Late Thursday evening, a Northrop Grumman rocket is set to take off from the Virginia coast, carrying an advanced space toilet for the astronauts on the International Space Station. Touted as smaller and lighter than the current toilets on the ISS, the new commode is also supposed to be more accommodating for women astronauts needing to use the space facilities.

Called the Universal Waste Management System, the toilet is one of two upgraded toilets that NASA is making to the tune of $23 million. While the one launching tonight is destined for the ISS, a second identical toilet will also be added to NASA’s future deep-space crew capsule, called Orion. NASA plans to send astronauts to the Moon using Orion in the coming years, and the Universal Waste Management System, or UWMS, will be inside the capsule for anyone needing a pitstop along the way.

Since this toilet will be traveling into deep space, NASA needed something compact but just as efficient as the toilets of the past. Heavier and bulkier objects are more expensive and more difficult to launch. So NASA did its best to optimize the size of the toilet, making it 65 percent smaller and 40 percent lighter than current ISS toilets. The agency also says engineers have made the toilet more energy efficient. “You can imagine that optimizing those can help out in lots of ways because space and power are at a premium on a spacecraft,” Melissa McKinley, the project manager for the UWMS at NASA, said during a press conference last week.

Despite these upgrades, the new UWMS toilet more or less functions the same way as the toilets already in space. All microgravity toilets rely on one important thing: suction. Suction makes sure that the waste produced by the astronauts actually gets pulled into the toilet and doesn’t inadvertently float around the crew cabin. To pee in the current toilets on board the ISS, astronauts use a funnel attached to a hose, with a fan inside, which pulls the urine into a tank. For number two, astronauts “sit” over a tank that uses the same fan that pulls their business into a baggy.

The UWMS also relies on a fan system, as well as a funnel attached to a hose. But NASA says it worked diligently with the women astronauts at the agency to better design both the shape of the funnel and the toilet “seat” to suit them. “The funnel design was completely re-contoured to better accommodate the female anatomy,” McKinley said. “And particularly this is a concern when the crew members are trying to do dual ops — when they’re doing both defecation and urination at the same time.” The women’s input helped inform the funnel’s shape, length, and position next to the toilet, according to McKinley. The seat was also shaped to make it easier for the women astronauts to go number two while using the hose.

Another major feature of this toilet is that NASA engineers used a special 3D printing technique to make various parts of the system out of exotic metals like Inconel, Elgiloy, and titanium. These are robust metals, which are needed so that the toilet can withstand a very acidic solution used inside the system to treat the urine. Urine can sometimes contain solid deposits that get stuck in the toilet and build up over time, so NASA pretreats the urine with an acidic solution to break those deposits down before it sends it to an on-board recycling system.

“The acid that we use as the pretreat is very strong,” Jim Fuller, the project manager for the UWMS at Collins Aerospace, which helped develop the toilet, said during the press conference. “It’s so strong that there’s only a handful of metals that NASA is aware of that can hold up to this pretreat over an extended period of time.” Those metals tend to be heavy, though, so NASA came up with a special 3D printing technique to create the parts it needed, allowing them to be made more lightweight than usual. Perhaps the biggest 3D-printed piece in the system is the toilet’s titanium fan, which is responsible for pulling in all the waste.

Image: NASA

One last big upgrade on this system is that it’s all automatic. Right now, astronauts need to turn on a switch to use the other toilets on the ISS, but the UWMS fan automatically comes on when astronauts either remove the funnel from its cradle or lift the seat to the “commode.”

NASA has done some testing with the toilet on the ground, orienting it in different positions to see how well the suction worked. Now, the toilet is slated for takeoff at 9:38PM ET on Thursday, on top of Northrop Grumman’s Antares rocket from NASA’s Wallops Flight Facility in Virginia. Riding inside Northrop’s Cygnus cargo capsule, the toilet will be retrieved by the astronauts once the capsule is attached to the ISS. The astronauts will install the UWMS next to one of the current toilets already on board and test it over the first three months. Eventually, the toilet will just become another restroom option for the astronauts on board the ISS.

In the meantime, NASA has even more space toilets to design. In June, the space agency started looking for designs for toilets that astronauts could use when working on the Moon. When it comes to all kinds of human spaceflight, the messy parts of sending people to space have to be considered in order to achieve a smooth mission. “When the astronauts have to go, we want to allow them to boldly go,” Fuller said.

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