Why You Can't Come Back from Mars | Brian Greene
Where Physics Breaks
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The question nobody in the optimistic narrative about Mars missions answers directly: once you're there, how do you get home? In this video, Brian Greene works through every physical barrier to a Mars return mission with the precision they deserve. By the time you land on Mars after a 210-day transit, you have lost seven to ten percent of bone mineral density in the most vulnerable regions, twenty to thirty percent of lower body muscle mass despite maximum countermeasures, and cardiovascular capacity adapted to zero gravity — not to 0.38 Mars gravity and certainly not to the one Earth gravity you need to survive re-entry. The radiation accumulated during the transit adds 150 to 300 millisieverts, the surface stay adds another 95 to 140 millisieverts, and the return transit adds another 150 to 300 millisieverts. Total mission dose of 400 to 750 millisieverts, at or beyond NASA's career limit, producing cognitive effects in animal models that precisely target the memory and executive function you need to operate a spacecraft. The propellant for the return requires an autonomous industrial plant on Mars producing 1,200 tonnes of methane and liquid oxygen from Martian CO2 and water ice before the crew arrives — a plant operating at eight thousand times the throughput NASA's MOXIE experiment demonstrated. The return launch window opens approximately 500 days after landing and stays open for weeks. Miss it and wait 26 more months. Re-entry produces 3 to 4 Earth gravities on a cardiovascular system adapted to 0 to 0.38 gravity for three years. Every one of these conditions must be met simultaneously for the return to succeed. Here is the physics.
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12 Comments
But I’m happy to help fund unmanned exploration, even of deep space. I’ll be long dead before any deep space info can be returned to Earth but I’m still for it.
But manned missions outside the Earth Moon system are a foolish waste of resources.
Why You Can't Come Back from Mars | Brian Greene
Where Physics Breaks
13,221 views
Ready to change how you see the world? 🧠I've broken down the deepest secrets of existence into 12 actionable principles. Get your copy of 12 Principles for Understanding the Fabric of Reality here:
👉 https://realityprinciples.com/
👇 What principle resonated with you the most? Let me know in the comments!
The question nobody in the optimistic narrative about Mars missions answers directly: once you're there, how do you get home? In this video, Brian Greene works through every physical barrier to a Mars return mission with the precision they deserve. By the time you land on Mars after a 210-day transit, you have lost seven to ten percent of bone mineral density in the most vulnerable regions, twenty to thirty percent of lower body muscle mass despite maximum countermeasures, and cardiovascular capacity adapted to zero gravity — not to 0.38 Mars gravity and certainly not to the one Earth gravity you need to survive re-entry. The radiation accumulated during the transit adds 150 to 300 millisieverts, the surface stay adds another 95 to 140 millisieverts, and the return transit adds another 150 to 300 millisieverts. Total mission dose of 400 to 750 millisieverts, at or beyond NASA's career limit, producing cognitive effects in animal models that precisely target the memory and executive function you need to operate a spacecraft. The propellant for the return requires an autonomous industrial plant on Mars producing 1,200 tonnes of methane and liquid oxygen from Martian CO2 and water ice before the crew arrives — a plant operating at eight thousand times the throughput NASA's MOXIE experiment demonstrated. The return launch window opens approximately 500 days after landing and stays open for weeks. Miss it and wait 26 more months. Re-entry produces 3 to 4 Earth gravities on a cardiovascular system adapted to 0 to 0.38 gravity for three years. Every one of these conditions must be met simultaneously for the return to succeed. Here is the physics.
Subscribe to Brian Greene Universe for the honest science of human space exploration.
👉 https://realityprinciples.com/
👇 What principle resonated with you the most? Let me know in the comments!