Mars Direct Hab - What is made of - Help for Master's Thesis

Aquarius · 2017-06-25 14:34:18

Goodmorning everyone.

I am a student in Energy Engineering and I am preparing a thesis that need an energy efficiency analisys of a Mars Direct Hab.
The problem is....... that I don't know what is made of.

I don't know anything about the layers, the materials, thermal conductivities, and so on. The only thing I know is that dr. Zubrin would have chosen a type of Weldalite for the outer shell, but nothing else.

Is there anyone that know where find a clear table with this kind of values? I though I could have used the data about Nasa's TransHab (being the mars direct hab a transhab itself, afterall), but I didn't find anything for this, too.

I kindly ask for your help.

Thank you!!

RobertDyck · 2017-06-25 14:59:46

You know about what we know. Get a copy of the book "The Case for Mars", written by Dr. Robert Zubrin. I have the first edition, published 1997, purchased in the spring of 1998. There are newer editions if you want an update. That has what we know.

However, to give you addition data not included, a Mars Direct habitat would have a pressure hull made of Weldalite. That's aluminum-lithium alloy. That's explicitly stated in Dr. Zubrin's book. However, the International Space Station has modules of aluminum alloy, but they're covered in blankets. The blankets are multi-layer insulation, which is multiple layers of aluminized Mylar designed to reflect radiant heat. They have fish-net spacers between to minimize thermal conduction. It's outside the aluminum alloy pressure hull, so exposed to the vacuum of space. Think of space as the world's largest Thermos bottle. That's the thermal layer. Outside this is a single layer of Orthofabric. That's a double layer fabric consisting of 400 denier Goretex outer layer, the backing is 400 denier Nomex, and every 3/8" in both the warp and weave directions two threads of Nomex are replaced by 400 denier Kevlar. The "Goretex" is actually a fibre of PTFE (PolyTetraFluoroEthylene), with the formula (C2F4). This is the same chemical formula as Teflon, but "Teflon" is a brand name of Dupont, this fibre is manufactured by the Gore Textile Company, hence the brand name "Goretex". Notice the micrometeoroid protection layer is the same fabric as the EMU spacesuit, the white spacesuit used on the Space Shuttle and now the Space Station. And the multi-layer insulation is also the same. So thermal blankets that are applied to the Weldalite hull of modules of ISS are the same as "thermal and micrometeoroid protection garment" that is outer layers applied to the neoprene rubber pressure layer of spacesuits.

We assume a Mars Direct habitat would have these same blankets as modules of ISS.

Last edited by RobertDyck (2017-06-26 15:11:32)

kbd512 · 2017-06-26 13:29:08

The information you need can often be found in NTRS reports (NASA Technical Reports Server), research papers from universities, and on various manufacturers' websites.

Current research for deep space habitation at NASA has focused on use of Hydrogen rich fabrics and Hydrogenated Boron Nitride NanoTubes (HBNNT's) for providing radiation protection for long duration habitation. HBNNT's provide the highest protection, lightest mass, and lowest volume of all materials tested thus far. NASA is still trying to figure out if it can affordably mass produce HBNNT's and whether or not it can also use HBNNT's as structural materials in pressure vessels. If the answer to the first question is "yes" but "no" to the second (the mechanical properties of the material are not yet completely characterized), then you'll see HBNNT liners in Aluminum-Lithium pressure vessels. If the answer to both questions is "yes", then you'll see extraordinarily light and protective pressure vessels for human habitation. HBNNT's are also exceptional thermal and electrical insulators in much the same way that CNT's and Graphene are exceptional thermal and electrical conductors.

NIAC Final Report - Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study - Phase I

Boron Nitride Nanotube: Synthesis and Applications

Bigelow Aerospace has further developed NASA's inflatable TransHab concept after the agency was forced to terminate further research in some sort of political deal made with Congress. These multi-layer fabrics also provide substantial radiation protection, as a function of mass, for the pressurized volume provided and compare very favorably with Al-Li pressure vessels in terms of mass and durability. These multi-layer inflatable fabric structures also provide very good insulation and substantially better protection from space debris than Aluminum alloys of equivalent mass.

I think the most probable avenue for future development in the near term is Al-Li with HDPE radiation protection liners. This has already been done as part of the Orion program. In the next decade, inflatables will become a way to provide more habitable volume per unit mass. In the far term, advanced composites made with HBNNT may become feasible. Aluminum alloys are what aerospace engineers know best. All inflatable fabrics and advanced composites are less well characterized when it comes to ultimate durability and are much more difficult (read expensive) to properly test. Bigelow's BEAM is attached to ISS right now. The plan is to test the durability and radiation protection properties of the design and then incorporate the technology into future deep space or surface habitation hardware.

Incidentally, the mechanical properties of the materials used in the ISS modules and the Bigelow BEAM module are not that difficult to find. You have to know the names or trade names for the materials, but that's about it. Some examples of the trade names for flexible fabrics that can provide insulation or other required mechanical properties include Mylar, Kapton, Dacron, Vectran, Spectra, and Kevlar. Use of Mylar film for insulation is very common. The most common aluminum alloys used are 2195 (Aluminum-Lithium) and 2219 (often referred to as "hard alloy" by NASA). In any event, 2219, 2195, 6061, and 7075 are all common as dirt in space flight applications. Steels are used sparingly, but stainless steels like 316 are fairly common for corrosive environments and the Centaur upper stage for the Atlas V rocket uses pressurized stainless steel LOX/LH2 bladder tanks because of the low thermal conductivity of the material in relation to aluminum alloys. Ti-6Al-4V is one of the most commonly used Titanium alloys and can be found in tanks used to contain storable chemical propellant combinations like NTO/MMH.

Here's an example of a manufacturer's data sheet:

DuPont - Mylar Polyester Film Physical-Thermal Properties

RobertDyck · 2017-06-26 15:12:56

Correction. EMU spacesuits use urethane coated nylon for the pressure bladder. And Dacron restraint layer on top of that.

RobertDyck · 2017-06-26 15:42:34

NTRS: Deep Space Habitat Configurations Based on International Space Station Systems

Exterior Micrometeoroid Debris Protection System (MDPS) is used to protect the pressure vessel from puncture. For the DSH it is the same system used on the MPLM.
The exterior MDPS includes:
0.8 mm AL alloy bumper shield
127.6 mm multi-layer insulation (MLI) with Nextel ceramic fiber

The molecular properties of water and polyethylene provide a physical advantage for radiation protection. The thickness of the water serves as a storm shelter during a solar particle event (SPE) to keep the crews’ exposure limits within the National Council for Radiation Protection (NCRP) recommended levels (Figure 23). The water thickness for sixty and five hundred day missions is ~11 cm which provides sufficient protection for the crew exposed to SPEs. To date, there is no agreed approach for long term galactic cosmic radiation (GCR); this design does not provide GCR protection.
Radiation Water Wall
0.55 cm thick polyethylene tanks
9.9 cm thick wall of water

RobertDyck · 2017-06-26 15:47:27

Aquarius,

I have been looking for someone who knows how to do Energy Engineering. I would like help with energy analysis of a transparent polymer film greenhouse for Mars. I'll give details that we came up with, including materials. Would you be willing to do this? And show me how to do it?

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#1 2017-06-25 14:34:18

Mars Direct Hab - What is made of - Help for Master's Thesis

#2 2017-06-25 14:59:46

Re: Mars Direct Hab - What is made of - Help for Master's Thesis

#3 2017-06-26 13:29:08

Re: Mars Direct Hab - What is made of - Help for Master's Thesis

#4 2017-06-26 15:12:56

Re: Mars Direct Hab - What is made of - Help for Master's Thesis

#5 2017-06-26 15:42:34

Re: Mars Direct Hab - What is made of - Help for Master's Thesis

#6 2017-06-26 15:47:27

Re: Mars Direct Hab - What is made of - Help for Master's Thesis

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