A dying NASA spacecraft orbiting an asteroid will go out with a bang on 12 February when it is allowed to fall onto the asteroid surface.
The Near Earth Asteroid Rendezvous spacecraft was launched in 1996 and has been orbiting 433 Eros since Valentine鈥檚 Day 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.
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Instead, it turned out to be one large rock with a rubble-strewn surface. Eros also appears never to have melted, indicating that it hasn鈥檛 been compressed. That means it is not a fragment of a long-dead planet and has been hanging around largely unchanged since the earliest days of the Solar System.
Final countdown
But now NEAR has spent almost all the fuel for its thrusters and will soon become uncontrollable. That would mean a dreary drift into oblivion, so NEAR researchers decided to use what fuel is left to bring the affair to a dramatic climax: they will 鈥済ently鈥� drop NEAR onto Eros, taking pictures all the way down.
鈥淲e鈥檝e been trying to come up with a fitting end,鈥� says Robert Farquhar, NEAR mission director at Johns Hopkins. 鈥淲e decided to do some bonus science, and to try some new things with a spacecraft.鈥�
While NEAR falls, researchers hope to take pictures revealing rocks just 5 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.
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,鈥� he adds. 鈥淚t is not a landing.鈥�
While NASA hasn鈥檛 scheduled any more missions to asteroids, Cheng hopes someday to be able to answer some of the questions raised by NEAR. 鈥淚n the future, we鈥檇 like to land a space package on an asteroid and maybe bring back a sample,鈥� he says. Correspondence about this story should be directed to news@newscientist.com