At the end of Elon Musk's big Mars event yesterday, there was a Q&A session riddled with weirdness, but one question really stuck out. It wasn't the guy who wanted to give Elon a comic book or the Funny Or Die rep with a plan to send Michael Cera to Mars for a show. It was the man with the circuitous question about what Musk plans to do with all the poop generated by 100 colonists, screaming through the void on their way to the Red Planet.
On Earth, sewage systems tend to be one of the many invisible infrastructure systems we take for granted. We flush it out of sight right there in the bathroom and then never think of it again. But on a journey to Mars—whether it's one, three, or six months—the crap is going to add up.
You could jettison it into space, but it's not like we don't already have enough untracked space junk floating through our solar system. You could send canisters of dung into solar orbit and track them heavily. You could try to just hang onto it the whole time and then stash it on Mars likethe Apollo missions left souvenirs on the moon. And really, .
But you can also put it to good use. Indeed, it's been proposed before. NASA provided a grant to a researcher who wants to turn urine byproducts into vitamin supplements using yeast to synthesize omega-3 fatty acids. That takes care of problem number one.
But as for problem number two? There's a lot of methane in there, as well as some food scraps. A group of University of Florida researchers are studying using that as rocket fuel. And as it ends up, SpaceX is hoping to harness methane (which might be abundant on Mars) as a fuel source that can be created in situ. Maybe they can create it in-seat-too.
In The Martian, Mark Watney famously uses his feces as a fertilizer but that comes with its own set of perils. There's the potential for harmful pathogens, . That's not to mention the potential for , though others have found a way to make things work with . Of course, with just a wave of Elon Musk's hand, the problem can be dismissed. Postponed for a few years down the road, the same way he dealt with some concerns about radiation during the very same press conference.
But as silly as they might sound, don't knock questions about space toilets until you've tried to answer them.