Mankind is reaching out to the Moon again — on a rocket with less thrust than a puff of breath. So feeble is the engine of Europe’s Smart-1 probe, it will take more than a year to reach the Moon. Apollo astronauts took three days to blast to the lunar surface.
Yet the European space engineers’ first Moon mission is being hailed by scientists who believe its technological secrets could revolutionise interplanetary research.
‘Smart-1 has an ion drive, a new form of space propulsion. It will get us to parts of the solar system we have not been able to reach,’ said Professor David Southwood, the European Space Agency’s science director. Ion drives were once the stuff of science fiction: the USS Enterprise uses one as a back-up when Scotty’s warp engines go on the blink. Now scientific reality has caught up.
The ion engine on Smart – Small Mission for Advanced Research and Technology – operates by shooting out streams of electrically charged gas at thousands of miles an hour, thus generating a thrust, albeit a tiny one that is the equivalent of a postcard resting on a person’s hand.
Unlike current chemical rockets, which can fire only in brief bursts before exhausting their fuel, an ion engine can burn continuously for months, even years, and so build up formidable velocities. Smart will reach a speed of 10 miles a second — 36 000 mph.
The current ion engine is small and experimental, so will get the probe to the Moon only by pushing it on a complex pirouette after first being blasted into space on an Ariane rocket. But in a few years’ time ion engines are expected to become mankind’s main interplanetary workhorse.
‘An ion engine is an interplanetary tortoise compared to the chemical hares we use at present. It starts slowly but will get us to the planets in months rather than the years we now need,’ said Giuseppe Racca, Smart’s project manager. ‘All you need is electricity from the probe’s solar panels and a small supply of propellant, Xenon.’
Southwood said: ‘We still have major problems understanding the planets, and given that we live on one that is a serious flaw.’
A key example is provided by Mercury, a strange, scorched world only approached once before, in 1974, by the US probe Mariner 10 which briefly provided scientists with a glimpse of a pock-marked, cratered world that possessed a powerful and baffling magnetic field. ‘Mercury shouldn’t be like that,’ said Southwood. ‘It should be dead and dormant. All our theories said so, and still say so. It is an insult to astronomical theory and, given the importance of our own magnetic field in protecting us from solar storms and radiation, that is something we should worry about.’
Hence the importance of Smart, forerunner of a series of European planetary probes beginning with a mission to Mercury. ‘We will put several far more powerful ion thrusters on a rocket that we will blast into orbit round Mercury to solve its riddles,’ said Smart’s project scientist, Bernard Foing.
Ion thrusters are not the only revolutionary technology to be tested on Smart, which is scheduled for launch in July. The craft bristles with state-of-the-art equipment, including a British-built X-ray detector that will map all the elements on the Moon’s surface, and so solve another equally puzzling astronomical mystery: the origin of the Moon.
‘It is thought that about 4,5-billion years ago a giant asteroid struck our planet, flinging vapourised rock into space. This congealed to form the Moon,’ said Professor Manuel Grande of Britain’s Rutherford Appleton Laboratory. ‘However, this theory is based on studies of the lunar rocks that were brought back by Apollo astronauts, and as these missions only visited the Moon’s equator we have a problem — for rocks there have been battered and pulverised by meteorite impacts, unlike rocks in the highland regions. So we cannot be sure these rocks are typical and our theory correct. We need a global survey.’
Grande will do this using a detector that will study the wavelengths of solar X-rays that bounce off the Moon’s surface, revealing the composition of its rocks. ‘If our theories are right we should see relatively little iron on the Moon’s surface,’ he said . ‘If we see quite a lot, then we are going to find our theories are in deep trouble.’ – Guardian Unlimited Â