Techniques used in the ISAR project:

Optical microscopy:

Optical microscopy of thin sections is widely used in geology for characterising petrology and petrography. For space exploration, high-magnification imaging instruments (cameras) and optical microscopy are carried out on the rough and abraded surfaces of rocks, or on their powders.

Instruments used:

- Olympus BX 51

Magnification up to 1000 x. CBM, Orléans, France.

X-Ray diffraction (XRD):

X-Ray diffraction is used to measure the lattice parameters of a mineral in order to identify it. This technique is generally used on powdered samples, but can also be used on bulk samples or thin sections. It is used on Mars in the MSL mission (APXS device).

Instruments used:

- INEL XRM3000/CPS120

Equipped with a λ K_α beam emitted by a Co generator. ISTO, Orléans, France.

- Brucker D8 Advance

Equipped with a Cu anticathode (λ_CuKα = 1.541838 Å). Hydrasa, Poitiers, France.

Infrared spectroscopy:

Infrared spectroscopy is used to identify mineral and organic phases in a sample from the vibration spectra of the molecules that make up components of the sample. In geology laboratories, this technique is mostly used in transmission on a pellet made of powdered sample and KBr but analysis in reflectance on powdered samples, thin sections or bulk samples is also possible. A large part of the mineralogical data from Mars is obtained from the orbit by IR spectroscopy (MRO, Mars Express). This technique is widely used in space exploration (MSL, ExoMars 2020, Mars 2020, Rosetta…).

Instruments used:

- Nicolet spectrometer

Wavelength 400 to 4000 nm. ISTO, Orléans, France.

- Nicolet Magna IR 760 ESP

Wavelength 400 to 4000 nm for transmission analyses interfaced with a Thermo scientifique Integrating sphere Near IR Nicolet 6700 FT-IR, wavelength 4000 to 10000 nm, for reflectance analyses. Hydrasa, Poitiers, France.

Raman spectroscopy:

Raman spectroscopy uses a laser to identify mineral and organic phases in a sample from the vibration spectra of the molecules making up the components. It is a non-destructive method and can be used on bulk samples, thin sections or powders. 2D and 3D compositional maps of a sample can be made using a confocal scanning system. A Raman spectrometer will be used during the ExoMars 2020 (RLS) and Mars 2020 (SHERLOCand SuperCam) missions.

Instruments used:

- WITec Alpha500 RA

Equipped with a green laser (Nd:YAG frequency doubled, λ = 532 nm) and a near IR diode laser (λ = 785 nm). Scan size up to 10x15 cm². Confocal system for 3D mapping. CBM, Orléans, France.

Scanning electron microscopy (SEM):

Scanning electron microscopy uses an electron beam to scan the surface of a sample in order to make very high resolution, nm-scale imaging. Due to the interactions of the electrons with the matter, this technique can also be used to make elemental analyses by EDX for instance. SEMs have yet not been miniaturised for space exploration.

Instruments used:

- JSM-6400 JEOL

Equipped with a tungsten filament and operating between 0.2 and 40 kV. Maximum magnification 300000x. ISTO, Orléans, France.

- FEG-SEM Hitachi S4200

Equipped with EDX detector. Centre de Microscopie Electronique, Université d’Orléans, France.

Electron microprobe:

Electron microprobe is a spectroscopic method using the X-ray emitted during the interaction of an electron beam with the matter to determine the elementary composition of a sample (structural formulae of minerals) with a very high precision. By scanning the surface, it is also possible to conduct chemical element mapping. Electron microprobes have not yet been miniaturised for space exploration.

Instruments used:

- Cameca SX50

Equipped by 5 spectrometers with classic monochromators (PET, LiF and TAP ) for chemical analyses and special monochromators (Ni-C, W-Si and Mo-B₄C) for light elements. Low resolution SEM imaging is possible. ISTO, Orléans, France.

Mössbauer spectrometer:

The Mössbauer spectrometry uses gamma ray radiation to determine the degree of oxidation and the chemical environment of elements in a sample. The technique is widely used for the study of iron minerals. The MERs Sprit and Opportunity and the probe Beagle 2 were equipped with Mössbauer spectrometers.

Instruments used:

- MIMOS II analogue

Flight analogue miniaturised Mössbauer spectrometer MIMOS II. Guttenberg University, G. Klingelhöffer team, Mainz, Germany.

Cathodoluminescence:

TCathodoluminescence is used to detect trace elements and crystalline defects in minerals using the photoluminescence of the sample induced by an electron beam. It can be used on thin sections or hand samples. Cathodoluminescence has not yet been used for space exploration but it could equip a probe in the future.

Instruments used:

- Cathodyn chamber

Developed by OPEA interfaced with a simplified microscope, a high quality cold camera and a spectrometer. The electron emission is controlled by a cold electron gun. ISTO, Orléans, France.

Inductively coupled plasma (ICP-MS/OES):

Inductively coupled plasma mass spectrometry is used to make analyses of elemental composition. Elements ionised by nitrogen plasma are analysed by two main types of techniques: optical emission spectroscopy (ICP-OES ) for the major elements and mass spectroscopy (ICP-MS ) for traces elements. ICP has not yet been sent into space.

Instruments used:

- Thermo Elemental IRIS radial (ICP-OES ) and Thermo Elemental X7 (ICP-MS )

SARM, CRPG, Nancy, France.