The Mammoth Book of Space Exploration and Disasters

Although NASA has already launched a space probe using ion engines, the ESA project will test several advances in technology, and also be far more manoeuvrable than NASA’s craft.

Smart 1 should gradually accelerate from 0 to 70,000 mph. At its slowest, the craft travels at 0.2mm per second – slower than a snail – but over several years this increases to speeds of up to 70,000 mph.

The Smart 1 craft weighs about 367kg, less than a small family car. It is no more than a metre square at launch (the size of a washing machine) but extends to the length of three delivery vans. The initial push created by the ion engine feels no more powerful than having a postcard dropped onto your hand. Smart 1 will get to within 300km of the moon’s surface, far closer than previous orbiting probes.

Smart 1 was launched by an ESA Ariane 5 booster and was the smallest part of the payload of the Ariane 5 V162 mission. The main payload was INSAT-3E, India’s largest telecom satellite to date, and e-Bird, the first of Eutelsat’s craft, purpose built for high-speed, two-way, Internet access.

Two minutes after being released, Smart 1’s on-board computer was activated and 21 minutes later its 14-metre solar generators unfolded over a lengthy nine minutes. An hour later, ground controllers at ESA’s Satellite Operations Centre in Darmstadt got their hands on the baby. The new-technology solar drive motor is due to function for the first time on 30 September, the lunar journey itself taking between 15 and 18 months. After so much interest in the launch, ESA hoped that public interest continued during the journey as “we” all ride up to the moon.

On 6 January 2004 the spacecraft reached its 176th orbit with all functions performing nominally. It had achieved its first mission target: to exit the most dangerous part of the radiation belts. The pericentre altitude (the closest distance of the spacecraft from the centre of the Earth) reached the prelaunch target of 20,000km on 7 January 2004.

Between 23 December 2003 and 2 January 2004, the thruster fired continuously for a record duration of more than 240 hours. Later in the week Smart 1 changed from a continuous thrust strategy to a more orbitally efficient thrust arcing.