Michael Landon Gernhardt (born May 4, 1956) is a NASA astronaut and manager of the Environmental Physiology Laboratory, and principal investigator of the Prebreathe Reduction Program (PRP) at the Lyndon B. Johnson Space Center.

[1] During his diving career, Gernhardt attended graduate school at the University of Pennsylvania, and developed a new theoretical decompression model based on tissue gas bubble dynamics.

During this time, he led the development of a telerobotic system for subsea platform cleaning and inspection, as well as a variety of new diver and robot tools.

[3] In 1988, he founded Oceaneering Space Systems, a company formed to transfer subsea technology and operational experience to the ISS program.

His technical assignments to date include:[1] Gernhardt presently serves as a member of the astronaut office EVA branch, as Principal Investigator of the Prebreathe Reduction Program, and as Manager of JSC's Environmental Physiology Laboratory.

[1] Gernhardt served as an aquanaut on the first NEEMO (NASA Extreme Environment Mission Operations) crew aboard the Aquarius underwater laboratory in October 2001.

Gernhardt was one of two astronauts to perform a spacewalk to evaluate future Space Station tools and hardware, logging 6 hours and 46 minutes of EVA.

[1] This was the Microgravity Science Laboratory (MSL-1) Spacelab mission, and it was cut short due to problems with one of the Shuttle's three fuel cell power generation units.