CNN
(CNN) -- An asteroid photographed by a passing deep space probe proved twice as large as expected, according to NASA scientists, who on Tuesday released the first image of the encounter.
After the Stardust craft passed within 2,000 miles (3,300 km) of asteroid Annefrank, mission researchers determined that it is about 5 miles (8 km) in diameter.
The crater-pocked, oddly shaped boulder turned out to reflect much less sunlight than originally thought, which accounted for the error of the earlier size estimate.
"It was a challenge for the navigation camera to see Annefrank during approach," said Stardust scientist Ray Newburn of NASA's Jet Propulsion Laboratory in Pasadena, California.
Added Mike Wang, optical navigation specialist at JPL: "Annefrank was not cooperating. It was just too dim."
The robot ship took dozens of images as it flew by the asteroid this weekend at about 16,000 mph (26,000 km/h). More pictures and data should beam back to Earth during the week.
Despite the obstacles, the robot ship's instruments and systems performed well during the flyby, a dress rehearsal for its primary mission, an encounter with a comet in 14 months, NASA said.
Launched in 1999, Stardust should return to Earth in 2006 with samples from comet Wild-2 as well as interstellar dust particles near the asteroid belt. The mission is the first designed to return with materials from beyond the moon.
Annefrank was discovered in 1942. The asteroid was later named for Anne Frank, a young Dutch girl and writer who died in a Nazi concentration camp in 1945.
