SpaceX has suffered another setback with the first manned flight of its Crew Dragon spacecraft being delayed until 2018. According to NASA, the SpaceX Demonstration Mission 2 will not fly until May 2018 instead of in the second quarter of 2017 as previously planned. Though no reason was given for the postponement, it's likely related to the ongoing investigation of the September 1 launchpad explosion of a SpaceX Falcon 9 rocket during fueling operations.

The NASA announcement comes on the heels of the decision to move the next Falcon 9 flight originally scheduled for December 16 back until January of next year. The September accident is still under investigation by a team from SpaceX, the US FAA, US Air Force, industry experts, and NASA. Though the exact cause of the explosion remains unconfirmed, it's believed to be due to the failure of one of the liquid helium bottles in the second stage liquid oxygen tank. Until the FAA clears the Falcon 9 for flight, it will remain grounded.

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One probable cause for the delay of the first manned Crew Dragon flight is NASA's reservations about SpaceX's unorthodox fueling procedures. Normally, astronauts board the spacecraft at the last minute with the help of a minimum ground crew to maximize safety. However, SpaceX uses supercooled liquid oxygen to carry more propellant and improve rocket performance. Since the oxygen must be kept at extremely low temperatures, it must be loaded shortly before launch. This means the Crew Dragon astronauts would need to board the ship before fueling, which NASA does not like.

In an unconfirmed statement, SpaceX founder and CEO Elon Musk said the helium bottle failure was due to the supercooled oxygen freezing solid on the graphite fibers on the outer surface of the helium bottle. If this is so, SpaceX could be facing one of four unpleasant alternatives.

First, the fueling procedures may need a simple modification, which NASA would need to sign off on. Second, there may be a design fault in the Falcon 9, which will require a redesign and refit. Third, NASA may require SpaceX to abandon using supercooled oxygen, which would reduce the performance of the booster. Or fourth, NASA may refuse to man rate the Falcon 9, forcing SpaceX to use an alternative rocket rated to carry astronauts.

We've reached out to SpaceX for comment and will update this article if or when we receive a response.

Source: NASA