Solar flare silences Mars probe

Probe is due to reach Mars in December 2003

By Dr David Whitehouse BBC News Online science editor

A solar flare has crippled Japan's first Mars probe, Nozomi, cutting communications with Earth.

Japanese scientists say the spacecraft's onboard computer can repair itself, though it could take six months.

Japanese space officials said that communications with Nozomi were severed on 21 April, following severe radiation from a solar flare. However, the mishap has only just been made public.

Solar flares are explosions on the surface of the Sun that release radiation and energetic particles. They can cause disruption to electronic systems on board satellites and sometimes electronic and power systems on Earth.

Unlucky probe

Nozomi, which means hope, is only Japan's third probe to go into deep space and its first probe to a planet.

Probe was launched four years ago

In 1986, two Japanese spacecraft, Suisei and Sakigake, flew past Halley's Comet making measurements.

Yoshihisa Nemoto, of the Education Ministry, said the computer systems aboard Nozomi were still intact and engineers would work to repair them. He added that the spacecraft remained on course to reach Mars in December 2003.

It is not the first mishap to befall this unlucky Mars probe. Nozomi was launched in July 1998 and was supposed to reach Mars a year later.

However, an orbit correcting manoeuvre in December 1998 used up too much fuel, throwing the probe off course and delaying its arrival by four years.

Mars facts

Equatorial diameter: 6,791km

Martian day: 24 hours, 37 minutes, 23 seconds

Martian year: 687 days

Mars-Sun distance: 227.7m km

Moons: Phobos and Deimos

Nozomi is a Mars orbiting platform designed to study the Red Planet's upper atmosphere and its interaction with the solar wind, as well as to develop technologies for use in future planetary missions.

Instruments will measure the structure, composition and dynamics of the ionosphere, effects of the solar wind and the escape of atmospheric constituents.

It will also look at the intrinsic magnetic field, the penetration of the solar-wind magnetic field, the structure of the magnetosphere and dust in the upper atmosphere and in orbit around Mars.

The mission will also be returning images of Mars' surface. The spacecraft cost 11 billion yen (£60m) and is designed to study the Mars's upper atmosphere and ionosphere.