NASA selected Astrobotic Technology this week to develop a scalable gravity offload device for testing rover mobility in simulated lunar gravity. When the $599,000 two-year contract is completed, the device will be made available for reduced-gravity testing of rovers, excavators, and spacesuits developed by space agencies and Google Lunar X PRIZE teams.
Simulating lunar gravity is simple in essence but challenging to perfect. The objective is to remove five-sixths of a test object’s weight so that the experienced weight is one-sixth of its Earth weight. This is done by applying a force directly opposite of gravity right at the robot’s center-of-gravity (CG). The challenge is to keep that suspension point centered over the robot’s CG as it moves. Any off-center tugging introduces forces that distort the test results. Additionally, a constant force must be maintained as the robot traverses terrain, rolls over rocks, and dips into craters.
NASA awarded funding under the Small Business Technology Transfer Program, to be split between Astrobotic and Carnegie Mellon University. It ties into another NASA small business award of similar size and duration for Astrobotic’s development of a lightweight lunar excavator. The gravity offload device will help in measuring the excavator’s ability to get sufficient traction to dig in frozen polar soil despite its low mass and low lunar gravity.