SpaceX has confirmed that NASA's former chief of human spaceflight, William Gerstenmaier, has joined the company as a consultant as it prepares to launch astronauts for the first time.

This is a consequential hire for SpaceX—it is difficult to overstate the influence Gerstenmaier has over human spaceflight both in the United States and abroad. He led NASA's space shuttle, International Space Station, commercial crew, and exploration programs for more than a decade.

He immediately brings credibility to the company's safety culture. Former Space Shuttle Program Manager Wayne Hale, who now chairs the human spaceflight committee of NASA's Advisory Council, told Ars last summer, "Bill was recognized by everybody as being technically well-grounded and very astute. He was known to listen carefully and to make his judgments based on good technical reasons."

NASA Administrator Jim Bridenstine demoted Gerstenmaier in July 2019 because he felt the space agency's exploration programs were not moving forward fast enough. Sources reported at the time that this decision shook some of the agency's partners, who were comfortable with the long-time leader of NASA's human spaceflight program. Some called the engineer in tears after hearing the news.

For example, less than an hour after CNBC first reported Gerstenmaier's hiring, the head of Russian state space corporation Roscosmos, Dmitry Rogozin, tweeted his congratulations: "I wish my friend success in his new job!"

In his new position, Gerstenmaier is reporting to Hans Koenigsmann, the vice president of mission assurance at SpaceX. Although the role is officially a consultancy, it is expected to become a full-time position. SpaceX is poised to launch the first crewed mission of its Dragon spacecraft by June of this year. Gerstenmaier will play a key role in ensuring the safety of those missions and helping SpaceX secure certification for the Crew Dragon vehicle.

The hiring could have longer-term implications as well. Few people in the global aerospace community have as much gravitas as Gerstenmaier or as much understanding of how to build coalitions to explore space. As SpaceX seeks partners—including NASA—to work with it on developing Starship to take humans to the Moon and Mars, Gerstenmaier is well-positioned to offer advice, stitch together mission plans, and open key doors.

Gerstenmaier and SpaceX have a complicated relationship, but he has supported Elon Musk at key moments during the company's development. In December 2008, Gerstenmaier saved a cash-strapped SpaceX with a Commercial Resupply Service contract for operational cargo missions to the International Space Station.

Gerstenmaier's decision to maintain two competitors as part of the commercial crew program in 2014 (SpaceX and Boeing) was also essential, although it was not a company-saving move. Boeing was lobbying hard for all of the funds and very nearly got them. Gerstenmaier was the deciding official who kept two providers in the competition. It has proven to be a smart decision, as SpaceX is poised to beat Boeing into space by months, if not years, at 50 percent less cost.