The widely-respected Gerstenmaier is a NASA veteran who joined the agency in 1977, rising to become one of its top managers, overseeing the space shuttle program and USA operations on the International Space Station before becoming head of HEO.
Bridenstine placed Ken Bowersox, a former astronaut and vice president of Astronaut Safety and Mission Assurance for Elon Musk's SpaceX, as acting associate administrator for the human exploration wing.
Next week marks 50 years since man first walked on the moon.
Both Armstrong and Aldrin then reportedly spent over 21 hours on the Moon's surface during which they collected the surface samples, took photographs, and performed some experiments.
Two top House Democrats panned Bridenstine's decision to remove Gerstenmaier from his leadership role.
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 was also spearheading the agency's effort to return astronauts to the moon.
He promised to work with her and other members "to achieve our mutual goals in science and exploration". An extended-time NASA veteran, Hill helped manage the growth of the company's new heavy-lift rocket, the Space Launch System, or SLS wanted to hold astronauts again to the moon. But Vice President Mike Pence, who announced the accelerated 2024 target in March, has criticized NASA for "bureaucratic inertia" and asked for a new mindset.
"What we need now is urgency", Pence said during a speech to a crowd at the US Space & Rocket Center in Huntsville, Alabama.
The new timeline gives NASA only five years to acquire the hardware and funds it needs. "It is the stated policy of this administration and the United States of America to return American astronauts to the moon within the next five years".
The hardware that NASA needs is either delayed, way over budget or doesn't yet exist.