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#226 Yesterday 11:14:57
- Void
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- Registered: 2011-12-29
- Posts: 8,222
Re: The Moon
Working from the materials of this post elsewhere, I have some notions about heat shields to be made from Moon materials: https://newmars.com/forums/viewtopic.ph … 04#p230804
I am wondering if a craft coming from the Moon to air brake to Earth orbit, could consist of a braking surface on one side, and an Oxygen wicking surface on the other side. So, it might use both ablative and active cooling.
And the heat shield would be recycled in orbit to supply bulk materials.
This is what I have in mind: 
So, a craft like the Stoke Space NOVA might use a one-time heat shield created in mass on the Moon, to assist and protect it to achieve a lower Earth orbit than the Moons, when coming from the Moon.
The heatshield would then be repurposed to be raw materials to convert into orbital resources.
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Last edited by Void (Yesterday 11:25:56)
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#227 Yesterday 15:13:14
- Void
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- Registered: 2011-12-29
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Re: The Moon
It is probably good to have a challenge from (th): https://newmars.com/forums/viewtopic.ph … 13#p230813
In part, quote:
In thinking about the interesting scenario you have painted, it occurred to me that the people of Earth cannot tolerate this idea.
We do not currently have a traffic regulation system. Everything people do (from all Nations) is done by taking a calculated risk they will not collide with the property of someone else.
This is literally like a road system on Earth. where people drive across intersections at 60+ miles and hour, without regard to whether the intersection is occupied.
For that reason, I expect that at some point, after some serious collisions no doubt, humans will muster the will power to cooperate with each other, instead of just doing whatever they feel like in orbit.
At that time, I would expect that use of heat shields to slow down would be discouraged.
Your vision appears to be of vessels arriving from the Moon with 12 km/s velocity, having to dip deep into the atmosphere to slow down, and necessarily crossing all regions inhabited by satellites, including ones inhabited by humans.
An alternative is to develop a space tug system similar to the marine tug systems in use in all maritime nations on Earth today.
(th)
I think you are excessively absolute in your assessment. It is possible that a choice as you have portrayed, might be the nature of the future, but not a mandate, yet.
Space Junk being the greater threat, any resource to clean it may justify, arrivals from the Moon.
Of course propellants to use in cleaning craft, might come from Earth, but also could come from the Moon. I think the question is how many flights would come from the Moon in a time period?
And what era are we then in?
In transition from now to early mastery of the Moon, I think a number of airbrakes could be tolerated. Similar to how we currently expect Starships to airbrake from Mars and maybe from the Moon to Earth. Air braking to orbit does include the extra skipping upward to orbit, which does increase the problem. But as I have said, if you can get propulsive mass to orbit at a good cost, then you can hunt down and eliminate significant space junk, the kind that is likely to shed multiple smaller impacts if the Kessler syndrome begins to occur.
But I will agree, that if something like fusion propulsion develops, air braking might not be as much of a permitted option for reasons that it will not be as needed.
A thing I do not like about your commentary is that it is a binary absolute, seeking to shut the idea down. In so doing it gets in the way of evaluating evaporative cooling on the leeward side of the heat shield, using Oxygen, and also the potential melt process options that may exist. These would be phase change methods similar to the idea of active cooling with Hydrogen, Methane, and water, but would involve materials that are harder to handle, but are available in bulk from stony objects like the Moon.
While this may or may not be permitted for use in the Earth's atmosphere at an undetermined frequency, they may very well be adopted to do similar maneuvers in other atmospheres.
Without too much anger I point out that your comments were awkward in effect for encumbering discussion of the factors I have now pointed out.
Such is the way words work though, you did not make it impossible for me to make these points.
So, it is OK. Your points have value also.
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#228 Today 04:40:00
- Void
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- Registered: 2011-12-29
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Re: The Moon
In the hopes of going back to sleep prior to sunrise............
In post #226:
Can we name this as an "Overshield" scheme?
Something like wearing overshoes, in nasty conditions.
There is a concern, that aerobraking to orbit may be an excessive collision/crash hazard. Fair enough. We have something like the FAA to evaluate risk/rewards for things like this.
We also have the emerging "Doomster Goblin" idea that things burning in the atmosphere from orbit may cause harm to the atmosphere.
However, it is natural for there to be material infalls from space. Unnatural infalls are potentially a hazard, and a method of manipulation. If we construct an "Overshield" of Lunar materials, it may be that we can degrade or enhance the character of the atmosphere, as per judgements of utility or harm.
There may be many cooling methods with the "Overshield" Schemes.
The leeward side of the overshield will naturally radiate heat as heat from the windward side will conduct through the overshield to the leeward side.
The overshield may have thermal inertia due to existence of mass which may provide heat sinking.
You might ablate materials from the overshield. Heat sinking might also involve phase change from solid to liquid inside of the overshield, of some selected substances.
You might pump LOX or gas Oxygen to the front of the overshield, through ports.
You might do active reflective cooling using rocket engines. This is also an opportunity to alter path with a thrust that reflects from the leeward side of the overshield.
If you could run something like a Oxidizer preburner through the rocket engine(s), but not a full burn, you might squirt a fluid mix from those engine(s), against the leeward side of the overshield. This may also produce cooling.
So, quite a lot of options.
And of course, my preferred end of process is that the shield ends up in a suitable Earth orbit with the ship, where the shield materials become raw materials to construct resources in orbit of Earth.
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Last edited by Void (Today 04:55:37)
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