NASA has sounded the death knell for its Dawn mission to study two of the solar system鈥檚 largest main-belt asteroids, Vesta and Ceres, according to a news report.
Mary Cleave, the space agency鈥檚 associate administrator for science, cancelled the Dawn mission on Thursday after a US congressional hearing on NASA鈥檚 science budget, reports NASAWatch.com, a website run by former NASA employee Keith Cowing. 快猫短视频鈥檚 calls to NASA to confirm the news have so far not been returned.
The decision to cancel the mission comes more than a month after the agency was expected to complete an extensive review of the mission鈥檚 progress. In October 2005, NASA ordered Dawn managers to stop work on the mission, citing excessive technical problems and a budget overrun.
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NASA originally approved the mission in December 2001 as the ninth mission in its Discovery programme, which works under the 鈥渂etter, faster, cheaper鈥� motto. It was scheduled to launch in June 2006 on a journey to study the 550-kilometre-wide asteroid Vesta and the 950-km-wide Ceres.
Mysterious differences
Both asteroids are thought to be remnants of the first objects formed in the solar system. But they show mysterious differences in their structures 鈥� Vesta has melted and separated into layers, while Ceres has not. Dawn was to probe these differences, using close-range scrutiny.
But development, launch and operation costs were not to exceed $371 million. And several technical problems, mainly with the spacecraft鈥檚 ion propulsion engine, led managers to believe the mission would require up to $40 million more.
Shortly after the 鈥渟tand down鈥� went into effect in October, Andrew Dantzler, director of NASA鈥檚 solar system division in Washington DC, said Dawn was running behind schedule and its launch had already been expected to slip at least two months, to August 2006.
In early February, Dawn principal investigator Christopher Russell, at the University of California Los Angeles, told 快猫短视频 the stand down had been frustrating. 鈥淲e were going full bore toward launch, running as fast as we could. We saw the finish line in sight and then someone shot the gun and said we鈥檙e cancelling the race for a bit.鈥�
