Since 2011, NASA has been trying to wean itself off Russian rockets as the only way of getting astronauts up to the International Space Station, and in 2014, Boeing and SpaceX won contracts to carry out launches. Now, though, Boeing says it's going to have to delay its crewed flights, pushing them back from 2017 to 2018. Boeing's executive vice president Leanne Caret made the announcement, reports GeekWire, telling investors at a briefing: "We’re working toward our first unmanned flight in 2017, followed by a manned astronaut flight in 2018."

Boeing's first crewed and uncrewed test flights were originally scheduled to take place in 2017, with an astronaut-led trip to the space station planned for mid-December. So the delay to 2018 isn't that dramatic, but it still leaves rival SpaceX out in front in the race to be the first private US company to deliver astronauts to the ISS.

SpaceX say it's still on track to take astronauts to the iss in 2017

A spokesperson for SpaceX told ArsTechnica that the company is still on track to launch crewed missions in 2017. The company has carried out an abort test of its Crew Dragon capsule, and plans to make an uncrewed flight in the first half of 2017, followed by a crewed test flight later that year.

After the Space Shuttle was retired in the summer of 2011, NASA started paying Russian space agency Roscosmos to take astronauts to the ISS on Soyuz rockets. On average, it costs $70 million a seat to fly with the Russians, and NASA wants to bring that figure down to $58 million by contracting to SpaceX and Boeing. NASA administrator Charles Bolden has criticized the US government for underfunding crewed launches, and told reporters last year, "I don't ever want to have to write another check to Roscosmos."