MoonIS Spectrometer on RASHID Lunar Rover

Introduction:  The MoonIS instrument is a VIS-IR spectrometer onboard the Emirates Lunar Mission (ELM) of the Mohammed Bin Rashid Space Centre (MBRSC). The mission is part of the MBRSC lunar exploration program and involves the development and launch of the series of "Rashid" lunar rovers. The Rashid Rover 3 has the aim of exploring the lunar South Pole region with a suite of dedicated instruments. MoonIS spectrometer is  a heritage of the MA_MISS instrument on board the Rosalind Franklin rover of the ESA ExoMars mission [1]. The launch of the mission is scheduled for 2028 and it will explore a polar area including Permanent Shadowed Region (PSR).

 Mission main objectives: The rover is designed to travel and explore areas of interest located in the South Lunar Pole region with the aim of:

• Examining the geographic and geological features of the lunar polar region​
• Analyzing the geological characteristics of the Lunar South Pole, examining the surface properties and composition of the soil.
• Exploring the Permanent Shadowed Region (PSR)
• Studying the presence of water in the southern polar region, identifying ice and hydroxyl on the surface and under the surface.

 Lunar Permanent Shadowed Regions (PSRs) and presence of ice: The lunar PSRs are expected to host large quantities of water-ice, which are key for sustainable exploration of the Moon [2-4]. Characterizing water ice in the PSRs is a primary goal of lunar science and exploration. Nevertheless, only limited information is available about the amount and distribution of ice within PSRs because the orbital imagery obtained to date lacks sufficient resolution and/or signal. Also, it is extremely debated the fine-scale geomorphology of the areas hosting ice and if the ice is superficial or if it is present immediately under the surface. Permanently shadowed regions on the Moon and other solar system bodies [5-10]  act as cold traps for the accumulation of water ice and other volatiles, which are thought to have been released over time by impacts of comets, asteroids, or even possible outgassing and interaction of the surface with the solar wind [11], or related to the formation of pits or volcanic outgassing [12,13]. The origin of water ice in the PSRs through the solar system is still disputed  and the study of lunar PSRs could help in understanding the history of volatiles on the lunar surface and on other planetary bodies. Moreover, in case of exogenic origin water ice would represent a record of icy planetesimals scattering history in the early solar system.  The  Moon’s spin axis is nearly perpendicular to the ecliptic, creating cold traps in polar craters where water ice could accumulate and be preserved over geological timescales.   In situ investigations are therefore essential to better understand the nature of the ice and its abundance. For this reason, several space agencies are planning to utilize rovers to better investigate water-ice and overall surface composition within PSRs. This is a high priority step necessary to pave the way for future human exploration.

The MoonIS instrument:  MoonIS  is designed to acquire spectra of the lunar surface in the 0.4-2.3 μm spectral range. The MoonIS spectrometer design is inherited from the Ma_MISS [1] instrument aboard the ESA’s ExoMars Rosalind Franklin Rover, but with improvements in the optical head design, calibration target, thermomechanical, and electronics design. In particular, MoonIS Optical Head (OH) will be mounted on the rover mast and connected through optical fibers to the spectrometer unit housed on the rover bus. Each fiber is coupled to a dedicated optical element in the OH to allow it to observe the scene while the other end is coupled to the spectrometer’s slit. This configuration allows to disperse the signal of each fiber across multiple pixels on the detector. The resulting hyperspectral image consists of the same number of “spots” on the detector as the number of fibers that will be accommodated and acquired. The area in front and surrounding the rover is scanned through the rover mast rotations that will allow it to investigate the entire region. Using this concept, MoonIS will acquire  images of multiple “pseudo-pixels”, thanks to the mast and rover movements. An external Calibration Target for radiometric and spectral calibration  is also being considered. MoonIS will be equipped with an illumination system, capable of illuminating the region of interest in the PSRs.

Main scientific objectives: The instrument is designed to achieve high-quality, advanced scientific results in characterizing the composition of the lunar surface. A key focus is the identification, distribution, and analysis of water ice, one of the mission's primary objectives. In this respect, MoonIS spectral range will allow a thorough investigation of several diagnostic water ice absorption features, namely at 1.04 µm, 1.25 µm, 1.5 µm and 2 µm being important indicators of water ice grain size and abundance [7]. The main goals can be summarized as follows:

• identify and distinguish H₂O and OH;
• evaluate the amount of H₂O and OH and their distribution;
• characterize H₂O physical properties (grain size, temperature);
• recognize the main class of lunar rocks;
• identify and quantify different minerals (e.g. pyroxenes, olivines, feldspars, spinels, etc.);
• identify different mixtures and determine their spatial distribution.

MoonIS characteristics in terms of S/N, spectral resolution,  range, and spatial resolution are suitable to achieve the above mentioned goals both in the sun-illuminated regions and in the PSR, the primary focus of the mission. 

Acknowledgments: This work is granted by Accordo ASI – INAF n. 2024-64-HH.0. The instrument is funded by ASI and manufactured by Leonardo S.p.A. (Italy).

References: [1] De Sanctis et al. (2017) (2017): Astrobiology 17, 6, 7. [2]  McCubbin et al. (2015) American Mineralogist 100: 1668-1707. [3] Honniball et al. (2021) Nature Astronomy 5: 121-127. [4] Pieters et al. (2009) Science, 326, 568–572. [5] Filacchione et al. (2020), MNRAS, 498, 1308-1318. [6] Raponi et al. (2018), Science Advances, 4, 3. [7] Deutsch et al. (2016), Icarus, 280, 158. [8] Paige et al. (2013), Science, 339, 300-303. [9] Schorghofer et al. (2016), GRL, 43,13. [10] Ermakov et al. (2017), GRL, 44,6. [11] Yeo et al. (2025), JGR, 130, 3. [12]  D.T. Blewett et al, Science 333 (2011). [13] P.K. Byrne et al. In: GRL 43.14 (2016)