美国国家公共电台 NPR Making Space Food With Space Poop（在线收听）

SCOTT SIMON, HOST:

There's only so much space on a spacecraft, which means limited space for food and water. American crews on the International Space Station recycle their own sweat and urine to produce fresh drinking water - bottoms up. Now new research from Penn State University may have figured out a way to not let another human waste go to waste by turning effluvia into food - got that? Dr. Lisa Steinberg was lead author on the study and joins us now. Thanks so much for being with us.

LISA STEINBERG: Thank you for having me.

SIMON: So I gather microbes do the heavy lifting here, right?

STEINBERG: They sure do. So microbes catalyze most of the major processes on Earth to recycle nutrients, and we're putting them to work in the life-support system to do the same thing.

SIMON: And how's that work?

STEINBERG: We collect the solid and liquid waste from the astronaut, and we put it into a reactor where we have a mixed group of bacteria that break that waste down. And from that, they produce methane which is a gas. And then that methane can be fed to a second type of bacteria that it grows up. And then the cells themselves have a lot of protein, have a lot of fat, and they can serve as a supplement to the diet of the astronauts in the life-support system.

SIMON: And the final product looks and taste like what?

STEINBERG: My collaborator on the project, Dr. Chris House, described it as a marmite or Vegemite-like substance. I'm not familiar with either of those because I don't eat them. But he does and said that the consistency reminded him of that.

SIMON: Kind of - Vegemite and marmite - I've had both. Let's just describe it as kind of a translucent peanut butter except it don't taste like peanuts, OK?

STEINBERG: I'm sure it probably has a much yeasty or richer flavor than, you know, just peanut butter would.

SIMON: Yeah, but you haven't tasted it, right?

STEINBERG: No, so that would have required special permissions that we didn't obtain. So no, we did not taste it. But it has been used for years as a supplemental food for animal husbandry and aquaculture. And at some point, there were some tests done with people who described it as somewhat bland.

SIMON: Oh, that's much better than I was faring. Yeah. All right.

STEINBERG: I recommended just bringing some Sriracha on board, and that'll make anything taste good.

SIMON: (Laughter) Absolutely true. And you know what the French say - as long as the sauce is good. And why is this a great step forward for mankind?

STEINBERG: Well, if we are going to have manned space missions to near-Earth asteroids or Mars - anything that is quite a distance away - it's not going to be feasible at this point to try to pack along all of the food and the water that astronauts would need for the duration of the trip. So we need to have some way of recycling the nutrients from waste material back into food material in a pretty short span of time. So we're hoping that this will make those kinds of manned space missions more feasible in the future.

SIMON: What remains for this to become a reality?

STEINBERG: Well, to put it on a life-support system, you would definitely need to have a lot of safety precautions in place. Astronaut protection would be first and foremost. You would need to make sure that there's no potential of pathogens from the waste getting into the food source. And then beyond that, you would just the system to be incredibly reliable and predictable. Nobody wants surprises in space.

SIMON: So so far, no plans for recipe book?

STEINBERG: No, not for me - I don't even cook at home, so I wouldn't know what to do with this.

SIMON: Dr. Lisa Steinberg, who's a post-doctoral astrobiology researcher at Penn State and lead author of the study - thanks so much for being with us.

STEINBERG: Thank you.

(SOUNDBITE OF MATERIAL SONG, "COSMIC SLOP")