MIRS Instrument

To carry out the MMX mission, the MIRS is meticulously conceptualized. It has several components that ensure the effectiveness of observations. The fundamental part is represented by 2 interdependent boxes: the OBOX and the EBOX.

The OBOX is the mechanical part containing the optical components of the mission, explaining the name “Optical BOX”, while the EBOX is the electronic part that manages the MIRS interface, explaining the name “Electronic BOX”.

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The OBOX contains :

• a scanner (capturing the light rays emitted by the observed object)

• a telescopic system (an assembly of optical equipments, precisely mounted to observe qualitatively an object from a long distance),

• a cryostat (keeping certain components at low temperature),

• a detector (allowing to read the light spectrum emitted by the observed object),

• a calibration lamp (ensuring that the colors observed in space are faithful to reality).

Two protection systems are added to the optical part to keep the instruments immaculate. A shutter is placed at the slit of the telescope to close the cavity when the observations are over. A cover is used at the entrance of the OBOX to prevent dust from getting in when the vehicle lands on Phobos. The OBOX therefore ensures that observations are possible and reliable in space, it allows infrared data to be collected by MIRS.

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Data are the recieved by the EBOX via an interconnection cable to analyze them and to save them for future studies. This second box is “black anodized” to benefit from effective thermal insulation in space. It works mainly thanks to 2 electronic components:

• The Low Voltage Power Supply assembly, called LVPS (it generates the supply voltages that might be missing to stabilize the signal received by the MMX system),

• The Instrument Control Unit assembly, called ICU (it controls all the mechanical parts of the OBOX – EBOX system and communicates with the MMX mission data processor).

The observations made by MIRS must be qualitative enough to have a real scientific progress. That is why quality constraints and objectives have been defined by the scientific team of the laboratory. One can for example conceive the importance of the spectral resolution (accuracy) of the detector or even the range of wavelength within which the light must be observed (this allows to focus on the infrared rays).

The MMX mission has the broader objective of exploring the Martian moons, thus requiring technological advances and contributing to the efficiency of future space missions. The spacecraft will enter an orbit (Quasi Stationary Orbit: QSO) of Phobos in 2025 (one year after the launch of the mission) and will leave this orbit in 2028 (one year before the samples’ return to Earth). During this time, many instruments will allow a maximum of observations to make the best use of the spacecraft. It will be equipped with the MIRS near-infrared spectrometer, the MEGANE gamma-ray and neutron spectrometer, the MSA mass spectrometer, the SMP sampling device accompanied by its sample return capsule, the OROCHI wide-angle camera, the TENGOO narrow-angle camera, the LIDAR laser altimeter, the CMDM dust detector, but also a rover developed by CNES and DLR which will be dropped on Phobos.

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The push – broom strategy is used to observe and to analyze as good as we can the different celestial bodies. It consists in privileging the save of the light spectrum emitted by losing a dimension of space (in order to obtain a maximum of data in the end). Indeed, when MMX will orbit around Phobos, the MIRS will focus on a single band as an image, and the detector will record the spectrum emitted by each point of this band. The movement of MMX will be perpendicular to this band, it will then allow MIRS to observe a new band, corresponding to the 2nd dimension of space (not observable at a given moment). These observations will be used to determine the ideal location for a MIRS landing. The objective will be to find 2 secure areas, whose composition is attractive (composition estimated using the spectrum emitted by the area), in order to take a sample there. These samples will be carefully guarded so that they can be brought back to Earth in good condition, so that they can be studied properly by our scientists.