In August 1998 Wheelock reported for NASA Astronaut Candidate Training.
Having completed the initial two years of intensive Space Shuttle and Space Station training, he was assigned to the Astronaut Office ISS Operations Branch as a Russian Liaison, participating in the testing and integration of Russian hardware and software products developed for the ISS.
He worked extensively with the Energia Aerospace Company in Moscow, Russia, developing and verifying dual-language procedures for ISS crews.
Wheelock led joint U.S./Russian teams to the Baikonur Cosmodrome in Kazakhstan to oversee bench reviews, inventory, loading and launch of the first four unmanned ISS resupply capsules.

In 2001, Wheelock assumed duties as the Crew Support Astronaut for the ISS Expedition 2 crew, which was on orbit for 147 days from March 2001 to August 2001, and for the ISS Expedition 4 crew, which was on orbit for 195 days from December 2001 to June 2002.
He was the primary contact for all crew needs, coordination, planning and interactions, and was the primary representative of the crews while they were on orbit.
In August 2002, Wheelock was assigned as a Spacecraft Communicator (CAPCOM) in the Mission Control Center in Houston, Texas.
In this role, he was the primary communication link between crews on orbit and the ground support team in the Control Center.
His work as a CAPCOM culminated in his assignment as the lead CAPCOM for the ISS Expedition 8 mission, which was 194 days in duration.

In July 2004, Wheelock served as an aquanaut during the NEEMO 6 mission aboard the Aquarius underwater laboratory, living and working underwater for ten days.

In January 2005 and again in 2016, he was assigned as NASA's Director of Operations – Russia where he served at the Gagarin Cosmonaut Training Center in Star City, Russia.
 He was responsible for supporting Russia-based training, logistic, and administrative needs of NASA astronauts preparing for flight on the ISS.
Wheelock was the primary liaison between Star City and NASA operations in Houston, including medical, training, science, contracting, public affairs, and administration departments.
He was also responsible for liaison duties between NASA and the Russian Space Agency, as well as the Russian aerospace industry.

After his first spaceflight, Wheelock was assigned as the backup to T.J. Creamer for the Soyuz TMA-17/Expedition 22/Expedition 23 mission to the International Space Station.
Creamer completed a successful 163 day mission from 2009–2010.

As of September 2019, Wheelock is currently working as an astronaut trainer testing systems aboard the Orion spacecraft.
That month, he contributed to an article in The Columbus Dispatch detailing the inaccuracies of the space science fiction film Ad Astra.
In August 1998 Wheelock reported for NASA Astronaut Candidate Training. Having completed the initial two years of intensive Space Shuttle and Space Station training, he was assigned to the Astronaut Office ISS Operations Branch as a Russian Liaison, participating in the testing and integration of Russian hardware and software products developed for the ISS. He worked extensively with the Energia Aerospace Company in Moscow, Russia, developing and verifying dual-language procedures for ISS crews. Wheelock led joint U.S./Russian teams to the Baikonur Cosmodrome in Kazakhstan to oversee bench reviews, inventory, loading and launch of the first four unmanned ISS resupply capsules.
In 2001, Wheelock assumed duties as the Crew Support Astronaut for the ISS Expedition 2 crew, which was on orbit for 147 days from March 2001 to August 2001, and for the ISS Expedition 4 crew, which was on orbit for 195 days from December 2001 to June 2002. He was the primary contact for all crew needs, coordination, planning and interactions, and was the primary representative of the crews while they were on orbit. In August 2002, Wheelock was assigned as a Spacecraft Communicator (CAPCOM) in the Mission Control Center in Houston, Texas. In this role, he was the primary communication link between crews on orbit and the ground support team in the Control Center. His work as a CAPCOM culminated in his assignment as the lead CAPCOM for the ISS Expedition 8 mission, which was 194 days in duration.
In July 2004, Wheelock served as an aquanaut during the NEEMO 6 mission aboard the Aquarius underwater laboratory, living and working underwater for ten days.
In January 2005 and again in 2016, he was assigned as NASA's Director of Operations – Russia where he served at the Gagarin Cosmonaut Training Center in Star City, Russia.  He was responsible for supporting Russia-based training, logistic, and administrative needs of NASA astronauts preparing for flight on the ISS. Wheelock was the primary liaison between Star City and NASA operations in Houston, including medical, training, science, contracting, public affairs, and administration departments. He was also responsible for liaison duties between NASA and the Russian Space Agency, as well as the Russian aerospace industry.
After his first spaceflight, Wheelock was assigned as the backup to T.J. Creamer for the Soyuz TMA-17/Expedition 22/Expedition 23 mission to the International Space Station. Creamer completed a successful 163 day mission from 2009–2010.
As of September 2019, Wheelock is currently working as an astronaut trainer testing systems aboard the Orion spacecraft. That month, he contributed to an article in The Columbus Dispatch detailing the inaccuracies of the space science fiction film Ad Astra.
Douglas H. Wheelock