Earth today, Eros in a year's time, for asteroid spacecraft

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NEAR view: a composite image of Antarctica, taken by the spacecraft's multi-spectral imager. Credit: JHU/APL

The NEAR (Near Earth Asteroid Rendezvous) spacecraft swung past Earth last week in a manoeuvre that puts it on target for an encounter with asteroid 433 Eros a year from now.

In addition to using Earth's gravity to change the spacecraft's trajectory, the swing-by gave project managers the chance to calibrate the craft's instruments by pointing them at their planet of origin.

Among the pictures snapped by the craft's Multi-Spectral Imager were a ‘family portrait’ of the Earth and Moon, and views of Antarctica and the surrounding ocean (above) taken after the closest Earth approach, which occurred 336 miles above southwest Iran. Sun glinting off NEAR's solar panels made it visible to observers throughout the world as a steady light moving across the sky.

The spacecraft is expected to return its first, dot-like images of Eros next summer. On 20 December it will begin firing braking rockets in anticipation of the rendezvous, and will enter orbit around the 25-mile-long asteroid on 10 January 1999 at an altitude of 1,000 km above the surface.

The orbit will then drop to as low as 35 km during an intensive year-long study, which will include mapping the surface at high resolution and characterizing the asteroid's bulk properties, mineral composition, geology and magnetic field.

The mission will end on 6 February 2000 with a slow ‘controlled crash’ on to the asteroid's surface.

NEAR follows last year's Mars Pathfinder as the second in the US space agency NASA's Discovery series of low-cost planetary missions.

Built and operated by Johns Hopkins University's Applied Physics Laboratory, it is the first planetary mission to be managed from outside the agency.

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