ExoMars exhibits self-control in sampling Mars terrain

In simulations, now being backed up by laboratory tests in the “Mars Yard”
at the University of Wales, Aberystwyth, the rover first builds up a three-dimensional model of its surroundings and then analyses each rock for surfaces suitable for drilling. The rover can then calculate the adjustments needed to position its chassis, robotic arm and instruments to acquire the sample.

Dr Dave Barnes, who is presenting results at the European Planetary Science Congress in Potsdam on Monday 20th August, said, “This system allows the rover to do more than find nice flat areas to drill. The versatility of our system and its ability to pinpoint the best site to take samples, even from complex micro-features on rocks, could be vital when looking for evidence of exobiology.”

In recent Mars missions, up to 40% of operations time has been taken up with defining, planning, rehearsing, scheduling and uploading every move that the rover makes on the surface of Mars. For NASA’s Mars Exploration Rovers, three Martian days can elapse between a target being identified and the rover actually acquiring the sample. The autonomous systems developed by the Aberystwyth team should bring that time for ExoMars down to less than one Martian day.

Software developed by the team, who worked with EADS Astrium on the Phase A study for ExoMars, uses stereo images to build up a digital elevation model and to classify features into six categories: peaks, ridges, passes, planes, channels and pits. The level of detail for each feature can be varied by adjusting the number or data points, the slope and the minimum curvature for the model. The rover selects a suitable surface, then ‘tags’ the optimum drilling point and calculates how to move the instruments at the end of its robotic arm into position.

Dr Barnes said “We are now starting an exciting experimental phase of study with our Concept-E rover chassis model, which has six wheels that can drive, turn and move up and down independently. This gives us eighteen degrees of freedom when adjusting the pitch, roll and yaw of the chassis. We are working on a unified control system for the chassis and the robotic arm, which itself has four degrees of freedom, so the rover can manoeuvre itself to access samples even in hard to reach places. This puts us at a new level of manoeuvrability compared to Mars landers that have flown to date. ”

The Concept-E rover will be operated on the newly completed Planetary Analogue Terrain (PAT) at Aberystwyth, a 50 metre squared sculpted landscape, complete with a drilling pit, covered with soil and rocks that have been selected for their Mars-like properties. Dr Barnes said, “The majority of our work to date has been in simulation but there is no substitute for experiments with real hardware. We are looking forward to repeating our experiments with a real rover and instruments in our new PAT laboratory.”

FURTHER INFORMATION

ExoMars
ExoMars, which is scheduled to launch in 2013, is the first mission in the European Space Agency’s Aurora programme to explore Mars and the Moon. It will search for traces of past and present life on Mars and gather information the Martian environment in preparation for future missions.

The ExoMars rover will carry a comprehensive suite of instruments dedicated to exobiology research. The rover will be able to travel several kilometres during its nominal lifetime of 6 months and analyse samples from with in surface rocks and from the subsurface, down to a depth of 2 metres.

For further information see:
http://www.esa.int/SPECIALS/Aurora/SEM1NVZKQAD_0.html
University of Wales Aberystwyth
The University of Wales, Aberystwyth (UWA) has been a member of the ESA Mars Express consortium since before the spacecraft's launch in 2003. UWA’s major involvement focused upon the Beagle 2 lander and responsibilities included creating a suite of calibrated 3D software based simulation tools for Beagle 2. More recently, UWA has become a key member of the international teams for both the European Space Agency (ESA) ExoMars Rover, and the ESA ExoMars Panoramic Camera instrument.

UWA responsibilities include advanced software based rover/arm simulation and visualisation tools, PanCam image data processing and 3D terrain modelling, rover/robot-arm/PanCam calibration, and the development of new techniques for autonomous rover/arm science sample acquisition.

Planetary Analogue Terrain (PAT)
An award of £0.25M from the UK Higher Education Funding Council Wales has enabled the creation of a new Planetary Analogue Terrain (PAT) Laboratory at the University of Wales, Aberystwyth. The aim of the PAT Lab. is to perform comprehensive mission operations emulation experiments. These trials and experiments are essential when learning how deploy science instruments for a given mission using a robot, and hence maximise quality scientific data return. Work has resulted in a unique facility that has a terrain region composed of Mars Soil Simulant-D (from the German Space Agency – DLR). It includes ‘science target’ rocks that have been fully characterised, and donated to the project by the UK Planetary Analogue Field Studies network (PAFS-net). These rocks have been characterised independently, hence results can be compared with those generated using the PAT Lab. robots. The terrain also has an area for sub-surface sampling. The total floor area of the PAT Lab. is 100 m2, and half of this is dedicated to the terrain region.