Artemis II astronauts have toilet trouble on their way towards the Moon

Nasa is set to send humans deeper into space than ever before, but there's one piece of technology that still has some kinks - the Orion space capsule's toilet.

Since launching from Earth on Wednesday, the four astronauts aboard the Artemis II mission's Orion capsule have had some intermittent issues with their toilet.

At one point on Saturday, the toilet was unable to dump its waste overboard, possibly due to a frozen vent line, Nasa said. The astronauts have instead used an alternative system which involves collapsible plastic containers that collect their urine.

Despite some toilet troubles, Artemis II is successfully into day five of the historic 10-day mission around the Moon.

The four crew members - Nasa's Reid Wiseman, Victor Glover and Christina Koch and Canadian Space Agency astronaut Jeremy Hansen - are in a small cabin about the size of a camper van, just 5m (15ft) wide and 3m (9ft) high.

"I'm proud to call myself the space plumber, I like to say that it is probably the most important piece of equipment on board," she said.

Then Nasa said in a press release on Saturday that a wastewater vent line had clogged.

The flight crew had to adjust the spacecraft to point the vent toward the Sun to help clear the clog. The adjustment did not change the trajectory of their path, the agency said.

They were able to free up space in the waste management system tank, but it did not fully clear the problem, Nasa said.

"Engineers have been using the vent heaters to melt any potential ice that may be clogging the line," Nasa said, adding that they were continuing to orient the vent toward the Sun.

"The wastewater tank is not full and the toilet is operational; however, the crew was instructed to use backup collection devices overnight if needed," Nasa said.

John Honeycutt, the chair of the Artemis II Mission Management Team, summed up the public interest in the space toilet during a news conference on Saturday evening.

"I think the fixation on the toilet is kind of human nature," he said. "Everybody knows how important that is to us here on Earth. And it's harder to manage in space."

In a Sunday interview on CNN's State of the Union, Nasa Administrator Jared Isaacman mentioned the waste issue and said they "can do a lot of extraordinary things in space right now, but nailing this capability is one that we need to certainly work on".

Artemis II is now on a looping path that will carry the crew around the far side of the Moon and back again. It is the first time since 1972 that humans have left Earth's orbit.

The four-person crew will not land on the Moon but will circle it, aiming to set the stage for an eventual human landing for the first time since the 1960s and 70s.

During the mission, the astronauts will test how Orion handles. This will involve manually flying the capsule in Earth's orbit to check the steering and lining up the spacecraft for future Moon landings.