How Scientifically Accurate is The Martian?

Robert Zubrin / Interview
The Guardian (UK), October 6, 2015

Overall it’s a very good movie, and while there are mistakes in it, it is the first genuine Mars movie. It is the first movie that attempts to be realistic and that is actually about human beings grappling with the problems of exploring Mars, as opposed to various movies set on Mars that are essentially either shoot ’em ups or horror films. It does not engage in fantasy: no monsters, no magic, no Nazis. However, there are a number of technical mistakes.

The storm
This is the only thing I noticed that was completely impossible, as opposed to improbable or sub-optimal. The Martian atmosphere is only 1% as thick as Earth’s, so a Mars wind of 100mph, which is possible although quite rare on the surface, would only have the same dynamic force as a 10mph wind on Earth. You could fly a kite in it, but it wouldn’t knock you down.

The spacecraft
The diameter of the torus and the rate of rotation on the Mars Orbiter spacecraft looked about right to create an artificial gravity level somewhere between Mars and Earth, so that was OK. It’s just that the ship was so big and elaborate and expensive-looking. Going to Mars is not about realising the vision of a giant science-fiction spaceship, it is about sending a payload from Earth to Mars that is capable of supporting a small group of people, and then sending that or a comparable payload back. There’ll be ships like that someday, just like there were ocean liners a few hundred years after Columbus made his voyage. But if Columbus had waited for ocean liners, or even clipper ships, he never would have gone anywhere.

Mars has about one third the gravity of Earth, which is an asset to explorers because you’re wearing a heavy space suit, but it doesn’t feel that heavy. If you’ve got a 150lb person with a 150lb suit, that’s going to feel like 100lb on Mars – lighter than the person alone on Earth. As far as I can see they didn’t bother with that in the movie. Even climbing the ladders in the initial scenes, they seem to be exerting themselves.

Making water
Matt Damon’s character took hydrazine from the rocket fuel and dissociated it into nitrogen and hydrogen, which you can do, and he burned the hydrogen with oxygen to make water. That’ll certainly work, but if I was stranded on Mars I would just make water out of the soil. Water is available in its natural state on Mars as ice, permafrost, or soaked into the soil. Martian soil is about 5% water by weight at low latitude, and up to 60% water near the poles. Martians are not going to get their water by importing hydrazine from Earth and burning it with precious cabin oxygen, they are going to bake it out of the soil.

The toilets
This was a little odd. The easiest way to deal with waste is to bag it, seal the bags in something and then burn them once a day. We do something like that with Arctic exploration. But it’s more productive to recycle the waste, using greenhouse systems or physical chemical processes, and turn it into fuel, water and oxygen. Would they really seal them individually and label them with the astronauts’ names for later scientific study? I can’t imagine anyone wanting to bring that stuff back to Earth, or study it on Mars. You’re not on Mars to study your fecal waste, you’re there to study Mars.

The nerd-genius solution
One thing in the movie that is possible, and perhaps the producers knew the story, is the character of the nerd (played by Donald Glover) who comes up with the gravity-assist trajectory that rescues the mission. It may appear to be a Hollywood device, but in fact there is a basis in history for such a person. His name is Michael Minovitch. He was a trajectory analyst at Nasa’s Jet Propulsion Laboratory in the 1960s and he came up with the idea of the gravity assist that became the basis of the Voyager programme to go to Jupiter, Saturn, Uranus and Neptune. Initially no one believed him. He was a very junior person, somewhat analogous to the character in the movie. The managers making the decisions are typically people who were once engineers but haven’t done it in a while and perhaps are not so good at maths any more. So Minovitch had to get out the chalk and walk them through it and convince them that it would actually work.

Removing the windows from a rocket
Would you need windows in a rocket to survive a launch from Mars? It’s an interesting question. The atmosphere is very thin, so can you get high enough that the atmosphere becomes irrelevant before you’re going fast enough that the atmosphere is a threat? It depends on the thrust profile. The question is, at what altitude do they reach 1km per second? Let’s figure it out: OK, so 1,000 metres per second squared, divided by … [Zubrin mutters some equations to himself] … you want to go slow in this case, so let’s say 1G. Let’s try [more muttering] … 50 kilometres. So, with a slow acceleration of 1G taking off from Mars you’d get to 50 kilometres before you’re travelling at 1km per second. So I’d lean towards yes, it’s possible.

Nasa communications
Would Nasa not tell the other astronauts that Watney [the Matt Damon character] was still alive? Well let me put it this way: they didn’t tell the Columbia astronauts everything [the space shuttle Columbia disintegrated on re-entry in 2003, killing all seven crew members]. And it was unfortunate, because they didn’t give those astronauts their best shot at potentially solving the problem they had. I don’t know if those astronauts could have saved themselves if they had all the info, but they should have had all the info. What was unrealistic to me was that you had the whole Earth knowing that Watney was alive, but the crew on the interplanetary spaceship did not. That’s impossible right now. The crew on the International Space Station can email you. Not all of their communications go through mission control, so they can be in touch with their loved ones at home. It’s tremendously useful to have the crew be able to directly access people on Earth. If they’re exploring Mars and they come across a very odd-looking mineral, say. To be able to access a professor at some university somewhere and say is this a fossil? A mineral? What do you think? Or, how do I reboot my computer, it’s locked up? If you have all this going through one person at mission control, it isolates the crew much more than is necessary.

The U.S. space programme today is frozen in its tracks. Nasa talks about sending humans to Mars in 2043, but that’s just postponing it for another generation. We’re much closer today to being able to send people to Mars than we were to sending people to the Moon in 1961. If Barack Obama’s successor were to commit the nation, in the spring of 2017, with the same kind of courage and determination that JFK did in 1961, we could be on Mars before the end of his or her second term. It’s a question of political will to me. That’s the real positive message of The Martian. It’s saying, “we can do it. If we use our minds, we can take on all these challenges”.

Dr. Robert Zubrin is an aerospace and astronautics engineer and an advocate for manned exploration to Mars. He is founder and president of the Mars Society and co-author of Mars Direct, a strategy for manned expeditions to Mars that has been broadly adopted by Nasa (and replicated in The Martian).

Dr. Robert Zubrin was speaking to Steve Rose.

A Martian Odyssey: We Can Do It


by Robert Zubrin
September 29, 2015


The exploration and settlement of Mars is one of the great challenges of our time — a point strongly underlined by Monday’s announcement of the discovery of potentially life-holding liquid water on that planet — so it is not surprising that there have been many good novels investigating its possibilities. There have, however, been no worthwhile movies on the subject. True, there have been a fair number of big-budget extravaganzas that nominally involve Mars, but these have been simply a bunch of shoot-’em-ups, horror stories, or journey-to-the-fantastic-revelation remakes set on the Red Planet.

That is about the change. This week Twentieth Century Fox will release The Martian, based on the fine novel of the same name by Andy Weir, and theater audiences everywhere will finally be able to see with their eyes a piece of the vision that many of us working in the Mars-exploration community have been trying to see with our minds for the past half century. The Martian is thus historic, being in point of fact the first actual Mars movie.

The story line of The Martian is simple. It is a tale of survival, of a single astronaut, Mark Watney, played in the movie by Matt Damon, who is stranded on Mars and needs to use his wits and his grit to figure out how to survive. He has some help, to be sure, from his comrades aboard a distant interplanetary spacecraft and those who stand by them at Mission Control, but ultimately it is up to him to find expedients to defeat the hazards of the hostile Martian environment and in fact put it to work to create the resources necessary to last until rescue can arrive.

If one were to compare The Martian to other works, the obvious choice would be Robinson Crusoe, as they both face and deal with similar predicaments. But as it relates to the situation of our space program today, I think that an analogy with Homer’s Odyssey would be more apt.

Think about it. At the time Homer spun his tale, the Greeks were just beginning their career as a nation of seafaring explorers, traders, and overseas settlers. Surely there must have been more timid souls who warned of the dangers of such ventures into the unknown. But Homer had an answer: Odysseus, the clever man who uses his mind. Poseidon the sea god is his adversary, but Odysseus has made Athena, the goddess of practical wisdom, his friend, and with the kind of help she has to offer, he can win through despite storms, cyclopes, sorceresses, giants, monsters, or whatever other threats there might be.

Fear not; human ingenuity and determination can prevail over the hidden terrors of the unknown. This is certainly a message our society could use now. For example, on September 21 the New York Times published a dire op-ed by Ed Regis, a philosopher specializing in “pathological technology,” warning of the incredible dangers barring the way to Mars. It would take nine months to get to Mars, says Regis, quite counterfactually, because we have done it in six, which is the standard length of a space-station crew rotation. This would be unendurable, he says, even though it has been repeatedly endured by space-station crews, and other people under much more difficult circumstances throughout human history have endured much worse for much longer. Microgravity exposure would destroy the crew’s bodies, he warns, despite the fact that it has not done so on the space station, and can be avoided entirely by rotating the spacecraft. Furthermore, upon reaching Mars, they would find a planet with a carbon dioxide atmosphere, and thus no source of oxygen other than water frozen in the soil, despite the fact that carbon dioxide contains oxygen, and there are several proven technologies for making oxygen from CO2, including one that has been available for about 2 billion years. Mars is a “veritable hell,” he says, and we cannot currently “put human beings on Mars and expect them to live for more than five minutes” — a statement that surely would surprise those Americans of an older generation who lasted a lot longer than five minutes on the much more hostile surface of the moon.

In the Middle Ages, there were artists who made a living inscribing illustrations of dragons on maps of unexplored oceans, and, as we can see from the above, their modern-day equivalents are now out in force again, providing similarly useful navigational aids to the space program. But it is not just ignorant outsiders who are spreading terror: The NASA leadership itself has embraced fear to justify paralysis. Consider the following: NASA included radiation-detection instruments on probes sent to Mars in 2001 and 2012. Both returned the same results, showing that a crew undertaking a six-month voyage to Mars would receive a cosmic-ray dose about double that received by a space-station crew member over the same period. Announcing the results from the first probe in 2002, NASA proclaimed, accurately, that this showed that cosmic rays were not a showstopper for human missions to Mars. But in 2013, nearly identical data was used by NASA as the basis of an announcement that humans should not attempt to go to Mars until a much faster space drive is developed, which is not in the cards for decades, if that. Thus, with all the sincere regret of a ten-year-old observing that a four-inch snowfall must certainly preclude school attendance for at least a week, the space agency leadership sought a rationale from exaggerated danger for several more decades of stagnation.

Odysseus and Mark Watney demonstrate the kind of mind needed to take on the unknown. They are fictional, but the leaders of America’s space program once showed those qualities in real life. In 1961, we did not know how we could get to the moon. But we knew we were Americans and that we had what it took to do what had never been done, and which had to be done in order to astonish the world with what free people can do. Today we face similar challenges — from Putin, from China, from the Islamists, each of whom in their own way is saying that our time is past — which require a similar response. So once again, our space program needs to do something grand. I think we can do it, but to do so, we will need to look within ourselves and find once again those characteristics, not only of ingenuity, but of faith in our powers, resolution, and above all, courage, shown by the Martian.

— Dr. Robert Zubrin is president of Pioneer Energy and the author of The Case for Mars: The Plan to Settle the Red Planet and Why We Must. The paperback edition of his latest book, Merchants of Despair: Radical Environmentalists, Criminal Pseudo-Scientists, and the Fatal Cult of Antihumanism was recently published by Encounter Books.