Engineers Sound Off on the Accuracy of The Martian

Sci-fi mission to Mars gone wrong is rooted in science and engineering - mostly.

If you haven’t read The Martian yet, do it. It is the perfect follow up book to the recent announcement that NASA has discovered liquid water on Mars.

The survival story about mechanical engineer/botanist/astronaut Mark Watney being stranded on Mars is rooted in so much science and engineering you won’t need a major motion picture to appreciate the dedication author Andy Weir has for STEM.

Naturally, a book with this much technical savvy means many engineers have sounded off about what was wrong and what was right. Recently, a team from the University of Michigan have joined in on the conversation.

Though yet another movie based on the government spending tons of money and risking lives to save Matt Damon is perhaps interesting, Hollywood will likely get much more of the science and engineering wrong so this commentary will focus on the novel.

It should go without saying that there will be “SPOILERS” from some steely eyed missile men.

There Are Storms A-Plenty on the Desolate Mars Landscape

Take Nilton Renno, professor of climate change, space sciences, and engineering. He has assisted with many robotic missions to Mars. His recent work with NASA was on the Mars Science Laboratory and Phoenix Lander.

Renno’s bone to pick with the novel was regarding the dust storms on Mars.

Though Watney does have his battle with the sands on Mars, Renno notes that it doesn’t happen nearly as often as it should. “I think dust is going to be a big problem in the exploration of Mars,” he said. “The winds can pick up a lot of dust. Noon on Mars can be almost as dark as midnight.”

Perhaps one of the most nail biting parts of the story is when Watney is making his epic journey to Schiaparelli and a massive dust storm is in his way. The reader, NASA, and the fictional world know that the hero is making his way toward a death trap and there is nothing they can do to warn him.

Renno suggests that more of these nail-biter sand storms should have been in the novel to improve the accuracy of the story. He even noted that at times these storms will cover the whole planet. Seems Watney will be cleaning those solar panels more often.

However, there is another issue when it comes to Mars’s sand that Renno and Weir missed: perchlorates. This nasty toxic oxidizer was recently found in abundance in Mars topsoil. Though protected from the hazardous chemical in his space suite, Watney would have to deal with the dust on his suit and equipment whenever he re-enters his habitats.

Weir notes in an interview with Jacob Shamsian of that he didn’t know about the perchlorate salts when he wrote the novel. As a result, a real life Watney would have to cut into a lot of his water reserves to wash off the salt every time he entered through an airlock. However, the water reclamation system should be able help with this problem.

Radiation is Hard on Martian Potato Farms

The lead engineer in research at U-M’s Space Physics Research Lab, Ryan Miller, was concerned with the science of growing potatoes on Mars.

For about 30 years Miller has worked with NASA on space instrumentation that looks into the composition of Martian soil and the atmosphere.

“Mars is an extremely harsh environment with very cold temperatures, and because the atmosphere is so thin and there’s no magnetic field on the whole planet, it’s constantly bombarded by radiation from the sun,” Miller said. “Mark Watney’s greenhouse-like enclosure would have had to block this radiation.”

However, Watney took the soil into his habitat to shield it from the Martian atmosphere. If humans are to travel to Mars, their habitat will clearly have shielding from the solar radiation. As a result, Watney bringing his farm indoors would have solved this issue whether the book mentions it or not.

What remains a problem with Watney’s solution is, once again, those pesky perchlorates. As mentioned, these salts have some significant health effects to humans, and might cause some issues for the potatoes themselves. Due to these health effects, bringing several cubic meters worth of Martian soil into the habitat is clearly a bad idea without dealing with the salts first.

Now that Weir is aware of the chemical, he told that Watney could have washed out the salt by soaking the soil in water. However, Watney has a limited supply of water, even though he finds a way to chemically make more.

To solve his water problem, Watney would have to wash the soil outside of the habitat, boil off the water and collect the vapour so that the water reclamation system could recollect it later. Though not unsolvable, it would have added a few extra log entries into the already interesting novel.

Additionally, Miller notes that the soil on Mars does have many of the chemicals needed to grow plant life. Unfortunately, by washing the perchlorates out the soil, many of these minerals will be flushed out along with the perchlorates. However, Watney’s process to enrich the soil with “personal compost” would work to replace much of these minerals. Though due to the pathogens now growing on the potatoes from Watney’s manure, sharing on the Hermes would be dangerous to his would-be rescuers.

As alternatives, Watney could wait for the microbes to neutralize the perchlorate salts, or neutralize them himself chemically. On Earth, microbes are used to clean perchlorates out of contaminated water supplies. The salts can also be reacted to release oxygen, another limited resource on Mars. Unfortunately, these processes take a considerable amount of time and resources. And Watney needs to start growing those potatoes yesterday.

Rescue Mars 911 Has Bad Response Times

When it comes to Watney’s rescue mission, Jon Van Noord’s nine years of experience in spacecraft propulsion at NASA Glenn Research Center gives him significant steely eyed missile man credibility.

He explained that Earth and Mars are closest to each other once every 22 months, and the fastest we could send a rescue mission to Mars from Earth is six to eight months.

In comparison, the Hermes rescue maneuver to Mars added 211 days to the mission. Considering that Hermes had to sling-shot around the Earth, get to Mars and come back in 211 days, we are looking at a trajectory that will take much less than six months to get from Earth to Mars.

Van Noord also explained his thoughts on Hermes’ ion drive. Though this technology exists, he said, “we’d have to have a fictional nuclear reactor that’s beyond what we currently have, to be light weight but generate the massive amount of force for the rocket to get to Mars quickly.”

Now, these findings are mere nit-picks at the end of the day. Weir did everything he could to ensure the book was accurate for our current understanding of the red planet. An engineer will have plenty of fun trying to think of the solutions to Watney’s problems before the characters can. And when you see the solutions, they will certainly seem impressive.

What inconsistencies did you find in Watney’s journey? What was your favorite scientific principle Watney used to survive? Comment below.

Written by

Shawn Wasserman

For over 10 years, Shawn Wasserman has informed, inspired and engaged the engineering community through online content. As a senior writer at WTWH media, he produces branded content to help engineers streamline their operations via new tools, technologies and software. While a senior editor at, Shawn wrote stories about CAE, simulation, PLM, CAD, IoT, AI and more. During his time as the blog manager at Ansys, Shawn produced content featuring stories, tips, tricks and interesting use cases for CAE technologies. Shawn holds a master’s degree in Bioengineering from the University of Guelph and an undergraduate degree in Chemical Engineering from the University of Waterloo.