Europe’s first Moon probe prepares for launch


Testing solar electric propulsion and studying the Moon
 
The European Space Agency's Science Programme encompasses, in addition to the ambitious 'Cornerstone' and medium-sized missions, recently dubbed 'flexi-missions', small relatively low-cost missions. These have been given the generic name SMART - 'Small Missions for Advanced Research in Technology'. Their purpose is to test new technologies that will eventually be used on bigger projects.

SMART-1 is the first in this programme. Its primary objective is to flight test Solar Electric Primary Propulsion as the key technology for future Cornerstones in a mission representative of a deep-space one. ESA's projected BepiColombo mission to explore the planet Mercury could be the first to benefit from SMART-1's demonstration of electric propulsion. Another objective is to test new technologies for spacecraft and instruments.

The planetary objective selected for the SMART-1 mission is to orbit the Moon for a nominal period of six months. It is the first time that Europe sends a spacecraft to the Moon. The project aims to have the spacecraft ready early in 2003 for launch as an Ariane-5 auxiliary payload. In addition to the use of solar electric primary propulsion to reach Earth's natural satellite, the spacecraft will carry out a complete programme of scientific observations in lunar orbit.


 
A piggyback ride into space, on Europe's Ariane-5 launcher, will put SMART-1 into orbit around the Earth, from where it will begin a long, slow journey to the Moon.

Close-up view of SMART-1's stationary plasma thruster
 
Electrons attracted into the discharge chamber collide with xenon atoms from the propellant gas supply, making charged atoms (ions). Current-carrying coils, inside and outside the doughnut-shaped discharge chamber, sustain a magnetic field oriented like the spokes of a wheel. By the Hall effect, ions and electrons swerving in opposite directions in the magnetic field create an electric field. This expels the xenon ions in a propulsive jet. Other emitted electrons then neutralize the xenon, producing the blue jet.



Release date: 12 May 2004