Sample Return from “water” Seeps on Mars

Motivation: Some of the most intriguing science discoveries on Mars came from sites that are currently inaccessible for in-situ analysis and sample return. The recent discovery of recurring slope lineae (RSL), such as those observed in Newton crater, are on steep slopes (25° – 40°) that are hundreds of meters down from the crater rim. In-situ analysis and sample capture of out-flow deposits that have interacted directly with water on Mars would be directly responsive to science priorities described in both the Decadal Survey [1] and the goals of MEPAG [2]. The requirement for liquid water in habitable environments makes the retrieval of out-flow samples scientifically important for future return to Earth. Challenges: Terrains where such features are observed have demanding topographies that are beyond the reach of current rovers. In-situ measurements across such steep and rugged terrains not only demand mobility with a high level of robustness to negotiate challenging features, but also an ability to recover from failures such as: tipping over, driving into sand traps, or high centering on rocks. Power and communication challenges must be addressed in light of topographic features that could occlude direct line-of-sight needed for communication and direct sunlight needed for solar energy. Approach: We propose a mission concept for in-situ target characterization and sample retrieval using novel field-demonstrated surface mobility platforms: the Axel rovers. Axel is a two-wheeled rover with two large wheel-encased science bays and a boom (Fig. 1). Using its body-mounted tether and yoyo-like operation , it is capable of accessing extreme terrains. It combines mobility and manipulation functionality of a robotic arm with its science payload-populated turrets. A single 30 kg Axel can carry multiple science instruments and a small sample acquisition and handling system in its science bays. In essence, Axel is a mobile science kit capable of placing and orienting instruments on sloped targets. Fig. 1 shows the Axel rover acquiring spectroscopic measurements and microscopic images of stratigraphic layers on a 40° slope at Black Lava Point in Arizona. Due to the large pay-load volume to system volume ratio, a series of cor-roborative, yet independent optical spectroscopic plus mass spectrometric measurements are envisioned for this robotic stratigrapher. Axel can be deployed by its tether either from a lander or another rover. It can also be configured as an independent dual Axel (DuAxel) rover that not only