Satellite heads for rendezvous with Eros on Valentine's Day

Some say it with chocolates, some with flowers, but nobody can top the St Valentine's Day greeting expected to be delivered later this afternoon from a satellite half-way across the solar system.

It will be enough to make the grown men and women who control the satellite weep: news that it has gone into safe orbit around an asteroid more than 161 million miles away.

It might not be a match made in heaven, a $224.1 million satellite and a 21-mile-long, peanut-shaped lump of rock named after the Greek god of love, Eros.

However, the US scientists behind the venture are hoping for big things given that it will be the first time a satellite has gone into orbit around an asteroid.

The satellite is very unromantically named NEAR, for Near Earth Asteroid Rendezvous, but getting it into orbit around Eros was at least as challenging as any task faced by the Milk Tray man.

NEAR was launched from Cape Canaveral by NASA in February 1996. It flew close to another asteroid, Mathilde, before returning for a gravity-powered swing-by of the Earth early in 1998, sending it on the final leg of its journey to Eros.

The satellite's hoped-for relationship with the asteroid almost came a cropper when a rocket malfunction caused NEAR to go off-line. All was feared lost, but after 27 hours, NASA staff regained control over the satellite.

NEAR has been making slow but steady progress towards its target over the past week and should drop into a variable orbit by about 3.30 p.m. Irish time. It will come to within 31 miles of the surface and spend over a year observing the asteroid with cameras and scientific equipment.

In December, controllers might bring it to within a mile of Eros and at the end of its mission might try for a touch-down, but all this is predicated on a safe arrival in orbit.

Scientists hope to learn about the chemical and physical makeup and evolutionary history of asteroids. Until NEAR arrives, we won't even know whether Eros is a big chunk of rock or just an accumulation of junk.