Nasa has given an update on two American astronauts who are stuck on the International Space Station (ISS)
Astronauts Sunita Williams and Barry 'Butch' Wilmore launched into space on 5 June for a mission expected to last eight days - they've been in space for more than two months
The spacecraft that took them there - Boeing's Starliner – has faced technical issues which has halted their return to Earth
Nasa officials have said the duo could be in orbit for eight months if they can't return on the Starliner
The Starliner is still the contingency vehicle if the astronauts need to return to Earth, Nasa officials said
But they could return on SpaceX's Dragon, however Nasa said this could pose other risks
The update from Nasa on the two astronauts stuck on the International Space Station has just begun.
We're now hearing from Ken Bowersox, the associate administrator at Nasa’s Space Operations Mission Directorate.
He says that Nasa does not have major announcements today, but will give a status update on the situation.
The Nasa update is about to start. These are the people we will be hearing from:
You can listen live at the top of this page.
Pallab Ghosh
Science correspondent, BBC News
Image source, ReutersThe Starliner launch on 5 June
Starliner was sent up with a small helium leak and two further leaks developed on the way to the International Space Station, one about the size of the small leak at launch and the other about five times larger.
Five of its 28 manoeuvring thrusters cut out during the approach to the space station, four of which were restarted. Then two further helium leaks were discovered in the propulsion system.
Ground tests revealed that the likely source of the thruster problems is that their Teflon seals swell when hot, blocking propellant getting into the combustion chamber.
Boeing’s Mark Nappi said that these issues could only have been spotted in a crewed flight test.
But some engineers wonder whether this problem should have been shaken out in the earlier uncrewed test missions – or even at the initial design stage of the spacecraft.
Pallab Ghosh
Science correspondent, BBC News
It’s been a long road for Boeing’s Starliner to the launchpad.
Its first uncrewed test flight in 2019 didn’t make it to the Space Station because a software fault caused the spacecraft’s engines to misfire.
A second attempt in 2022 did make it, but there were issues with some thrusters and the craft's cooling system.
Meanwhile Boeing’s rival, Elon Musk’s Space X, docked its Dragon Spacecraft four years ago and has ferried crews and cargo ever since.
All this while on Earth Boeing was facing growing scrutiny because of faults with some of its aircraft.
Martha Henriques
Editor, BBC Future Planet
Image source, Getty ImagesGetting two astronauts back to Earth is proving complicated enough.
But what about getting the entire International Space Station (ISS) back home?
In 2031, the space station is due to be "de-orbited", after it comes to the end of its operational life. It will be the biggest re-entry to the atmosphere in history.
Nasa recently announced that SpaceX has been selected to develop a "deorbit vehicle" to push the ISS out of orbit and back into the Earth's atmosphere.
It is expected to break up as part of the re-entry process, but that comes with the risk of a lot of debris – the ISS is as big as a football field and heavier than 200 elephants.
As Jonathan McDowell, an astronomer at the Harvard–Smithsonian Center for Astrophysics in the US, puts it: "A 400-tonne object falling out of the sky is not great."
An ideal space for a splashdown may be a remote part of the Pacific Ocean, far from land where falling debris could pose a risk to safety.
Read Jonathan O'Callaghan's story for BBC Future on the epic plan to bring the ISS back to Earth.
Richard Gray
Editor, BBC Future
During their prolonged stay on the ISS, Suni Williams and Butch Wilmore have been undergoing regular health checks, external to monitor how their time in the low-gravity environment is affecting their bodies.
One particular area they focus on is their eyes – each crew member on the ISS has scans to check their cornea, lens and optic nerve.
Space travel can do strange things to an astronaut's eyesight.
Without the tug of the Earth's gravity, blood can accumulate at the back of the eye leading to oedema and difficulty focusing on objects.
Cosmic rays and high-energy particles from the Sun can also hit the retina and optic nerves, causing other problems.
Find out more about what spending time in space does to the human body in my feature for BBC Future.
Nasa: 'The Lord is in control' - wife of stranded astronaut
Stephen Dowling
Deputy editor, BBC Future
Image source, Getty ImagesA file photo of Sergei Krikalev aboard the ISS in 1998
The two astronauts currently overstaying on the International Space Station (ISS) aren't the first to find themselves spending longer than planned in orbit.
Spare a thought for former Soviet cosmonaut Sergei Krikalev: in 1991, Krikalev was stuck aboard the USSR's Mir space station while the Soviet Union dissolved.
He ended up spending 311 days in space before returning to Earth.
By the time he returned, the USSR had ceased to exist.
Read Richard Hollingham's story for BBC Future on the other times astronauts got stuck in space.
Martha Henriques
Editor, BBC Future Planet
The messages coming from Barry Wilmore and Sunita Williams have been pretty cheerful considering their longer-than-expected stay on the International Space Station (ISS).
But even the most motivated astronauts can eventually face challenges on long missions. In simulated space missions, some experience the "third quarter phenomenon". This is a dip in motivation that comes from realising there's as long left in their situation as they have already lived through.
Isolated researchers in Antarctica also sometimes experience is "psychological hibernation", leaving people feeling flat and detached.
Research suggests there are ways astronauts and polar explorers alike can tackle these challenges – including prioritising good sleep.
Read Kelly Oakes' story for BBC Future on the psychological impacts of long space missions.
Boeing Starliner: Nasa astronauts arrive at International Space Station
Stephen Dowling
Deputy editor, BBC Future
The human body goes through some surprising changes when it's subjected to the rigours of space travel.
Returning astronauts are often lifted out of their capsules because their time in space reduces their muscle mass.
The most affected are those muscles that help to maintain our posture in our back, neck, calves and quadriceps – in microgravity they no longer have to work nearly as hard and begin to waste.
After missions lasting six months, muscle mass can fall by as much as 30%.
Bone mass, too, can also fall by between 1% and 2% for every month they spend in space.
Read Richard Gray's feature about how astronauts bodies are transformed during an extended stint in space.
Stephen Dowling
Deputy editor, BBC Future
There are benefits in having extra pairs of highly trained hands on board the space station – more work can be done more quickly.
But the extra bodies use up more of the station's consumables like food and water, and also produce a lot more waste too.
Normally the astronauts' sweat and urine is recycled into drinking water, but a recent fault has meant the crew have had to store urine instead – far from ideal onboard a cramped space station.
Fortunately, among the things Williams and Wilmore carried with them to the ISS were replacement parts for its microgravity plumbing system.
The two astronauts have consequently spent a fair bit of their time trying to fix the problem.
Read Richard Hollingham's story for BBC Future about what happens when astronauts get stuck in orbit.
Pallab Ghosh
Science correspondent, BBC News
Boeing’s new Starliner spacecraft was launched on 5 June despite there being a small leak of helium gas.
Helium is used to push propellent to the thruster systems used for manoeuvring in space and slowing down to re-enter the Earth’s atmosphere.
The leak was extremely small and engineers believed that it would not affect the mission and so went ahead with the launch.
But four further helium leaks developed during the mission and five of its 28 manoeuvring thrusters cut out during the approach to the space station, four of which were restarted.
Nasa "adjusted" the spacecraft’s return to a date in July, saying that flight engineers wanted to study the spacecraft to get to the bottom of the faults before it re-entered into the Earth’s atmosphere.
The space agency stressed that the astronauts were not stranded and that Starliner was certified to return to Earth in the event of an emergency on the ISS.
What happens next will depend on the outcome of the agency review.
You can read more here
Image source, .Starliner is 5m tall and 4.6m wide (16.5ft by 15ft), when attached to its rear service module.
It's wider than the capsule used in the Apollo missions.
There's room for up to seven astronauts.
It's intended to be reusable and fly up to 10 times.
Starliner has an Apollo-like design with conical sides - a shape that's stable when the capsule is plummeting at high speed through the Earth's atmosphere.
But it has more autonomy than either the Apollo spacecraft or the shuttle.
Boeing's vehicle travels to the ISS and docks with little to no intervention from astronauts. It's also designed to be safer.
Unlike the space shuttle, which was retired in 2011, Starliner has an escape system that can propel the crew away from its rocket if an emergency occurs during launch.
You can read more here.
Pallab Ghosh
Science correspondent, BBC News
Starliner is a spacecraft built by Boeing to provide a second private sector route to send crew and cargo to and from the International Space Station (ISS).
The other, by Elon Musk’s SpaceX, has been sending astronauts to the ISS since 2020.
Boeing’s spacecraft has taken longer to develop because it has had numerous technical setbacks in its development process, but was due to have its first crewed test flight at the start of May.
The launch was aborted because of a faulty valve in the rocket sending up the spacecraft, but a closer inspection revealed that there was a small leak of helium gas in Starliner. It was in a system that pushes propellent to the thruster systems used for manoeuvring in space, and slowing down to re-enter the Earth’s atmosphere.
Nasa, Boeing and United Launch Alliance decided to go ahead with another launch on 1 June in spite of the leak, because it was thought to have been small and would not have affected the mission.
The second launch was aborted too, because of an issue with the ground support equipment, but it was third time lucky for Starliner when it launched successfully four days later.
Pallab Ghosh
Science correspondent, BBC News
Image source, GettyMay 6: Launch aborted because of a valve continually opening and closing the Atlas Rocket’s upper stage. Teams later noticed a small helium leak of up to 70 pounds per square inch (psi) in Starliner’s service module.
June 1: A review concluded it was safe to launch Starliner with the small helium leak. But the launch was aborted with less than four minutes to go because of a problem with a power supply on the rocket’s ground support equipment.
June 5: Successful launch. But on the way to the International Space Station (ISS), two new helium leaks were identified. One was more than five times larger than the “small” leak, at 395 psi per minute.
June 6: Docking delayed when five thrusters went offline. Thrusters were reset and docking was successful.
June 10: Two further helium leaks detected on Starliner.
June 18: Press conference – return date for Starliner set for June 25-6.
June 20-21: High-level meetings concluded that the scheduled return should be "adjusted" to a date in July.
July 25: Ground tests revealed that the likely source of the thruster problems is that their Teflon seals bulge well when hot, blocking propellent getting into the combustion chamber. Boeing’s Mark Nappi said these issues could only have been spotted in a crewed flight test.
August 7: Nasa announces it is evaluating options to have the two astronauts who flew to the ISS on Starliner return home on a SpaceX Dragon Spacecraft in early 2025, given questions about the safety of Starliner.
Image source, Getty ImagesHello and welcome to our live coverage.
At 13:00 EDT (18:00 BST), Nasa is scheduled to give an update on the two American astronauts who have been stuck on the International Space Station (ISS) for more than two months.
Nasa astronauts Sunita Williams and Butch Wilmore began what was supposed to be an eight-day mission into space via Boeing’s new Starliner spacecraft on 5 June.
Officials say the spacecraft has faced problems including leaks in its propulsion system and some thrusters have powered down.
Stick with us as we bring you live updates on the situation.