THE HARRISON DROP TEST
Scaled Models
The drop test, as developed by Jon Harrison at Applied Dynamics Laboratories, involves building a dynamically scaled model of the full-size spacecraft, spinning the model and dropping it 30 feet into a catch box, recording nutational data as it falls. The nutation time constant for the model is computed and scaled back to the spacecraft.
Flight data obtained from Mars Global Surveyor (1996) verfied test results to within 0.2% error. (Artist rendering, NASA)
Accuracy Verified
Flight data have demonstrated the validity of the Harrison Drop Test: Ford Aerospace (1983), Hughes Aircraft (1984), RCA (1984), British Aerospace (1985), NASA Goddard (1992), Martin Marietta (1993) and Lockheed Martin (1996) spacecraft data compared favorably with test data developed for those spacecraft designs. Flight data obtained from Mars Global Surveyor (1996) verfied test results to within 0.2% error. All tested spacecraft successfully performed the spin-stabilized maneuvers during flight.
Solutions Found
When testing revealed unacceptable time constants, Dr. Harrison helped develop and test the design and/or mission changes that would result in acceptable results.