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Overview

Thermal Control During Astronaut Traverses

Principal Investigator:
Jeffrey A. Hoffman, Ph.D.

Organization:
Massachusetts Institute of Technology

Astronauts will be required to conduct a number of difficult extravehicular activities (EVAs) on the surface of the moon to carry out exploration missions and to build a lunar base. These moonwalks, which will likely require the use of vehicles and robotics, will be complicated and have limited resources, such as oxygen, electricity and water, at the astronauts disposal.

In order to insure crew safety and improve efficiency, Dr. Jeffrey A. Hoffman and colleagues have developed the Mission Planner, a navigation tool to aid in the planning and real-time execution of lunar EVAs. The Mission Planner uses an algorithm to calculate the most efficient path between EVA locations based on an astronauts metabolic rate.

This project’s goal is to improve the Mission Planner’s ability by to calculate thermal constraints on the lunar surface, which will allow the modeling of thermal stress astronauts will endure during EVAs and during travel in pressurized rovers.

NASA Taskbook Entry

Technical Summary

NASA's future plans to explore the Moon and establish a lunar outpost will require extravehicular activities (EVAs) of a quantity and scope never before attempted. Astronauts, robotic assistants and astronaut-carrying vehicles will be used in concert to complete a wide variety of challenging activities. Because of the enormous numbers of EVAs, it will be essential to maximize crew safety and productivity while minimizing the energy cost on the explorers and making most efficient use of limiting consumables like water and electrical energy.

We have developed over the past few years a path-planning and navigation tool, called the Mission Planner (Johnson et al. 2009, with references to past work), to assist with pre-mission planning, scenario simulation, real-time navigation and contingency re-planning during planetary traverses. The Mission Planner calculates the most efficient path between user-specified waypoints. Efficiency is based on an exploration cost algorithm, which in the current implementation is set equal to the estimated astronaut metabolic rate.

We propose to improve our ability to calculate thermal constraints for planetary surface exploration by incorporating solar illumination into the path-planning tool developed over the past few years at MIT. The results will allow modeling thermal stress during on-foot astronaut EVAs as well as during astronaut travel in pressurized rovers. It will also apply to thermal modeling of traverses by robotic exploration vehicles. We will incorporate into our Mission Planner lunar topography and surface roughness data as it becomes available from the Lunar Orbiter Laser Altimeter (LOLA) experiment on the Lunar Reconnaissance Orbiter.

Deliverables:

  • Predict position of the sun for any given time and place on the moon
  • Calculate sunlit and shadowed area for a given topographical model
  • Incorporate LOLA altimetry data into topographic model
  • Calculate thermal loading for sample EVA traverses
  • Investigate extension of model to small pressurized rovers
This project's funding ended in 2010