Worked for TRW in Redondo Beach, California, for 28 years from 1964 to 1992 starting with Apollo program, followed by Pioneer 10 and included work on many Space Shuttle related programs including development of the S-Band Communications Transponder.
Worked for Oceaneering Inc. in Houston, Texas, as Vice President of Space Systems and then President of Oceaneering Advanced Technologies from 1992 to 1998.
Worked for NASA in Huntsville, Alabama, from September, 1998 to June 2003 as Director of NASA's Marshall Space Flight Center (MSFC).
As Director of MSFC Stephenson oversaw the Shuttle Space Transportation System propulsion elements including the Orbiter Main Engines, Solid Rocket Motors, and External Tank.
Other programs at MSFC during his tenor included Advanced Space Transportation development programs X-33, X-34, X-37, and Space Launch Initiative, International Space Station programs Element Structural Testing, Standard Rack development, and waste water recycling development, Microgravity Science experiment development and operations, the Chandra X-Ray Observatory development and on-orbit operations, and the Gravity Probe B spacecraft development oversight.
Served as Chairman of the Mars '98 Orbiter Failure Investigation Board and testified before the U.S. Senate.
NASA's annual budget during his tenor averaged about 2.3 Billion dollars.
Worked at Northrop Grumman from 2004 to 2008 as Vice President of Laser Programs, then Executive Vice President of Human Space Programs and then Executive Vice President and Deputy Program Manager of the NPOESS program.
Worked as President of Stephenson Consulting LLC. from 2008 to 2015 consulting for various Aerospace Companies.
Retired full time in 2015.
Published Autobiography in 2019 titled "Out of The Blue" available from Amazon in paperback or e-book format. Also available from sifat.org.
^"The Marshall Star. Vol. 39 / Num. 4 September 23, 1998" (PDF). Archived from the original (PDF) on July 20, 2011. Retrieved June 2, 2011.
^Spires, Shelby G. "Marshall director says exit not connected to Columbia". The Huntsville Times. p. 1A. The director of Marshall Space Flight Center is leaving his post in three weeks to take another NASA job here, but he denied Tuesday the move had anything to do with the Space Shuttle Columbia disaster. In a hastily called news conference Tuesday morning, Marshall Director Art Stephenson told reporters he will step down from his $142,500-a-year job at Marshall...