SpaceX had intended to launch its first Dragon capsule with a human crew on board in 2017, as part of a NASA mission. The planned launch has been pushed back to 2018, however, representing a delay of around half a year. SpaceX has pushed back the timing for the momentous mission as it revamps its fueling procedures for Falcon 9 rockets following a launchpad explosion this September.

Officially, SpaceX told TechCrunch in an official statement that it needs added time for “assessment and implementations” regarding its “designs, systems and processes” following the explosion earlier this year, hence the alternation in schedule. It notes that it is “finalizing the investigation” into the “anomaly” responsible for the September 1 accident. Meanwhile, SpaceX says that its commercial crew team “has continued to work closely with NASA and is completing all planned milestones for this period.”

The Wall Street Journal reports that SpaceX’s unique plans to fuel its rockets while astronauts were already in the crew capsules mounted on board may be part of the planned changes, though members of a NASA committee assigned to review the practice are apparently sworn to secrecy in terms of discussing details with the media regarding those briefings.

In its official comments, however, SpaceX details the progress regarding its process of fueling the rocket while astronauts are present on the spacecraft, noting only that they will be further examined as a result of the investigation, with changes to be made as determined necessary.

Still on track for 2017 is an uncrewed demo launch, now targeting Q4 with the updated timeline. Dragon’s being designed with reuse of up to 10 missions possible, SpaceX notes, and other testing happening for crewed missions during 2017 include testing of spacesuits, parachutes, the crew access arm and more.

This puts SpaceX and rival Boeing in closer proximity in terms of crewed commercial mission launches, with the latter aiming for a first test flight in June 2018, and a crewed test to follow in August. If SpaceX hits its revised timeline, we should see the demo without astronauts launch in November 2018, with the first crewed launch in May 2018, so still ahead of Boeing’s time frames.