Abstract DGP2026-108

The WISDOM (Water Ice and Subsurface Deposit Observation on Mars) Ground Penetrating Radar (GPR) is a key scientific instrument aboard the Rosalind Franklin rover, part of the European Space Agency’s (ESA) ExoMars 2028 mission. Designed to probe the shallow subsurface of Mars with unprecedented resolution, WISDOM aims to detect and characterize water ice and hydrated minerals down to depths of approximately 3 meters, providing insights into the planet’s geological history and potential habitability. The instrument operates in the 500–3000 MHz frequency range, enabling high-resolution imaging of subsurface layers while maintaining sufficient penetration depth for meaningful scientific return. Moreover, the instrument will deliver a crucial contribution for the precise application of the rover’s drill unit to probe the Martian soil down to two meters depth.

WISDOM’s design comprises two main components: a compact electronic box housed within the rover’s internal avionics compartment and the antenna assembly mounted at the rear of the rover. The antenna system consists of two dual-polarized Vivaldi antennas for transmission and reception. Due to this design, four different channels (two co- and two cross-polarizations) can be observed at a single sampling position, and hence, certain geological features can be clearly distinguished compared to a single polarization measurement.

The instrument employs a stepped-frequency continuous wave (SFCW) technique, allowing for precise control of signal parameters and an enhanced signal-to-noise ratio. Data acquisition is synchronized with the rover’s mobility and positioning systems, enabling accurate geolocation of subsurface features.

To validate the instrument’s performance under Mars-like conditions, extensive field campaigns have been conducted in extreme environments on Earth, including the Atacama Desert (Chile) and the Arctic (Svalbard). These tests simulated Martian regolith properties, temperature extremes, and surface roughness. Results from these campaigns demonstrate WISDOM’s ability to resolve subsurface stratification with centimeter-scale vertical resolution and detect buried ice layers with thicknesses as low as 10 cm. In particular, data collected in permafrost-rich regions of Svalbard revealed clear reflections from ice-rich layers buried beneath dry regolith, closely mimicking expected Martian subsurface conditions.

Actual work for the mission preparation encompasses new contributions to the signal processing algorithms to account for, e.g., the challenging gap between antennas and ground of 38 cm or to enhance the interpretability of the resulting radargram.

The WISDOM GPR represents a major advancement in planetary radar technology, combining high resolution with reliable operation in harsh extraterrestrial environments. Its integration into the ExoMars Rosalind Franklin rover will provide the first in-situ, high-resolution subsurface survey of the dedicated landing site Oxia Planum, directly supporting the mission’s goal of assessing past habitability and identifying accessible water resources. The upcoming 2028 launch marks a pivotal step in our exploration of Mars, with WISDOM poised to deliver transformative insights into the planet’s hidden geology.