An Integrated Traverse Planner and Analysis Tool for Planetary Exploration

Abstract

Future planetary explorations will require surface traverses of unprecedented frequency, length, and duration. As a result, there is need for exploration support tools to maximize productivity, scientific return, and safety. The Massachusetts Institute of Technology is currently developing such a system, called the Surface Exploration Traverse Analysis and Navigation Tool (SEXTANT). The goal of this system is twofold: to allow for realistic simulations of traverses in order to assist with hardware design, and to give astronauts an aid that will allow for more autonomy in traverse planning and re-planning. SEXTANT is a MATLAB-based tool that incorporates a lunar elevation model created from data from the Lunar Orbiter Laser Altimeter instrument aboard the Lunar Reconnaissance Orbiter spacecraft. To assist in traverse planning, SEXTANT determines the most efficient path across a planetary surface for astronauts or transportation rovers between user-specified Activity Points. The path efficiency is derived from any number of metrics: the traverse distance, traverse time, or the explorer's energy consumption. The generated path, display of traverse obstacles, and selection of Activity Points are visualized in a 3D mapping interface. After a traverse has been planned, SEXTANT is capable of computing the most efficient path back home, or "walkback", from any point along the traverse -an important capability for emergency operations. SEXTANT also has the ability to determine shadowed and sunlit areas along a lunar traverse. This data is used to compute the thermal load on suited astronauts and the solar power generation capacity of rovers over the entire traverse. These both relate directly to the explorer's consumables, which place strict constraints on the traverse. This paper concludes by presenting three example traverses, detailing how SEXTANT can be used to plan and modify paths for both explorer types.

Future Needs for Science-Driven Geospatial and Temporal Extravehicular Activity Planning and Execution

“…SEXTANT is a resource-based path planning tool which optimizes human traverses based on a variety of cost functions, specifically distance, time, or energetics (Johnson et al, 2010; Gilkey et al, 2011). Once the traverse plan was created in xGDS, SEXTANT calculated a more granular path between waypoints, only taking the terrain elevation into account.…”

Minerva: User-centered science operations software capability for future human exploration

“…SEXTANT is a resource-based path planning tool that aims to optimize human traverses through terrain with elevation provided via data elevation models, applying different cost functions -traverse length, traverse time or metabolic rate [14]. SEXTANT also has the capability to optimize the concurrent paths of multiple humans and vehicles [11].…”

Human Assisted Robotic Vehicle Studies - A conceptual end-to-end mission architecture

“…Errors on these maps may still be a potential problem of the mission design [13]. However over the last two decades, we have improved our knowledge and accuracy of the lunar topography thanks to a combination of laser altimetry and imagery collected from orbiting spacecrafts [14]: -Clementine spacecraft (launched 1994) -Japanese Selene Kaguya spacecraft (launched 2007) -Chinese Chang'e-1 spacecraft (launched 2007) -Indian Chandrayaan-1 spacecraft (launched 2008) -LRO (Lunar Reconnaissance Orbiter) These missions have allowed the creation of Digital Elevation Models for the lunar landscape with higher accuracy than ever before, which is critical for the analysis of potential landing sites and robotic traverses [14] [15]. For the HARVeSt mission the south pole region has been selected as the ideal region to carry out the operations.…”