NASA astronaut Tom Marshburn is bringing his 337 days of spaceflight experience to a private company.
Marshburn flew to the International Space Station (ISS) three separate times, in 2009, 2012-2013 and 2021-2022. He rode to and from the ISS on a different vehicle each time, making orbital journeys aboard NASA's space shuttle, a Russian Soyuz and a SpaceX Crew Dragon.
The former flight surgeon announced his retirement from NASA on Thursday (Dec. 1). Marshburn is moving on to Sierra Space; he will be chief medical officer for its human spaceflight center and astronaut training academy, as the company continues designing a NASA-funded space station.
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Sierra Space is working to position its Dream Chaser spacecraft for contracted NASA cargo missions to the ISS, along with military cargo flights. The spacecraft also will be used for flights for private astronauts in the coming years, Sierra Space has said, including to a private space station called Orbital Reef. (Orbital Reef is among a few envisioned private complexes collectively supported by $415 million in NASA funding announced in December 2021. NASA hopes one or more of these private stations eventually replace the ISS, which the agency expects to use until at least 2030.)
"I look forward to creating and developing the rules, regulations and training that will ensure Sierra Space properly equips the future astronaut corps with the tools to succeed," Marshburn said in a statement.
Marshburn was with NASA for 28 years, serving for a decade as a flight surgeon and for 18 years as an astronaut. His spaceflight medical experience includes supporting NASA personnel working at Russia's training center in Star City outside Moscow, serving as co-chair of medical operations for space shuttle visits to the Russian space station Mir, and leading medical operations for the ISS.
His departure to the private sector is becoming more typical for NASA astronauts these days, with recent examples also including Peggy Whitson and Michael López-Alegría to Axiom Space. Houston-based Axiom operates private missions to the ISS and is working to build its own NASA-supported space station in the coming decade.
Related: NASA looks to private outposts to build on International Space Station's legacy
Some of Marshburn's other career highlights include performing an emergency repair to a leaking ISS ammonia pump during a spacewalk in 2013, days before landing with a Soyuz crew. The Expedition 34/35 crew that included Canadian Chris Hadfield and Marshburn was also one of the most scientifically productive of that era, according to Canadian Space Agency officials speaking to Space.com at the time.
Marshburn's other missions included the STS-127 shuttle flight in 2009, whose major task was completing construction of the Japanese Kibo module on the ISS, and SpaceX's Crew-3 from November 2021 to May 2022. On Crew-3, Marshburn's final mission, he piloted the Crew Dragon and worked with a crew that completed 250 experiments aboard the ISS, according to NASA statistics.
Elizabeth Howell is the co-author of "Why Am I Taller?" (ECW Press, 2022; with Canadian astronaut Dave Williams), a book about space medicine. Follow her on Twitter @howellspace. Follow us on Twitter @Spacedotcom or Facebook.