FANCY having your name whizzing through space on the back of an asteroid? A mission to bring back the first ever rock samples from an asteroid could be your chance.
So far, the Moon is the only place from which rock and dust samples have been recovered. But scientists are keen to know more about the make-up of near-Earth objects such as asteroids, not least because it will help them assess how big a threat one would pose if it ended up on a collision course with Earth.
Last year, NASA鈥檚 NEAR Shoemaker spacecraft orbited Eros and took snaps of the giant potato-shaped asteroid before crash-landing onto its surface (快猫短视频, 10 February 2001, p 12). Now, the Japanese Institute of Space and Astronautical Science (ISAS) in Kanagawa is putting the final touches to a mission to bring back samples from an asteroid.
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By December this year, spacecraft MUSES-C will be launched into orbit on a Japanese M-V rocket. Once in Earth orbit, the probe will fire up an ion drive that kicks out high-speed xenon ions, pushing it away from Earth. After circling the Sun a couple of times it will catch up with an asteroid called 1998SF36 in 2005.
As soon as MUSES-C reaches the asteroid, it will start mapping the surface using a camera and a laser range-finder. X-ray and infrared spectrometers on board the probe will carry out a basic chemical analysis of the asteroid鈥檚 surface.
To grab samples of the asteroid, MUSES-C will drop down until it just brushes the surface. Controlling such a delicate manoeuvre from Earth in real time will be impossible because signals will take around 20 minutes to reach the probe, so it could easily overshoot and crash. Instead, the probe will eject a shiny rubbery 鈥渢arget marker鈥�. This will appear as the brightest object on the probe鈥檚 cameras, allowing it to use the marker to judge its altitude without being steered from Earth.
Samples from the surface of the asteroid will be collected using a metre-long 鈥渉orn鈥� protruding from the probe. Sensors in the horn will detect when it makes contact with the surface, and the horn will firea bullet. In low gravity, rock fragments sprayed out by the bullet should bounce up the horn into a collecting chamber.
Hajime Yano of the planetary sciences division of ISAS says MUSES-C will perform several of these 鈥渢ouch-and-go鈥� grabs before jettisoning a re-entry capsule which will hopefully splash down on Earth with the samples some time in 2007.
To get the public involved in the mission, ISAS has made room to etch up to a million names onto the target marker. 鈥淪o far over 170,000 have signed up,鈥� says Yano. You can register your name free of charge until 6 July by visiting the website at .
Such missions are invaluable, says space technologist Duncan Steel of the University of Salford. 鈥淢USES-C will tell us a lot about near-Earth asteroids and the hazard they pose,鈥� he says.
