Wilmore and fellow NASA astronaut Suni Williams spent more than nine months in space after their return was continually delayed due to mechanical issues

The astronaut is stepping away from NASA shortly after returning from a troubled test flight that left him aboard the ISS months longer than expected.

NASA has announced the retirement of test pilot and astronaut Butch Wilmore after 25 successful years of service and flights aboard four different spacecraft. Wilmore, a veteran pilot and graduate of the U.S. Naval Test Pilot School, has logged 464 days in space since his selection by NASA in 2000.