Last weekend. former astronaut, fighter pilot and David Bowie fan, Commander Chris Hadfield posted some stats about the safety of flying, showing that per mile traveled, planes are about 10 times safer than trains, and 100s of times safer than cars. 

Planes travel further and faster than cars and motorcycles,  and that got me to thinking about the safety of all kinds of travel.

Space travel certainly looks pretty risky, and astronauts are selected for their ability to stay calm in the face of danger. But just how risky is spaceflight, by Hadfield's measure? It turns out that human beings have spent a total of 144.1 years in space.* An astronaut orbits the earth at around 18,000 miles or 28,000 kilometres / hour, so the total distance covered by human beings in space is about 35 billion kilometres.** On the other side of the ledger, 18 astronauts have died in flight (excluding those deaths that happen in training and testing, such as the Apollo 1 fire), making for roughly one death per 2 billion kilometres traveled. In Hadfield's units that's about 0.8 deaths per billion passenger-miles, putting space travel in much the same category as riding the subway.*** 

The second thing we learn from Hadfield's numbers is that it is not just planes that are safe. By this measure, commercial or public operators (trains, buses, planes) are all safer than cars by at least a factor of 10, and are vastly safer than motorcycles. Hadfield shared his numbers to reassure nervous fliers. But because we are nervous about flying, we have – as a society – insisted that commercial flying be as safe as it can possibly be. People launching rockets likewise go to enormous lengths to make safety a paramount priority.

Conversely, cars actually come out looking pretty dangerous for those inside them. On top of that, Hadfield's numbers make no mention of deaths among bike riders and pedestrians, most of which result from collisions with motor vehicles. On a per-mile basis, pedestrians and cyclists are killed about ten times as often as people in cars, although this varies vastly by location. 

How can this happen? Cars are designed and built using the latest technologies, with all manner of safety features as their selling points. But unlike trains, planes, buses – and spacecraft – cars are vehicles that are typically operated by their owners, and thus mostly driven by amateurs like you and me, on roads that are too often designed to facilitate speedy travel.

As a result we kill ourselves, our passengers, and other people on the road at a rate that would be unacceptable for commercial operators, or even for astronauts flying in space.

That "we" is important, because human beings are terrible at statistics and great at fooling ourselves.  "We" don't get behind the wheel expecting to kill ourselves or someone else, so we don't necessarily see solving this problem as a priority. 

However, many cities and countries around the world are now talking about Vision Zero; the position that traffic fatalities of all kinds are not an unavoidable nuisance, but a menace that can be eliminated through good design, policy choices and decent engineering. People aren't perfect, but the idea is that – as in the workplace – nobody should pay for a mistake with their own life or somebody else's.

The key first step is to SLOW DOWN; a collision between a car and a person at 50 km/hr is far more likely to be life-changing or lethal than one at 30 km/hr. That's just the laws of physics. And safer road design helps make safer speeds intuitive. Also, making it easier for people to use "active modes" (bikes and walking), and improved access to public transport can all make a huge difference to our collective safety on the roads and our personal and social wellbeing in general – by helping us shift from less safe modes to ones that are not only safer, but better for us and incidentally, the planet.

It is easy to make rules for pilots and airlines. The challenge of Vision Zero is that it asks us to make rules for ourselves. But just imagine living in a world where walking and biking was as safe – by Commander Hadfield's measure – as flying in space. 

As the Six Million Dollar Man put it: we have the technology. All we we need is the will to use it. 

CODA: There is a lot to say about the coming era of commercial suborbital spaceflight, which will make for a lot of new "astronauts". And then there is the whole separate topic of self-driving cars, which are often touted as a boon for safety – but an urban environment with people walking and biking on the streets is far more challenging for autonomous vehicles than the highway. The question may be whether these cars can adapt themselves to human cities, or whether their designers will attempt to reshape cities to better accomodate autonomous vehicles – just as the first carmakers did a century ago. 

IMAGE: The header image shows the failure of the Antares 3 launch vehicle; the image is from Wikimedia and was taken by NASA/Joel Kowsky. 

 

* That link refers to "man years". Sigh. 

** This does not account for the small number of astronauts who traveled to the moon; they move faster than orbiting astronauts at the beginning and end of their trips, but more slowly in the lunar environment. 

*** The total number of "astronauts" includes people who achieved an altitude of 100km or more during suborbital flights – the so-called Karman line at which aerodynamic control becomes impossible and space effectively begins. It's also worth noting that Hadfield's statistics are per mile, not per trip.  Plane trips are much longer than car trips so this statistic makes each individual flight look safer than a typical journey by car; if the average car trip is a few kilometres and the average plane ride is more like a thousand kilometres, the risk per trip is actually roughly similar for cars and planes. Those 18 astronaut deaths occurred among the roughly 560 people who have been into space, putting the overall death rate per participant at about 3% and at maybe 1% per trip (since some people have made multiple flights) which of course puts the safety of space travel in a very, very different light. Lastly, the deaths all occurred during launch or reentry so it's not being in space that is dangerous, its getting there and coming home.