Marspedia - User contributions [en]

List of Construction Materials

2020-11-05T17:49:13Z

Olawlor: Fix link to brick article

{{Bootstrap}}

*[[Sintered regolith]]
*[[Fiberglass]]
*[[Steel]]
*[[Blacksmith|Meteoric iron]]
*[[Brick]]
*[[Universal bricks]]
*[[Carbon fiber]]
*[[Plastics]]
*[[Glass]]
*[[Compressed regolith|Compressed Regolith Blocks]]

[[Category:Construction, Assembly, Maintenance]]

Multi-layered vault settlement

2020-11-05T17:39:24Z

Olawlor: Small grammar fixes

{{SettlementType}}
[[File:Mezquita on Mars.jpg|thumb|400x400px|An early evolution of a multiple dome settlement. With only one layer of steel domes and with a thick regolith covering.]]
A '''multi-layered vault settlement''' is a [[building]], consisting of several shells. Each shell serves a different purpose: The central shell is the best protected part of the settlement, best useful for living rooms. The outermost shell contains store rooms, [[greenhouse]]s, machinery, etc. It can be dome or barrel shaped.
[[Image:MultiLayeredDomeSettlement.gif|thumb|right|300px|Principle of a Multi-layered Vault Settlement]]

==Properties==
Rectangular column, beam and girder design with steel structural members as used on Earth would not be appropriate on Mars for any structure intended for human habitation. On Mars the first need for a habitation is that it be a pressure vessel to hold in enough air pressure for human survival, so cylindrical and spherical buildings would be built.

One option is to dig a semicircular cross section ditch and build a cylindrical building in the ditch with its axis horizontal. Structural tension members would wrap around the entire building; roof, wall and floor to hold air pressure in. Tensile reinforcement would also run lengthwise through the outer wall from end to end. Another option for brick construction is to have a flat slab floor semi cylindrical roof structure and enough fill material over the roof so that the weight of the fill holds in the air pressure in the building below without the need for tensile strength in the walls of the structure. About 30 feet of brick and fill would be required to provide the necessary pressure. The inner surface of the pressure vessel must be lined with a gas-impermeable layer.

Buildings would be made to their design size when first built. There would be no particular advantage to building a new layer of habitation above a previous building because the previous pressure vessel would be wasted and a new outer pressure retaining layer would be required.

==Material==
===Plastics===
[[Image:FoamDome.png|thumb|left|300px|Arrangement of plastic foil hoses filled with PUR foam]]
A combination of inflatable hose arcs and a filling with polyurethane [[foam]] allows the construction of huge buildings without big machines. Such a [[foam dome]] is probably the first big building in a Martian settlement.

The dome is started with one arc, made from a hose that is pumped up with air, thus erected. The hose has, for example, a diameter of 50 cm and a length of 100 m, so the arc spans
about 60 m. Then the hose is filled with PUR foam, which hardens after a short while. A series of arcs is erected, touching each other, creating a tunnel with 60 m width and, for example, 100 m length, resulting in a building with 6000 m2 floor space.

When all arcs are erected and hardened and the side walls are closed with smaller arcs, the surface is finished with an extra layer of PUR foam. This layer glues all arcs together and fills all gaps. It is reinforced with plastic or glass fibers, possibly with several layers. Finally the building is covered with a layer of regolith.

===Brick===
[[Image:MultiLayeredDomeBrick.gif|thumb|right|300px|Multi-layered Vault Settlement made from Bricks with steel reinforcement in the outer layer. Only the above ground half of structure is shown]]
Bricks from [[sintered regolith]] allow the construction of vaults without any further material if the building is for unpressurized storage. Gravity alone stabilizes the building. Neither reinforcement nor grout is necessary. However, for people to inhabit a structure on Mars it needs to retain atmospheric pressure.
[[Image:SpecializedBricks.gif|thumb|left|160px|Specialized Bricks]]
Specialized bricks (e.g. [[arch segments]]) can be made for every vault radius and for special shapes. Advantage: The strength of a brick vault can be optimized. Disadvantage: The effort for manufacturing a great variety of bricks is high. A brick dome on Mars will require steel, fiberglass, or some other structural reinforcement strong in tension to hold in air pressure. It will be most economical to continue the tension members below ground level to form a fully spherical building with the hemispherical dome showing on top and the inverted dome section for a basement and sub basement.

[[Image:UniversalBricks.gif|thumb|left|160px|Universal Bricks]]
[[Universal bricks]] allow different vault radius and shapes with only one sort of brick. Advantage: The manufacturing can be automated easily. Disadvantage: The strength of the masonry depends on the connection between the bricks. It is inevitably weaker than a vault from specialized bricks, for the pressure does not act perpendicular at the surface of each brick in most cases. The requirement for reinforcement material in the outermost wall to retain air pressure is the same as for other brick.

===Steel===
[[Image:MultiLayeredDomeSteel.gif|thumb|right|300px|Steel Construction]]
[[Steel]] allows the construction of a great variety of vault shapes. Since steel provides great strength even with thin girders, such vaults provide optimal space inside. Disadvantages: Steel is probably more expensive to produce than bricks.

==Layers==
===Innermost layer===

*Sleeping rooms
*Living rooms

===Middle layer===

*Working rooms
*Vital machinery

===Outermost layer===

*Storage of material and inventories

==Open issues==

*What is better for radiation shielding and protection against meteorites: A brick vault or a steel vault?

{{SettlementIndex}}

[[Category:Construction, Assembly, Maintenance]]

Chaotic Terrain

2020-08-09T02:53:26Z

Olawlor: Add a link to permafrost melting, which can create small scale chaotic terrains on Earth in the polar regions.

Chaotic Terrain terrain is used two ways by planetary scientists.

*The first is when a giant impactor on one side of a world causes massive shockwaves to travel thru the crust. When these shock waves collide on the opposite side of the world, the antipode, the shockwaves either cancel out, or combine chaotically, fracturing the curst, and making strange formations which planetary scientists call chaotic terrain.
*The second is when terrain saturated in ice, melts from below. The water turns to liquid and flows away, (sometimes emerging explosively downhill), leaving a strange area of collapses, shifted landforms, and gullies.

Both of these types of terrain have occurred on Mars.

=='''Examples of Chaotic Terrain in the Solar System:'''==

*On Mercury there is the Caloris Impact Basin which is about 1,550 km in diameter. On the exact antipode from this impact is chaotic terrain which (also known as "a weird terrain"), which is made up of hilly, grooved terrain with few impact craters.
*On Earth, at the antipode of the Chicxulub Impact Event is India. At the time of the impact, the Deccan Traps formed. The Deccan Traps were caused when huge cracks opened in the Earth's surface and massive amounts of Lava flowed out, forming lava flows, in some areas, 2 km thick. (Approximately 1,000,000 cubic kilometres of lava were produced.) Gerta Keller, in a 2015 paper, has argued that the Chicxulub Impact created chaotic terrain in India, and the fractures produced in the crust allowed the Deccan Traps to form.

*On Jupiter's moon, Europa there is the Conamara Chaos. No impact on the opposite side the world remains, but the ice plates over a liquid ocean may have erased a previous impact basin.

*On Pluto chaotic Terrain can be found at the antipode from the Sputnik Planitia impact basin.
*

=='''Possible Impact(s) on Mars Formed Tharsis:'''==
The Tharsis Bulge and the Hellas basin are at approximate antipodes from each other. In particular, Alba Mons, (an old, very large shield volcano north east of Olympus Mons), is exactly opposite from Hellas Planitia. It is possible that chaotic terrain caused by the Hellas impact weakened the crust at Tharsis and triggered, or aided, the formation of the Tharsis Bulge. Also note that the Isidis Impact basin (half the diameter of Hellas) is also opposite the Tharsis Bulge.

=='''Water formed Chaotic Terrain on Mars:'''==
The closest analog on Earth may be the mass wasting observed during permafrost melting.<ref>US National Park Service, "Mass Wasting". https://www.nps.gov/subjects/erosion/mass-wasting.htm</ref>

On Mars, it is thought that a large area of soil saturated with ice may melt to create chaotic terrain. This melting may be caused by asteroid impact, gradual geothermal heating, a magma intrusion, seismic activity, increased pore pressure, or the dissociation of carbon dioxide & methane clathrates. (Different areas may well have had different forms of melting.) Some land near chaotic terrain appears undisturbed, and may be an area where the ground water did NOT melt.

However this water liquified, it flows downhill (causing collapses in the soil where it leaves), and may emerge to the surface lifting up and tilting huge blocks of rock. Chaos terrain is associated with a confusion of mesas, hills, valleys, gullies, & buttes. The chaotic terrain is often associated with the heads of large river systems on Mars, and it is theorized that massive amounts of water catastrophically emerged from some of these areas in sudden, huge floods.

By counting craters (old terrain has more craters), it is thought that these channels formed from 2.0 to 3.8 billion years ago.

====''Major areas of Chaotic Terrain:''====

*Chris Planitia
*Oxia Palus quadrangle
*Along the Martian Dichotomy (The border between the Martian lowlands to the north, and the southern highlands.)
*Margaritifer Sinus Quadrangle
*Phaethontis Quadrangle
*Lunea Palus Quadrangle
*Hydraotes Chaos
*Galaxias Chaos (this lacks an outflow river).

=='''Noctis Labyrinthus is cool, but not chaotic terrain:'''==
Note that Noctis Labyrinthus (the Labyrinth of the Night), west of Valles Marineris, was once thought to have been created by this process, but now is believed to have been created by faulting. (That is, this mesa and gully terrain is created when horsts remain still, and the corresponding gaben sink.)

=='''Biography:'''==
"Deccan Volcanism, the Chicxlub Impact, and the end-Cretaceous mass extinction: Coincidence? Cause and effect?" by Keller, G. Published in Volcanism, Impacts, and Mass Extinctions: Causes and Effects, GSA Special Paper 505. https://web.archive.org/web/20170618024315/http://specialpapers.gsapubs.org/content/early/2014/06/10/2014.2505_03.1.abstract

"Chaos Terrains on Pluto, Europa, and Mars -- Morphological Comparison of Blocks", Skjetne et. al. https://www.hou.usra.edu/meetings/lpsc2019/pdf/2146.pdf

"Martian Chaos Terrain on wikipedia. https://en.wikipedia.org/wiki/Martian_chaos_terrain

Noctis Labyrinthus on wikipedia. https://en.wikipedia.org/wiki/Noctis_Labyrinthus

"The Geology of Mars: Evidence from Earth-Based Analogs", published by Cambridge Planetary Science, Edited by Mary Chapman.

Greenhouse

2020-08-09T02:32:22Z

Olawlor: Add a note that a greenhouse may require cooling (and link to new article).

[[File:Greenhouse_tile.JPG|link=Create_a_settlement|alt=|border|right|frameless|100x100px|[[Create a settlement]]]]
[[image:Eden_project.jpg|thumb|right|300px|[[The Eden Project]]] (near St Austell, Cornwall, UK) is a terrestrial example of the possible use of large ''biomes'' as greenhouses and life support for Mars colonies. ''Image credit: Jürgen Matern'']]
Greenhouses and grow rooms are types of agricultural facilities. Growing [[:category:plants|plants]] in a '''Greenhouse''' delivers [[oxygen]] and [[food]]. It can play an important part in human recreation ([[Mars Garden Wins Gold at London’s Chelsea Flower Show (MarsHome.org)|Mars Garden]]) and may be the place for [[funeral]]s. The [[sunlight]] is not bright enough on Mars to allow most terrestrial plants to thrive, but it provides a valuable part of light energy for plants. Additional [[energy]] is necessary for [[lighting]] and [[heating]]. [[Food|Food production]] [[Settlement facilities|facilities]] may include biological reactors for bulk protein and carbohydrates production, sidestepping plant production altogether.

[[image:TropicalIslandsInside.jpg|thumb|right|300px|The Tropical Islands (Germany) is a terrestrial example of a huge dome to create an inhouse habitat.]]
The greenhouse may be constructed from transparent material, allowing maximum sunlight to pass, generating an artificial "[[greenhouse effect]]". This effect may be enhanced by filling the greenhouse with potent greenhouse gasses such as [[sulfur hexafluoride]] The spectral properties of the material should be optimized to match the absorption characteristics of chlorophyll, maximizing the energy gain, possibly using a layer of quantum dots<ref>http://dx.doi.org/10.33383/2017-084</ref>.

Plants need a mix of air pressure and temperature. The greenhouse must be strong enough to hold that air pressure, and it must be [[insulation|insulated]] to hold the temperature inside. Photosynthesis works only at fairly high temperatures.

==Side-lit Greenhouse Concept==

[[Image:Greenhouse_marsfoundation.jpg|thumb|left|300px|The [[Mars Foundation]] concept for a side-lit greenhouse.]]
The [[Mars Foundation]] concept for a greenhouse involves the maximum use of local materials to avoid waste, maximize energy input and optimize space. Spawned from the [[Hillside settlement]] design, the greenhouse would most likely be located inside/next to a hill side (possibly in the location of [[Candor Chasma]]). Therefore [[regolith]] or some other absorbent material could be suspended above the greenhouse to protect occupants and plants from [[solar radiation|harmful radiation]]. The source of light would therefore be directed from the side, via an array of adjustable mirrors. A system of vents and ducts would allow warm air to circulate, perhaps even used to heat the main habitat.

==Underground Greenhouse Concept (Grow room)==
[[Image:Underground Greenhouse.png|thumb|right|300px|Underground Greenhouse Concept]]

If geothermal energy or [[nuclear power]] is not available the [[heating]] will consume large amounts of electrical energy. In this case the sum of energy used for [[lighting]] and heating must be considered. An underground greenhouse is easier to insulate to hold warmth inside. On the other hand the effort of lighting is higher, since no direct sunlight is used. This concept has some additional advantages: It is [[meteorites|meteorite]]-safe and [[radiation]]-safe.

[[caves|Natural caves]] and [[artificial cave]]s can be utilized to build such an underground greenhouse, which requires a preparation with high effort in either case. The maintenance is quite cheap, for the ambient temperatures are steady and the radiation levels are low, so it is a good long term solution. A combination of greenhouse and living space for the settlers is suggested. In most cases, high productivity greenhouses will be warm, humid, richin CO2 and with very high lighting levels. These are not necessarily the best conditions for humans, so grow rooms may need to be build as separate environments from the general habitat.

The [[Mars One]] concept for the initial settlement is an inflatable greenhouse with a thick cover of [[regolith]].

==Water-shield Greenhouse Concept==

[[Image:WaterShieldGreenhouse.png|thumb|right|300px|Water-shield Greenhouse Concept]]
[[Hydrogen]] does a good job absorbing [[cosmic radiation]]. [[Water]] contains highly concentrated hydrogen, and hence serves as a good radiation shield. On the other hand it is highly transparent for visible light and UV. The combination of both makes it an interesting material for greenhouse shielding.

Under a strong pressure resistant housing the water is placed in a thick layer. It absorbes the dangerous parts of cosmic radiation and [[sunlight]] and passes most of the spectral parts needed by [[human]]s and plants. Additionally, it helps to buffer daily temperature variations because of its high specific heat capacity.

The layering could be as follows: The outer layer is a construction of [[steel]] and [[glass]], providing enough strength for the difference in [[atmosphere|atmospheric pressure]]. It also serves as insulation for [[temperature]] differences. Additional sheets of glass or [[Synthetic materials|plastics]] improve the insulation effect. A [[self-healing puncture protection]] should be considered. The innermost layer is the water. It can be held by transparent canisters.

==Multiplying Sunlight==
[[Image:MultipleMirrorsForGreenhouse.png|thumb|left|300px|Multiple Mirrors for Greenhouse]]

A [[solar concentrator‎]] is a set of mirrors that can be used to bring more sunlight into the greenhouse than the base area of the greenhouse receives directly from the sun. Three times the amount of Martian sunlight should be enough to serve terrestrial plants. During good weather periods this allows growing vegetables without additional energy.

However, 40% or more of martian light is diffuse light. This light cannot be focused by a mirror and therefore the surface required may be much larger.

==Flora and fauna==
Plants can be grown either in liquid fertilizer ([[hydroponics]]) or in [[soil]]. Many plants live in symbiosis with [[microbes]] and [[insects]]. [[Bee]]s can be used to pollinate the blossoms for fruit plants. Probably, the greenhouse is less labor-intensive with as many natural processes as possible, including decay of dead parts of plants to [[compost]]. The growth of flora and fauna under the low Martian [[gravity]] bears some uncertainties.

==Nutrition and Energy Calculations==
Based upon the figures in the [[food]] and [[sunlight]] articles the following calculations can be carried out for an artificially lit greenhouse:

The minimum size of cropland per person is about 365 m2. The needed [[lighting|light energy]] can be assumed with 1000 kWh per m2 and year. The result is an annual amount of 365 MWh per person. In other words: An average illumination power of 41,67 kW per person is required.

The usage of fluorescent lamps with an efficiency factor of 30% results in a requirement of about 140 kW per person in electrical energy. The overall efficiency of food production with artificially lit greenhouses is less then 1 permille, or in other words, to produce food with a content of 1 kWh the amount of more than 1 MWh in electricity must be spent.

Parts of the required light can possibly be provided by direct or indirect sunlight.

If spread out or poorly insulated against the cold ground, heating the greenhouse may require additional energy. If stacked vertically for minimum volume usage, the energy added for lighting may cause the space to require active [[cooling]].

==Open Issues==

*How long can plants survive without sunlight (e.g. during a dust storm)?
*How many persons are needed to work in the greenhouse to produce enough food for a hundred persons?
*How much energy is required for heating, especially during long lasting dust storms? This question can not be answered without an [[experimental setup#greenhouse heating|experimental setup]].
*What temperature and air pressure do plants need?
*What air pressure is needed for persons to work in the greenhouse?
*What transparent materials match the absorption characteristics of chlorophyll?
*Do plants need wind? How can it be provided?
*What is known about radiation tolerance of food crop?

==See Also==

*[[Research on greenhouses & assumptions]]
*[[Experimental setup]]

==External links==

*[http://www.marshome.org/archives/2007/03/sidelit_greenho.php The Mars Foundation Side-lit Greenhouse design.]

{{SettlementIndex}}

{{Featured_red_ring}}

[[category:Growing Methods]]
<references />

Cooling

2020-08-09T02:31:19Z

Olawlor: Add brief description of the solutions and challenges for cooling on Mars.

Because industrial, residential, or agricultural activities use energy, they will produce heat. This heat eventually needs to be dissipated into the environment, or the [[temperature]] will continue to rise. Heat can be transported via convection, conduction, and radiation.

== Convection ==
Convection on Mars is minimal due to its very thin atmosphere, with even fan-assisted convection appearing to be less mass efficient than radiative cooling<ref>von Arx and Delgado, "Convective heat transfer on Mars", AIP Conference 1991 https://aip.scitation.org/doi/abs/10.1063/1.40133?journalCode=apc</ref>.

== Conduction ==
Conduction into Mars regolith or megaregolith (soil or bedrock) may be feasible, since the ground's average temperature is around -60C. On Earth ground-source heat pumps are feasible for cooling. On Mars, depending on the ground conditions, sufficient cooling may be available via the building's foundation alone, or this could be augmented with cooling channels, which could be combined with existing utility trenches used for power or materials.

Challenges include the low temperature of the ground requiring a careful choice of working fluid, and interior humidity may deposit frost on cooling panels.

Some regolith, such as dry dust or loose rock, may have poor thermal conductivity, requiring either additional conduction area such as drilled cooling pipes or channels, or a soil treatment such as water injection to increase thermal conductivity by filling the soil pore voids with ice.

== Radiation ==
Radiative cooling is a standard solution for spacecraft, since the large temperature difference between outer space (around 3K) and human habitable areas (around 300K) gives substantial radiative cooling from high emissivity surfaces.

The Stefan-Boltzmann law describes the thermal emission of a black body radiator as j=e σ T4, where the radiated power in watts j is equal to the surface emissivity e (between 0 and 1), a constant σ, and the fourth power of thermodynamic temperature T. For a surface at 293K (about 20C) with emissivity 0.8, the black body radiative cooling is 334 W/m2 when facing the cold dark of space.

On Mars, during the nighttime a structure's roof could be used for radiative cooling, which could be as simple as a high-emissivity coating applied to the existing roof.

One challenge with radiative cooling is keeping sunlight from warming the radiator panels. A possible mitigation is a careful arrangement of mirrors<ref>Lunarpedia Lunar Radiator https://lunarpedia.org/w/Lunar_Radiator</ref> to reflect sunlight away, or a paint with high visible reflectance but high thermal emittance.

[[Category: HVAC]]

User:Olawlor

2020-08-09T01:22:29Z

Olawlor: Add a basic intro.

Dr. Orion Lawlor, lawlor@alaska.edu, is a faculty member at the University of Alaska Fairbanks. His research interests center around In-Situ Resource Utilization (ISRU), with applications both in space and in remote areas on Earth.

He coaches the student team in the NASA Robotic Mining Competition, and has built dozens of mining robots with increasing degrees of autonomy.

He wrote much of the Unity code for the open source Virtual Colony project, which seeks to build an interactive Mars city that works from WebGL to VR: https://github.com/VirtualSpaceExplorers/VirtualColony

Aerobraking

2020-08-09T01:14:27Z

Olawlor: Add a paragraph of technical details from the 1990 MSFC paper on Mars aerocapture.

Aerobraking is a technique used by mission scientists to reduce the height of spacecraft orbits by allowing atmospheric drag to slow the spacecraft's velocity. Often the [[solar panel|solar panels]] onboard orbiters can be used to maximize and control the amount of drag applied to the craft. This technique will ultimately minimize the requirement for the use of [[propellant|propellants]] (to slow the craft down), thereby optimizing cost effectiveness.

This technique was used to great effect on missions such as the [[ExoMars Trace Gas Orbiter]] in 2017, [[Mars Reconnaissance Orbiter]] in 2006 and [[Mars Odyssey]] in 2001, and is standard practice when spacecraft are being inserted into orbit or when a reduction in velocity is required.
[[File:128days.jpg|thumb|600x600px|This screen capture shows the NASA trajectory planner for a flyby mission of 128 days to Mars in 2022. The flyby could be transformed into a transit by aerocapture in the Martian atmosphere.]]

===Aerocapture===
Aerocapture is a subcategory of aerobraking. Atmospheric drag is used to reduce velocity to a point the vehicle can enter a stable orbit with a minimum or no propellant burn. Aerocapture can be the prelude to [[Landing on Mars|descent and entry]] into the atmosphere. Aerocapture can subject a vehicle to very high accelerations, and for future manned mission will require very precise attitude controls for the vehicles.

For example, in a typical manned Mars mission concept, using aerobraking cuts the initial vehicle mass in half<ref>Braun, Powell, Hartung, "The effect of interplanetary trajectory options on a manned Mars aerobrake configuration
," 1990 NASA Marshall Technical Report. https://ntrs.nasa.gov/citations/19900016720</ref> compared to purely propulsive capture, even including the mass of a large heatshield required for aerobraking. This is because aerobraking can scrub off several km/s of arrival velocity per aerobraking pass without using propellant. However, high arrival velocities can impose significant radiative and convective heating loads on the heatshield, and sustained accelerations on the crew of as much as 5g for several minutes. A typical Mars aerobraking atmosphere entry corridor has a periapsis of 40-50km and a height tolerance of less than 5km, requiring accurate navigation and aerodynamic control.

Aerocapture can be used to shorten travel times between Earth and Mars, as well as with other planetary bodies in the solar system with atmospheres. The time of travel to Mars, for a similar deltaV expense, can be reduced from nine months, 270 days, for a Hohmann transfer orbit to about four months (128 days). This would reduce radiation doses by over 60% compared to the Hohmann transfer. This trajectory uses 4.62 km/s of deltaV. SpaceX Starship is designed for about 6 km/s of deltaV.
[[File:244 days.jpg|thumb|600x600px|Typical Mars rendez-vous trajectory. 244 days to Mars, with the same deltaV than an aerocapture mission, but less risk.]]
This type of orbit is much more dangerous than the Hohmann transfer orbit, as it requires a successful capture or the vehicle and crew are left on an elliptical solar orbit that may not approach any planet for centuries. The return velocity of Apollo was about 11 km/s, so the 9 km/s relative speed shown in the illustration should be manageable.

The images show orbits determined by the NASA Ames research center trajectory planner tool<ref>NASA Ames Research Center, "Trajectory Browser", web tool. https://trajbrowser.arc.nasa.gov/traj_browser.php?maxMag=25&maxOCC=4&chk_target_list=on&target_list=mars%0D%0A&mission_class=oneway&mission_type=flyby&LD1=2020&LD2=2030&maxDT=200&DTunit=days&maxDV=5&min=DT&wdw_width=-1&submit=Search#a_load_results</ref>.

== References ==
[[category:Spaceflight science]]