A simulated Mars landing took place at a remote airfield in Shropshire, England, at dawn on Friday, in a crucial last test for the UK鈥檚 first Martian probe.
The trial run tested the parachute that will slow the Beagle 2鈥檚 rapid descent to the red planet鈥檚 surface. It was a success, with a dummy payload safely carried to the ground from a height of 90 metres. A prototype of the unique parachute design underwent testing in Arizona in September, but Friday鈥檚 experiment tested the final design.
Colin Pillinger, head of the Beagle 2 project and from the Open University, told New Scientist: 鈥淚t opened really perfectly. It demonstrates the absolute capability of Lindstrand Balloons to make the real thing.鈥�
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Beagle 2 is a clam-shaped module that will open up on landing to examine the surface of Mars with an array of scientific instruments. It will hitch a ride on Mars Express, a European Space Agency spacecraft scheduled for launch in June 2003, with touchdown expected in December 2003. Mars Express will remain in orbit after releasing Beagle 2.
Hit the brakes
Beagle 2鈥檚 parachute system has undergone a major redesign in the last few months. Tests in June 2002 showed that an older design did not brake the descent sufficiently, meaning the probe would suffer serious damage on impact. But the parachute had to be improved without increasing its overall mass or volume.
鈥淲e were required to deliver a much slower descent rate for lower parachute mass than has ever been achieved before,鈥� says David Northey, lead engineer for the main parachute design team at consultants Analyticon. 鈥淭his is certainly the best yet in terms of drag coefficient and weight.鈥�
The new canopy is made from lightweight nylon and its rigging is made from a high density polyethylene material called Spectra. Its design is an improved version of one first used to return manned modules back to Earth during NASA鈥檚 Mercury missions of the 1960s.
Falling fast
Beagle 2 will travel much faster than the dummy payload used in Friday鈥檚 test. Mars has only 37 per cent of the gravity found on Earth, but its atmosphere is significantly thinner. The lander will reach speeds of 18 metres per second during its descent.
To help soften the impact, the lander will inflate three large airbags shortly before touching down. When it has come to a rest on the planet鈥檚 rocky surface, these airbags will fall away leaving Beagle 2 to conduct its experiments.
Mars has proved a challenging target for previous missions especially for NASA. In September 1999, the agency鈥檚 Mars Climate Orbiter was destroyed when engineers mixed imperial and metric measurements for crucial orbit calculations.
The spacecraft consequently smashed into the planet instead of reaching a safe orbit. Just weeks later, NASA鈥檚 Mars Polar Lander disappeared during landing.