Before humans go to Mars, as NASA is planning for the 2030s, there's a lot of work to be done, such as developing and testing a rocket that can get there and studying the effects of long-term space habitation on the human body.
This is because it's going to be a long trip. It took Curiosity just over eight months to get to Mars from Earth. NASA is trying to reduce that time to around six months, but even so, that's at least a year travelling in space without any access to fresh food. Unless, of course, NASA can figure out a way to grow plants, not just in microgravity transit conditions, but on the Red Planet itself.
This is where Bruce Bugbee, director of the Plants, Soils & Climate Department at Utah State University, enters the picture.
"I have a long-term relationship with NASA to help them develop biological life support systems for space. And that includes Mars, it includes living on the space station, it might include living on the Moon. Any place that the goal is to be as independent from Earth as possible," he said in an interview.
"This goes back over 30 years, that I've worked with NASA to develop these systems. So then ["The Martian"] came out, and it's a red-hot topic because of Mark Watney in the book and movie growing potatoes on Mars."
Bugbee and his team of researchers have been growing plants primarily in ground-based growth chambers, although if you remember theearlier this year, that was Bugbee's work too. Between the ground-based growth chamber and the growth chamber aboard the International Space Station, Bugbee believes that it's very possible for plants to grow in space and on Mars with current technology.
The growth chambers on Earth are closed systems, like a huge refrigerator, where the plants are grown hydroponically. There is no natural light. Humidity, temperature and carbon dioxide levels are tightly controlled so as to simulate the environment aboard the ISS.
In fact, Bugbee said, microgravity is one of the smallest concerns.
"When you think about going into space, everybody thinks it's about the lack of gravity and what's that gonna do." he said. "But, as far as we know, from many years of studying this, the lack of gravity doesn't hurt plants at all. In fact, we think they might even grow better because there's no gravity pulling them down."
In a closed microgravity environment, there is minimal stress on plants. They don't have to fight gravity to grow. There's no wind, so the plants don't need to expend energy thickening their stems. Harmful radiation isn't present, and the temperature is always optimum and even.
But when it comes to the Mars mission new implications come into play. Any astronauts sent to the red planet would need to spend several months there. This would require very careful long-term planning, including planting a vegetable garden.
Growing plants on Mars might be very different to growing plants in microgravity, but overall, Bugbee said, "The Martian" got it more or less right.
"I could nitpick it and say this wasn't exactly right and that isn't exactly right. But, the concept is correct. He can grow potatoes like he did, and he can grow them from recycled waste [human excrement]. And, it's possible to live up there a long time. So, the concepts were all correct," Bugbee explained.
But those nitpicking details could be crucial in real life.
The biggest problem, he said, is that Mars is about 1.5 times farther from the sun than the Earth is, and only gets about 60 percent of the light. This means that plants on Mars would grow at about 60 percent of the rate of Earth plants, even when exposed to full Mars light. Watney's habitat was designed to block radiation, which would lower the light levels even more.
"How would he get enough light for his plants? He didn't go into that. But plants need bright, bright light," Bugbee said. "We normally use a lot of solar panels and a lot of electric lights, but one of the things we're working on now is fiber optics: big, concentrating mirrors and fiber optics to bring that bright light in to grow plants."
The other problem is the soil. While it's theoretically possible to grow plants in the Mars soil, it's simply not how it would be done.
"It's mostly iron oxides. And iron makes stuff red, like rust. So it would be pretty hard to just take soil the way he did in the movie and put a little bit of composted human waste on the plants, and magically grow these great potatoes," he said.
"You would normally grow the plants in hydroponics. So you have some sort of liquid media, and we wouldn't initially use any Martian soil. But after we conditioned the soil, the way you condition the soil on Earth for a garden, then you could grow plants in it."
Within a science-fiction framing, it's understandable if some small details aren't entirely correct.
"You got to skip over some stuff, that's why I say it's silly for me to nitpick these little details. But they're important, I mean, how close to reality is that? Everybody wants to know," Bugbee said.
While the scientist in him notices the small details, he loved the film.
"I would encourage everybody to see the movie and to read the book. I think they're wonderful and it inspires the imagination. I hope that inspires the youth of the world to continue our work."