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Tribology and Space Mechanisms - Lunar Surface Mobility Components
Research Objectives
The objective is to develop concepts and methods to achieve mission-based surface mobility requirements for extraterrestrial vehicles with focus on NASA’s planned missions to return to the moon. In partnership with other NASA partners we are learning lessons from the Apollo Program, assessing the technologies used for Apollo missions, and determining technology shortfalls relative to the new NASA mission requirements. Our focus for surface mobility includes analytical techniques to determine traction capability and propulsion system power requirements. Wheel concepts suitable for lunar missions are evaluated and studied including experiments to determine pulling and climbing capabilities.
Technical Challenges
  • Engineering solutions for wheels used on earth are generally not applicable to lunar missions because of the extreme temperatures, vacuum, and radiation environment
  • Specialty wheels and/or other “running gear” will be required, the optimal solution depending on the mission requirements and the maturity of available concepts and technology
  • Proven methods for predicting traction and propulsion system power requirements are needed for mission planning, vehicle concept selection and development, and for mission execution
  • Surface mobility systems for the new lunar mission will require significantly greater durability relative to the required durability of the short-term Apollo missions
Current Research
Several wheel concepts have been designed, built, and tested for traction capability to determine appropriate wheel designs for lunar missions. One such concept is a flexible spiral wheel which deflects under load and torque (as shown below), creating a larger contact area and thus more traction than a rigid wheel in a lunar-like terrain. The performance effects of other design characteristics, such as tire diameter, width, material, and tread pattern, are also being tested. Currently, exact replicas of the original Lunar Roving Vehicle (LRV) wheels are being traction tested, which will provide very useful information on how to design tires that will carry more load, travel much longer distances, and be able to climb steeper slopes than the LRV was required to do.

Lunar dust endurance test
 
Above: The spiral wheel during a traction test. Experimental traction data shows that spiral wheel traction is significantly better than a rigid wheel.
 

Testing of vehicle pull and traction in the Simulated Lunar OPErations (SLOPE) facility
 
Above: Testing of vehicle pull and traction in GRC’s Simulated Lunar OPErations (SLOPE) facility as the vehicle approaches a sloping terrain. A CBS “60 Minutes” film crew gathers footage during this test run.
 

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Last Updated: April 21, 2009