July 20 (UPI) -- A pair of European Space Agency rovers have spent the past nine days testing their navigation abilities among the lunar-like terrain of Tenerife, the largest of the seven Canary Islands.
ESA engineers tested the two rovers throughout the day and night.
"Until now, planetary rovers have always been operated during local daylight," ESA robotics engineer Martin Azkarate said in a news release. "But for proposed missions to the polar regions of the moon, lighting conditions will be more difficult."
On the poles of the moon, the sun stays low on the horizon and casts long shadows. For the rovers, many days will be spent in darkness so engineers must train the vehicles to operate in limited lighting.
"We're seeking to find out the best ways of navigating the lunar surface in varied illumination and terrain, analyzing different sensors and software tools," Azkarate said.
During the nine days of testing, engineers tested a variety of sensors, including stereo cameras outfitted with night lamps, lidar sensors, inertial sensors and wheel sensors.
The rock strewn landscape of Tenerife's Teide National Park offers an ideal place to the replicate the conditions of the lunar surface.
"Compared to rockier volcanic areas nearby where the rovers would not be able to traverse at all, this place is maneuverable while also moon-like -- with sand and small stones above rock," Azkarate said.
Though the rovers were remote-controlled for most the nine days, engineers spent some time experimenting with autonomous navigation systems. The moon is close enough to allow for time-delayed remote operation.
ESA scientists hope further testing will yield improved autonomous capabilities.
"This is a slow process however. A faster, self-navigating rover is seen as a necessary technology for future missions, like self-driving cars on Earth," said robotics engineer Levin Gerdes. "But with no roads, the rover will have to work out its own route -- first by taking images, then using these to map the surrounding area, followed by identifying obstacles and planning a path to safely reach its assigned goal."
Researchers will return to Tenerife in September to conduct additional rover navigation tests.