Nasa is working on a spacesuit that will have a built-in toilet for its next space mission. Technically called "long-term waste disposal system", such toilets have not been in use since the Apollo missions.

The new suit, being made for human space flight beyond low-Earth orbit, is called the Orion Crew Survival Systems Suits (OCSSS), reports Space.com. They will be used for deep space human exploration. Orion is, as of now, big enough only to support human flight to the Moon and back. The craft is unlikely to be used in Mars missions. Seeing as how Nasa has turned its attention back to the moon, this is likely to be used first.

Nasa has said that the Orion will have toilets, just like the Shuttle, but the suit-based toilet will be used in case the cabin should de-pressurise and the astronauts have to stay in their suits to survive. The new spacesuit is built to sustain life for up to six days, notes the report.

Astronauts, both men and women will be able to eat, urinate and defecate in their suits for six days without having to take it off, if needed.

"That is a really long time...but then to live in a suit with all of your waste right by you for that long of a time, it could get gnarly pretty quickly," said Kirstyn Johnson, Nasa engineer leading the design of internal systems for the suit.

As of now, astronauts like the ones who live and work in the International Space Station (ISS), have two types of suits – one for launch and re-entry and the other one for when they work outside the space lab and space walks called the extravehicular mobility unit. Both suits have maximum absorbency garments that work like diapers. The report mentions that this was sufficient in most cases as they are not meant to be worn for longer than 10 hours at a time.

The advantage with having diapers is that the user can easily remove and replace them at short notice. The diapers, however, "may not work 100 percent of the time — you might have leakage — but it gets the job done without us having to put too much effort into it up front in terms of design and certifying it," said Johnson.

For design inspiration, Nasa opened a "Space Poop Challenge" in 2016, notes the report. In spite of many ideas coming in, the space agency was unable to integrate them into a working spacesuit without a lot of redesign and development. This is when they looked back to the Apollo days for inspiration.

The suits will have several ideas carried over from the old suits like the urine collection condom catheter for men and fecal matter collection bags for both men and women. Urine collection for women is a bit trickier. "For females, it gets a little harder, obviously, because of the geometry of a person's body, and then you have to deal with issues like pubic hair," Johnson said of the in-suit system.

The team is currently working on the female urine disposal system and a lot of the design is still secret, noted Space.com. The design is expected to be similar to the tube system used by pilots on long flights.