The lack of gravity in space can pose a number of challenges - one of which includes astronauts being able to go to the toilet. There was a small issue before launch with the loo - but after engineers took a look, systems were cleared to go.

"We do recommend letting the system get to operating speed before donating fluid", mission control told the astronauts just before launch.

Nasa has spent more than $23m (£17.4m) to address the issue, which has resulted in the "Universal Waste Management System".

Men and women are able to use the system, which includes a funnel attached to a hose to process urine while using gentle airflow to eliminate spills.

A specialised seat allows for stools to be sucked into a sealed container, with a variety of tethers and restraints being used to stop the crew from floating away while using the system.

The Artemis II crew are due to fly around the Moon on 6 April.

The unmanned Artemis I flight, the predecessor to this year's mission, reached the Moon on day six of its mission in 2022.

Apollo 8 currently holds the record for being the fastest crewed mission to the Moon after taking just under three days - 69 hours and eight minutes.

It was also the first crewed flight to orbit the celestial body.

Unmanned objects can reach the Moon more quickly, with Nasa's New Horizon's probe passing the moon in eight hours and 35 minutes when it departed for Pluto in 2006 - though it didn't approach lunar orbit.

Image source, Getty Images

Canadian astronaut Chris Hadfield says he watched on with "amazement, excitement and gratitude" as "four friends" risked their lives on a brand new space craft blasting into space.

Hadfield is a former International Space Station commander, where his social media posts - including a performance of David Bowie's Space Oddity at zero gravity - made him a star.

Now, speaking to the BBC after the Artemis II launch, he stresses the uniqueness of Nasa's latest mission to the Moon.

"In the history of humanity, our entire species, there have only ever been 24 people... that have gone fast enough to be able to leave the orbit of the Earth and go to the Moon," he explains.

The 24 astronauts who took part in the Apollo missions were all American, but the Artemis II crew has seen the inclusion of Canadian Jeremy Hansen, which Hadfield says gives him "great pride".

"The fact that for this return to the Moon as we're now transitioning from exploration to settlement, the fact it is an international crew is really significant, especially in times of turmoil," he says.

Rebecca Morelle
Science editor, reporting from the launch

The Artemis I mission took place in 2022, and saw Nasa’s mega moon rocket - the Space Launch System - and the Orion capsule fly for the first time on a 25-day mission around the Moon.

But there were no humans onboard.

For Artemis II, astronauts are very much at the front and centre of the mission.

The crew will be the first people to fly in the SLS and Orion as they travel around the Moon. Their mission will last about 10 days.

Artemis IV will see astronauts land on the lunar surface - Nasa says by 2028. However this is an ambitious timeline.

A lander has to be selected, built and tested, and there are delays with the spacesuit that the future Moonwalkers will wear.

In later Artemis missions there are plans for a lunar space station called Gateway that will orbit around the Moon, as well as the construction of a Moon base.

Image source, European Photopress Agency

More than 50 years have passed since America's Apollo missions landed humans on the Moon for the first time in July 1969.

And, while Nasa's Artemis II crew won't make a lunar landing themselves, their mission over the next 10 days will to pave the way for the next human footsteps on the Moon.

During their trip the four astronauts will fly 6,400 miles (10,299km) beyond the far side of the Moon, which always faces away from the Earth - marking the first time this has taken place.

Nasa says that during this three-hour period, the crew will "analyse and photograph geologic features, such as impact craters and ancient lava flow", which will help future missions to explore the Moon's South Pole region.

Studies on the astronauts' health will also help Nasa to better understand how deep space travel influences the human mind and body, protecting astronauts on future lunar missions as well as travel to Mars.

If the crew pass safely around the Moon on this trip, Nasa's goal is for Artemis IV and V to become lunar landing missions - and is aiming for both to happen in 2028.

As we've been reporting, the Artemis II's crew of four astronauts are currently working through a "pre-sleep" stage, but what exactly does this involve?

Speaking to BBC Radio 4, University College London aerospace professor Kevin Fong tells the Today programme that it largely means the crew is "winding down", though not in the same way you might on Earth.

"It's not straightforward going to sleep up there, you've got to strap yourself into a sleeping bag, Velcro yourself to the wall," Fong explains.

And that's before you've considered the adrenaline that will be coursing through the bodies of the four circling more than 30,000 miles above Earth.

"I just don't know anyone who's going to sleep," Fong admits, as the astronauts ready for their four-hour sleep window.

After hopefully getting some shut-eye, the crew will accelerate their way to the Moon's orbit - our science correspondent explains how.

With their rocket now far above the planet, the Orion spacecraft - which houses the crew - separated from its launcher and is now orbiting the Earth.

The astronauts must now decide whether to continue the mission. While they are close to Earth, getting back is relatively straightforward if there are any issues that cannot be fixed.

If all is well, Orion will fire its main engine to blast free of the Earth’s gravity and set a path to the Moon.

Pallab Ghosh
Science correspondent

The Orion capsule is now safely in Earth orbit, where flight control teams are putting its engines, navigation and life support systems through their paces to make sure everything is working perfectly before committing to deep space.

If all the checks are passed, they will later fire Orion’s main engine for 5 minutes and 45 seconds, a single burn that will accelerate the spacecraft fast enough to send the four astronauts on their way to the Moon.

Orion’s next major milestone is still to come – the powerful engine burn that will sling the crew out of Earth orbit and on towards the Moon.

The astronauts and ground teams need to make sure everything is working perfectly before committing to deep space.

If engineers are not completely satisfied, they can simply cancel tonight’s so-called “trans-lunar injection” burn - which puts the spacecraft on the right trajectory to the Moon - and bring the astronauts home.

Image source, Reuters

As the astronauts aboard Artemis II prepare to get some sleep, we're hearing snippets of the checks taking place on the spacecraft. You can listen too by tapping watch live at the top of the page.

The radio occasionally crackles to life, as Commander Reid Wiseman and his team continue the process of "cabin containing".

This means working through a checklist to make sure everything the astronauts have used is correctly stowed and configured for the rest of the mission.

And, the details are so specific that they even communicate with the team on Earth about where they're putting their laundry - as we hear from one "stowage note".

"We stored our used comfort garments in the block bags in the F4 locker," we hear the shuttle relaying to Nasa.

"We copy," Nasa replies.

Pallab Ghosh
Science correspondent

If you're just catching up on last night's launch, our science correspondent Pallab Ghosh has this look back at the moments just before Artemis II blasted off.

In the hour before take-off there were issues which threatened launch concerning the Launch Abort System - which enables Nasa engineers to eject the astronauts and blow up the rocket if there is a malfunction.

The countdown clock was held at 10 minutes while engineers resolved the problem – which they speedily did.

Then came the staccato rhythm of the calls by each engineer responsible for the rocket’s critical systems.

One by one the voices came back: “Booster, go”, “GNC, go”, “Range, go” – each reply, a tiny release of tension and a build-up of expectation.

“Artemis II, this is Launch Director – you are go for launch,” the crew was told. "We go for all humanity", Commander Reid Wiseman responded.

The four RS‑25 engines and twin solid rocket boosters lit with a sheet of flame that seemed to engulf the rocket, driving more than 8.8m lbs of thrust into the Florida evening sky.

The pad erupted into a sheet of brilliant white flame and fury as the mightiest rocket ever built rose from its launch tower.

Nasa’s Space Launch System (SLS) crept upwards majestically, slow at first, then gathering pace, riding on two blinding pillars of flame that crackled and roared with an impact we could feel watching three miles from the pad.

SLS arced out over the Atlantic like a fiery white angel, shrinking to a single bright star as it chased the Moon.

Image source, Getty Images

Image source, Reuters

Image source, Getty Images

Image source, Reuters

Image source, Reuters

• See more: Artemis II roars into space on historic Moon mission

"Oh my goodness... That is spectacular!"

Watch as the BBC's science editor Rebecca Morelle witnesses last night's launch.

Katie Williams
Live reporter

Image source, Reuters

After a successful lift-off just over six hours ago, the Artemis II crew are now orbiting the Earth and have been conducting tests on their spacecraft. Here's a recap:

Technical issues before launch

A couple of technical issues in the lead-up made for a nervy couple of hours before launch.

There were issues with both the flight termination system - which is designed to destroy the rocket if it goes off course - and a battery for the Launch Abort System - which would pull the crew capsule away from danger in case of an issue.

It looked like take-off could've been delayed.

But Nasa managed to resolve the issues by being "quick on their feet", an official told the media later. One was fixed by using hardware from the previous Space Shuttle programme.

The roar of flames at lift-off

Launch was met with giddy euphoria among Nasa employees, our science correspondent reports.

You could hear the roar of the engines and cheers from the crowd as the rocket took off. The boosters were later seen separating from the rocket.

We then had confirmation the astronauts had passed the Kármán line, entering space and Earth orbit.

Epic views... and an issue with the loo

The crew have been treated to "epic views", one astronaut said - but it hasn't all been plain sailing.

There was a short-lived comms issue, which meant ground control couldn't hear the astronauts. And, among other things, there was an issue with the toilet - that's since been fixed.

What happens next?

• Here's a rundown of the next 24 hours
• And a road map for the 10-day mission as a whole

Katie Williams
Live reporter

"While all the families and friends are certainly feeling a lot of relief after the successful launch, everyone is keenly aware that this is just the start of a very dangerous 10-day mission and a risky re-entry," says Stacey Morgan.

She was at the launch supporting the Artemis crew members' family and friends. Her husband, astronaut Andrew Morgan, was a Nasa classmate of Reid Wiseman and Jeremy Hansen.

Morgan adds: "There is relief and excitement but also the reality of what lies ahead. After all, we’re going to the Moon! And back!"

Image source, Stacey Morgan

It appears that, after the problems reported earlier, the toilet is ready for use.

"Happy to report that toilet is go for use," mission control says. "We do recommend letting the system get to operating speed before donating fluid".

A little earlier, we heard that mission specialist Christina Koch had the happy job of troubleshooting the issue. It seems to have worked.

"It's been a great day guys, and we're going to try and get you to bed a little bit early," mission control says to the Artemis crew.

There are a couple more operations to run through first, including troubleshooting the issue they've been having with the toilet.

"I don't think it will take very long," mission control says.

The astronauts' sleep will be divided into two slots. They are scheduled to get around four hours before waking to monitor something called the "perigee raise burn" - this will put Orion back in a stable orbit for the loop back towards Earth.

After that, they are then scheduled to have another four and a half hours of sleep.

Image source, NASA

Stephen Dowling
Deputy editor, BBC science features

Image source, Getty Images

You can watch live at the top of the page as the Orion crew continues tests in orbit. You'll also regularly see the view from Nasa's mission control - more on that below:

Nasa's historic space missions succeeded or failed thanks to the help of mission control.

Devised by Christopher Kraft for the Mercury programme of the early 1960s, the nerve centre of US space missions grew to become hives of activity by the time of the Apollo missions.

Photos of white-shirted technicians frowning over cumbersome consoles became almost as iconic as the images of the Apollo 11 astronauts on the Moon.

Now, Artemis mission control looks very different to those of 50 years ago. The massive consoles have given way to sleek terminals and overhead lighting that are reminiscent of tech start-up offices.

But look behind the tech, and mission control now has the same job as half a century ago.

"The structure that Chris Kraft put together as the first flight director has really stood the test of time," says Fiona Antkowiak, one of nine flight directors assigned to the Artemis II mission.

• Read more: The nerve centre running a new mission to the Moon

Pallab Ghosh
Science correspondent, reporting from the launch

Before Nasa commits Orion to the long burn that sends it away from Earth, the crew are spending hours quietly trying to break their spacecraft - on purpose.

They cycle computers through different modes, switch radios between ground stations and relay satellites, and deliberately move around the cabin to see how the life‑support system copes as carbon dioxide and humidity build up.

Engineers also command small thruster firings and check the European‑built service module responds exactly as the models predict.

All of this is designed to answer a simple question: is the ship healthy enough to risk flying hundreds of thousands of kilometres from home with no quick way back?

If any of these tests throws up something they do not understand, Nasa will not hesitate to call off the trans-lunar injection burn and use Orion’s engine to bring the astronauts straight back to Earth.

Leyla Khodabakhshi
Reporting from the Kennedy Space Center

Nasa astronaut Stephen Bowen says one of the first things you notice in space is something simple. You are floating.

“Floating never gets old,” he told me. “And I actually sleep better in space than I do on Earth.”

Bowen has been an astronaut for more than 25 years and has taken part in multiple missions, including 10 spacewalks.

“On the space station, you strap yourself into a sleeping bag attached to the wall,” Bowen says. “You just float and sleep - there’s no real sense of up or down.”

A typical day begins with breakfast and a check of the schedule. From there, Bowen says, it is work from start to finish.

“You’re scheduled continuously from the time you wake up to the time you go to sleep,” he says. That includes hours of exercise, scientific experiments and maintaining the spacecraft.

Even small things behave differently. Tears, for example, do not fall. “They just stay in your eyes,” he says, describing how a crewmate once found it hard to stop laughing as the tears built up.

For Bowen, spacewalks are among the most extraordinary parts of the job. “You’re holding on to the space station, and the Earth is passing below you,” he says. “The view is absolutely unbelievable.”

Pallab Ghosh
Science correspondent, reporting from the launch

The Artemis II crew are already discovering that even a trip to the Moon comes with very down‑to‑Earth plumbing problems.

According to flight controllers, sensors in Orion’s waste‑management system – essentially the spacecraft’s toilet and urine‑processing gear – have thrown up some readings they did not expect, and engineers are now working with the astronauts to run extra checks and reconfigure the system.

For now, Orion has plenty of backup options, from alternative collection bags to different ways of routing liquids, so this is more about comfort and long‑term reliability than an immediate health risk.

But with ten days in deep space ahead, Nasa wants to be absolutely sure the system is behaving before committing to the burn that will send the crew away from Earth, and they say they won’t hesitate to cut the mission short if the problem worsens.

As well as toilet trouble, the astronauts have discovered a few other niggles with their brand‑new spacecraft.

A valve linking two sets of water tanks was found closed when it should have been open - probably jostled by the violence of launch - and has had to be reset.

Engineers have also seen a repeat of a minor electronics hiccup from Artemis I, where a component briefly tripped after a radiation hit before automatically recovering.

None of these issues are classed as mission‑threatening, but they underline why Artemis II is very much a test flight.