European Moon mission set for blast off

Europe's first mission to the Moon is set for blast off from Kourou in French Guiana just after midnight, local time, on Sunday.

SMART 1 will be launched from the European spaceport between 2302 and 2321 GMT. It will be taken into space by European's Ariane 5 rocket, along with an Indian science probe and a commercial satellite.

It will take 15 months for SMART 1 to reach the Moon. On arrival it will enter into polar orbit enabling it to view the Moon's surface from every angle.

The probe will then spend six months combing the lunar landscape for signs of frozen water and will map the distribution of surface minerals and chemicals.

"Despite decades of research, we have never fully discovered what the Moon is made of," says Manuel Grande at UK's Rutherford Appleton Laboratory, who built the spacecraft's X-ray spectrometer.


Complete picture

The Apollo missions provided an opportunity to analyse only limited areas of the Moon near its equator. More recently, NASA's Lunar Prospector probe used a gamma ray spectrometer to create a global map of heavy metals such as iron on the Moon's surface.

SMART 1 should complete the picture. Its X-ray instrument will determine the distribution of metals such as magnesium, aluminium and silicon. These will produce different X-rays after absorbing the Sun's rays.

Apostolis Christou, research astronomer at Armagh Observatory in Northern Ireland, says this is the most important aspect of the mission.

"We need the global picture to test the theory that Moon was once covered with a molten ocean," Christou told New Scientist.

X-ray observations could also provide the first glimpse of a type of Moon rock - the lunar mantle - which may be exposed at the Moon's surface in what is the largest crater in the Solar System.

A more complete picture of the Moon's mineral composition could help confirm the theory that the Moon broke off from the Earth due to a huge collision with a Mars-sized object in the past.


Blue jet

Another spectrometer will be used to search for the infrared signature of frozen water hidden in the shadows of lunar craters. This instrument may also detect frozen carbon dioxide and carbon monoxide on the surface of the Moon.

Crucially, surface water ice could eventually provide supplies for permanent bases on the Moon.

Even while the probe is travelling towards its target it will not lie idle. Its X-ray spectrometer will be pointed towards bright comets in order to test the theory that solar wind can excite the gas surrounding these mysterious bodies causing them to emit X-rays.

On its long trek through space the cube-shaped probe will test a revolutionary solar electric propulsion system. Electrical power generated by the craft's solar panels will be used to excite xenon, which will generate thrust by emitting a blue jet of ions.


Smaller engine

Ion propulsion systems are less powerful than conventional chemical rockets but can run for ten times as long using the same mass of propellant. This makes it possible to reach a target with a much smaller engine, reducing overall launch costs dramatically.

SMART 1 is miniscule compared to many spacecraft. It weighs 367 kilograms and measures one metre on all sides, although its solar panels will unfurl to measure 14 metres across.

The mission is part of a European Space Agency drive to reduce the cost and complexity of its space projects. These missions will all be identified by the title SMART, meaning Small Mission for Advanced Research in Technology.

By Will Knight