Replica Martian soil set to aid development of ESA rovers

Researchers from the UK have developed replica Martian soil that will be used to help test and develop the European Space Agency’s (ESA’s) next generation of robotic rovers.

A team from Cranfield University’s centre for automotive technology has recreated Martian soil using a finely ground form of silicon dioxide known as silica flour in a project funded by ESA.

One of a number of soil types characterised by the current NASA Mars exploration rovers (MERs), Spirit and Opportunity, the so-called ‘soil surrogate’ will be used to help recreate the terrain of the Martian surface and conduct a number of experimental tests on Earth prior to sending the ESA rover (ExoMars) to Mars in 2018.

NASA performed similar experiments when developing its rovers to enable characterisation of the physical environment on Mars, to maximise the performance of its vehicle and to minimise the possibility of the rover getting stuck in the soil.

These experiments were repeated on Mars and involved wheel trenching and slipping, creating ruts that were used to reliably infer the soil physical properties.

The Cranfield group decided to simulate the most complex of the Martian soils identified, which meant there were a number of strict criteria around grain size (greater than 50 per cent of the sample had to be within a very narrow size range), relative density, cohesion and angle of internal friction.

The resulting material, dubbed engineering soil 4 (ES4), will now be used by space company Astrium in the development of the ExoMars rover.

Based on the experience developed over the course of this activity, Cranfield has also been awarded a further contract by Astrium to test a number of potential new wheel designs as part of the ESA Sample Fetching Rover study.

Using the ES4 replica soil, wheels of varying stiffness have been tested and new test data produced to further improve understanding of Martian terramechanics.