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Cake day: December 14th, 2024

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  • So I was curious about this from a superconducting electromagnet aspect which prevented me from responding to OP on the radiation thing so thanks for getting to that.

    There isn’t a way to efficiently convert heat into radiative heat fast enough to keep a superconductor cool enough long enough.

    You could, theoretically, create a system that exchanges the heat through convection and conduction that then stores it in something like water. Then with the water, you pass that through fins to radiate the heat. This would give you more time with the magnet being cool enough to function.

    I didn’t have any useful numbers, but it looks like at some point along the trip you’d need to disable the magnet cooling system or dump the stored water. At some point the system will just not be able to maintain the temperature.



  • The radiation hazard still exists, it’s a long trip, easily 6 moths for a flyby, probably closer to 9-10 for an orbit transfer or atmospheric entry. You’re right, once they’re in Venus’s upper atmosphere, the combination of its thick atmosphere and induced magnetosphere would create radiation shielding once there.

    There is a nice “zone” that’s about 15km tall 50km above the surface. Still have to deal with the carbon dioxide and sulphuric acid rain, and have to provide your own oxygen and nitrogen to mimic our atmosphere. Surface exploration is probably out of the question without some serious material science discoveries to withstand the temperature, pressure, and corrosion.




  • Lifetime dose limit, fine. 100mSv/year is the lowest associated with a significant increase in cancers. 2Sv is severe radiation poisoning, possibly even fatal. Of course we’re talking over maybe a 18month period, probably more like 2 to 3 years.

    Ok, so let’s say upper side of the full dose is 2Sv over 3 years. That’s 666 mSv/year, so right now that doesn’t look great. But it gets worse as you break it down. ~55mSv/ month. ~2mSv/day. That’s a lot. Like ~500 dental X-rays a day. Obviously distributed throughout the body.

    5% of people exposed to 1Sv lifetime dose will die of a fatal cancer.

    I can’t find a lot on what 666mSv/year would do to you, but from everything I gather, it would definitely shorten your lifespan. I certainly wouldn’t volunteer for it.







  • Not to mention, there is still a scale of size, time and resource contraint. We can’t send humans to Mars with all the tools they don’t know they need yet, just like we can’t send the rovers with all the tools we can imagine.

    For humans to benefit from rapid discovery on Mars, they’d need to be able to produce those tools, chemicals, power, etc.

    It would take decades to set up anything useful for a longer term mission on Mars, and it again becomes a numbers game. The longer period of time you have to account for, the wider the room for error. I don’t know many people who would be comfortable traveling through space knowing that they may not see Earth again either.




  • I’m of the opinion we can’t safely travel to mars. Not in our lifetimes.

    The earth has a nice magnetic field that protects us from background ionizing charged particles, and an atmosphere that catches most other radiation (X-ray, gamma).

    The length of time it would take with modern rockets to get to mars exposes the crew to extreme radiation. They could survive it, but radiation over time kills you with cancer, if you survive any acute effects.

    We could maybe make superconducting magnets strong enough to create a field to reduce the charged particles, but then you have to keep them powered, and still deal with the uncharged background radiation (mostly gamma/X-rays). You could create a giant cylinder of lead around the crew capsule, but that would take an extraordinary amount of time to build in orbit.

    Not to mention once you are on mars, you have to maintain those protections too - the Mars atmosphere is too thin to be very helpful and it does not have a a magnetic core.

    There has been a notable lack of progress in that realm, and it will likely remain the reason we don’t see a human to mars program.