Fall proof

European ambitions to launch missions to the Moon or Mars could take a step closer thanks to a project that will test lander technology on earth by dropping it from a helicopter.

EADS Astrium is working with the German Aerospace Centre (DLR) to develop and demonstrate a set of equipment for soft landings on planetary surfaces that could one day be used for supply vehicles delivering to a lunar base.

The project will see systems integrated on a lander simulation platform that will be dropped from a helicopter at a height of 1.5km and carry out a controlled landing on a moon-like surface at a test centre, using steady-state and pulsed engines.

The first phase, which started this month, is a €1m (£850k), nine-month technical feasibility study. Dr Mark Kinnersley, Astrium's director of business development for orbital systems and space exploration, explained: 'We want to raise the technology and integration readiness levels, because the interaction between all of these systems is quite complex. You can imagine these engines pulsing and firing at different times and this has to be handled together with all the instruments that will help to land on the Moon.'

The instruments in question will include optical-navigation systems, LiDar (light detection and ranging — similar to radar but using a laser) and radar altimeter, as well as more traditional space instrumentation such as a star sensor and inertial measurement sensors.

A mix of existing liquid bi-propellant-fuelled engines with powers ranging from 200-500N will be used for the testing. For the landing itself, a much larger throttleable engine will be developed at a later stage of the project.

'We will use the same engines as we would for a lunar or Mars landing, but we will need more of them to demonstrate it under Earth's higher gravity,' said Kinnersley. 'The beauty of this test is, though it won't be identical to landing on the moon, it will demonstrate that we're capable of creating the systems and using the sensors to land safely on the lunar surface.'

Initially, a set of sensors will be tested on their own during a helicopter flight. Then they will be attached to a trial carrier, made as similar as possible to the lander, with legs designed for a lunar terrain. The test lander will also be carried aloft by helicopter and dropped first by parachute to get it away from the helicopter, then the lander will be released under its own thrust and land itself, hopefully gently, at a test site designed to simulate the surface of the Moon.

The test-bed trial carrier will be built from scratch in the second phase of the project. It may have to stray a little from the intended final design to cope with Earth's gravity. The atmosphere could also have an effect on the engines, but Kinnersley said that bi-propellants should not be overly affected by atmospheric oxygen.

Astrium is drawing on its experience of developing the ATV (automated transfer vehicle), the 'space truck', which delivers supplies to the International Space Station. Though different technologies are involved, ATV is also a complex system with similar engines to those proposed for the lander and was an entire system designed from scratch.

Similarly, Astrium's PHOENIX project to test a glided-landing reusable launch-vehicle was also dropped from a helicopter and used similar Guidance, Navigation & Control (GNC) solutions.

Though the lunar lander is a DLR-sponsored project, the intention is it will later enter into ESA's space-vehicle stable. An ESA- sponsored lunar lander could fit in with the NASA-led international effort to return to the Moon, which already has a buy-in from a number of European member states.

Kinnersley added: 'Though the Americans and Russians carried out manned and robotic landings on the Moon decades ago, this project will be a first for Europe. We're using techniques that will allow us to land precisely using hazard avoidance, meaning we can cope with the rocky surface around the south-pole of the moon and explore this little-examined area.

'The ultimate dream is to have a lander that can bring scientific payloads to the Moon, and potentially a larger cargo-version could bring supplies to a US lunar base like ATV does to the ISS, and potentially pay Europe's way in the upcoming Moon missions.'

The demonstrator could be realised by 2012, with its first Moon-landing scheduled for between 2016 and 2020, coinciding with NASA's plans to return humans to the Moon.

Berenice Baker