Recurring Slope Lineae (or RSL) are dark streaks that repeatedly appear on some Martian crater walls during the warm seasons. Their seasonal behavior and preferential occurrence on warm equator-facing slopes suggest that some volatile, such as liquid brines, may be involved. Since their discovery in 2011, several hypotheses that include dry and wet flows have been proposed, but to date, there has been no single hypothesis that can explain all current observations. Conducting in situ science investigations on RSL requires advances in science concepts of operations, instrumentation and robotic access and in situ measurements on these steep slopes.
The goal of this task is to advance technologies that enable hypothesis-driven exploration of RSL. These technologies include accessing and in situ measurements centimeters below the surface to determine the nature of the regolith and its interaction with the atmosphere, the presence or absence and amount of water, its pH and salinity, and the mechanism by which putative water is replenished, and the presence or absence and identity of organic molecules. We will determine how these measurements affect mission architecture and access/mobility requirements.
For access and in situ measurements, we will advance extreme-terrain rappelling mobility and investigate alternate options for above-surface access from a lander inside the crater. The latter include options for deliver a sensor payload via a guided missile or a Mars helicopter. For the extreme-terrain mobility, we will develop/adapt mobility hardware and surface navigation software to enable >100 m rappelling distance in a 5-sol period (rate 20 m/sol) on characteristic terrain topographies. To enable remote operation (i.e. without direct-line-of-sight observations) on RSL, we will develop functional-level onboard autonomy for local motion planning under tether constraints and hazard avoidance given large occlusion from perception. To support field operations, Caltech, a partner on this effort, will develop ground tools for global route planning that analyzes orbital and onboard terrain information to suggest to remote operators potential routes that minimize risk for tethered rovers, which are subject to slip, falling, and entrapments.
The work will culminate in a science-driven field campaign to demonstrate integrated science and operations for the rappelling option.