Scientists are making final preparations to steer a washing-machine-sized probe into the near side of the moon, an act of silent violence that will help unravel the mysteries of our celestial neighbour.
The Smart-1 probe, an experimental spacecraft built to test gadgetry for future missions, will end its journey by slamming into a dusty basin at 8 000kph, scattering debris over almost 77 square kilometres.
European Space Agency (ESA) researchers expect Smart-1 to collide with the moon at 6.43am on Sunday morning, but its shallow angle of approach means it may clip the 800m-high mountains surrounding the intended crash site as early as 8.31pm on Saturday.
Thousands of amateur astronomers are expected to train their telescopes on the landing site, known as the Lake of Excellence, in the hope of glimpsing the probe’s final seconds, which mission controllers expect will leave a 10m-wide scar.
Manuel Grande, a planet scientist at the Rutherford Appleton Laboratory in Didcot, Oxfordshire, and leading researcher on the Smart-1 project, said its mission is on target. ”We don’t think there’s much that can go wrong now. It’s going to crash, and that’s what we want.”
If the collision happens on Sunday morning, it will be recorded by telescopes in the United States, South America and Hawaii, but if it crashes on Saturday evening, the plume of moon dust may be visible from Britain. Mission scientists believe the impact should be visible through a 10cm telescope or powerful binoculars.
The £80-million spacecraft has spent 18 months mapping the moon and collecting information on its chemical and mineral composition. The data will help answer questions about the moon’s origin. The leading theory is that it formed after a violent collision between the Earth and a smaller planet about 4,5-billion years ago.
Using a detector that measures X-rays from the sun as they bounce off the moon, the probe was able to map surface levels of iron, aluminium, magnesium, calcium and silicon. Smart-1 made its way to the moon by spiralling outwards from Earth until it fell under the grip of the moon’s gravitational pull.
”As the father of Smart-1, I feel a bit sad my baby will get such a rough landing. But this will give us a kind of Smart-I sculpture on the moon, and that will be a monument to what Europe has done,” said Bernard Foing, ESA’s chief scientist. The mission was designed as a test bed for a suite of miniaturised sensors and instruments for future exploration, such as India’s first moon mission, Chandrayaan, due next year.
It was powered by an ion thruster engine that uses electricity from solar panels to charge xenon atoms and fling them out the back. The thruster produces only a tiny puff of thrust, but because it can operate almost non-stop, it can propel a spacecraft to much higher speeds than a conventional chemical rocket.
The thruster, which broke records by using only 60 litres of fuel en route to the moon, will be fitted to ESA’s upcoming BepiColombo mission to Mercury.
The high efficiency of ion thrusters makes them contenders for powering future generations of interplanetary spacecraft, although prototype engines rely on sunlight to generate electricity and so can only be used for planets orbiting close to the sun. Nasa scientists are working on electrical power supplies that are expected to make ion thrusters viable for even more distant missions.
Near term, the US space agency is focused on replacing its ageing fleet of space shuttles. On Friday, Nasa officials announced an $8-billion contract to Lockheed Martin to build Orion, an Apollo-style space vehicle that will replace the shuttle in 2010. The first manned flight for Orion is scheduled for 2014 with a tentative timetable to land on the moon by 2020, the first time humans will have done so since 1972.
A mission to the moon will be Nasa’s first step in fulfilling President George Bush’s $230-billion pledge to construct a moon base as a stepping stone for the first crewed missions to Mars. — Guardian Unlimited Â