August 21, 2003. Copyright 2002. Graphic News. All rights reserved.

EuropeÕs first moon probe prepares for launch

LONDON, August 21, Graphic News: EuropeÕs first probe to the moon is about to begin a unique journey that will take it into orbit around our closest neighbour, powered only by the eerie blue glow of an ion engine.

The 367kg (809lb) spacecraft, SMART-1 (Small Mission for Advanced Research in Technology), will blast off on September 4 atop an Ariane V launcher, piggybacking a ride with two commercial payloads: the Indian Space Research OrganisationÕs Insat 3E and EutelsatÕs e-Bird communications satellite.

It will take about 16 months before SMART-1 reaches its destination, where it is expected to carry out a number of studies of the moon. Once in orbit it will also become a science platform for lunar observation.

ÒSMART-1 will search for signs of water-ice in craters near the moonÕs poles, provide data to shed light on the still uncertain origin of the moon, and reconstruct its evolution by mapping its topography and the surface distribution of minerals and key chemical elements,Ó announced ESA.

In its role as technological demonstrator, SMART-1Õs primary goal is to test its futuristic ion drive, which Europe will be using for the first time as main spacecraft propulsion. This is a form of continuous low-thrust engine that uses electricity derived from solar panels to produce a beam of charged particles that pushes the spacecraft forward. Such engines are commonly called ion engines, and engineers consider them essential for future, long-range space missions. 

ÒThis is the first European mission to the moon, this is the first smaller, faster mission and this is the first solar-powered spacecraft,Ó said Professor Manuel Grande, of the Rutherford Appleton Laboratory in Oxfordshire.

This is only the second time that ion propulsion has been used as a missionÕs primary propulsion system; the first was NASAÕs Deep Space 1 probe launched in October 1998. 

The ion drive is the dream of a high school physics lesson. It takes the theory of Isaac NewtonÕs third law of motion: ÒFor every action, there is an equal and opposite reactionÓ; adds the frictionless vacuum of deep space; and then uses the concept of a TV cathode ray tube with the screen cut off to spew out a beam of ionised gas, exerting no more force than a sheet of paper resting on the hand.

As solar panels of a normal size supply only a few kilowatts of power, a solar-powered ion engine cannot compete with the blast of a chemical rocket. But a typical chemical rocket burns for only a few minutes. An ion engine can go on pushing gently for months or even years -- for as long as the sun shines and the small supply of propellant lasts. 

SMART-1Õs ion engine will be used to accelerate the probe and raise its orbit until it reaches the vicinity of the moon, some 350,000 to 400,000km (217,500 to 248,500 miles) from Earth. Then, following a series of lunar swingbys in late September, late October and late November 2004, SMART-1 will be ÒcapturedÓ by the moonÕs gravity in December 2004 and will begin using its engine to slow down and reduce the altitude of its lunar orbit. Once it enters into a near-polar orbit in January 2005, SMART-1 will become a science platform for lunar observation.

SMART-1 will be the second ESA-led planetary mission to be launched in 2003 following Mars Express in June. 
/ENDS

Sources: ESA, NASA