NASA has already extended its contract with Roscosmos for astronaut transportation through 2018 too, at an additional cost of $490 million for six more seats. In addition, the space agency has already ordered two crew missions from SpaceX, awarding them the maximum number of “guaranteed” missions for Crew Dragon, with the possibility that up to four others may follow.

As of July 2016, SpaceX was fabricating four Crew Dragon vehicles, of which two will be utilized for qualification tests and the others for later flights.

The delay confirmation from SpaceX comes three months after a Sept. 1 explosion at Cape Canaveral Air Force Station, Fla., which occurred while fueling for a test and took out their Falcon-9 rocket, launch complex, and their customer’s AMOS-6 satellite.

Though the investigation into the AMOS-6 accident remains ongoing, SpaceX is confident it was related to flight preparation, not an engineering design issue with the vehicle itself. The investigation has focused heavily on a breach in the cryogenic helium system of the rocket’s second stage liquid oxygen tank, with special attention narrowed to “one of the three composite over wrapped pressure vessels (COPVs) inside the LOX tank,” noted SpaceX in a recent update.

That said, the company is currently aiming to return their Falcon-9s to launch next month with a mission to deliver 10 satellites to orbit for Iridium from Vandenberg AFB, Calif. The mission, Iridium-1, was scheduled to fly Dec. 16, but then slipped to January to “allow for additional time to close-out vehicle preparations and complete extended testing to help ensure the highest possible level of mission assurance prior to launch,” said SpaceX.

However, SpaceX wants to fuel their rockets with astronauts already onboard too, not just for unmanned satellite launches, and in the wake of the AMOS-6 accident serious questions have been raised about the safety in doing so, regardless of the Dragon’s ability to quickly abort crew safely away from a failing rocket.

“We are carefully assessing our designs, systems and processes” to incorporate lessons learned and take corrective actions in the wake of the September explosion. The schedule change “reflects the additional time needed for this assessment and implementation,” said SpaceX in an email Dec. 12 to WSJ reporter Andy Pasztor.

“As needed, additional controls will be put in place to ensure crew safety,” added SpaceX.

SpaceX conducted a very successful Dragon Pad Abort Test in May 2015 with a 21,000-lb prototype capsule, demonstrating its capability to quickly abort crew from a bad situation on the launch pad. The company will conduct one more abort test, an In-Flight Abort atop a Falcon-9 rocket launch, using the same Crew Dragon prototype capsule, at some point in 2017 (hopefully).

NASA originally wanted the first crewed flights to and from the ISS happening in 2015. A Sept. 1, 2016, report from NASA’s Office of Inspector General on the Commercial Crew Program’s progress notes further delays expected too, with the first crewed flights slipping to late 2018—more than three years after NASA’s original 2015 goal.

“While past funding shortfalls have contributed to the delay, technical challenges with the contractors’ spacecraft designs are now driving the schedule slippages,” noted the report, which you can read in full HERE.

“NASA Program officials anticipate SpaceX will encounter additional delays on the path to certification,” the report states. “For example, in January 2015, the tunnel that provides a passageway for astronauts and cargo between the Dragon and the ISS was reported to have cracked during the heat treatment phase of the manufacturing process. As a result, SpaceX delayed qualification testing by approximately one year to better align the tests as SpaceX moves toward certification. SpaceX has also experienced ongoing issues with stress fractures in turbopumps. Additionally, SpaceX has not yet completed parachute system level testing which may reveal issues that would require redesign that could further delay the test flights.”