How we view risk for a one-way mission to Mars

Today we have a special treat! Andrew Rader, Canada’s Know It all and front runner for the Mars One project, has agreed to let us post parts of his book!

Below is an excerpt from his book Leaving Earth: Why one way to Mars makes sense. Read it and enjoy.


I am by no means a risk taker. Probably the riskiest thing I have ever done 123 is skydive, and this was only because it was part of a challenge on the reality TV show where I appeared in early 2013 124. Although I have a pilot’s licence and am an aviation enthusiast, I’d never given a lot of thought to skydiving. Hesitant at first, when put to the test, and assigned a mission to remember a dozen letters spread out on a landing strip, I decided to go for it. Admittedly, part of it was peer pressure – I was certainly conscious that I was on TV. Others on my team were also nervous, some probably even more than I. Seeing my ex-airforce teammate Beth jump first helped a lot (I wonder what the first skydiver was thinking?125). But mostly, I decided that it was worth the risk in order to accomplish something, even if that something was no more than winning a challenge in a competition. Having a mission to accomplish, and a task to focus on, goes a long way to justifying risk for me. In fact, the main thing that was going through my mind at the time was “If I die here in a stupid skydiving accident, I’m never going to make it to Mars…”. I even remember discussing the relative risks and potential benefits of a trip to Mars vs. skydiving with the television host.

123. Apart from living, which still unfortunately carries a mortality rate of 100%.

124. Canada’s Greatest Know-it-All.

125. Actually, the first parachutist, Franz Reichelt, was killed on his first jump off the Eiffel tower in 1912 — I wonder what the second thought!?

Clearly, going to space is much, much riskier than skydiving. Just how risky is it? It is currently one of the riskiest jobs you can do, at least in the western world. As a species, we’ve sent over 500 people to space, and at least 18 have been killed there 126, with at least 10 more being killed in training 127. This means that as an astronaut, you have something like a 5% chance being killed on the job. How does this compare with other risky careers? As of 2013, over 2,000 US soldiers have been killed in Afghanistan, with a peak deployment of over 100,000 troops. If you don’t consider rotations, this means that over a 12 year time frame (a typical astronaut career), the equivalent rate is roughly 2%. The risk per soldier is lower if you account for the fact that troops are rotated, however, military training accidents are not uncommon, and soldiers often see multiple tours or action in other theaters such as Iraq (with a similar deployment loss ratio of 2.5%)128, which somewhat offsets this.

126. They were: Vladimir Komarov (1967), Georgi Dobrovolki, Viktor Patsayev, & Vladislav Volkov (1971); Greg Jarvis, Christa McAuliffe, Ronald McNair, Ellison Onizuka, Judith Resnik, Michael J. Smith, & Dick Scobee (Challenger, 1986); Rick Husband, William McCool, Michael P. Anderson, David M. Brown, Kalpana Chawla, Laurel Clark, & Ilan Ramon (Columbia, 2003).

127. They were: Valentin Bondarneki (1961); Theodore Freeman (1964); Elliot See & Charles Bassett (1966); Virgil Grissom, Edward White, & Roger Chaffee (Apollo 1, 1967); Clifton Williams (1967); Robert Lawrence (1967); Yuri Gagarin – first human in space (1968); Sergei Vozovikov (1993).

128. US loses in Iraq have been over 4,500 killed with over 32,000 wounded for a peak deployment over 175,000.

Over a 21 year period from 1990 to 2011, encompassing both relatively quiet and active times, the average death rate for US active duty military personnel from all causes was 72 per 100,000 person-years 129. This means that over a 40 year career, your chance of being killed in service was about 2.8%. However, this is an average across all branches and duties. Clearly, it would be far less risky to perform the majority of support roles, and far more risky to be in front-line infantry service. Additionally, this figure fails to account for that fact that the chance of being wounded is seven times as high as that of being killed130, meaning that compared with an astronaut, even if your chance of being killed is lower, your chance of being wounded is much, much higher in the military.

129. Medical Surveillance Monthly Report, Vol. 19 No, 5. May 2012.

130. Coalition losses in Afghanistan to 2013 have been approximately 3,400 killed plus more than 24,000 wounded.

In the civilian sector, things aren’t actually better. According the Bureau of Labor Statistics (2011), assuming a career length of 40 years, the ten riskiest jobs by occupational death rate per worker over a career are: fishermen (4.6%), logging workers (3.6%), aircraft pilots (2.8%), farmers (1.6%), roofers (1.1%), miners (1.0%), waste collectors (1.0%), truck drivers (0.9%), machine operators (0.8%), and police & firemen (both around 0.7%). Kind of makes you think twice about becoming a fisherman, doesn’t it?

We should also keep in mind that, although these are currently amongst the riskiest jobs in the western world, they are nowhere near the riskiest jobs of all time, nor even the riskiest jobs in the world today. These figures are for the United States, where figures are reliable and conditions are relatively good, even for risky jobs. The equivalent rates for civilian jobs in developing countries around the world must surely be higher – and just think of how much more dangerous it would be to be a soldier fighting in a third world conflict zone, or even be a civilian living there.

Obviously, we don’t want to voluntarily subject people to more risk than we have to, but it is still illustrative to reflect upon some examples from history. Over 3 million soldiers fought during the four years of the US Civil War, and over 600,000 died in it, along with another 450,000 wounded. This is a relative death rate of around 20%, for just four years of fighting. Yes, life was shorter and harder back then, but this astonishing rate – more than ten times what we see today – just goes to show you the level of risk we have tolerated in the past when we thought it was justified. For a 20th century example, the US lost around 5% of men deployed in the Second World War 131, and these figures would have been much higher had the scheduled invasion of Japan taken place 132.

131. Around 420,000 were killed from around 8.5 million deployed.

132. Projected US casualties were in the hundreds of thousands. Of the 500,000 Purple Hearts manufactured in anticipation of the 1945 invasion, over 100,000 have yet to be given out as of 2013 – they are so overstocked that units carry around spares for immediate award in the field.

Moreover, US losses were extremely mild compared with most. The Soviet Union lost as many as 36% of deployed personnel – almost 9 million men, or roughly the population of Sweden 133. Poland has the dubious distinction of having lost the largest population percentage, with around 16% killed, counting both civilian and military deaths 134. Indeed, during the Second World War, more than 2.5% of the population of the entire Earth was killed!

133. Of around 25 million deployed, in addition to at least 15 million more civilian deaths.

134. Around 5.5 million of a population of around 35 million.

So what’s my point? Obviously, no one wants to recreate the conditions of the US Civil War, the Second World War, or any other conflict. My point is that in times of crisis, humans have tolerated extreme sacrifices and levels of risk to accomplish major goals, such as maintaining the Union and ending slavery, or defeating the Nazis and Imperial Japan. We may not think about it in our comfortable lives, but if you were shopping for a job throughout human history, you could do a heck of a lot worse than going to Mars, even one-way.

The history of exploration isn’t much better. Columbus’ ships were tiny craft less than 60 ft long, and they sailed into the unknown without any of the modern risk assessment we would expect today. His largest ship, Santa Maria, was wrecked along the way, and he had to leave men behind in the New World. Magellan’s expedition, sailing around the world for the first time starting in 1519 was perhaps the greatest exploratory achievement of all time. However, of five ships that set out with 237 men, only one ship, Victoria, completed the circumnavigation and struggled back to Europe with only 18 men on board135. Franklin’s 1845 expedition to discover the Northwest Passage was lost with all 134 souls when his ships, Erebus andTerror, froze into the ice136. Ernest Shackleton’s ship Endurance became similarly stuck in Antarctic ice during his 1914-1917 expedition. However, thanks to his leadership, he managed to save all his men after what must have been one of the worst ordeals in exploratory history137.

135. One ship, San Antonio, had previously abandoned the expedition and returned to Spain. Magellan himself was killed by natives in the Philippines when he meddled in local politics.

136. This was during the early days of using canning for food preservation, and it seems that lead poising and the associated symptoms – including insanity – may have played a role in the fate of the expedition.

137. Shackleton’s expedition earns the title of “most successful failed expedition”. Like Apollo 13, it was meaningless in exploratory terms – but as a human story of courage, teamwork, and endurance, it is one of the greatest of all time. Check out Endurance: Shackleton’s Incredible Voyage by Alfred Lansing.

Looking back on these exploratory endeavors with a modern eye, they no doubt seem reckless – but would we consider them to have been mistakes? Would we prefer that they had stayed at home where it was safe138? I certainly would not: these explorers had the bravery to do what they could to change the world, even if they were often motivated by dreams of personal advancement. If explorers of centuries past had insisted on a 99% or even 90% chance of return, the whole course of human history would have been dramatically different, and we would not be where we are today. I am by no means suggesting that we assume risks as recklessly as those we accepted throughout the history of exploration. I am simply suggesting that, compared with the risks we have already taken, a human mission to Mars would not rank at the top of the list, either in terms of risk to the individual, or in terms of total lives put at risk. As perhaps the explorers of the past understood far better than we do today, great achievement is worthy of great risk.

138. Not so safe for some of course, considering Europe during the age of exploration was a cauldron of war and disease, with a life expectancy of around 35.

In comparison with what our ancestors have done, a one-way mission to Mars sounds downright reasonable. No flights would be sent to Mars before multiple successful demonstrations of the same launch and landing technologies. No crew would head off to Mars until there was a base already in place, with system checks complete and everything backed-up with spare parts. How Bering and his Russian explorers would have envied their Martian counterparts. There are certainly risks, but we simply can’t apply same standards of risk to exploration as we do for routine operations139. While a 5% chance of fatality is far too high for a mission to the International Space Station, it should be perfectly acceptable for a mission to Mars. These days, we seem incapable of making this distinction.

139. Some would argue that any human space operation can be called “routine”, but this is precisely my point. For space exploration, fewer, riskier, and more ambitious missions are preferable to a large number of safer mission with less ambitious goals.

So what are the major risks of a Mars mission? There are several types. There are of course risks associated with all spaceflight, particularly with launch and landing. Then there are the risks associated with operating complex equipment far from Earth, for example micrometeoroid impact140, or multi-system mechanical failure. Finally, there are the risks associated with having humans in space and on Mars for long periods of time, both physiological141 and psychological.

140. This is actually rarer than most people think. Space is big and mostly empty. Compared with interplanetary space, Earth orbit is utterly filled with debris, and significant collisions are still exceedingly rare. This is even more true of asteroids, even though there are millions in our solar system. Remember in The Empire Strikes Back where C-3PO said “the chance of successfully navigating an asteroid field is approximately 3,720 to 1”? He’d have been closer if he’d said “the chance of hitting anything is 3,720 to 1”.

141. I.e., to do with the body, such as medical risks, but also things like long term exposure to the space environment.



Andrew is a spacecraft engineer with experience on half a dozen space missions. In March 2013, he won Discovery Channel’s #1 Competitive television series Canada’s Greatest Know-it-All.

He is currently a second-round candidate for the Mars One project, which aims to send human settlers to the red planet starting around 2023. He is an avid trivia player and public speaker, giving talks at schools, on convention panels, at museums, and other venues. He also also a Youtuber and tabletop game designer.


  • Get a copy of his “Leaving Earth: Why One-Way to Mars Makes Sensehere (print or E-book) or find the E-book here on Amazon (print/Kindle), orhere on Smashwords (for any other platform).

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