February 23, 2024

Astronauts on interstellar missions will feel less thirsty after NASA’s new system successfully recycles 98 percent of wastewater aboard the International Space Station (ISS) by converting substances like urine into a drinkable state.

Future crewed deep-space missions that will last months, if not years, will be very different from any that came before. Until now, astronauts either carried their own supplies or relied on regular visits from cargo ships. As for waste, it is simply disposed of in various ways. Unfortunately, deep space missions don’t have that luxury.

For example, a mission to Mars might last two years. One gallon (3.8 liters) per person per day is a lot of water to carry. If the spacecraft had a crew of four, then at least about nine tons of water would be produced. It also ends up turning into tons of urine.

NASA's water recycling system
NASA’s water recycling system


The ideal spacecraft would be basically self-sufficient, able to recycle air and water, and grow its own food like a closed ecosystem. As a first step toward this goal, NASA has been testing the water recovery component of its Environmental Control and Life Support System (ECLSS) aboard the International Space Station.

Consisting of the Water Recovery System, Water Processor Assembly (WPA), Urine Processor Assembly (UPA) and Brine Processor Assembly (BPA), the ECLSS recovers and reprocesses water from urine and crew on board the space station through a series of steps The breath and sweat accumulate in the air, which is then purified into drinking water.

Collecting water from the air is relatively simple with an advanced dehumidifier system. Urine, however, is a bit trickier to deal with. UPA removes most of the water through vacuum distillation, leaving behind a nasty-sounding urine-saline solution. This goes into BPA, which uses special membrane technology to blow warm, dry air over the salt water to evaporate water, which is recycled in the same way as water in breath.

Filters used in brine treatment
Filters used in brine treatment


The recovered water then passes through a series of filters and catalytic reactors to break down contaminants while sensors check for purity, before adding iodine to kill any microbes present.

The result is a 98% recovery rate. This can be done on Earth, but ECLSS can do the same thing in zero gravity. However, NASA is still trying to address what might be called a consumer boycott.

“The treatment process is essentially similar to some terrestrial water distribution systems, except it’s done in microgravity,” said Jill Williamson, ECLSS Water Subsystems Manager. “The crew aren’t drinking urine; Recycled, filtered and cleaned water, cleaner than the water we drink here on earth. We have a lot of processes and a lot of ground testing to provide confidence that we are producing clean drinking water.”

The video below discusses water reclamation projects.

NASA ScienceCasts: Water Recycling on the Space Station

source: nasa