His technical assignments included work in the Shuttle Avionics Integration Laboratory (SAIL), the Shuttle Remote Manipulator System (RMS), telerobotics systems development for Space Station, the Hubble Space Telescope servicing mission development, spacecraft communicator (CAPCOM) in Mission Control, and extravehicular activity (EVA) for the International Space Station (ISS).

He was assigned as the backup EVA crew member and capsule communicator (Capcom) for STS-61, the first Hubble Space Telescope servicing mission.

From 1997 to 2001 Harbaugh served as Manager of the Extravehicular Activity Project Office, with program management responsibility for all aspects of NASA's spacewalk industry, including spacesuits, tools, training, tasks and operations for the Space Shuttle, the International Space Station, and future planetary missions.

Harbaugh flew as a mission specialist and was responsible for operation of the RMS and the Infrared Background Signature Survey (IBSS) spacecraft, and he was one of two crewmen trained for EVA in the event of a contingency requiring a spacewalk.

[5] STS-54 Endeavour (January 13–19, 1993) was a six-day mission which featured the deployment of TDRS-F, and a 4-hour 28-minute space walk by Harbaugh.

[6] STS-71 Atlantis (June 27 to July 7, 1995) was the first docking mission with the Russian Space Station Mir, and involved an exchange of crews.

Inducted into the Order of Constantine, the highest honor bestowed upon members of Sigma Chi for commitment, dedication and service to the fraternity (2017).