Jared Isaacman, who made the first private spacewalk in September, is one of the US president-elect’s recent favorites.

Jared Isaacman, a tech billionaire who performed the first private spacewalk in collaboration with Elon Musk’s SpaceX, has been appointed by US President-elect Donald Trump to head NASA, the National Aeronautics and Space Administration.

Isaacman’s nomination was announced Wednesday as Trump named a series of appointees, including his former White House adviser Peter Navarro, who was jailed this year for obstructing a congressional investigation, as his senior adviser on trade and manufacturing .

Isaacman, 41, a self-described “space geek” who made his money as the founder of a payment processing company, is also an experienced fighter pilot who owns a company in Florida that trains Air Force pilots.

He traveled to space in September with a mission to test SpaceX’s new custom spacewalker suits.

If confirmed by the U.S. Senate, Isaacman will replace 82-year-old Bill Nelson, a former Democratic senator and astronaut, and would likely continue to work closely with Musk as NASA plans to use SpaceX’s Starship rocket to to return astronauts to the moon for the first time in more than 50 years. The reusable rocket, the largest ever built, is currently undergoing test flights.

The space agency also uses SpaceX to deliver supplies and astronauts to and from the International Space Station. At the same time, NASA is expanding its horizons beyond the moon by flying unmanned spacecraft to Jupiter’s moon Europa and exploring the surface of Mars for signs of living organisms.

Although NASA is not a Cabinet-level agency like the Defense Department, its leader is nominated by the president and must be confirmed by the Senate. While NASA is best known as the U.S. government agency responsible for space exploration, it also conducts studies of the Earth using satellite technology, as well as aeronautical research and testing new aircraft.

Isaacman said he was honored to be nominated and was “grateful to serve.” “Having been fortunate enough to see our amazing planet from space, I am thrilled to see America lead the most incredible adventure in human history,” he said of X.

Musk congratulated Isaacman on X, describing him as a man of “high ability and integrity.”

Trump has now largely completed filling top positions in his government. The nominees will appear in Senate hearings beginning in January.

Other appointments Trump made Wednesday included Daniel Driscoll, a military veteran and senior adviser to Vice President-elect JD Vance, as Army secretary and Adam Boehler, a senior negotiator on the Abraham Accords team, as special presidential envoy for hostage issues.