Máni - a Lunar photoclinometric mapping mission

The Máni mission will contribute to the overarching goal of enabling Europeans to explore the Moon by providing high-value and novel information that will assist in mission planning, de-risk landings, and facilitate scientific exploration. This will be achieved through a mapping mission that is designed from its inception to take advantage of recent advances in the field of photoclinometry and photometry.

The Máni mission will be the first mission to employ a targeted multi-angular photoclinometric mapping approach to map key regions of interest of the Lunar surface. We aim to acquire the highest resolution orbital images of the Lunar surface, including the Polar regions, across a wide range of viewing geometries. From these images, we will produce detailed maps of the topography and reflectance properties at a resolution like that of the images. Additionally, through photometric analyses, we will provide sub-pixel information on surface properties down to mm-scale. Uniquely, from the probabilistic nature of the novel data processing employed, mission data products will all be accompanied with a measure of their level of confidence. This implies that future missions can select, e.g., landing sites that are not only predicted to comply with their mission requirements but also have a high level of confidence of complying with their requirements, thus lowering risks and increasing chances for mission success.

The mission data processing is improved relative to already published work by mission members (1) in its integration of high-resolution imagery with available a priori information like laser altimetry data.  It features a computationally efficient and advanced photoclinometric model that accounts for complex illumination and observing geometry. This enables pixel-level resolution in the simultaneous output of both topographic maps and surface reflectance maps. While novel and under ongoing development, the mission data processing approach is validated using available Lunar images.

Exploration and scientific goals

Below, we present a selection of studies that highlight the range of investigations that can be undertaken based on Máni mission data products.

Assessing landing and mission sites of importance for human and robotic exploration

The primary focus of the Máni mission is to provide higher-resolution mapping of potential landing sites and locations of interest for exploration. The high-resolution images (as good as 20 cm/px at 50 km altitude) and topographic maps provided by the Máni mission enable unprecedented identification of hazards such as boulders, craters, and slopes that could jeopardize landing success. In particular, the ability to provide not only an accurate high-resolution topography of candidate landing sites but also assess the level of confidence of this presents a novel ability to not only select sites that are predicted to meet mission/lander requirements but sites that do so with a high probability.

Sites of importance to future human and robotic exploration imposes demanding requirements on the operational orbit of the mission as many of these, e.g. for the Artemis missions, are situated close to the Lunar South Pole (2–4).

Quantifying Earths albedo – a key parameter in climate models

Detailed mapping of the lunar reflectance properties for two key regions, Grimaldi and Crisium, that has historically been used for Earthshine observations (5, 6)  will enhance the value of lunar Earthshine data. It will not only strengthen future earthshine measurements but also enable a transformative reanalysis of archived earthshine data. This will yield more precise global (semi‐hemispheric) albedo estimates and facilitate targeted assessments of polar albedo—a critical parameter given current concerns over ice-cap melt, as well as address the observed decline in terrestrial albedo over a 20-year period.

Effects of space weathering on the micro-texture of Lunar regolith

With the Máni mission we can take a new step forward in efforts to characterize and understand the lunar micro-texture. By deliberately targeting geological units from different ages and levels of maturity, we will be able to decipher the processes creating the regolith and estimate the evolution timescale. The Máni mission will augment these studies by mapping photometric properties at a resolution as good as ~20 cm/px. The high resolution provided by the Máni mission will also enable investigation of how other geological processes – e.g., lunar swirls, crater rays and volcanic flow – affect and modify the surface micro-texture.

 

Mission and spacecraft

The Máni mapping methodology requires the acquisition of at least 5, preferentially 10, overlapping high-resolution images of a region of interest covering a range of viewing angles separated by more than 100°. Furthermore, at least two illumination angles, separated by at least 20°, must be captured as part of the images acquired of a region of interest. These requirements imply that at least two overflights, acquiring 5 images during each, of the target area separated in time by at least a full Lunar sideral period are needed to acquire the necessary image-data to map a region of interest.

The Máni spacecraft is developed around the single large primary payload of the mission - an optical 300 mm telescope with a panchromatic 2D detector capable of acquiring images of the Lunar surface at a resolution as good or better than 20 cm/pixel at 50 km altitude. A secondary smaller colour imager intended to provide context for the primary images is also included.

References

• I. Fernandes, K. Mosegaard, Planet. Space Sci. 218, 105514 (2022).
• E. Peña-Asensio, Á.-S. Neira-Acosta, J. M. Sánchez-Lozano, Acta Astronaut. 226, 469–478 (2025).
• C. Orgel et al., Planet. Sci. J. 5, 29 (2024).
• S. J. Boazman et al., Icarus. 421, 116240 (2024).
• P. R. Goode et al., Geophys. Res. Lett. 48 (2021), doi:10.1029/2021gl094888.
• P. Thejll, H. Gleisner, C. Flynn, Astron. Astrophys. 573, A131 (2015).