New York, May 21 (IANS): NASA's head of human spaceflight, Doug Loverro, has stepped down from his position at the agency this week ahead of the upcoming SpaceX crewed mission to the International Space Station (ISS) on May 27.

In an email sent to colleagues, Loverro cited a "mistake" that happened earlier this year, although no official reason for the resignation was provided, the BBC reported on Wednesday.

In an interview with news website Axios, Loverro said his sudden departure from the agency had nothing to do with the upcoming SpaceX mission.

"I have 100 per cent faith in the success of that mission," Loverro told Axios.

In the absence of Loverro, NASA's deputy associate administrator for human spaceflight Ken Bowersox will take over as acting chief, said the report.

It has been less than a year since Loverro became NASA's head of human spaceflight programmes.

NASA named Loverro as the agency's new associate administrator for the Human Exploration and Operations Mission Directorate in October last year.

"I worked with Doug for many years on the Hill, and he is a respected strategic leader in both civilian and defense programs, overseeing the development and implementation of highly complicated systems," NASA Administrator Jim Bridenstine said on Loverro's appointment.

Meanwhile, NASA astronauts Robert Behnken and Douglas Hurley on Wednesday arrived at the launch and landing facility at NASA's Kennedy Space Center ahead of SpaceX's Demo-2 mission.

NASA's SpaceX Demo-2 mission is the first launch with astronauts of the SpaceX Crew Dragon spacecraft and Falcon 9 rocket to the International Space Station as part of the agency's Commercial Crew Program.

The flight test will serve as an end-to-end demonstration of SpaceX's crew transportation system.