The final preparations to try to crash-land a dying spacecraft onto an asteroid are underway. NASA plans to use the last remaining fuel on the Near Earth Asteroid Rendezvous probe to 鈥済ently drop鈥� it onto Eros.
NEAR has been orbiting Eros since Valentine鈥檚 Day 2000. The descent will begin at 1631 GMT on Monday 12 February.
While NEAR falls, researchers hope to take pictures revealing rocks just five to 10 centimetres across, about one-tenth the size of those in pictures taken from NEAR鈥檚 latest orbit 35 kilometres from the centre of Eros. They will try to ease the spacecraft down at no more than 11 kilometres per hour.
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But even at that speed the delicate machine probably won鈥檛 survive its 鈥渃ontrolled descent鈥� onto the boulder-strewn surface, says Edward Weiler, associate administrator for space science at NASA: 鈥淣ote that I didn鈥檛 say landing: it is not a landing.鈥�
The descent will serve as a test run for future attempts to land probes on asteroids. 鈥淚n the future, we鈥檇 like to land a space package on an asteroid and maybe bring back a sample,鈥� says Andrew Cheng, a planetary scientist at Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.
Potato shape
NEAR was launched in 1996 and has been orbiting Eros since February 2000. The potato-shaped rock measures roughly 33 by 13 by 13 kilometres and is currently more than 300 million kilometres from Earth, between the orbits of Mars and Jupiter.
NEAR has returned hundreds of thousands of pictures, and reams of other data that have transformed researchers鈥� understanding of asteroids.
But now NEAR has spent almost all the fuel for its thrusters and will soon become uncontrollable. 鈥淲e decided to do some bonus science, and to try some new things with a spacecraft,鈥� says Robert Farquhar, NEAR mission director at Johns Hopkins.