Accessing Mars Recurring Slope Lineae: Mobility Systems Analysis

Abstract

Recurring Slope Lineae, RSL, are visible steaks on the sides of Martian craters and other steep landforms with three distinct characteristics: i) they occur seasonally, ii) they lengthen with time, and iii) they fade. Recently, 474 RSL-like (>= 1 characteristic) and 69 RSL (all 3 characteristics) sites have been identified and are located in four primary regions of Mars: Chryse and Acidalia Planitiae, Valles Marineras, the Equatorial highlands, and the Southern Mid-Latitudes. There are several hypotheses that explain the origin of RSL, ranging from the motion of dry, granular material downhill, to the presence of underground aquifers. These hypotheses can be partially resolved by proximal (<= 100m) or even distal (>= 1km) observations. However, complete disambiguation can only be achieved through surface contact science. The Jet Propulsion Laboratory recently conducted a study into the methods by which a landed asset could access RSL sites to assist in the separation of RSL hypotheses. During this study, 8 of the 69 RSL sites were considered to be landable based on their latitude, elevation, topography, and ability to support an 8 km landing ellipse. In this paper, the accessibility of these sites is detailed through a discussion of their geometry, terrain types, slope and surface roughness. Particular attention is paid to three craters: Selevac, Andapa, and Garni, which were assessed to be strong candidates for scientific investigation. The challenges of accessibility provide the basis for which an assessment of the concepts of operation of 22 architectures is given. Though individually assessed, these concepts can be broadly compiled into balloon, helicopter, missile, and ground ascent/descent groups. First order sizing, power, and mass calculations for each group are detailed along with their advantages and concept specific challenges. The merits of each concept is assessed as a function of the science they enable, technology readiness and feasibility, cost, and risk. A ranking matrix is presented along with selected weightings. Based on the results of the trade study, the highest rated concepts are identified and their next stages of analysis and development are proposed.