SpaceX has revealed the reason why they decided to move the schedule of demonstration flights with NASA. This comes amidst the finalization of their investigation on the Falcon 9 rocket explosion.

It was previously reported that SpaceX has officially delayed the first crewed flight of its Dragon capsule. The vehicle is intended to be used to take NASA astronauts to and from the International Space Station (ISS).

Initially, the flight was expected to happen late next year. However, the mission has been postponed to May 2018. SpaceX is scheduled to have a demonstration on Nov. 2017. This will be an uncrewed flight test prior to sending the crew to ISS.

According to Space News, some kind of delay had already been expected due to the explosion of SpaceX's Falcon 9 rocket on Sep. 1. NASA did not provide a reason for the new demonstration flight schedules.

SpaceX spokesperson Phil Larson confirmed the new test schedule. Elon Musk's space company issued a statement on why they decided to postpone the demonstration flights.

"We are carefully assessing our designs, systems, and processes taking into account the lessons learned and corrective actions identified," SpaceX revealed. "Our schedule reflects the additional time needed for this assessment and implementation."

SpaceX also added that it has partnered with NASA to perform "a detailed safety analysis of all potential hazards" regarding its fueling process. A report approved by NASA's Safety Technical Review Board in July identified several controls that will be implemented to address said hazards.

NASA had concerns about SpaceX's "unique and contrarian fueling process." It seems that the space agency is concerned with the process because it involves people on board the spacecraft.

Experts criticize the use of the same fueling process especially when it happens just 30 minutes before the launch. Around this time, the crew would already be required to be strapped to their seats.

Former astronaut and retired Air Force Lt. General Thomas Stafford wrote to NASA and expressed his concerns over the issue. He described SpaceX's fueling process as "a hazardous operation" and noted that the company's approach has been questioned by several experts.