I just wanted to quickly ask - if humans are kept "on ice" during space travel, whether in a slow-metabolic hibernation, or even literally frozen cryogenically - then how would it affect their radiation resistance/tolerance? Sure, your regular active metabolism can cause cancer to grow, but it also fights cancer and radiation damage - so would slowing it down or even stopping it completely then improve or impair your ability to withstand the damaging effects of radiation?For instance, I could imagine some cryogenically frozen astronaut waking up after a century of space travel, only to find that he's accumulated a century's worth of radiation damage in space, so that his cells quickly start malfunctioning from the cumulative damage after he's thawed out.Likewise, I can similarly imagine an astronaut waking up after a decade of metabolically-slowed hibernation in space, finding out that he's got lots of tumors growing within him, because his previously slowed immune system wasn't able to repair radiation damage or fight off cancerous growths fast enough.What's going to prevent scenarios like that?
oh hey- I found a thing:https://www.newscientist.com/article/2116040-future-air-conditioning-could-work-by-beaming-heat-into-space/a new(?) Heat Rejection idea?
Quote from: Stormbringer on 12/13/2016 08:27 pmoh hey- I found a thing:https://www.newscientist.com/article/2116040-future-air-conditioning-could-work-by-beaming-heat-into-space/a new(?) Heat Rejection idea?This is quite astonishing. The nearest I recall for this was an EE Smith story about thermopiles on 2 different planets. I've always wondered if you could enhance surface emission by making pits sized to the radiation to be emitted as a sort of resonance effect. This is clearly a "high tech" solution, starting with the 10^-6 Torr vacuum in the chamber to the ZnSe window and the sub micrometre thick layers of the Al/Si/SiN sandwich. Interesting points are that this being in the near IR a cheaper window material could be used that was not even transparent to visible light. That still leaves the high quality vacuum and the emitter technology.
Thermal dumping in space is hard, because you generally only have radiative.These atmospheric IR window targeting narrow band emitters are simply exploiting a convenient hole in the blanket that is our atmosphere. If you are in space, as long as your primary radiator surface isn't facing the sun and the earth, you can radiate in a much wider band generally towards deep space, so no need for these frequency converting narrowband tricks.
Use of selective surfaces to modify radiative properties might be used to keep things like LOX storage tanks in space below 90K by purely passive means. Here is a presentation from a year ago modeling such surfaces - predicting potential cooling to 47K in the presence of illumination by the sun.
Quote from: sanman on 09/27/2016 06:43 amI just wanted to quickly ask - if humans are kept "on ice" during space travel, whether in a slow-metabolic hibernation, or even literally frozen cryogenically - then how would it affect their radiation resistance/tolerance? Sure, your regular active metabolism can cause cancer to grow, but it also fights cancer and radiation damage - so would slowing it down or even stopping it completely then improve or impair your ability to withstand the damaging effects of radiation?For instance, I could imagine some cryogenically frozen astronaut waking up after a century of space travel, only to find that he's accumulated a century's worth of radiation damage in space, so that his cells quickly start malfunctioning from the cumulative damage after he's thawed out.Likewise, I can similarly imagine an astronaut waking up after a decade of metabolically-slowed hibernation in space, finding out that he's got lots of tumors growing within him, because his previously slowed immune system wasn't able to repair radiation damage or fight off cancerous growths fast enough.What's going to prevent scenarios like that?If they're sedated, they only need about 0.1 m3 of pressurized volume each for the trip. It's much cheaper to put an arbitrarily large amount of radiation shielding around a smaller volume than a large one. I imagine that, if hibernation ever does become a useful technology for human space travel, the humans would be stored in tiny drawers between the propellant tanks, with a heavy layer of radiation shielding around the entire unit.
10 *meters?* anyway I'd prefer not to have a consumable used as a shield particularly if there is a leak or a micrometeorid or something like that.so 10 meters of water is equivalent to a little over three inches of lead? cause if i remember my old days (30+ years ago now) of reading about fall out shelters a yard of water was equal to an inch of lead for radiation shielding or was that a yard of earth equal one inch of lead?
Quote from: Stormbringer on 12/14/2016 06:50 pm10 *meters?* anyway I'd prefer not to have a consumable used as a shield particularly if there is a leak or a micrometeorid or something like that.so 10 meters of water is equivalent to a little over three inches of lead? cause if i remember my old days (30+ years ago now) of reading about fall out shelters a yard of water was equal to an inch of lead for radiation shielding or was that a yard of earth equal one inch of lead?Not to mention it takes a big rocket to take that into orbit in the first place.Are you beginning to see why asteroid redirect is potentially a major game changer for exploration?
Quote from: john smith 19 on 12/13/2016 09:22 pmQuote from: Stormbringer on 12/13/2016 08:27 pmoh hey- I found a thing:https://www.newscientist.com/article/2116040-future-air-conditioning-could-work-by-beaming-heat-into-space/a new(?) Heat Rejection idea?This is quite astonishing. The nearest I recall for this was an EE Smith story about thermopiles on 2 different planets. I've always wondered if you could enhance surface emission by making pits sized to the radiation to be emitted as a sort of resonance effect. This is clearly a "high tech" solution, starting with the 10^-6 Torr vacuum in the chamber to the ZnSe window and the sub micrometre thick layers of the Al/Si/SiN sandwich. Interesting points are that this being in the near IR a cheaper window material could be used that was not even transparent to visible light. That still leaves the high quality vacuum and the emitter technology.i was wondering if it could be used to get rid of thermal waste heat in space?
But convective cooling only works at room temperature, obviously.
the Japanese seem to have found a room temperature up to the temperature of molten tin superconductor. Not a creepy disjunction filled microscopic here or there useless bits and pieces superconductor in name only but a real let's make a damned conductor out of it super conductor out it already superconductor.