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#1 2017-04-21 12:34:32

Dook
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Registered: 2004-01-09
Posts: 1,409

A Mars Hab with Radiation Shielding

The Mars Hab could have a very strong outer shell of thin carbon composite, maybe 1/4" thick, an 18" thick inner shell of hydrogen impregnated fabric, and a second inner shell that is a plastic water sack for shielding.  The plastic water sack would have two sections, an inner sack and an outer sack, both would be 6 inches thick.  Only the outer sack would have water in it for the journey to Mars.  The inner sack would be filled with water produced by the WAVAR unit once on Mars. 

The water sack would be in the ceiling and sides of the Mars Hab, not the floor because the planet would provide shielding for that direction on Mars. 

The Mars Hab also has a WAVAR unit (with a thick zeolite panel and microwave unit) mounted inside the ceiling of the Hab to provide some shielding as well.   

The Mars Hab is launched into orbit and docks with the rover hanger.  The rover hanger has an oxygen tank, a hydrogen tank, and a recessed rocket engine to send both spacecraft to Mars.  Having the rover hanger docked to the bottom of the Mars Hab provides some shielding.

The carbon composite outer shell and the hard fabric layer would provide an extremely strong structure.  Way more than would be needed for just strength alone.   

Before Mars aero-capture the landing struts recessed into the bottom of the rover hanger would be extended from the bottom of the rover hanger.  The struts would not spread outward, they would extend downward and they would be very strong, maybe 1' wide struts with heavy springs. 

So, for shielding on Mars the Mars Hab has thin carbon composite, 18" of hydrogen impregnated fabric, two 6" water sacks, and regolith on top.

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#2 2017-04-21 14:57:22

Oldfart1939
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Registered: 2016-11-26
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Re: A Mars Hab with Radiation Shielding

What, pray tell, is a "Hydrogen impregnated fabric?" Hydrogen is a gas until extreme cryogenic temperatures are reached. Tell me how to make a Hydrogen impregnated fabric, and I'll maybe supportive.

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#3 2017-04-21 15:37:35

Dook
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Re: A Mars Hab with Radiation Shielding

Oldfart1939 wrote:

What, pray tell, is a "Hydrogen impregnated fabric?" Hydrogen is a gas until extreme cryogenic temperatures are reached. Tell me how to make a Hydrogen impregnated fabric, and I'll maybe supportive.

It seems the Bigelow space habitat is made of hydrogen impregnated fabric and it provides radiation shielding.

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#4 2017-04-21 16:06:06

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,314

Re: A Mars Hab with Radiation Shielding

Hydrogen impregnated fabric or plastics are designed with extra Hydrogen in the chemical make up of the product.
The same holds true of carbon impregnated and other chemicals that are considered extra and do not add to the stability of the original formular.

https://en.wikipedia.org/wiki/Plastic

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#5 2017-04-23 14:16:57

Dook
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Re: A Mars Hab with Radiation Shielding

If the rover hanger (with recessed rocket engine and oxygen and hydrogen tanks) was launched first, then this Mars Hab (with heat shield on top) with a crew of 4 would be launched and both vehicles docked together in orbit to make one spacecraft.  The rover hanger's rocket engine could fire to leave Earth orbit with the Mars Hab heat shield facing Mars for aero-capture. 

The entire side of the Mars Hab and rover hanger could be covered with a thin solar array to provide power in flight and on Mars.     

In flight the rover hanger's oxygen tank would need to vent.  You could vent the oxygen directly into the Mars Hab for breathing oxygen.  As for the hydrogen, I would just vent it into space. 

Also, does anyone know how the ERV aero-brakes in Mars atmosphere, lands, then takes off from Mars and aero-brakes in the Earth atmosphere using the same heat shield?

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#6 2017-04-23 18:28:33

SpaceNut
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Re: A Mars Hab with Radiation Shielding

A mars landed heatshield is expended to land on mars while the earth return heatshield is dead weight mass for the landing. That is why we normally talk of a MAV to join the ERV as you do not need to carry the heavy earth shield or the water and food for the return trip back out of the mars gravity. Not to meantion the added fuel mass for the return trip back.

Working with a space x lander design from the first stage but with a mars reloadable fuels we would be using the rocket engine plume to land as a heat shield from orbit. But if that is not enough we really have problems for making a reuseable MAV as a heat shield would need to be afixed before each landing use.

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#7 2017-04-23 19:32:10

Dook
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Re: A Mars Hab with Radiation Shielding

So the ERV has two heat shields, one for Mars entry that needs to be removed before it leaves Mars?

I believe they are using ablative material now, not steel, can they double the ablative material so the heat shield will work twice?

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#8 2017-04-23 19:48:56

SpaceNut
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Posts: 29,314

Re: A Mars Hab with Radiation Shielding

The mars entry shield is jetisonned never to be used again as its in the way of the landing engines ..all the while carrying down to the mars surface the dead mass of the earth heatshield......so no double use heatshield in the ERV.....
Mars Heat shield are made of Pica or Pica X which are the light mass carbon based while Earth heat shields are made of Avcoat are metal alloys ....

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#9 2017-04-23 21:58:57

Dook
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Registered: 2004-01-09
Posts: 1,409

Re: A Mars Hab with Radiation Shielding

So a rocket launches the ERV from Earth into orbit and it alone gives it enough push to send it to Mars? 

Or does the ERV have it's own rocket mounted outside the Mars heat shield to send it to Mars?

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#10 2017-04-23 22:20:50

SpaceNut
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Re: A Mars Hab with Radiation Shielding

The later as a stage to depart earth orbit is required to move the ERV to mars before it can make use of the mars heat shield, during the landing phase. The larger the diameter of the heat shield the greater the amount of mass entering mars can be for a parachute and engines soft landing.
That is why we are looking at retro-propulsion that space x is using to get to that greater mass without increasing the diameter.

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#11 2017-07-27 20:31:30

RobS
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Re: A Mars Hab with Radiation Shielding

Have you all seen this report about a space settlement in a 500 km equatorial orbit around the Earth? It has two-fold relevance to Mars: 1) it provides data about the use of lunar regolith, water, and plastic for radiation shielding, and acceptable radiation levels; and (2) it says 4 rpm is not a problem to produce artificial gravity in space, and there is good evidence people can adjust to 6 rpm as well. The adjustment period is (as I suspected) rather like the adjustment required when one gets seasick.

Here's the link: http://www.nss.org/settlement/journal/N … er-Way.pdf

Last edited by RobS (2017-07-27 20:31:42)

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#12 2021-09-10 07:56:44

Mars_B4_Moon
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Registered: 2006-03-23
Posts: 9,774

Re: A Mars Hab with Radiation Shielding

Mars Is Bombarded With Radiation, But We May Have Just Found Natural Shelter
https://www.sciencealert.com/these-mart … n-shelters

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#13 2023-11-27 12:10:22

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 29,314

Re: A Mars Hab with Radiation Shielding

Calliban wrote:

Building underground brings us four benefits simultaneously.  Firstly, a layer of rock and soil greater than two metres thick shields out cosmic rays and reduces dose rates comparable to those on Earth surface.  Secondly, a layer of rock and soil some 10m thick will provide about 1 bar of downward pressure on Mars, sufficient to balance the internal pressure of any structure.  Thirdly, a layer of overburden several metres thick, provides excellent thermal insulation once a stable temperature gradient is achieved.  And Mars gets extremely cold.  Finally, any small meteors that get past the atmosphere would be stopped by a thick layer of overburden.

The weight of overburden eliminates the need for tensile structures to counteract the pressure of a breathable atmosphere.  This is important because masonry materials can be produced with minimal energy and resources.  We can build quite impressive walls on Mars using nothing more complex than loose rocks or compressed adobe bricks, cemented together with wet regolith.  Simple economics will drive us underground.  Mars will be a subterrainian civilisation until the atmosphere is thick enough to allow habitable ambient pressure domes.  Even then, the cold will make livihg above ground expensive.

Mars does not appear to have any near surface ground water or precipitation. This makes it easy to produce habitable volume, simply by heaping size sorted regolith over a frame.  A densely packed matrix of micron sized clay particles will form a very effective labyrinth seal, preventing air from leaking out.  As soon as we can produce cast iron or cast basalt for roof members, this will be a very cheap way of producing habitable space.  We could even build walls from dry stone, provided there is regolith behind them.

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#14 2023-11-28 11:11:45

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 5,620
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Re: A Mars Hab with Radiation Shielding

Beware of proposals to eliminate structure so that weight of overburden balances internal pressure.  That way lies fatal accidents.

You have to hold it up during construction,  when it is unpressurized.  So you have to build it strong,  anyway.  No way around that.

Not paying attention to effects of loads on partially-completed structure has cost many lives in construction accidents here on Earth.  That danger persists on Mars,  and the risk is amplified by the additional environmental hazards there.

GW

Last edited by GW Johnson (2023-11-28 11:12:43)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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