ExoMars (rover)

ExoMars rover

A prototype in Hatfield, England
Operator	European Space Agency & Roscosmos
Major contractors	Lander: Roscosmos Rover: Astrium, Airbus
Mission type	Lander and rover
Launch date	July 2020[1]
Launch vehicle	Proton rocket
Mission duration	≥ 6 months
Homepage	exploration.esa.int/mars/48088-mission-overview/
Mass	Lander: 827.9 kg (1,825 lb) Rover: 310 kg (680 lb)
Power	1200 W solar array[2]
Batteries	1142 W·h Lithium-ion[2]

The ExoMars rover is a planned robotic Mars rover, part of the international ExoMars mission led by the European Space Agency.^[3][4]

The plan calls for a Russian launch vehicle, an ESA carrier module and a Russian lander that will deploy the rover to Mars' surface.^[5] Once safely landed, the solar powered rover would begin a six-month (218-sol) mission to search for the existence of past or present life on Mars. The ExoMars Trace Gas Orbiter, launched two years earlier in 2016, will operate as the rover's data-relay satellite.^[6]

The spacecraft was scheduled to launch in 2018 and land on Mars in early 2019,^[5] but due to delays in European and Russian industrial activities and deliveries of the scientific payload, it was moved to the launch window in July 2020.^[1]

History

The rover is an autonomous six-wheeled terrain vehicle once designed to weigh up to 295 kg (650 lb), approximately 60% more than NASA's 2004 Mars Exploration Rovers Spirit and Opportunity,^[7] but about 1/3 that of NASA's Curiosity rover launched in 2011.

In February 2012, following NASA's withdrawal, the ESA went back to previous designs for a smaller rover,^[8] once calculated to be 207 kg (456 lb). Instrumentation will consist of the exobiology laboratory suite, known as "Pasteur analytical laboratory" to look for signs of biomolecules or biosignatures from past or present life.^{[9][10][11][12]} Among other instruments, the rover will also carry a 2-metre (6.6 ft) sub-surface drill to pull up samples for its on-board laboratory.^[13]

The lead builder of the ExoMars rover, the British division of Airbus Defence and Space, began procuring critical components in March 2014.^[14] In December 2014, ESA member states approved the funding for the rover, to be sent on the second launch in 2018,^[15] but insufficient funds had already started to threaten a launch delay until 2020.^[16] The wheels and suspension system are paid by the Canadian Space Agency and are being manufactured by MDA Corporation in Canada.^[14]

In May 2016 ESA announced that the 2018 launch will be moved to the next available Mars launch window in July 2020 due to delays in industrial activities and a scientific payload.^[1]

An early design ExoMars rover test model at the ILA 2006 in Berlin

Another early test model of the rover from the Paris Air Show 2007

A prototype of the ExoMars Rover at the 2015 Cambridge Science Festival

Navigation

The ExoMars mission requires the rover to be capable of driving 70 m (230 ft) across the Martian terrain per sol to enable it to meet its science objectives.^[17][18] The rover is designed to operate at least seven months and drive 4 km (2.5 mi), after landing in early 2019.^[14]

Since the rover communicates with the ground controllers via the ExoMars Trace Gas Orbiter, and the orbiter only passes over the rover approximately twice per sol, the ground controllers will not be able to actively guide the rover across the surface. The ExoMars Rover is therefore designed to navigate autonomously across the Martian surface.^[19][20] A pair of stereo cameras allow the rover to build up a 3D map of the terrain,^[21] which the navigation software then uses to assess the terrain around the rover so that it avoids obstacles and finds an efficient route to the ground controller specified destination.

On 27 March 2014, a "Mars Yard" was opened at Airbus Defence and Space in Stevenage, UK, to facilitate the development and testing of the rover's autonomous navigation system. The yard is 30 by 13 m (98 by 43 ft) and contains 300 metric tons (330 short tons) of sand and rocks designed to mimic the terrain of the Martian environment.^[22][23]

Payload

Mars rover being tested near the Paranal Observatory.

The scientific payload is as follows:^[3]

Imaging system

Panoramic Camera System (PanCam)

The PanCam has been designed to perform digital terrain mapping for the rover and to search for morphological signatures of past biological activity preserved on the texture of surface rocks. The PanCam assembly includes two wide angle cameras for multi-spectral stereoscopic panoramic imaging, and a high resolution camera for high-resolution colour imaging.^[24][25] The PanCam will also support the scientific measurements of other instruments by taking high-resolution images of locations that are difficult to access, such as craters or rock walls, and by supporting the selection of the best sites to carry out exobiology studies. Stained glass will be used to prevent ultraviolet radiation from changing image colors. This will allow for true color images of the surface of Mars.^[26]

Core drill

The present environment on Mars is exceedingly hostile for the widespread proliferation of surface life: it is too cold and dry and receives large doses of solar UV radiation as well as cosmic radiation. Notwithstanding these hazards, basic microorganisms or their ancient remains may be found in protected places underground or within rock cracks and inclusions.^[27] The ExoMars core drill is designed to acquire soil samples down to a maximum depth of 2 metres (6.6 ft) in a variety of soil types. The drill will acquire a core sample 1 cm (0.39 in) in diameter by 3 cm (1.2 in) in length, extract it and deliver it to the inlet port of the Rover Payload Module, where the sample will be distributed, processed and analyzed. The ExoMars drill embeds the Mars Multispectral Imager for Subsurface Studies (Ma-Miss) which is a miniaturised infrared spectrometer devoted to the borehole exploration. The system will complete experiment cycles and at least two vertical surveys down to 2 metres (with four sample acquisitions each). This means that a minimum number of 17 samples shall be acquired and delivered by the drill for subsequent analysis.^[28][29]

Scientific instruments

The science package in the ExoMars rover will hold a variety of instruments collectively called Pasteur suite;^[10] these instruments will study the environment for habitability, and possible past or present biosignatures on Mars. These instruments are placed internally and used to study collected samples:^[30][31]

Pasteur instrument suite

• Mars Organic Molecule Analyzer (MOMA) is the rover's largest instrument. It will conduct a broad-range, very-high sensitivity search for organic molecules in the collected sample. It includes two different ways for extracting organics: laser desorption and thermal volatilisation, followed by separation using four GC-MS columns. The identification of the evolved organic molecules is performed with an ion trap mass spectrometer.^[3] MOMA is being developed in partnership with NASA.^[32] The Max Planck Institute for Solar System Research is leading the development. The mass spectrometer is provided from the Goddard Space Flight Center, while the GC is provided by the two French institutes LISA and LATMOS. The UV-Laser is being developed by the Laser Zentrum Hannover.
• Infrared imaging spectrometer (MicrOmega-IR) is an infrared imaging spectrometer that can analyse the powder material derived from crushing samples collected by the drill.^[3] Its objective is to study mineral grain assemblages in detail to try to unravel their geological origin, structure, and composition. These data will be vital for interpreting past and present geological processes and environments on Mars. Because MicrOmega-IR is an imaging instrument, it can also be used to identify grains that are particularly interesting, and assign them as targets for Raman and MOMA-LDMS observations.
• Raman spectrometer (Raman) will provide geological and mineralogical context information complementary to that obtained by MicrOmega-IR. It is a very useful technique employed to identify mineral phases produced by water-related processes.^[33][34][35] It will help to identify organic compounds and search for life by identifying the mineral products and indicators of biologic activities (biosignatures).

External

• Ground-penetrating radar, called WISDOM (for Water Ice and Subsurface Deposit Information On Mars) will explore the subsurface of Mars to identify layering and help select interesting buried formations from which to collect samples for analysis.^[36] It can transmit and receive signals using two, small Vivaldi-antennas mounted on the aft section of the rover. Electromagnetic waves penetrating into the ground are reflected at places where there is a sudden transition in the electrical parameters of the soil. By studying these reflections it is possible to construct a stratigraphic map of the subsurface and identify underground targets down to 2 to 3 m (6.6 to 9.8 ft) in depth, comparable to the 2 m reach of the rover's drill. These data, combined with those produced by the PanCam and by the analyses carried out on previously collected samples, will be used to support drilling activities.^[37]
• Mars Multispectral Imager for Subsurface Studies (Ma-MISS) is an infrared spectrometer located inside the core drill. Ma-MISS will observe the lateral wall of the borehole created by the drill to study the subsurface startigraphy, to understand the distribution and state of water-related minerals, and to characterize the geophysical environment. The analyses of unexposed material by Ma-MISS, together with data obtained with the spectrometers located inside the rover, will be crucial for the unambiguous interpretation of the original conditions of Martian rock formation.^[3][38] The composition of the regolith and crustal rocks provides important information about the geologic evolution of the near-surface crust, the evolution of the atmosphere and climate, and the existence of past or present life.
• Close-Up Imager (CLUPI), to visually study rock targets at close range (50 cm/20 in) with sub-millimetre resolution. This instrument will also investigate the fines produced during drilling operations, and image samples collected by the drill. The close-up imager has variable focusing and can obtain high-resolution images at longer distances.^[3][31]

Russian instruments

• The Infrared Spectrometer for ExoMars (ISEM),^[31][39] will be installed on the rover's beam. It will be used to assess bulk mineralogy characterization and remote identification of water-related minerals. Working with PanCam, ISEM will contribute to the selection of suitable samples for further analysis by the other instruments.
• ADRON-RM is a neutron spectrometer to determine the amount of subsurface hydration, and the possible presence of water ice.^[31][39][40] Adron will be used in combination with WISDOM to study the subsurface beneath the rover and to search for suitable areas for drilling and sample collection.
• Fourier spectrometer, mounted on the rover's mast will acquire temperature and aerosol measurements.^[40]
• Roscosmos will also provide radioisotope heater units (RHU) for the rover.^[3]

De-scoped instruments

The proposed payload has changed several times. The last major change was after the program switched from the larger rover concept back to the previous 300 kg (660 lb) rover design in 2012.^[31]

• Mars X-Ray Diffractometer (Mars-XRD) - Powder diffraction of X-rays would give exact composition of the crystalline minerals.^[41][42] This instrument includes also an X-ray fluorescence capability that can provide useful atomic composition information.^[43] The identification of concentrations of carbonates, sulphides or other aqueous minerals may be indicative of a Martian [hydrothermal] system capable of preserving traces of life. In other words, it would examine the past Martian environmental conditions, and more specifically the identification of conditions related to life.^[31]
• The Urey instrument was planned to search for organic compounds in Martian rocks and soils as evidence for past or present life and/or prebiotic chemistry. Starting with a hot water extraction, only soluble compounds are left for further analysis. Sublimation, and capillary electrophoresis makes it possible to identify amino acids. The detection would be by laser-induced fluorescence, a highly sensitive technique, capable of parts-per-trillion sensitivity. These measurements would be made at a thousand times greater sensitivity than the Viking GCMS experiment, and would significantly advance our understanding of the organic chemistry of Martian soils.^[31][44][45]
• Miniaturised Mössbauer Spectrometer (MIMOS-II) provides the mineralogical composition of iron-bearing surface rocks, sediments and soils. Their identification would aid in understanding water and climate evolution and search for biomediated iron-sulfides and magnetites, which could provide evidence for former life on Mars.
• The Life Marker Chip was for some time part of the planned payload. This instrument was intended to use a surfactant solution to extract organic matter from samples of martian rock and soil, then detect the presence of specific organic compounds using an antibody-based assay.^[46][47][48]

Landing site selection

Oxia Planum, near the equator, is the selected landing site for its potential to preserve biosignatures and smooth surface

After a review by an ESA-appointed panel, a short list of four sites was formally recommended in October 2014 for further detailed analysis:^[49][50]

• Mawrth Vallis
• Oxia Planum
• Hypanis Vallis
• Aram Dorsum

On 21 October 2015, Oxia Planum was chosen as the preferred landing site for the ExoMars rover assuming a 2018 launch. If the launch is delayed until 2020, Aram Dorsum and Mawrth Vallis will also be considered.^[51][52]

After the ExoMars 2020 surface platform lands, it will deploy ramps to deliver the ExoMars rover to the surface. The platform will remain stationary and will start a one-year mission to investigate the surface environment at the landing site.^[53]

See also

• List of missions to Mars

References

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External links

• ExoMars lander (not EDL)