Movies

What ‘The Martian’ gets right — and wrong — about life on Mars

Matt Damon, call your agent to complain.

Despite earning top billing and appearing on all the posters, the A-lister is forced to take a back seat in “The Martian” to another star — science.

Ingenuity is the real hero in this sci-fi tale, directed by Ridley Scott and out Friday.

While on a mission to explore the red planet, astronaut Mark Watney (Damon) is accidentally left behind, forced to fend for himself in the harsh environment as NASA officials (including Jeff Daniels and Chiwetel Ejiofor) race to bring him home.

The film is based on the best-selling book by Andy Weir, a California-based programmer and son of a particle physicist, who originally self-published the story online. It quickly became a word-of-mouth hit, especially among scientists, due in part to its accuracy.

“The Martian” certainly presents a lot of mind-bending concepts. But how out-there is it really? Let’s take a look. Warning: Book-learning and mild spoilers ahead.

You can grow crops on Mars?

When his rations begin to run low, Watney builds an improvised garden using Martian soil and his own, er, waste as fertilizer.

NASA’s Curiosity Mars rover vehicle takes a self-portrait on Mars in August.EPA

“We could probably grow something on Mars,” says Dr. Michael Shara, curator, Department of Astrophysics, Division of Physical Sciences at the American Museum of Natural History.

Watney’s choice to farm potatoes is especially smart.

“It’s the most bang for your buck in terms of calories,” Shara says of the starchy tuber. “If you want to keep someone alive, pound for pound, it’s a really good way to go.”

A 2014 study found that crops could grow in Martian soil and survive for 50 days without additional nutrients, and, in August, astronauts orbiting the Earth dined for the first time on food grown in space: romaine lettuce.

Is there anything duct tape can’t do?

The glass face shield on Watney’s helmet cracks at one point, leaving him to quickly patch it with tape before he suffocates.

Dr. Michael Shara says potatoes would be the smartest thing to grow on Mars.Everett Collection

This would work, actually.

“The tape is better than nothing,” Shara says. “As long as the pressure on the inside is around 30 percent, you could hold it together before your eyes blow out or you had an embolism.”

About those monster dust storms .  .  .

Mars is a bit like Burning Man — only with fewer drum circles. It’s maddeningly dusty and home to the solar system’s largest dust storms. One of these storms strands Watney and nearly destroys the crew’s ship.

That said, such a meteorological phenomenon is unlikely to pack much of a punch. Mars’ atmosphere is about .01 as thick as Earth’s, meaning a 100-mph gust would feel like a light breeze.

Weir has conceded the error, saying he made it for dramatic purposes.

What about the gravity?

Damon is shown walking around Mars just as he would on Earth — probably a concession to the realities of filmmaking as opposed to a bid for accuracy.

The cast of “The Martian” from left, Chen Shu, Jessica Chastain, Ridley Scott, Damon, Kata Mara, Jeff Daniels, Chiwetel Ejiofor and Sean Bean, at the European premiere September 24th.WireImage

Mars’ gravity is 38 percent that of Earth’s. (Comparitively, the moon is 16 percent.) Astronauts would be much lighter on the red planet.

“You could set world records in the long jump and high jump, but you’re not going to bound off into space accidentally,” says Rick Sachleben, a research fellow in chemical development for Momenta Pharmaceuticals.

Is it really that cold on Mars?

Colder. Watney rolls around the planet’s surface in his rover, but decides not to turn on the heat to preserve battery life.

Depending on where he is on the planet, he might regret that decision. The average temperature is a bracing minus-80 degrees Fahrenheit, and it’s cold enough on Mars to snow carbon dioxide.

The average temperature on Mars is minus-80 degrees Fahrenheit, and the gravity is 38% that of Earths.Getty Images

If the cold doesn’t kill him, the radiation might.

“One of the major challenges in space is to shield astronauts from radiation,” Sachleben says. “Our atmosphere does it on Earth, but what happens when you put someone in a habitat that doesn’t have that shield?”

Shara says a spacecraft on Mars is currently measuring radiation levels.

Would astronauts crack wise like Watney?

“I’m very much a fan of the book,” Shara says. “I like that Watney is this anti-hero. He’s funny and self-deprecating.”

Damon with Jessica Chastain, Sebastian Stan, Kate Mara, and Aksel HennieEverett Collection

In the film’s signature line, Watney declares that, to save his life, he’s going to have to “science the s–t out of this.”

The American Psychological Association studied the kinds of people that are best-suited to survive the psychological stresses of outer-space travel, and found that a sense of humor is crucial.

The group also found that the ideal space crew would be diverse and mixed-gender. Jessica Chastain, Michael Peña, Aksel Hennie and Kate Mara round out Damon’s mates.