International Mars Ice Mapper Mission: Detection, mapping and characterization of subsurface water ice and overburden on Mars with Synthetic Aperture Radar combined with VHF Sounding and High-Resolution Imaging
Authors: Amoroso Marilena , Flamini Enrico , Ammanito Eleonora , Viotti Michele , Mugnuolo Raffaele , Haltigin Timothy , Boulais Etienne , Usui Tomohiro , Hollibaugh Baker David M. , Davis Richard M. , Kelley Michael S. , Collom Bob , Lafrance Sébastien , Plourde Patrick 
Published: March 2024

The primary goal of the International Mars Ice Mapper (I-MIM) mission concept is to identify and characterize accessible water-ice and its overburden in the upper 0-10 m of the Martian subsurface in preparation for future human-robotic exploration. The I-MIM concept mission has been developed by the Italian, Canadian, Japanese, and US space Agency Partners (ASI, CSA, JAXA, and NASA).In 2021, the Agency Partners competitively selected a Measurement Definition Team (MDT) to define the core measurements for the mission&#8217;s primary payload, to suggest possible augmentations, and to develop a concept of operations. In August 2022, the MDT released a Final Report [1], concluding that the mission&#8217;s primary instrument, a Synthetic Aperture Radar (SAR) centred at 930 MHz, would satisfy all of the Reconnaissance Objectives (ROs) and would provide the opportunity to accomplish unique new science covering a broad range of international science priorities. In order to expand the capabilities of I-MIM to undertake high-priority science investigations, the MDT also recommended that the concept team consider the inclusion of complementary payloads identified as highest priority: a very high frequency (VHF) radar sounder, a high-resolution optical imager, and a sub-millimetre sounder for atmospheric profiling.Based on the MDT inputs, the Agency Partners have updated the I-MIM mission architecture to consist of three spacecraft elements with complementary science payloads:Element 1 &#8211; Ice-Mapping Orbiter: Provided by JAXA, with two radar instruments and an atmospheric sensor: a CSA-provided polarimetric L-band (930 MHz) SAR, an ASI-provided Very High Frequency (VHF) Shallow Radar Sounder (100-200 MHz), and a JAXA-provided sub-millimetre sounder. Moreover, an ASI-provided Large Deployable Reflector (LDR) would support the SAR and act as part of the ASI-provided telecommunications subsystem.Element 2&#8211; Demonstration Lander: A JAXA-provided demonstration lander would piggyback on the main orbiter to provide ground-truthing capabilities with a potential complementary small instrument package.Element 3 &#8211; Free-flying Smallsat: A NASA-provided, free-flying smallsat with a high-resolution imager would provide high-resolution imaging for context and continuity under a small low-cost mission profile and to meet the requirements for multiple scientific investigations and future mission site selection.Mapping the unstudied near surface of Mars thanks to the synergic observations L-band SAR and the VHF Sounder, augmented by the High-resolution Imager, has the potential to fill a major data gap unmet by prior instruments sent to Mars and provide a broad evaluation of the abundance of water ice reservoirs at medium latitudes.In order to characterize variability in the ionosphere both the SAR and the sub-millimeter sounder further addresses key questions about the connections in Mars&#8217;s dynamic climate regions and seasonal interactions of shallow subsurface volatiles with the atmospheric structure, of critical importance to both science and human-robotic mission planning.In the International Moon to Mars objectives context, I-MIM would provide core information about the role of water ice and other volatiles in prior and active changes globally on Mars, identifying landed locations in ice-rich areas that represent potential habitable environments, for future robotic and human missions. References: [1] I-MIM MDT Final Report (2022) 239 pp., online: https://science.nasa.gov/researchers/ice-mapper-measurement-definition-team