Astronauts on spacewalks famously have to relieve themselves inside their spacesuits. Not only is this uncomfortable for the wearer and unhygienic, it is also wasteful, as—unlike wastewater on board the International Space Station (ISS)—the water in urine from spacewalks is not recycled.
Why are they caring the whole purification plant on their backs?
Wouldn’t it be easier to carry the collection part and exchange wastewater and drinking water with the station?
Good question but I guess it doesn’t matter as much in space where you don’t weigh as much.
For the ISS it adds to the launch weight of suits and takes up additional space when using airlocks and in storage.
For a moon/mars mission (claimed use case in the article) it increases your center of mass and your inertia, resulting in more astronauts falling over.
I doubt launch weight would be a huge issue.
Mass still costs energy to move around. Spacewalks already sound pretty strenuous. Adding any additional exertion seems like it would need a really good benefit to be worth the tradeoff.
Depends on the weight. It might be lighter and easier to work with than a collection unit and a water supply tank.