Europe’s future Martian rover ExoMars will be tested this week in Mars-like conditions in the south-American Atacama Desert.
The testing, coordinated by the European Space Agency (ESA), will be carried out by engineers from ESA’s UK centre in Harwell, who will be communicating remotely with the rover as it drives thousands of kilometres away.
Researchers believe the hostile desert in the north of Chile presents the closest possible terrestrial match to the conditions the robotic vehicle would encounter on Mars, thus offering a suitable test-bed. Similarly to Mars, the Atacama Desert lacks vegetation and barely ever sees any rain.
“This field trial is about optimising the use of typical instruments and equipment aboard a Mars rover and generating a set of commands for the rover to execute the following day,” said Michel van Winnendael, coordinator of ESA’s Sample Acquisition Field Experiment with a Rover project (SAFER).
“Unlike satellites, planetary rovers operate in close interaction with the topography and physical properties of the planetary surface. This implies limited data return from the rover during relatively short communication windows, with an inherent time delay,” he said.
The team will simulate operating a rover on a Martian schedule using not terrestrial 24-hour days but Martian 24 hours 39 minutes and 35 seconds long sols.
For each sol the team will first downlink data and then prepare a set of commands for the next sol that the rover will then carry out on its own.
To make the whole experience even more realistic for the operators, an unmanned aircraft, simulating the role of a Mars orbiter, will be sending overview images of the situation on the ground to the UK-based team.
Using an early prototype of the six-wheeled ExoMars rover, the engineers are testing a full set of instruments, designed to be eventually mounted on the vehicle travelling to Mars – a panoramic camera for stereo 3D imaging, a ground-penetrating radar to probe subsurface geology, and a close-up imager for studying subsurface samples to a resolution of a thousandth of a millimetre.
These three instruments will work together to select a sample site with outcrops of bedrock beside looser material. A human-operated hand drill will gather underground samples for the rover to examine – although this human intervention will remain invisible to the remote operators.
“For the first time with SAFER we will attempt to integrate data from surface and subsurface instruments to explore how to transition from topsoil to underground operations,” said ExoMars project scientist Jorge Vago.
“Since drilling plays an important role in the ExoMars rover’s search-for-life strategy, this is an important step. On Mars the best chances of accessing well-preserved molecular biosignatures deposited during the planet’s early, water-rich history lie in the subsurface, at depths below 1m, where the topsoil provides shielding from cosmic radiation damage.”
The knowledge gathered during the Atacama test will help fine-tune the ExoMars concept for its 2018 mission.
“Since this is a rehearsal of a planetary exploration scenario there is an inevitable degree of uncertainty in the sequence of events,” said van Winnendael. “Nature is very inventive in presenting situations which were not fully anticipated by those who conceived the mission. That’s why we find it important to do field tests in a fairly representative environment.”