Author Topic: Technologies that will shape the future of aviation and space exploration  (Read 61595 times)

Offline LM13

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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?

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. 

Offline john smith 19

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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?
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.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Stormbringer

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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?
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?
« Last Edit: 12/13/2016 10:52 pm by Stormbringer »
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Offline Asteroza

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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.

Offline AnalogMan

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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.

Offline john smith 19

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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.
True, but in space the problem is backward. In the article the goal is "cold as possible." In space you're likely to be running at a (more or less) fixed inlet temperature. That implies you want maximum emission at that temperature with minimum surface area.

So the technique could have some use in terms of lowering the size of radiators in space, which is an under appreciated but very significant mass on most long term crewed exploration missions.

The obvious case would be a liquid metal cooled reactor. These can run very hot but the radiator size trade off means they tend to have fairly high exhaust temperatures (from the power conversion system) to keep the radiator mass down. A more efficient emission surface (and this one looks pretty rugged as it depends on layering, rather than surface topology) could lower that outlet temp, improving overall efficiency without sacrificing radiator mass to do it. For example a LBE loop running around 300c would need to optimize emission at 0.05eV roughly
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline john smith 19

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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.
Intriguing.

Not good enough for LH2 of course but putting this on top of an MLI blanket should cut the work the MLI has to do to begin with by quite a bit. I don't know about Barium but TiOx is very cheap in powder form given it's used in everything from toothpaste to paint.

[EDIT While not quite good enough for LH2 it should be fine for long term storage of Methane. Now what it needs is a space test. Ideally a small LOX bottle sitting in the payload bay of an X37 on orbit for 240 days, but that's very unlikely. Maybe a few hours on an F9? Either way it's chipping away at the long term space storage problem ]
« Last Edit: 12/14/2016 11:08 am by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Robotbeat

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That's correct. Both oxygen and methane are "space storable" using passive means.
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Offline Stormbringer

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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?

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.
Exactly how much shielding is needed to reduce all types of space radiation (in a worst case scenario) to earth background radiation levels? X inches of X material at X weight mass per square unit of area format :)
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Offline Robotbeat

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About 10m of water. Roughly.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Stormbringer

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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?
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Offline john smith 19

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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?
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?
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Robotbeat

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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?
No, lead sucks for the kind of radiation in deep space. Makes it worse due to secondaries. It's just about the worst material to use.

But you don't need 10m of shielding. Really, humans can tolerate a low dose just fine, which is why we get x-rays, ct-scans, fly on airliners, etc. I mean, do you ever go outside on a sunny day? You're exposing your skin to UV radiation that has basically the same kind of effects as other ionizing types of radiation.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Stormbringer

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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?
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?
I'm all for redirecting the metal bits or the bits that can be made into ceramics or stuff. the rest of it can stay in place...that and big honking space cruisers with meter thick hull armor...
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Offline john smith 19

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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.
BTW Methane melts at 91K

Assuming they can get the coating to work on a large scale this means that in fact on orbit sub cooled storage (except for LH2) becomes quite feasible.

In fact it may be a little too efficient. Left on their own both tanks would freeze solid at 46K. This suggests that a system with those propellants would actually need a heat leak into it to stop that.

It also opens up the interesting idea that if some stop gap existed while the tanks were cooling down you could dispense with the mass of a large radiator as you could (depending on how stuff was sized) dump excess heat to the tanks and they would radiate enough of it to keep the contents (just) liquid.

I'm not sure if this would still need the bulk of both propellants to be in a single settled mass to avoid excess boil off. From Saturn V results that would need a continuous 1-10 micro g of acceleration.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Stormbringer

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room temperature super conductor with options to remain superconducting to the melting point of tin

http://www.nextbigfuture.com/2016/12/researchers-at-japan-tokai-university.html

Got deleted from EM drive thread even though searching showed many posts about superconducting EM drives. oh well.

Anyway the things such an conductor could be used for is nearly unlimited space apps included.
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Offline lamontagne

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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?
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?
It's just a radiator.  That's already how cooling works in space. This is actually much less efficient that conventional atmospheric convective cooling.  But convective cooling only works at room temperature, obviously.  Yes the temperature can be low, but the rate of heat removal is also probably very small.  So useful in niche markets, with very small loads, but not much use elsewhere.
In other words, since it is at about 180 K, the same area at twice the temperature, 360K, or 90C would radiate out 2^4, 16 times more energy.



Offline john smith 19

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But convective cooling only works at room temperature, obviously. 
Convective cooling only operates in an atmosphere.

This coating (assuming it can be scaled up)  stops heat being absorbed by the tank above that temperature, allowing the tank itself to continue emitting until it gets closer to the ambient temperature, in this case 3K.

One joker in this pack for SX is that the question "At what temperature does a composite tanks start to develop brittleness issues " AIUI SX want to run LO2 close to its melting point, which is well below that of Methane. 47K should be OK but I don't think anyone really knows. 
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Stormbringer

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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 already superconductor.
« Last Edit: 12/22/2016 04:25 am by Stormbringer »
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Offline CameronD

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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.

Not according to the (badly worded) article you linked to above.. instead, they've discovered a promising line of research.  Most research folks need to do that to keep their funding.
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

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