William Gerstenmaier, the longtime associate administrator for human exploration at NASA, has been demoted amid President Donald Trump's plan  to send astronauts to the moon within the next five years.

Gerstenmaier has been assigned to take on a new role as special adviser to NASA Deputy Administrator Jim Morhard, a position that is something of a demotion for the agency veteran, who has been with NASA since 1977. 

Gerstenmaier started out as an engineer and eventually became the associate administrator for human exploration and operations in 2004.

Former NASA astronaut Ken Bowersox will take his place as the acting head of human exploration. Another top NASA employee, Bill Hill, who was deputy associate administrator of human exploration, was also reassigned to a special adviser position.

NASA administrator Jim Bridenstine said there was nothing wrong with what Gerstenmaier was doing. He said that it was just time for a new leadership when asked about the reason behind Gerstenmaier’s demotion. 

The high-profile executive changes at NASA come at a time when the agency is working on its new moonshot program named Artemis. 

In a memo addressed to the space agency’s employees, Bridenstine explained that the leadership change is a bid to meet the challenges of the upcoming 2024 moon mission. He said that a new generation of leaders will step up and move out on the goal of returning astronauts to the moon. 

“As you know, NASA has been given a bold challenge to put the first woman and the next man on the Moon by 2024, with a focus on the ultimate goal of sending humans to Mars,” Bridenstine wrote in the memo. “In an effort to meet this challenge, I have decided to make leadership changes to the Human Exploration and Operations (HEO) Mission Directorate.”

Several lawmakers, including Rep. Eddie Bernice Johnson (D-TX), who chairs the House Science, Space and Technology; and Rep. Kendra Horn (D-OK), chair of the House subcommittee on space and aeronautics; criticized the decision to reassign Gerstenmaier. 

Johnson said that amid the challenges that come with the moonshot project, removing experienced leaders at NASA appears to be an ill-guided decision.

Artemis would be NASA’s first attempt to land humans to the moon since the last Apollo landing in 1972. Critics do not think the 2024 deadline is realistic given budgetary issues and delays in the development of the rockets and equipment needed for the mission.  Despite the odds, Trump remains optimistic. 

"I want you to know that we're going to be back on the moon very soon, and, someday soon, we will plant the American flag on Mars," Trump said during his Fourth of July speech at the Lincoln Memorial in Washington, D.C.