THE launch of Boeing's new $1.5billion Starliner spacecraft has once again been sensationally called off just moments before takeoff.
The inaugural flight was abruptly halted on Saturday despite having the two astronauts ready to go and strapped into their seats with the mission now postponed for at least 24 hours.
The CST-200 Starliner's voyage up to the International Space Station (ISS) has been delayed once again as Boeing claims a "tech issue" has plagued the big day.
An automatic hold triggered by the computer that launches the rocket stopped the countdown clock, say reports.
Two NASA astronauts, Suni Williams and Barry Wilmore were said to have been strapped into the capsule awaiting liftoff at Cape Canaveral, Florida.
But the countdown was dramatically halted with just three minutes and 50 seconds left on the clock.
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Commander Barry “Butch” Wilmore, 61, is a retired Navy captain who's clocked some 178 days in space during his life already.
Fellow pilot Suni Williams, 58, a former Naval test pilot also has experience flying over 30 different aircraft.
She has spent a whopping 322 days in space in her two missions since her first flight in 2007.
They were due to spend around a week in the ISS.
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Both have now left the capsule and returned to the headquarters to get some clarity on the blunder.
The postponement was announced during a live NASA webcast.
The next available launch opportunities are on Sunday (June 2) Wednesday (June 5) and Thursday (June 6).
The launch has previously been delayed over leak checks and rocket repairs.
The first attempt in 2019 failed due to software and engineering glitches despite the craft being unmanned.
A second attempt in 2022 was successful however and led to a new test that would see a pair of astronauts in the cockpit.
But, on May 6, the countdown was again stopped early at just two hours before launch over a faulty pressure valve on the Atlas upper stage.
These launch dates are not magical. They are an opportunity to do our job. There will be more issues, and we'll be ready to handle them
Suni Williams
Williams has previously labelled spaceflight "complicated".
She recently said: "Every step of the way, we're realizing this makes us rethink how we do business.
"We have a capable spacecraft and we have people that can find solutions. We expect to find things that will help us make the spacecraft safer to fly.
"These launch dates are not magical. They are an opportunity to do our job. There will be more issues, and we'll be ready to handle them."
It was set to blastoff from NASA's Kennedy Space Center in Florida on top of an Atlas V rocket.
The capsule will go through a 26-hour flight before docking at the ISS at around 250 miles above Earth.
The two astronauts will stay at the space station before coming back to Earth in the Starliner before using a parachute and airbag-assisted landing platform.
The seemingly doomed craft has been made by United Launch Alliance - a Boeing-Lockheed Martin joint venture.
Starliner was created in collaboration with NASA’s Commercial Crew Programme, which is similar to its now-defunct Shuttle programme.
It's aimed at making space flights commercially available, frequently ferrying people and cargo back and forth from Earth.
“For Nasa service missions to the International Space Station, it will carry up to four Nasa-sponsored crew members and time-critical scientific research,” Boeing said.
With Boeing hoping the spacecraft can eventually transport humans to Mars if it ever gets off the ground.
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Aerospace giants Boeing have long been involved in Nasa's human spacecraft program, receiving more than $4billion to develop and fly the Starliner in 2014.
Boeing is competing with the likes of SpaceX to provide gear for future Nasa missions and has spent nearly $600million fixing engineering setbacks from the past mishaps.
Here we go again...
Analysis by Jamie Harris, Senior Technology and Science Reporter at The Sun
Boeing really hasn't had much luck with its first crewed space launch.
The company attempted to send an uncrewed Starliner to the ISS in 2019 but it failed because of a bunch of issues - not to mention disruption caused by the pandemic - and came back to Earth early.
A second uncrewed test went ahead in 2022 just fine but a year later experts uncovered new problems which held up a launch carrying astronauts.
Of course, safety is first so it's a necessary step.
Experts working on the billion dollar project have attempted to downplay the delay.
"I don't call it frustrating at all," Boeing's program manager Mark Nappi recently told press.
"We would like to have been further along at this time. There's no doubt about that. But we're here, and we're prepared, and we're ready to fly."
Space is also costly business, so Boeing - and Nasa - need this mission to succeed.
Development woes cost the firm a whooping $1.5billion in charges, as well as roughly $325million for Nasa in boosts to Boeing's $4.2billion fixed-price Starliner contract, according to securities filings and contracting data examined by Reuters.
Nasa also needs this to work if it's to keep up with China which is making huge advances to the Moon and beyond.