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.

NASA Administrator Bill Nelson has left the building, and while President Donald Trump’s nominee awaits a confirmation hearing, the head of Kennedy Space Center will keep things afloat. Nelson, who flew to space on board Space Shuttle Columbia while a member of the House of Representatives,

In a letter addressed to the next NASA administrator—who, if Trump’s nomination is confirmed, will be Shift4 CEO and SpaceX ally Jared Isaacman—Nelson highlighted the space agency’s work during his tenure and urged continuity. He emphasized NASA’s responsibility to return Americans to the moon and land them on Mars for the first time.

"America is leading humanity back to the Moon, onward to Mars, and into a golden age of space exploration," Nelson wrote,

Bill Nelson retires as NASA administrator; Janet Petro steps in as acting chief, awaiting Jared Isaacman’s confirmation.

NASA employees received a memo from acting agency administrator Janet Petro, Wednesday, mandating the closure of all diversity, equity, inclusion and accessibility initiatives and contracts.

An exploding budget and an unraveling schedule spell disappointment for NASA's mission to learn more about Mars's history.

NASA proposes a faster, cheaper plan to bring Mars samples to Earth, aiming for delivery by the 2030s while cutting costs significantly.

Weather organizations from around the world agree that the planet's average global surface temperature in 2024 could well have passed a crucial threshold meant to limit the worst effects of climate change.

The second Trump administration started with soaring rhetoric about sending humans to Mars but confusion about who was leading NASA on an acting basis.

"Once again, the temperature record has been shattered — 2024 was the hottest year since record keeping began in 1880."

After 15 consecutive months of tracking monthly temperature records, NASA confirmed the new temperature peak by recording the extraordinary heat streak. “Once again, the temperature record has been shattered — 2024 was the hottest year since record-keeping began in 1880,” said NASA Administrator Bill Nelson.