Summary

  • Engine problems scupper Nasa's launch of the first rocket in its Artemis project, which aims to send astronauts back to the Moon

  • The US space agency had a two-hour window for lift-off from the Kennedy Space Center in Florida

  • But the launch has been cancelled as engineers failed to fix an engine bleed

  • Nasa's most powerful rocket ever - known as the Space Launch System (SLS) - is set to send the unmanned capsule Orion around the back of the Moon

  • Nasa hopes that by 2025 it will be able to send astronauts back to the lunar surface for the first time in over 50 years

  • It wants to land the first woman and first person of colour on the Moon - but for this mission, the cargo is non-human and includes a Shaun the Sheep toy

  • You can watch Nasa's live feed from the Kennedy Space Center by clicking the 'play' button at the top of this page

Live Reporting

Edited by Thom Poole

  1. WATCH: A guide to Nasa's mega Moon rocket

    Fifty years after the Apollo Moon landings, Nasa is getting ready to send humans back to the lunar surface.

    The first step is today's uncrewed test flight of its colossal new rocket – the Space Launch System.

    Watch the video for in-depth look at how the technology will work from our science editor, Rebecca Morelle.

    Watch the full documentary Return to the Moon on iPlayer here.

  2. What happens today?

    Jonathan Amos
    Reporting from Kennedy Space Center

    Nasa's Space Launch System (SLS) pictured with its Orion crew capsule perched on top earlier this monthReuters

    Assuming all goes ahead, the launch will be quite the spectacle.

    The Space Launch System (SLS) will become the most powerful rocket ever lifted from Kennedy, producing the thrust off the pad equivalent to almost 60 Concorde supersonic jets on take-off.

    But leaving Earth is just the start.

    • After 8 minutes and 20 seconds of flight, the side boosters and core stage will have thrown Orion into a highly elliptical orbit that would see it come crashing back to Earth without any further effort
    • So, the upper segment, or stage, will have to raise and circularise that orbit before then boosting the capsule in the direction of the Moon
    • Two hours and five minutes after launch, Orion and its rear service module will separate from the upper-stage. They should then be on track, speeding through space at 30,000km/h (19,000mph)

    You can watch Nasa's live feed from the Kennedy Space Center by clicking the 'play' button at the top of this page.

  3. At the scene

    Still, at least the weather looks promising...

    A sunrise in Florida before the Artemis lift-off

  4. Nasa engineers 'working through' pre-launch operations

    The latest on those technical hitches from Nasa...

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  5. Technical problems mar build-up

    Rebecca Morelle
    Reporting from the Kennedy Space Center

    Time for some nail biting.

    What appears to be a crack in the intertank – the part of the rocket that links the liquid hydrogen and liquid oxygen tanks – has been found.

    Whether you’re a rocket expert or not, crack isn’t the word you want to hear in the run up to a launch.

    Engineers are currently evaluating the problem.

    There’s also an issue with one of the four huge RS-25 engines - which the team is also troubleshooting right now.

    If you remember the days of the space shuttle, its engineers were always “working issues” on the pad. Keep your fingers crossed that they find the solutions that enable them to proceed with the launch.

  6. Prepare for lift-off

    The Space Launch System prepares for lift-off on the launch padNASA

    Welcome to our live coverage of the scheduled launch of the Space Launch System (SLS), the most powerful rocket ever made by Nasa.

    We'll be bringing you updates from Rebecca Morelle and Jonathan Amos from the BBC's science team, who've travelled along with tens of thousands of space fans to see the launch at Florida's Kennedy Space Center.

    This is the first test flight in Nasa's Artemis programme - which aims to take humans back to the Moon for the first time in 50 years, and to put the first woman and the first person of colour on the lunar surface.

    The US space agency hopes to one day reach Mars in future Artemis launches.

    At 08:33 local time (13:33 BST), the team has a two-hour window to launch the mission, which relies on good weather and the avoidance of any technical hitches. Speaking of which though...