Asteroid sample being returned to Earth.
At the time when virtually every soccer fan on Earth's attention will be focused on South Africa, a Japanese spacecraft with a very precious load is scheduled to make a parachute landing in Australia. On board this JAXA (Japan Aerospace Exploration Agency) probe, Hayabusa, is potentially the first ever rock sample from an asteroid.
We say 'Potentially' because the mission was not quite without difficulty. Hayabusa spent three months near asteroid Itokawa in late 2005, studying it and attempting a series of close approaches to collect bits of rock and dirt. A pellet was to be fired into the asteroid's surface, forcing some rock through a funnel into a container into which it was to be sealed for the voyage back to Earth. Unfortunately these plans did not materialize and Hayabusa spent up to 30 minutes on the asteroid's surface during a failed retrieval attempt. Officials later reviewed telemetry data from a subsequent attempt and determined that the pellet probably did not fire because the system had been disarmed. Scientists still hope that some particles were funnelled into the collection chamber, even if the pellet did not fire as planned.
In early February 2009 this probe ignited a single ion engine to begin pulsing it for up to 8 000 hours to propel it back towards the Earth. The spacecraft's revolutionary ion propulsion system has already completed more than 31 000 hours of operations since its launch in 2003. It consists of four ion engines, but it is feared that some of these devices are not capable of long-duration firings, hence the conservative approach of using a single engine to reduce the odds of a major failure. The ion engine must accelerate Hayabusa to nearly 1 400 km/h by March 2010 when it will be turned off for the final approach to Earth.
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|Title Annotation:||news notes; retrieval of sample from Itokawa asteriod|
|Publication:||Monthly Notes of the Astronomical Society of Southern Africa|
|Article Type:||Brief article|
|Date:||Apr 1, 2009|
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