Chris Hadfield, most widely known for his zero-gravity guitar-playing, has seen an impressive amount of space travel.
Between his first spaceflight in 1995, his second in 2001, and a third in 2013, Hadfield has flown inside NASA space shuttles, a Russian Soyuz spacecraft, and the International Space Station.
Hadfield, who's now retired, shares his expertise about rockets, spaceships, spacewalking, and Mars exploration in a new web course on the online platform MasterClass.
To follow up on those lessons, we asked Hadfield what he thinks about the future rocket ships of three major players in the new space race: NASA's Space Launch System, SpaceX's Big Falcon Rocket, and Blue Origin's New Glenn rocket.
His response isn't encouraging to those who'd like to see boots on Martian ground within the next decade or two – let alone have people settle the red planet.
"Personally, I don't think any of those three rockets is taking people to Mars," Hadfield told Business Insider. " I don't think those are a practical way to send people to Mars because they're dangerous and it takes too long."
'The majority of the astronauts that we send wouldn't make it'
Hadfield's stance stems from the fact that all three rocket systems rely on similar fuels (plus oxygen) to lift off Earth and propel their ships through space.
"My guess is we will never go to Mars with the engines that exist on any of those three rockets unless we truly have to," he said.
NASA's Space Launch System, which is slated to debut in the 2020s, will power its engines with a combination of liquid hydrogen and solid chemical fuels.
Blue Origin, the rocket company founded by Jeff Bezos, is also looking to use liquid hydrogen. SpaceX, founded by Elon Musk, is staking its future on burning liquid methane, which the company believes it can generate on the Martian surface.
Like other experts, Hadfield doesn't doubt that any of the vehicles could actually get to Mars; his issue is about the safety of any humans on board. Explosions, radiation, starvation, and other problems would constantly threaten a mission.
"We could send people to Mars, and decades ago. I mean, the technology that took us to the moon back when I was just a kid, that technology can take us to Mars – but it would be at significant risk," he said.
"The majority of the astronauts that we send on those missions wouldn't make it. They'd die. Because the technology is still quite primitive."
Rocket makers aren't unaware of the challenges. NASA was founded with the understanding that spaceflight is an inherently risky enterprise and has lived through painful examples.
And Musk has repeatedly stated that people will probably die on his company's future voyages to Mars.
"The first journey to Mars is going to be really very dangerous," Musk said in 2016. "The risk of fatality will be high. There's just no way around it."
But Hadfield believes those risks mean we should instead be patient and slowly build up to the goal of putting humans on Mars.
"You really have to answer the question why," he said. "Why are we going? Why wouldn't we just send robots for quite a while until we learn a lot more about Mars?"
Crossing the vast ocean between Earth and Mars
Hadfield said the rocket ships currently being developed will be key stepping stones in the quest to explore our solar system.
But he added that using those vessels to shuttle people 140 million miles to Mars – even with new materials and computer automation – would be akin to crossing a giant ocean in a canoe or paddle boat.
"We're sort of like those early sailing ships, in that we don't even know what we don't know yet," he said, referring to the historic voyages of Columbus, Magellan, and Cook.
"I think we need some more improvements in technology before we'll cross the oceans that are between us and Mars in any sort of practical way."
Hadfield said he doesn't know what those technologies might be, though he noted recent advancements in ion propulsion and NASA's resurgent interest in nuclear reactors.
"Maybe the work that's going on with the Alpha Magnetic Spectrometer on the space station, and in the particle accelerator in CERN, and other places .. is going to show us how we can harness gravity," he said.
"It sounds outlandish, but we figured out how to harness electricity and what electrons do, and that seemed crazy and it's revolutionised life and travel. So who knows?"
This article was originally published by Business Insider.
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