The US agency boss said there is “no doubt” the schedule will change despite SpaceX insisting Crew Dragon could launch a pilot flight by the end of the year. A senior NASA manager said SpaceX is hoping to take corrective actions to launch two astronauts to the ISS. But Mr Bridenstine’s comments hit out at Mr Musk’s goal for this year.

Mr Bridenstine said: “There is no doubt the schedule will change. “It won’t be what was originally planned.” But he stopped short of offering a clear flight timeline for its multibillion-dollar Commercial Crew Program, and said he would not prejudge the results of an investigation into the incident. A source in SpaceX is confident the company can rebound from the explosion. READ MORE: Elon Musk warning: Tesla CEO fears ‘civilisation will end’

Elon Musk has been left red-faced as NASA boss, Jim Bridenstine

SpaceX's Crew Dragon exploded in leaked footage in April

For years, the United States has had to rely on Russia for rides to the space station and the Commercial Crew Program’s goal is to change that. Contractors have been hired by NASA to develop a separate rocket and capsule system to fly astronauts to space, has also delayed its own flights for months. Adding to the doubts, NASA has said it is considering paying for two more seats to the space station for autumn of 2019 and spring of 2020 to ensure US access. Originally, SpaceX’s astronaut flight was planned for July following a successful six-day round-trip unpiloted mission in March.

SpaceX is confident the company can rebound from the explosion