Bill Nelson has stepped down as NASA administrator, ending a half-century of public service.
Nelson and NASA Deputy Administrator Pam Melroy left the agency on Monday (Jan. 20), the day that Donald Trump began his second term as president. Trump has appointed Janet Petro, who most recently served as director of Kennedy Space Center (KSC) in Florida, as NASA's interim chief.
"As I leave public office today after 53 years, thank you for the great privilege of a lifetime of serving the people of our country. I am humbled and grateful," Nelson said in a Monday X post.
Nelson, a member of the Democratic Party, began his U.S. government career in 1972, when he was elected to the Florida House of Representatives.
He won a seat in the U.S. House six years later, representing Florida's 9th congressional district. The district is close to the state's famous Space Coast, which is home to both KSC and Cape Canaveral Space Force Station.
In January 1986, Nelson flew on the STS-61-C mission of the space shuttle Columbia, becoming the first sitting member of the U.S. House to reach the final frontier. The pilot of that flight was Charlie Bolden, who served as NASA chief during the Obama administration. STS-61-C was also the mission immediately before the STS-51-L flight of the space shuttle Challenger, which ended in tragedy just 73 seconds after liftoff on Jan. 28, 1986.
In 1990, Nelson tried to become the Democratic nominee in the Florida governor's race but lost the primary to Lawton Chiles. Four years later, Nelson won office as Florida's Treasurer, Insurance Commissioner and Fire Marshal. He was re-elected to that post in 1998 but stepped down in January 2001 after winning a seat in the U.S. Senate.
Nelson was re-elected to the Senate in 2006 and 2012 but lost narrowly to Republican Rick Scott in 2018. Nelson was appointed to NASA's advisory council in 2019, and President Joe Biden nominated him as NASA administrator in February 2019. The Senate unanimously confirmed him two months later.
Nelson's tenure as NASA chief was an eventful one, featuring the launch of the $10 billion James Webb Space Telescope, the Europa Clipper probe, the DART asteroid-smashing spacecraft and the Artemis 1 moon mission, among other high-profile efforts.
Artemis 1, as its name suggests, was the first mission in the Artemis program of moon exploration, which began during the first Trump presidency.
Petro is Trump's choice for interim NASA chief, but the president has someone else in mind for the full job — billionaire tech entrepreneur and private spaceflight veteran Jared Isaacman, whom Trump formally nominated on Monday.
In another X post on Monday, Nelson offered some words of advice to Isaacman — or whoever gets the job, if the Senate doesn't confirm Trump's first choice.
"We are merely temporary stewards of this extraordinary space agency. Humanity's dream in the stars is bigger than any of us — bigger than any one person, any one nation, and any one generation," Nelson wrote in a two-page "letter to the next NASA administrator."
"As a former administrator, as a proud American, I am rooting for you," he added. "Your success is NASA's success, and NASA's success is the nation's success. I am at your service to help in any way that I can."
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