Sensing winds on Mars: a new pathway toward local and global measurements

Understanding the Martian atmosphere requires direct, vertically resolved measurements of winds. Despite decades of orbital and in situ exploration, wind profiles remain poorly constrained, limiting our ability to validate general circulation models (GCMs), quantify dust-lifting mechanisms, and predict atmospheric variability relevant to entry, descent, and landing (EDL). Existing wind information relies primarily on surface sensors with limited spatial representativeness or on tracer tracking techniques using water vapor and clouds, both of which suffer from incomplete coverage and intrinsic ambiguities. To address this long-standing observational gap, we are developing two complementary Doppler wind lidars dedicated to profiling winds and aerosols in the Martian atmosphere: MADWIL (Mars Doppler Wind Lidar), designed for orbital observations, and MARBLL (Mars Boundary Layer Lidar), a compact surface-based system dedicated to the planetary boundary layer.

Both instruments rely on the same Doppler lidar concept. While MADWIL operates at 532 and 1064 nm, MARBLL only uses the 532 nm wavelength. Both are optimized for backscatter from ubiquitous Martian dust aerosols. Winds are retrieved from the Doppler shift measured at 532 nm using a quadrichannel Mach–Zehnder interferometer (QMZ) spectral analyzer, enabling line-of-sight (LOS) wind retrievals with expected precision on the order of 1 m s⁻¹ and a LOS ambiguity range of approximately ±270 m s⁻¹. Simultaneous aerosol backscatter profiling at 1064 nm provides information on dust and cloud vertical distributions, with polarization-sensitive detection enabling discrimination between aerosol types.

MADWIL has been preselected on ESA LightShip1 and is designed to provide global measurements of horizontal winds and aerosol backscatter from orbit. The instrument concept includes a multiwatt Nd:YAG laser transmitter, a co-aligned SiC telescope optimized to minimize solar background contamination, and a thermally controlled optical bench. MADWIL is expected to retrieve wind profiles from the surface up to ~60 km altitude, depending on atmospheric dust loading, with kilometer-scale vertical resolution. These measurements will constrain atmospheric circulation patterns, wave activity, and dust transport processes from local to planetary scales while providing key inputs for GCM validation and EDL studies.

MARBLL applies this observational capability to the near-surface atmosphere by targeting the Martian boundary layer, where exchanges between the surface and atmosphere control dust lifting, turbulence, and diurnal circulation. The instrument is conceived as a compact and resource-efficient lidar suitable for landed platforms. By continuously profiling winds and aerosols in the first kilometers above the surface, MARBLL will provide unprecedented insight into boundary-layer dynamics and their coupling to the larger-scale circulation observed by MADWIL from orbit.

A laboratory breadboard has been developed to validate the QMZ Doppler measurement principle and establish the performance prediction framework shared by both instruments. In parallel, an Observing System Simulation Experiment (OSSE) framework is under development using Mars climate model outputs and realistic aerosol scenarios to assess retrieval performance and support instrument trade-offs in laser energy, telescope aperture, and detector configuration.

Together, MADWIL and MARBLL form a complementary observational strategy spanning the Martian atmosphere from the surface to the middle atmosphere. By combining global orbital mapping with continuous local boundary-layer profiling, these instruments would provide the first comprehensive vertically resolved wind dataset at Mars, establishing a transformational benchmark for understanding Martian atmospheric dynamics, aerosol transport, and climate variability.