In a blog post Monday, NASA confirmed a months-long delay to the planned manned space missions that will be launched aboard SpaceX’s Dragon capsules. The private space launch company has been facing schedule delays ever since an explosion of one of its rockets Sept. 1.

SpaceX, an Elon Musk company, plans to use a variant of its Dragon spacecraft, called Crew Dragon, to send astronauts to the International Space Station, and the first launch was originally scheduled for 2017. Dragon has already made several trips to the ISS to deliver supplies and bring back important research data.

However, the Falcon 9 rocket that blew up while being refueled at the company’s Cape Canaveral launch pad in Florida has put a spanner in the works. Till SpaceX can identify and fix the exact problem, it will not receive clearance for further flights from NASA as well as the Federal Aviation Administration. The company says it is close to doing that but it has already been forced to postpone its plan for resuming flights to January 2017 from its earlier deadline of December 2016.

That delay has a cascading effect on the company’s launch manifest, and at least one of its clients, Inmarsat, has already moved the launch of a satellite to a SpaceX rival from France, Arianespace. And according to the flight schedule released by NASA, the test dates for the Dragon Crew launch with a crew onboard has now been moved to May 2018. Only after a successful test will the company be certified to fly manned missions to ISS, which will happen in the second half of 2018 at the earliest.

The flight schedule also mentioned August 2018 as the date for Boeing’s manned launch test. These are the two U.S. companies in the forefront of allowing the resumption of manned space launches from U.S. territory using U.S.-built rockets. As of now, NASA has to rely on Russian Soyuz rockets to fly its astronauts to the ISS.

NASA shuttered its own Space Shuttle program in 2011 and earlier this year, Russia said it will not send any U.S. astronauts to the ISS after 2018 — when current contracts between the two countries expires. If SpaceX and Boeing have any more delays for any reason, it might just mean there will be no NASA astronauts in space for some time, starting in 2019.