Laser-powered rover to explore Moon’s dark shadows

18 May 2020

ESA’s Discovery & Preparation program funds laser system to power rover from 15km away.

The European Space Agency’s Discovery & Preparation program has funded the design of a laser system to keep a rover powered by a remote laser source from up to 15 km away while it explores some of these dark craters.

The developers of the laser-powered rover say that it will achieve “robotic exploration of tantalising locations on Earth’s moon, particularly the permanently-shadowed craters around the Moon’s poles, which are believed to be rich in water ice and other valuable materials.”

Data from NASA’s Lunar Reconnaissance Orbiter, India’s Chandrayaan-1 and ESA’s SMART-1 orbiters show the Moon’s permanently shadowed regions are rich in hydrogen, strongly suggesting water ice can be found there.

The ESA explained the reason that a remote power source, such as has been developed, is required is that any rover prospecting the shadowed regions would have to do without solar power, while gathering data at temperatures as low as –240°C.

Challenge is staying cool

“The standard suggestion for such a situation is to fit the rover with nuclear-based radioisotope thermoelectric generators,” said ESA robotics engineer Michel Van Winnendael. “But this presents problems of complexity, cost and thermal management – the rover could warm up so much that prospecting and analysing ice samples would become impractical. As an alternative, our study looked at harnessing a laser-based power system, inspired by terrestrial laser experiments that keep drones powered and flying for long periods.”

The 10-month PHILIP Powering rovers by High Intensity Laser Induction on Planets project was undertaken for ESA by Italy’s Leonardo company and Romania’s National Institute of Research and Development for Optoelectronics, coming up with a complete laser-powered exploration mission design.

This included selecting a location for the mission lander, in a near-permanently sunlit region between the South Pole’s de Gerlache and Shackleton craters. This lander would host a solar-powered 500-watt infrared laser, which it would keep trained on a 250 kg rover as it entered the shadowed regions.

The rover would convert this laser light into electrical power using a modified version of a standard solar panel, with photodiodes on the sides of the panel keeping it locked onto the laser down to centimetre-scale accuracy.

Rover testing by night

The study has identified routes that would take the rover downward at a relatively gentle 10 degrees of slope while keeping it in the lander’s direct line of sight. The laser beam could be used as a two-way communications link, with a modulating retro-reflector mounted on the second of the rover’s solar panels, sending signal pulses in light reflected back to the lander.

Guiding the project requirements, ESA has previously performed field tests at night in Moon-like Tenerife to simulate rover operations in permanent shadow. “With the PHILIP project completed, we are one step closer to powering rovers with lasers to explore the dark parts of the Moon. We’re at the stage where prototyping and testing could begin, undertaken by follow-up ESA technology programs,” Michel aded.