Europe is going to the Moon
10 November 1999
A highly innovative and budget-priced mission to explore the moon has formally been approved by the European Space Agency. Meeting in Paris 9 and 10 November the Agency's Science Programme Committee has finalised all aspects of the SMART-1 project. This small lunar orbiter is the first in a new line of Small Missions for Advanced Research in Technology to demonstrate new key technologies for future deep space missions.The most important technology to be flown on the 350-kg spacecraft scheduled for launch at the end of 2002 as an Ariane 5 auxiliary payload will be solar electric propulsion. This will constitute its primary propulsion to escape the Earth's gravity, for its 17-month cruise to the Moon and to stay in lunar orbit for six months. It will be the first time that Europe uses Solar Electric Propulsion as primary propulsion.
In recent years, electric propulsion systems have principally been used by near-Earth telecommunications satellites for small orbit corrections. SMART-1 will employ a stationary plasma thruster which uses xenon gas as a propellant. Electrical solar power will be used to expel the gas at very high speed, generating, by reaction, the movement of the satellite.
"Compared with conventional chemical systems, electric propulsion expends very little mass to accelerate a spacecraft. But it ejects the propellant plasma up to ten times faster than a classical engine and so is ten times more efficient. SMART-1 is truly going to live up to its name!" says Project Manager Giuseppe Racca.
SMART-1 will carry a Scientific and Technology Payload consisting of seven instruments. The principal objective of three of them will be to monitor the operation of the electric propulsion system.
A diagnostic package (EPDP, provided by Laben, Italy) will characterise the plasma environment around the spacecraft; another payload (SPEDE, from the Finnish Meteorological Institute, Helsinki) will monitor plasma variations and dust environment during the cruise and lunar orbit phases; whilst a series of Radio Science investigations (RSIS, University of Rome) will monitor the performance of the electric propulsion system. In addition RSIS will measure the rotational state of the Moon by combining orbit and attitude determination with accurate imaging. The mission also carries an experimental deep-space telecommunications sub-system (KATE, Dornier Germany) operating in X and Ka frequency bands.
The lunar science payload consists of three instruments: a compact X-ray spectrometer (D-CIXS, provided by the Rutherford Appleton Laboratory, UK), a micro-imager (AMIE, developed in the framework of ESA's Technology Research Programme in conjunction with CSEM Switzerland) and an Infrared Spectrometer (SIR, Max-Planck-Institut für Aeronomie, Lindau, Germany).
According to SMART-1 Project Scientist Bernard Foing, the SMART-1 science mission will address key questions about the Moon: the origin of the Earth-Moon system and the role of accretional processes, long-term volcanic and tectonic activity on Earth's natural satellite, the thermal and dynamic processes responsible for lunar evolution and the external processes on the Moon's surface such as erosion, and ice deposition.
The SMART-1 project is now going forward to the development phase. The industrial prime contractor is Swedish Space Corporation, Stockholm Sweden supported by several Europaean subcontractors. The spacecraft's stationary plasma thruster is being provided by SNECMA, Paris France.