ESA - Robotic Exploration of Mars - Rover surface operations

The ExoMars Rover is designed to operate on the Martian surface for 180 sols. However, the vehicle's capabilities and on-board resources should allow an extension of the surface operations beyond the nominal lifetime.

These capabilities include:

• Surface mobility: in other words, travelling to reach sites of scientific interest,
• Conducting scientific investigations with the Pasteur instruments, supported by the drill and by the Sample Preparation and Distribution System (SPDS), on samples collected from surface outcrops and from the subsurface,
• Transmitting information to data relay satellites in Martian orbit,
• Receiving telecommands: This is how ground control instructs the Rover what to do next.

Blank sample

Organic cleanliness is essential to obtain valid scientific results when searching for evidence of organic compounds. After landing, the Rover will perform an initial measurement run using a blank sample. This will allow scientists to demonstrate that the entire Pasteur sample collection, processing, distribution, and measuring chain is free from organic contamination of terrestrial origin. More inert blanks will be used in the course of the operations to determine the level of cross-contamination between samples.

During the nominal lifetime, the Rover will be able to complete a Reference Surface Mission, which is based on two types of complex sequences of scientific operations: the experiment cycles and the vertical surveys. This Reference Surface Mission includes 6 experiment cycles and 2 vertical surveys.

Experiment Cycle

An experiment cycle comprises all actions necessary to select, approach, and study a target location, and to transmit the collected data to the Rover Operations Control Centre (ROCC). It consists of the following operations:

1. Identify the location at which to perform the next measurement cycle
2. Travel to the new location
3. Perform a full measurement cycle using all instruments
4. Transmit to Earth all relevant data: scientific, housekeeping, and navigation.

The Rover will be able to travel for several kilometres, whilst the incremental transverse distance is estimated to be between 100 metres and 500 metres. Visual, infrared and ground penetrating radar acquisition will be made in circular areas of approximately 20 metres diameter.

Measurement Cycle

A measurement cycle consists of the following operations:

1. Carry out a panoramic-scale investigation of the research site
2. Select an interesting surface target, typically a rocky outcrop, and approach it.
3. Collect a surface sample and analyse it to better understand the geological context.
4. On the basis of information acquired from the analysis of the surface sample, and on data from subsurface radar scans, select a region of interest and drill to collect a subsurface sample from a given depth.
5. The ExoMars Drill is designed to reach down to 2 metres. To search for biomarkers, ExoMars must penetrate through non-cohesive soils to reach buried formations that are protected from organic degrading agents, such as oxidants and radiation. These formations have potential exobiological interest, e.g. deep, well-compacted sedimentary deposits associated with the past presence of water.
6. Perform a complete series of measurements and analyses on the collected subsurface sample using the Pasteur analytical laboratory.
7. Process all data and prepare them for transmission.
8. If necessary, collect and analyse other samples.
9. Dispose of the sample material according to planetary protection rules.

Vertical Survey

The purpose of a vertical survey is to fully characterise, at a single location, the soil's geochemical, biological, water, and oxidant distribution as a function of depth.

A typical vertical survey consists of the following operations:

1. At one location, obtain samples from depths of: 0, 50, 100, 150, and 200 cm.
2. Analyse each sample with all Pasteur analytical laboratory instruments.

The Rover will be able to perform two orbiter communication sessions per sol, each lasting 5 to 10 minutes. Approximately 150 Mb of data will be transmitted to Earth per sol.