There are plenty of challenges in sending astronauts to Mars, but one big problem is nutrition. How do you keep a crew healthy and fed if they're voyaging away from Earth for several years?
For that task, researchers at NASA Ames are conducting a variety of experiments to find new ways for astronauts to grow what they need, either in space or even on the surface of Mars.
Last month, Ames researchers began a new project at the International Space Station (ISS) using yeast samples to grow vitamins that astronauts are expected to lack on prolonged space missions. The research into what they call bionutrients is a new avenue for producing critical compounds to supplement the crew's diet -- much like 18th century sailors getting rations of lemons to avoid scurvy.
For ISS space missions, astronauts on space tours usually subsist on dehydrated or canned food, typically for about six months. This approach works given the relatively short duration of the stay, but it presents problems if NASA attempts a longer mission over many years. That's because preserved foods tend to lose their nutritional value over time, said environmental scientist John Hogan, who is leading research on the bionutrients project.
"Just like here on Earth, every food has a shelf life, and there's certain vitamins that degrade substantially over time," Hogan said. "This bionutrients idea is one way that we could address this, by using microbes that are engineered to produce these nutrients."
In this case, Hogan and his team are investigating baker's yeast that has been modified to produce beta carotene and zeaxanthin, both of which are commonly found in vegetables. For the experiment, astronauts will receive packets of dried yeast that can be activated just by adding a little water. As the yeast microbes consume their food supply, they will produce the nutrients as a byproduct.
Eventually, the goal is to use selective breeding to create a strain of yeast that can survive in storage for the longest time without refrigeration. While it conducts the experiment, NASA officials are asking astronauts not to consume any of the yeast-made vitamins so they can be tested for safety first.
Hogan described his research as one piece in the larger push by NASA to develop new food systems for prolonged space travel. NASA has participated in multiple experiments to grow fresh vegetables at the ISS. This idea still requires much fine-tuning but it has a wide range of benefits, such as providing an extra supply of oxygen and acting as stress relief for astronauts on long space missions.
For a future Mars mission, NASA is currently crowdsourcing ideas to help convert the ample supply of carbon dioxide on the Martian surface into glucose, which can be used as a versatile energy source. If this step can be achieved, then it will open up vast potential for growing microbes on Mars, Hogan said. Another project in the works calls for producing medicinal compounds during space missions.
It's a long way off before astronauts will be eating what they produce from their experiments. Hogan says any produce or vitamins grown in space are being sent back to Earth for analysis. The goal for now is proving it can work, he said.
"We're still finding ways so that we're getting organisms growing safely and producing what we want them to produce," he said. "This is just the beginning of what we're trying to do."