Nasa engineers have encountered a second critical last-minute issue that could jeopardise the launch of Artemis II.
The space agency is now investigating a potential battery temperature issue.
Four astronauts are now sealed inside the Orion spacecraft at Kennedy Space Centre in Florida, awaiting tonight's historic departure for the Moon.
The two-hour launch window commences at 23:24 British time, with Nasa's Space Launch System rocket poised to carry the crew on their lunar voyage.
Earlier this evening, the quartet emerged to cheering crowds before making their way to the launch pad, where they were individually helped into their seats aboard the capsule.
The mission commander is Reid Wiseman, a veteran Nasa astronaut who will lead the crew through their ten-day journey around the Moon and back.
Victor Glover serves as a pilot, while Christina Koch serves as a mission specialist for the American space agency.
Joining them is Jeremy Hansen, a Canadian Space Agency astronaut and colonel who becomes the first non-American to venture beyond low Earth orbit.
FOLLOW BELOW FOR LIVE UPDATES THROUGHOUT THE NIGHT…
Critical failure resolved before battery issue discovered
Moments before a second issue was discovered, cheers rang out at the Florida launch site as the Nasa announced the historic mission was now "go for launch" following the resolution of a major failure.
This critical safety feature, at the heart of the fault, is designed to destroy the vehicle mid-flight if it deviates from its intended path, ensuring that any potential debris does not pose a risk to Earth.
The problem appeared to stem from a communications fault between ground control and the system, preventing teams from properly testing the hardware ahead of launch.
Hatch sealed as Artemis II 'ready for launch'
Nasa have confirmed the hatch of the Orion Artemis II spacecraft has now been sealed.
"The Artemis II astronauts are now strapped into their seats and ready for launch," the space agency announced.
PICTURED: Nasa engineers making final preparations as major issue fixed
In detail: The Orion spacecraft taking astronauts to the Moon
The Orion spacecraft atop the Artemis rocket
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The Orion spacecraft will be home to four astronauts for the next 10 days.
Nasa chief set sights on future Mars mission and talks alien life
The newly appointed Nasa administrator, Jared Isaacman, has spoken about the possibility of alien life in the solar system as the organisation prepares to launch its first moon mission in 50 years.
“If we can get to Mars and bring samples back, I put it at a better 90 per cent chance that we could prove there was some microbial life on Mars,” he told conservative commentator Benny Johnson.
“I would say there could be life everywhere. It doesn't mean it looks like us. It doesn't mean it has the tentacles you have in movies,” he added.
Nasa is planning a groundbreaking nuclear-powered mission to Mars, dubbed Space Reactor-1 (SR-1) Freedom, set to launch by the end of 2028.
PICTURED: Inside the Artemis module cockpit
Inside the Artemis II module
|NASA
Nasa has shared footage of the tiny Orion module cockpit that will be home to the four Artemis astronauts for the next ten days.
Astroauts reveal the treasured items they are taking to lunar orbit
The astronauts of Nasa's Artemis program have shared the meaningful personal items they plan to carry with them on their upcoming journey around the Moon.
Pilot Victor Glover, who is deeply religious and teaches Sunday school, will be bringing a Bible on board.
Meanwhile, Jeremy Hansen of the Canadian Space Agency has chosen four small moon-shaped pendants. He originally bought them for his wife and children, but has now gathered them back so they can accompany him on the landmark mission.
Mission commander Reid Wiseman is opting for simplicity, packing just a notebook and pencil so he can jot down reflections as he takes in views of both the Moon and Earth.
For mission specialist Christina Koch, the most meaningful items are handwritten messages from family members—tokens she says will feel especially significant when she is far from home.
MAPPED: The Artemis II mission
The route the mission will take
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The King's message to Nasa astronauts
King Charles has sent a personal letter to Canadian Space Agency astronaut Colonel Jeremy Hansen.
The monarch acknowledged the growing importance of responsible stewardship as space exploration and the commercial space sector continue to expand rapidly.
In his message to the crew, the King said: "As you embark on this momentous endeavour, I send you and your fellow crew members my heartfelt good wishes.
“May the stars align in your favour, and may your safe return inspire countless others to uphold the values of sustainability, cooperation and wonder that the Astra Carta inspires."
The British engineers helping take Artemis II to the moon
Dozens of science and technology firms based in the United Kingdom are making significant contributions to Nasa's first crewed Moon mission in more than half a century in a triumph for British engineering.
In January 2025, Thales Alenia Space signed a £750million contract with the European Space Agency (ESA) to contribute towards the Artemis programme.
Its scientists, based in Harwell, Oxfordshire, are designing the propulsion solution for the Lunar Gateway — more commonly known as "Gateway".
Another firm helping with the Artimus programme is John Crane, whose core engineering is based at its headquarters in Slough, Berkshire.
Jeroen Huizinga, the company's Senior Director for Auxiliary Products and New Energy Solutions, highlighted his team's work on filtration sieves, which are designed to keep propellant tanks required for manoeuvring Orion free of gas bubbles.
Welcome to the GB News Artemis II live blog
The four astronauts of the Artemis II mission
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Good evening and welcome to the GB News Artemis II launch live blog.
Join us throughout the night as we cover the launch of humanity's first crewed voyage to the Moon since Apollo 17 touched down on the Moon's surface in December 1972.
The Orion capsule will carry four astronauts roughly 4,700 miles past the Moon's far side, setting a new record for human spaceflight distance.
Nasa chief flight director Emily Nelson said: "The opportunity is immense for us to finally get the opportunity to send our crew farther than anyone's gone before."
Although the crew will not set foot on the lunar surface, their primary task is to rigorously evaluate Orion's life support, propulsion, power, and navigation systems during the deep-space portion of the flight.
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