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April 5, 2006

Gravity Probe B know-how plows into Space Technology Hall of Fame

By Bob Kahn and Dave Myers

A technology first developed at Stanford for the Gravity Probe B (GP-B) project to put Einstein's theories to the test has landed in self-steering farm tractors and plowed into the Space Technology Hall of Fame. On April 6, Clark Cohen, Michael O'Connor, David Lawrence and Tom Bell, four principal members of Novariant Corp., will be inducted into the Space Technology Hall of Fame at the 22nd National Space Symposium in Colorado Springs, Colo. The four are being honored for their work developing global positioning system (GPS) control technologies that have found uses from spacecraft to airplanes to tractors. Cohen, O'Connor and Bell were doctoral advisees of Professor Emeritus Bradford Parkinson (Aeronautics and Astronautics), and Lawrence was a student of Professor David Powell (Aeronautics and Astronautics, and Mechanical Engineering).

When Cohen joined Stanford's GP-B project in 1989 as a doctoral student, he may not have envisioned that his work with GPS to control the attitude of the GP-B spacecraft to a tenth of a degree accuracy would one day translate into better crop yields for farmers. But it did. In one of those unforeseen serendipitous coincidences, he arrived at Stanford when workers at the W. W. Hansen Experimental Physics Laboratory (HEPL) were conducting research in both GP-B and GPS. Cohen quickly realized that GPS technology could be applied to the automated landing of airplanes. Starting with a single-engine Piper aircraft, Cohen and fellow students from the GPS lab kept refining the system until it was able to land a Boeing 737 more than 100 times with no on-board human intervention.

That remarkable success spawned a robotically controlled tractor system, enabling farmers to plant seeds precisely in the middle of furrows at exactly the right distance apart. Such accuracy increases yields, reduces spraying and irrigation, controls costs and relieves the monotony of manually steering a tractor, often in dusty or hazardous conditions. In 1994, Cohen left Stanford to found a company that eventually became Novariant Corp., now home to several other Stanford graduates who also worked in HEPL on the GP-B/GPS technology. A subsidiary of Novariant holds the trademark to the tractor steering technology, named RTK (Real-Time Kinematic) AutoSteer.

The April 6 ceremonies also will recognize Novariant Corp. and the GP-B program for their roles as the innovating organizations under which this technology was developed. NASA's Marshall Space Fight Center, which administers the GP-B program, and HEPL also will receive organizational commendation awards for their roles in supporting the successful development and commercialization of space technology. Parkinson, co-principal investigator of GP-B and one of the fathers of GPS technology, will accept this award on behalf of Professor Robert Byer, director of HEPL. Parkinson also will receive an individual commendation award for his role in developing this technology.

Bob Kahn is the public affairs coordinator for Gravity Probe B at Stanford. Dave Myers is a freelance writer.



Bob Kahn, Gravity Probe B: (650) 723-2540,


Bradford W Parkinson, Aeronautics and Astronautics: (650) 725-4105,

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