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#76 2017-05-02 19:36:30

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Air. Shelter. Water. Food.

Marscat

Bobcat skid steer loaders are 6.5' tall, 5.3' wide with buckets that are 5.6' wide, and they weigh 6,500 lbs which is fine for moving Earth dirt but overkill for Mars.  Also, Martian bobcats won't need a fuel tank or an engine and radiator.  They would be replaced by deep cycle batteries and electric motors mounted on solid axles for movement and it would need an electric motor to power the hydraulic pump. 

A steel 1,600 lb Earth weight bobcat would weigh 608 lbs on Mars, add in the operator weight and it would weigh 684 lbs.  It could be a foot thinner and a foot shorter than an Earth bobcat and it might have a 3.5 foot wide bucket.  The 3.5 foot wide bucket, when full, would move about 322 lbs of Mars regolith. 

Zubrin's Mars Direct plan included two open rovers weighing .8 tonnes, that's 1,600 lbs, so they would be replaced by this battery powered Marscat. 

On the Earth the dirt has been laid down for millions of years as dust mixed with air.  The air molecules act as tiny balloons, preventing compaction, but as water sinks into the ground it forces out most of the air.  So, over time water helps naturally compact soil.  On the Earth we speed up the process of compaction by using water and heavy equipment to get the air out so that the dirt will be able to support very heavy structures.   

The process of natural soil compaction probably happened on Mars long ago when it had oceans and rain but it hasn't happened in a long time.  Now Mars probably has a relatively low compaction (low compared to Earth dirt) surface of mostly dust mixed with CO2 so it should be relatively easy to dig through until you hit permafrost.  Once you hit permafrost you just let the sun warm it up in the day time and melt the ice which will turn to water vapor, then start digging again.

Last edited by Dook (2017-05-02 19:37:54)

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#77 2017-05-02 20:35:31

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 26,803

Re: Air. Shelter. Water. Food.

Just taking a peek at the quoted supercapacitor BCAP3400 specifications ratings of 2.85V, 3,400 Farad.

The series resistance of this capacitor is 0.28mΩ for power loss as heat when charging or discharging to provide power to the circuit of choice. It has to be in a temperature controlled enviroment as the operation temperatures are Minimum -40 C, Maximum 65 C... with Maximum Continuous Current (ΔT = 15°C)9 131 A RMS, Maximum Continuous Current (ΔT = 40°C)9 211 A RMS bad news is that much like lithium batteries temperature heat degrades not only the working farads but also causes the series resitivance to also increase with both of these making the available charge to output for use less over time quickly the hotter you get it.

The farads to load account for the discharge time before its empty. Series test current was 100 amp's but if you want this device to last you will need to drop that to 50 amps and make pararell circuits to be able to have the power that we would need from them. The next problem with series charging is cell voltages will not be equal which is the same problem for lithium batteries.

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#78 2017-05-03 00:21:47

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,343
Website

Re: Air. Shelter. Water. Food.

Dook wrote:

You want to flatten the greenhouse with hold down straps?  If the greenhouse material is made in an oval shape it would not need to be flattened with hold down straps.  There are balloons of many shapes, they don't form a sphere when they are inflated.

A tube once pressurized will form a cylinder. In order to give that cylinder an oval cross-section, no circular, you need to apply force. Hold down straps provide that force.

It can't be designed to last just two years.

Tefzel has been tested in Florida by Dupont. It lasted over 20 years. Mars has far more UV, but PCTFE is highly UV resistant. And PCTFE is far stronger than Tefzel. You must be thinking of polyethylene or polypropylene film, they last 2 years. Fluoropolymer film is more expensive, but much more durable.

Dook wrote:

I don't have the right stuff for Mars? Okay Macgyver.  Please explain how you are going to make things easily on Mars.

Nothing on Mars is easy. There's a difference between "easy" and doable. The first steel foundries were the size of a backyard BBQ. Ever see a brick BBQ? The first foundry on Mars will be about that small. Then make material to make a larger one.

Dook wrote:

The sand on Mars will scratch a greenhouse?  Sounds like more evidence that we need to bury a series of habitats and grow hydroponics and vegetables and fruit trees in plastic regolith tubs instead of attempting to build greenhouses that you can't pressurize.
...
LED lighting in a buried habitat is a better option for growing plants.

I've already explained. The best space photovoltaic cells convert 30.7% of sunlight to electricity, beginning-of-life. 26.7% end-of-life. And LED lights are very efficient, but even they are not 100% efficient. It's far more efficient to simply use sunlight directly. And all life support systems have a single point of failure: power. If power fails, all life support fails. The only life support that operates during complete power failure is plants. An ambient light greenhouse will recycle both oxygen and water with no power what so ever.

Dook wrote:

You think the greenhouse needs a floor?  Connecting the floor to the dome would make the greenhouse a pressure vessel and evenly distribute the force all the way around so it would not lift.  And if you made all the panels small, maybe 2 sq ft, they would only have about 570 lbs of force on them. 

Adding a floor would about double the number of panels you would need, essentially reducing your greenhouse size to about half.

I have also argued for long-narrow greenhouses. "Narrow" is relative; I mean height to width ratio exactly 1:2, and designed so a human worker can reach the tops of plants. Place a flat mirror along both sides, sized so the mirror has the same height above ground as the top of the greenhouse. This means the mirrors do not have to track the Sun. Mirrors angle will have to be adjusted for season, but on Mars that means adjust the mirror 1° once every 14 Mars solar days (2 weeks). That can be done by hand by a worker in a spacesuit if necessary. Orient the greenhouse perfectly east-west. Of course this only permits one tier of plant trays. And the mirrors are only required for crops that require full Sun. But this also means force from pressure is distributed around an oval tube that is practical size, so the stress is reasonable.

I also argued that an advanced settlement the size of a town or city would be habitats built as pressurized buildings. Not a giant dome with Earth-style buildings inside. That makes it practical to build, practical to expand.

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#79 2017-05-03 07:37:43

kbd512
Administrator
Registered: 2015-01-02
Posts: 6,249

Re: Air. Shelter. Water. Food.

SpaceNut,

My last post was very off-the-cuff since I was busy with other things.  My math was wrong as a result.  The total mass isn't that far off, though.  In retrospect, the new K2 cells, not the BCAP3400 cells are what we'd want for this application.  Maxwell's K2 cell model number is "BCAP3000 P300 K04".  The K2 cell's nominal voltage is 3.0v, capacitance is 3000F, maximum stored energy is 7.2Wh/kg, nominal mass is still 520g (same as BCAP3400), and nominal cell dimensions are still 60.7mmD x 138mmL (same as BCAP3400).

To generate 120vdc, a minimum of 40 K2 cells per module must be connected in series.  We'd probably use 48 cells per module, 8 modules per bank, and 2 banks per vehicle installation.  Each installation contains 399.36kg of K2 cells and stores 2,875.392kWh of electrical power.  To deliver 15kW of output to a 120V or 240V electric motor, the amperage draw would be 125A [EDIT: draw is 125A for all modules in one bank or 15.625A per module, at 120V or 240V].

P = I * V
so...
15,000W = 125A * 120V (requires 8 modules with 48 cells per module)
or
15,000W = 62.5A * 240V (requires 4 modules with 96 cells per module; more realistic input voltage for an actual EV motor)
[Edit:
or even more realistic for the latest EV's...
15,000W = 31.25A * 480V (requires 2 modules with 192 cells per module; falls in line with actual EV motor operating voltages)

The reason EV motors use high voltages is to diminish resistive losses (electricity converted to waste heat) during power transmission and to reduce the diameter and thus mass of the copper conductors.  The electric motors found in Chevrolet and Tesla electric vehicles are all in the 300V+ range and higher voltages are quite common in EV racing motors.  Google "YASA Motors" for examples of high voltage EV motors.  Although YASA's motors are intended to run at high RPM, motors can also be designed to make nearly all of their torque at much lower RPM ranges.  DARPA has funded development of motors for electric aircraft that are excellent examples of motors designed for lower RPM ranges.

Power loss is defined in the following equation:
P = I^2 * R

I used 120V as the voltage in my examples because most people are familiar with the 120V that comes from their wall outlets.  This is unrealistic for a power train with minimal cooling requirements.

I should also define what I mean by a module.  The bus that carries the current to the electric motors is separate from the physical super capacitor modules.  To ensure that each super capacitor module in a bank is easily handled without mechanical assistance in the form of winches or cranes, an actual unit would use tool-less slide-in removable modules containing no more than 48 cells.  That equates to 24.96kg on Earth or 9.4848kg (a little less than 21lbs) on Mars.  There will also be an associated thermal management system mass, in the form of heat pipes and aluminum plates, added to the mass of the super caps.

The charge / discharge controllers would be built into the wiring bus as separate removable modules.  To use a 480V motor, at least 4 of the 8 modules (192 cells) have to be connected to the bus.  The 192 cells at nominal charge are charged to 576V, so voltage regulation electronics are also required.  An input/output or charge/discharge voltage regulation system is common to all EV's.]

Either way, current output is well below the maximum current limitation for individual cells.  Your comments about individual cell charge level apply equally to battery or super capacitor modules and both types of power packs include circuitry that adequately resolve such issues.

Our best electric motors are only about 95% efficient, so these figures are obviously not representative of the actual output requirement to deliver 15kW to the tracks of a tracked vehicle to maintain 20kph in an off-road environment.  To figure out what the actual power requirement is, there are a series of relatively accurate but complicated calculations to determine our losses and thus the actual power output requirements to maintain a given speed in a given terrain.

Edit: 95% efficiency means 5% is dissipated as heat and not converted into mechanical work.  At a 15kW draw, this correlates to 750W, therefore the actual output requirement to convert 15kWe into mechanical work is about 15.8kW.

If someone is interested in doing that, knock yourself out:

Google "Theory of Ground Vehicles by J. Y. Wong" or...

A Mobility Model for Tracked Vehicles by Karl H. Gleason

US Army TARDEC - Analytical Model for the Turning of Tracked Vehicles in Soft Soils

Australian Army Engineeering Development Establishment - Skid Steering of Wheeled and Tracked Vehicles - Analysis with Coulomb Friction Assumptions

Now, about super capacitor technology...

It's true that the operating temperature requires some thermal control, but no Lithium-ion battery I know of can operate at 150C nor -40C (yes, I'm aware of the fact that some very specialized Li-ion batteries can operate at -40C, but only at substantially reduced discharge rates).  Watch the video on this page and tell me what would happen if you did the same things to any Lithium-ion battery:

FastCAP Systems

The FastCAP super capacitors manufactured by the company from the link above currently has NASA contracts for use aboard satellites.

The graphene-based super capacitors still in the labs are the least temperature sensitive of all the current generation super capacitor technologies.  In about 5 years, this will become COTS technology because there are so many applications for the technology here on Earth.

Activated graphene breaks record for low temperature storage of electrical energy

Here's a tidbit of what NASA is working on, with respect to low temperature super capacitors:

Low-Temperature Supercapacitors

And then we have Murata's super capacitor technology for different applications:

Murata Super Capacitors

The point is, there are different types of caps available for different storage capacities, discharge rates, and operating temperature ranges.  To this day, we basically have a handful of different Lithium-ion cell chemistries to choose from since all other cell chemistries are distant seconds in a variety of ways unless mass, volume, or charge/discharge rates are irrelevant.

Last edited by kbd512 (2017-05-03 10:10:22)

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#80 2017-05-03 09:17:50

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Air. Shelter. Water. Food.

RobertDyck wrote:
Dook wrote:

You want to flatten the greenhouse with hold down straps?  If the greenhouse material is made in an oval shape it would not need to be flattened with hold down straps.  There are balloons of many shapes, they don't form a sphere when they are inflated.

A tube once pressurized will form a cylinder. In order to give that cylinder an oval cross-section, no circular, you need to apply force. Hold down straps provide that force.

It can't be designed to last just two years.

Tefzel has been tested in Florida by Dupont. It lasted over 20 years. Mars has far more UV, but PCTFE is highly UV resistant. And PCTFE is far stronger than Tefzel. You must be thinking of polyethylene or polypropylene film, they last 2 years. Fluoropolymer film is more expensive, but much more durable.

Dook wrote:

I don't have the right stuff for Mars? Okay Macgyver.  Please explain how you are going to make things easily on Mars.

Nothing on Mars is easy. There's a difference between "easy" and doable. The first steel foundries were the size of a backyard BBQ. Ever see a brick BBQ? The first foundry on Mars will be about that small. Then make material to make a larger one.

Dook wrote:

The sand on Mars will scratch a greenhouse?  Sounds like more evidence that we need to bury a series of habitats and grow hydroponics and vegetables and fruit trees in plastic regolith tubs instead of attempting to build greenhouses that you can't pressurize.
...
LED lighting in a buried habitat is a better option for growing plants.

I've already explained. The best space photovoltaic cells convert 30.7% of sunlight to electricity, beginning-of-life. 26.7% end-of-life. And LED lights are very efficient, but even they are not 100% efficient. It's far more efficient to simply use sunlight directly. And all life support systems have a single point of failure: power. If power fails, all life support fails. The only life support that operates during complete power failure is plants. An ambient light greenhouse will recycle both oxygen and water with no power what so ever.

Dook wrote:

You think the greenhouse needs a floor?  Connecting the floor to the dome would make the greenhouse a pressure vessel and evenly distribute the force all the way around so it would not lift.  And if you made all the panels small, maybe 2 sq ft, they would only have about 570 lbs of force on them. 

Adding a floor would about double the number of panels you would need, essentially reducing your greenhouse size to about half.

I have also argued for long-narrow greenhouses. "Narrow" is relative; I mean height to width ratio exactly 1:2, and designed so a human worker can reach the tops of plants. Place a flat mirror along both sides, sized so the mirror has the same height above ground as the top of the greenhouse. This means the mirrors do not have to track the Sun. Mirrors angle will have to be adjusted for season, but on Mars that means adjust the mirror 1° once every 14 Mars solar days (2 weeks). That can be done by hand by a worker in a spacesuit if necessary. Orient the greenhouse perfectly east-west. Of course this only permits one tier of plant trays. And the mirrors are only required for crops that require full Sun. But this also means force from pressure is distributed around an oval tube that is practical size, so the stress is reasonable.

I also argued that an advanced settlement the size of a town or city would be habitats built as pressurized buildings. Not a giant dome with Earth-style buildings inside. That makes it practical to build, practical to expand.

We need hold down straps to force a thin plastic oval greenhouse into a flatter shape?  A settlement is not going to use an inflatable greenhouse.  The only use for an inflatable greenhouse would be by the exploration team and they're not going to depend on it for their food.  When peoples lives depend on something it has to be durable.

Tefzel has been tested in Florida and lasted 20 years?  Does the temperature drop down to -297 at night and then climb to 70 degrees F in the day in Florida?  Did they throw sand on it once a week? 

The first steel foundries were the size of a backyard BBQ?  How big of a steel component can you make in a BBQ?  There's also a difference between doable and practical.  Just because it's possible doesn't mean it's a practical use of one's time, energy, and equipment.   

It's more efficient to use natural sunlight to grow plants on Mars?  It's not more efficient when you realize that plants need to stay in a narrow temperature range (about 50-90 degrees F) and that a greenhouse would not protect humans from radiation and that a sturdy greenhouse can't be pressurized. 

The only life support that operates during power loss is plants?  An RTG and solar panels aren't going to just stop working, the solar panels don't produce at night or in a dust storm but the RTG isn't going to just quit working.  If there was a fire in the tuna can that could be game over.  In that case, having some plants still alive doesn't matter.

Last edited by Dook (2017-05-03 09:18:28)

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#81 2017-05-03 09:32:36

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,306

Re: Air. Shelter. Water. Food.

I suppose that when I started this thread, I should have underscored that all of these essentials are involving endothermic processes, and having adequate energy available is the basis or foundation of this technological pyramid. I pointed out that loss of any of the 4 items listed would be fatal to the colony/base; inadequate energy is another fatal factor, since air production and water extraction are all energy intensive. As a dependent item, food production is based on Shelter, air, and water.
In a separate thread started by Robert, he suggests the greenhouse be built into a hillside for maximum solar gain in crop production. I cannot argue against that concept, and support it wholeheartedly. The only reason to support using artificial lighting in the greenhouse is in order to lengthen the growing day during winter. Direct solar illumination is by far the most efficient way of growing crops. Artificial lighting should be supplementary.

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#82 2017-05-03 11:31:31

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Air. Shelter. Water. Food.

The loss of oxygen would not be immediately fatal, they would have an emergency air cylinder and Mars suits to give them time to fix the problem unless it was a large and sudden structure failure.

They would have a water supply in their Mars Hab and once they finish the buried habitat they could have a waste settling tank for feces.  Urine would have to be boiled inside the habitat and the water vapor collected by a dehumidifier but those two processes would bring your water recycling to almost 100%.   

Inadequate energy should not be a problem if the energy use is applied to essential life support systems and not wasted on trying to make small steel brackets or separate regolith.

As for food, the Mars Direct plan had enough food for an exploration crew of four to eat for 500 days on Mars.  So, a settlement would have to establish a series of buried habitats and start growing food in hydroponics and regolith tubs in that time.  They would likely need one or more additional shipments of food though.

Building the settlement into a hillside is fine if there happens to be a hillside near your landing spot.  The SpaceX concept has you all fooled into thinking we can land wherever we want but the Dragon has a landing accuracy of 6.2 miles and it can't carry very much to Mars, only 2 tons, because it doesn't use parachutes.  That's not better than Mars Direct, that's worse.  The Dragon would be a nice little resupply mission, not a first settlement. 

Attempting to land near hills is dangerous if you can't manuever away from them and choose a spot that has level ground to land on.  Also, if the hills are too far away then you would have a Mars Lander Habitat miles away from your buried habitat when they should be close together. 

Direct solar illumination is by far the most efficient way of growing crops?  On the Earth it is, not so on Mars.

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#83 2017-05-03 13:10:19

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,343
Website

Re: Air. Shelter. Water. Food.

Dook wrote:

The first steel foundries were the size of a backyard BBQ?  How big of a steel component can you make in a BBQ?  There's also a difference between doable and practical.  Just because it's possible doesn't mean it's a practical use of one's time, energy, and equipment.

At the time of the Vikings, 1,000 years ago, they produced enough for one sword. Actually it was a two step process: ore smelted to bloomery iron, then the iron refined to produce crucible steel. One batch of steel plus another batch of iron were forge welded to produce one ULFBERHT sword. Or the iron could be used to make nails to repair long boats. I skipped a lot of historical details that are not relevant to Mars. Today we can do much better.

I'm suggesting we take the modern "Direct Reduced Iron" method aka "Direct Iron" method because it works with hematite concretions as ore, and because it works at a temperature low enough that a nuclear reactor can provide the heat directly. It's still +800°C to +1200°C, but a nuclear reactor can provide that without melting itself. And when it isn't smelting, the reactor can be used to produce electricity. Again remember, the Mars Homestead Project called for 3 reactors, each so large they require a separate lander just for the reactor. And a lander the size of a Mars Direct ERV, not Red Dragon.

Dook wrote:

It's more efficient to use natural sunlight to grow plants on Mars?  It's not more efficient when you realize that plants need to stay in a narrow temperature range (about 50-90 degrees F) and that a greenhouse would not protect humans from radiation and that a sturdy greenhouse can't be pressurized.

A sturdy greenhouse can. In fact a greenhouse has to be pressurized. Plants cannot survive night temperatures that plummet to -75°C to -111°C. The warmest night time low recorded by Mars Pathfinder was -75°C, the coldest temperature recorded by Viking 2 over more than a Martian year was -111°C. Remember I talked to Dr. Penelope Boston about an inflatable greenhouse because she wrote the paper in the "Case for Mars" study before the founding of the Mars Society. She raised the concern about plastic film material, so I looked for one that would do the job. PCTFE is the most impermeable to water of any polymer known to man, highly impermeable to oxygen and nitrogen, highly resistant to UV and can survive the UV of Mars, the second most transparent polymer known to man, and to address your concern it becomes brittle at -240°C. The coldest temperature recorded by Mars Global Surveyor at the Mars south pole was -140°C; you would never build a human base at the Mars south pole, but the point is this material can withstand 100°C colder than the coldest temperature on Mars. The polymer film would have the same spectrally selective coating that NASA currently uses for spacecraft and space station windows and spacesuit helmet visors. That's vacuum deposited gold, nickel, and silver oxide. Only silver is oxidized. It has been commercialized on Earth, although the commercial versions only use silver oxide. Windows on Earth need to reflect IR to control radiant heat, they don't need to block UV. You can buy commercial window film that has the same coating, so how to apply this to polymer film has already been developed. This will block UV, alpha, and beta radiation. The atmosphere of Mars blocks heavy ion galactic cosmic radiation. There isn't much X-rays in space, the metal coatings on windows are enough to reduce that to safe levels. That only leaves proton and light ion radiation, and gamma. The atmosphere partially blocks medium ion radiation. This means walking inside an ambient light greenhouse in shirt sleeves is as safe as walking outside in a spacesuit. Radiation on the surface of Mars is half that of ISS, but to reduce radiation exposure to equal a US nuclear reactor worker, time outside in a spacesuit has to be limited to 40 hours per week. (7 Mars solar days). That's a work week, so no one should object.

Temperature control would be achieved by passive means. An inflatable greenhouse would have 2 layers of film, the gap would be pressurized less than the interior, but more than Mars ambient. So a leak of either film would be detected by pressure change in the gap. Two layers provide redundancy. And the gap would be filled with argon gas, harvested from Mars atmosphere, to reduce heat loss. Some sort of insulation in the ground would be necessary. One suggestion is bubble wrap, made from polymer film from Earth but filled with argon gas on Mars. Walkways would require a hard polymer or composite walkway above the bubble wrap to ensure you don't burst the bubbles. Remember Mars atmosphere is very thin, it doesn't carry much heat. There would be more heat loss to the ground than to atmosphere. One suggestion Dr. Boston came gave in her paper was an aluminized Mylar curtain drawn across the ceiling at night. To reflect radiant heat in. Some on this forum have questioned whether we need that if we have a spectrally selective coating on windows. A detailed heat conduction analysis will have to be done, but the idea is to control heat with passive solar thermal.

Dook wrote:

The only life support that operates during power loss is plants?  An RTG and solar panels aren't going to just stop working, the solar panels don't produce at night or in a dust storm but the RTG isn't going to just quit working.  If there was a fire in the tuna can that could be game over.  In that case, having some plants still alive doesn't matter.

Shit happens. The more complex the system, the greater chance of failure. No one expected the hydrogen fuel cell on Apollo 13 to explode, but it did. And we aren't talking about a human mission using an RTG, we're talking about an actual reactor. Both SP-100 and SAFE-400 are actual nuclear reactors, both produce 100 kWe. The Radio Thermal Generator (RTG) on Curiosity produces 110 Watts. That's 100,000 Watts vs 110 Watts; orders of magnitude different.

Last edited by RobertDyck (2017-05-03 14:29:56)

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#84 2017-05-03 13:16:21

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Air. Shelter. Water. Food.

"The only reason to support using artificial lighting in the greenhouse is in order to lengthen the growing day during winter."

Really? Here are a few other reasons why artificially lit crop production is a winner:

1. Means dust storms have no effect on crop production.

2. Means you can grow any crop you like, pretty much.

3. Means you can guarantee perfect crops.

4. Means you can grow much more on the same footprint, which reduces labour time.

5. Means the farm hab/greenhouse structure is much smaller (probably by a factor of 3-5 but could be more).

6.  If you're talking about soil, then you are talking about a lot of soil manufacture and movement with the greenhouse approach.

And let's remember that Mars economics are different from Earth economics.

Of course, on Earth you have the soil, the air, the pressurised atmosphere, the water all readily available. On Mars, you have to factor in how much labour, time and resources you are going to have to put into making your dome or other structure, keep it repaired and dust free and how much time and effort you are going to have to put into monitoring and harvesting your crops.






Oldfart1939 wrote:

I suppose that when I started this thread, I should have underscored that all of these essentials are involving endothermic processes, and having adequate energy available is the basis or foundation of this technological pyramid. I pointed out that loss of any of the 4 items listed would be fatal to the colony/base; inadequate energy is another fatal factor, since air production and water extraction are all energy intensive. As a dependent item, food production is based on Shelter, air, and water.
In a separate thread started by Robert, he suggests the greenhouse be built into a hillside for maximum solar gain in crop production. I cannot argue against that concept, and support it wholeheartedly. The only reason to support using artificial lighting in the greenhouse is in order to lengthen the growing day during winter. Direct solar illumination is by far the most efficient way of growing crops. Artificial lighting should be supplementary.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#85 2017-05-03 14:26:32

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Air. Shelter. Water. Food.

RobertDyck wrote:

RobertDyck

The limits to population levels are not based on how much iron or steel you have.  They are based upon oxygen creation, water recycling and collection, food production, and then shelter.  Having steel production doesn't give you any of those things and wastes time, energy, and equipment. 

I should remember the Mars Homestead Project called for 3 reactors?  No, I shouldn't.  The first settlement isn't going to waste electricity on making swords or any other metal objects.

PCTFE can survive the UV and cold on Mars?  For how long?  What happens when it fails?  Are you suggesting that an inflatable habitat surface greenhouse will last longer and better maintain temperature than a buried habitat?

We could harvest argon gas from Mars atmosphere?  So, you think a Mars settlement needs 3 reactors so they can produce enough electricity to make steel swords and argon gas for a surface greenhouse that will leak the argon over time?

The more complex the system the greater chance of failure?  Exactly.  That's why we should limit the uneeded enterprises and have long lasting habitats with multiple life support systems and plenty of spare parts.  Making small steel parts on Mars does not provide any extra oxygen, food, power, water, or habitat. 

You aren't talking about a mission using an RTG, you want a real reactor?  I know you do because you have this perception that the settlers will need to make small steel components and argon when they won't.

Last edited by Dook (2017-05-03 14:26:45)

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#86 2017-05-03 15:06:19

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,343
Website

Re: Air. Shelter. Water. Food.

Dook wrote:

The limits to population levels are not based on how much iron or steel you have.  They are based upon oxygen creation, water recycling and collection, food production, and then shelter.  Having steel production doesn't give you any of those things and wastes time, energy, and equipment.

Mars requires a lot of things. It requires pressurized habitats for people, life support equipment, and greenhouses to produce food. Manufacturing all that requires materials. Remember Mars has not only resources to support life, but resources for a technological society.

Dook wrote:

I should remember the Mars Homestead Project called for 3 reactors?  No, I shouldn't.  The first settlement isn't going to waste electricity on making swords or any other metal objects.

I've said so (posted) on this forum many times. How many times to I have to say it? And yes, a settlement is going to need materials for equipment, including habitats, life support and greenhouses. (repetition on purpose)

Dook wrote:

PCTFE can survive the UV and cold on Mars?  For how long?  What happens when it fails?  Are you suggesting that an inflatable habitat surface greenhouse will last longer and better maintain temperature than a buried habitat?

Yes. For several years. Again I expect an inflatable greenhouse on a science mission, and the first construction missions. Greenhouses built for a permanent settlement will be made with in-situ materials. For windows, the easiest material to make is glass. As I've said (posted) before, to avoid scratches during dust storms we should use tempered glass. That's glass that has been heat treated. An inflatable greenhouse will eventually fail, our only disagreement is now long it will last. But a glass greenhouse will last much longer. And a greenhouse made of in-situ materials can be repaired.

Dook wrote:

We could harvest argon gas from Mars atmosphere?  So, you think a Mars settlement needs 3 reactors so they can produce enough electricity to make steel swords and argon gas for a surface greenhouse that will leak the argon over time?

If you want nitrogen in breathing air, you need to harvest it from Mars atmosphere. A greenhouse also needs nitrogen, either in air for nitrogen-fixing plants, or nitrogen fertilizer, or both. Mars has 2.7% nitrogen, 1.6% argon, as measured by Viking 2 lander. I've posted before how to harvest nitrogen. One by-product is argon. Rather than whine about, use it for something useful.

Dook wrote:

The more complex the system the greater chance of failure?  Exactly.  That's why we should limit the uneeded enterprises and have long lasting habitats with multiple life support systems and plenty of spare parts.  Making small steel parts on Mars does not provide any extra oxygen, food, power, water, or habitat.

I've given a detailed list of life support equipment on ISS. Now tell me all the materials they are made of.

Dook wrote:

You aren't talking about a mission using an RTG, you want a real reactor?  I know you do because you have this perception that the settlers will need to make small steel components and argon when they won't.

And glass. And aluminum. And plastic. And textile fibres for spacesuit repair.
Most tools are made of steel.

But let's go back to basics. Robert Zubrin's Mars Direct is the basic science mission. It uses an SP-100 reactor in the ERV to produce propellant for return to Earth. I have posted that an updated Mars Direct would use a SAFE-400 reactor because it's newer, developed by exactly the same team, produces exactly the same amount of electricity, operates in exactly the same environment, and lower mass.

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#87 2017-05-03 15:52:29

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Air. Shelter. Water. Food.

RobertDyck wrote:

RobertDyck

Mars requires pressurized habitats, life support equipment, and greenhouses?  But every crew will land in a pressurized habitat that has two mini-Moxies and a WAVAR unit built in so all they need is to build a buried habitat to be used as a hydroponics greenhouse. 

Manufacturing habitats, life support equipment, and greenhouses requires materials?  Please provide detailed instructions on how you are going to make life support equipment on Mars in a BBQ sized forge. 

Mars has resources to support life?  No, it doesn't.  Any life you expose to a Martian environment will die other than maybe some extreme single celled life forms. 

A PCTFE can survive the UV and cold on Mars?  So it will last forever? 

Greenhouses built for permanent settlement will be made with in-situ materials?  No, they won't.  You have no idea how difficult it is.  You think it just takes a BBQ sized forge, it takes a whole lot more than that. 

Glass is easy to make?  No, it's not.  Most countries of the world can't make glass and they have oxygen, water, and a pressurized atmosphere to work in.

If I want nitrogen in breathing air I have to harvest it from Mars atmosphere?  Or, I could just bring a large cylinder of compressed nitrogen gas.

You posted on how we could harvest nitrogen?  If it doesn't require a steel forge and moving tons of regolith and wasting kilowatts of power to process material in order to get tiny amounts of nitrogen, then I might be okay with it.   

You gave me a detailed list of all the life support equipment on the ISS so I should tell you all the materials they are made of?  I must have missed your detailed list of all life support on the ISS. 

I should tell you the materials the life support equipment is made of?  Or you can look at a table of elements chart.   

Settlers will need to make glass, aluminum, and plastic?  No, they really won't.  They will need to tend to the plants, check systems, perform routine maintenance, and be able to repair. 

They won't grow textiles and process them to repair spacesuits, they will use a repair kit that they brought with them. 

Let's get back to basics?  I'm trying to get you to do that but you want to make swords on Mars. 

The ERV uses a SAFE-400 reactor?  Okay, but that's a full Moxie unit that needs to make rocket fuel.  The settlers will be there to stay and would only need some mini-Moxie units to make enough oxygen to breathe AND the plants in the buried habitat/greenhouse would make oxygen. 

If you get rid of all this non-life support equipment that you want to bring to Mars you can have a settlement with more backup systems, more food supplies, and less re-supply missions.

Last edited by Dook (2017-05-03 15:53:06)

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#88 2017-05-03 17:26:03

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,343
Website

Re: Air. Shelter. Water. Food.

Dook wrote:
RobertDyck wrote:

RobertDyck

Mars requires pressurized habitats, life support equipment, and greenhouses?  But every crew will land in a pressurized habitat that has two mini-Moxies and a WAVAR unit built in so all they need is to build a buried habitat to be used as a hydroponics greenhouse.

First realize a Mars Direct habitat will not be as large as MDRS or FMARS. The first version of Mars Direct was a single deck/story. It was to include a single pressurized rover, later changed to two open rovers. Not sure how those were to be delivered; probably strapped to the underside of the hab, lowered with a winch. But exhaust from landing rockets will kick up rocks, they could damage the rover. So in 1991 Robert Zubrin added a garage. The lower deck will include landing rockets, propellant tanks to feed the landing rockets, RCS thrusters for in-space manoeuvres during transit, propellant tanks for RCS thrusters, mechanisms for landing legs, life support equipment, solar arrays, batteries (Mars has night), air lock, stairway to the upper deck, and storage compartment for rover(s) and surface science equipment. That storage compartment will be about the size of a single-car garage, with a garage door that opens down to form a ramp. That means the storage compartment must be able to depressurize without compromising the hab. That's about it. The storage compartment will be usable as lab or workshop once all equipment is unloaded, but again only as large as a single-car garage. It'll look more like this... (from the year 2000 movie "Mission to Mars")
lander2.jpg

Also realize my mission plan calls for sending all missions to one spot, building up a base by accumulating equipment. And the interplanetary vehicle will be reusable. Eventually a reusable Mars shuttle will be developed and delivered, based on land-on-tail rocket technology of Falcon 9. This rocket would use LCH4/LOX and be able to shuttle astronauts from Mars orbit to Mars surface and back. A means to deliver propellant to the interplanetary vehicle would also have to be in place. Once that is done, astronauts will no longer arrive with a new habitat.

And Elon Musk's vision is much bigger: the Mars Colonial Transport. That will deliver 100 settlers at a time, and be entirely reusable. His vision would transport from Earth surface to Earth orbit, refuel, then proceed to Mars surface. It would refuel on Mars, then proceed back to Earth surface. So again, no new habitat.

Dook wrote:

Manufacturing habitats, life support equipment, and greenhouses requires materials?  Please provide detailed instructions on how you are going to make life support equipment on Mars in a BBQ sized forge.

Use the small forge to make a medium size forge. The medium size forge will be able to make equipment for a small settlement. However, the medium size forge will make material for a large industrial size forge. It's called "bootstrapping".

Dook wrote:

Mars has resources to support life?  No, it doesn't.  Any life you expose to a Martian environment will die other than maybe some extreme single celled life forms.

If you believe that, why are you here? This is the forum of the Mars Society. We want to establish permanent settlements on Mars. They will have to be self-sustaining. We aren't talking about some flags-and-footprints mission like Apollo.

Dook wrote:

A PCTFE can survive the UV and cold on Mars?  So it will last forever?

RobertDyck wrote:

An inflatable greenhouse will eventually fail, our only disagreement is now long it will last.

Dook wrote:

Greenhouses built for permanent settlement will be made with in-situ materials?  No, they won't.  You have no idea how difficult it is.  You think it just takes a BBQ sized forge, it takes a whole lot more than that.

Do you have any idea how long members of the Mars Society have been working on this? How many people have applied their skills and knowledge to this endeavour?

Dook wrote:

Glass is easy to make?  No, it's not.  Most countries of the world can't make glass and they have oxygen, water, and a pressurized atmosphere to work in.

Compared to polycarbonate (Lexan) or any form of fluoropolymer, yes it is.

Dook wrote:

If I want nitrogen in breathing air I have to harvest it from Mars atmosphere?  Or, I could just bring a large cylinder of compressed nitrogen gas.

Do you realize how expensive transport from Earth is? If you have to transport something as basic as air, then just stay home.

Dook wrote:

You posted on how we could harvest nitrogen?  If it doesn't require a steel forge and moving tons of regolith and wasting kilowatts of power to process material in order to get tiny amounts of nitrogen, then I might be okay with it.

I've posted it many times. Here is one of many posts: click here or here.

Dook wrote:

You gave me a detailed list of all the life support equipment on the ISS so I should tell you all the materials they are made of?  I must have missed your detailed list of all life support on the ISS.

Light weight nuclear reactor, updating Mars Direct

Dook wrote:

Settlers will need to make glass, aluminum, and plastic?  No, they really won't.  They will need to tend to the plants, check systems, perform routine maintenance, and be able to repair.

Read "The Case for Mars": Amazon books - sponsor the Mars Society

Dook wrote:

They won't grow textiles and process them to repair spacesuits, they will use a repair kit that they brought with them.

Orthofabric is a double layer fabric: PTFE fibre facing, backing is mostly Nomex with 2 threads replaced by Kevlar every 3/8" in each direction (warp and weft). That's all synthetic, it isn't grown. But an MCP suit would use a synthetic elastomer of some sort.

Dook wrote:

Let's get back to basics?  I'm trying to get you to do that but you want to make swords on Mars.

The ERV uses a SAFE-400 reactor?  Okay, but that's a full Moxie unit that needs to make rocket fuel.  The settlers will be there to stay and would only need some mini-Moxie units to make enough oxygen to breathe AND the plants in the buried habitat/greenhouse would make oxygen. 

If you get rid of all this non-life support equipment that you want to bring to Mars you can have a settlement with more backup systems, more food supplies, and less re-supply missions.

The goal of self-sufficiency is to reduce re-supply missions. And realize what we're talking about. First there's a science mission, which sounds like what you're talking about. Then a second science mission to the same location, accumulating equipment. A few science missions. They will test/demonstrate basic techniques. Then a construction crew who do not intend to return to Earth. These will build a serious workshop, and build not just tuna-can habs, but the first apartments on Mars. They will start with equipment in tuna-can habs, build a larger workshop, then the settlement with apartments will have substantially larger workshops, and several of them. That initial settlement will then build a larger settlement to receive the first 100 settlers. Only then will the first SpaceX MCT arrive. And remember, the MCT will require refuelling to return to Earth, and it's tanks are big.

Last edited by RobertDyck (2017-05-03 18:41:16)

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#89 2017-05-03 17:42:32

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,306

Re: Air. Shelter. Water. Food.

Robert-

Do ever get the feeling that Dook is simply Trolling us here? We've responded many times to the same inane questions/comments, but he keeps returning to the same assumptions not based on fact, but based on opinion.

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#90 2017-05-03 19:04:10

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 7,343
Website

Re: Air. Shelter. Water. Food.

Oldfar1939: I think you're right.

One piece of construction equipment we have talked about many times is a "Bobcat". I suggested reducing weight for transport, others pointed out the weight is necessary to counter the load, to ensure it doesn't tip. Ok, here's a suggestion: add a large "can" on the back that can be filled with Mars regolith. I notice large cranes have steel weights they add to the back to counter the weight of their load, how about doing something similar on Mars? But instead of bring large steel weights, add an empty can that can be filled with Mars regolith. That reduces weight for transport, but adds weight once on Mars. I suggested aluminum alloy is far too soft for a loader, but we could use titanium alloy. It's actually as heavy as steel, but substantially stronger so we could make structural members thinner to reduce weight. I also pointed out a skid-steer loader works great on hard flat ground or pavement, but tracks work better on loose soil, especially a sloped hillsides with loose soil. So I envision a compact track loader, like...
bobcat-t650-construction-64a6728-16i1-fc_head_left.jpg

Last edited by RobertDyck (2017-05-03 22:03:53)

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#91 2017-05-03 19:20:13

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Air. Shelter. Water. Food.

RobertDyck wrote:

RobertDyck

A Mars Direct habitat will not be as large as some other habitats?  Who told you it had to be?  So, you think people should not live in the tuna can because it's not big enough. 

You think settlers on Mars should have something better than they can have on the Earth.  They should have some comfort, a certain level of luxury, because that's what you would want.  Having an agenda other than the mission specifications is what got us the 90 day report and it will endanger the colonists lives if you prioritize a small steel production machine over extra food, water, and spare parts for life support equipment. 

In 1991 Zubrin added a garage or Rover hanger?  Sounds good.  We can launch a rover hanger with a long range rover and a Marscat and then launch a tuna can and have them dock in orbit and head to Mars as one spacecraft. 

Going on and on about Mars Direct doesn't support your claims that Mars needs production capability.  Even if you did spend months gathering material, processing it for purity, and somehow could make small steel parts on Mars what life support system runs on small steel parts?  Just name one. 

Your mission plan calls for sending all missions to one spot?  A base, good, we finally agree on something. 

Once a means to deliver propellant (from Mars to the interplanetary vehicle in orbit over Mars) is developed colonists won't arrive in a new habitat?  If that ever happens, which it probably will in about 1,000 years, then we will need more habitat on Mars but that has nothing at all to do with the first settlement. 

Elon Musks vision is much bigger?  And much more dangerous.  His transport has to be refueled four times in orbit over the Earth.  He's not going to be able to make it profitable and, at some point, he's going to get people killed just like the other billionaire did with his space tourism idea. 

The goal should not be to put a lot of people on Mars at first.  The goal should be to put as few as possible to build buried habitats for vegetables grown in hydroponics and plastic tubs in a stable pressure/temperature.   The population grows from the production of oxygen, food, and water, and then habitat.  Habitat doesn't come before the other three.

We could use a small forge to make a medium size forge?  To make what exactly?  Please name all the life support equipment that you can make with a medium sized forge? 

Can you make a Moxie?  No, just the outer case but even then it would be very thick, not thin rolled steel plate because you need a pressure roller for that.  Can you make a WAVAR unit?  Nope, perhaps you could make the rack and pinion for it but you would need to cut the teeth with some other equipment.  Can you make a solar panel?  Nope.  An RTG?  Nope.  So, your forge can't make any of the things that limit your population level so why is it that you think it's a need? 

Why am I here?  Because I am an efficiency expert, that's why.  People cannot think efficiently.  I've seen it too often.  When you have to do something new and complex you come up with all these ridiculous Rube Goldberg ways of doing it instead of just keeping it simple so it works better for longer.  You can't turn off your agenda.  You can't put the mission first.  That's why NASA screwed up the 90 day report so bad.  They're smart people but they can't turn off their agenda.  Having a new space rocket engine that runs on excited particles has nothing to do with putting humans on Mars just as having a BBQ sized forge has nothing to do with providing life support on Mars. 

You think that having a small forge on Mars means that they are automatically in the "modern age".  As if that's somehow important to survival on Mars.  It's not.  Having extra food is a hundred times more important than making some steel brackets that you don't need. 

Do I have any idea how long the members of the Mars Society have been working on this?  Probably since "The Case for Mars" has been out.  People don't always become more efficient in time, they can and often do become less efficient because they always want to input something new, they want to add in their great new idea even if it has nothing to do with mission success. 

Glass is easier to make than flouropolymers?  Just being easier to produce than glass doesn't make it practical to use time, energy, and equipment to produce it on Mars. 

Do I realize how expensive transport from the Earth is?  I do but I don't really care how expensive it is.  To you that is important because you want the most people possible on Mars as soon as possible.  I want settlement survival, which means 4 settlers and an emphasis on maintaining equipment and growing food.  You could care less if hundreds die because their greenhouse failed and the food shipment rocket failed to fire so it went right on by Mars and kept going.  You would just send 100 more people. 

I should read the Mars Societies updated Mars Direct plans?  I really shouldn't.  I expect they are be full of inefficient ways of doing things, let me guess, you want to use an electrolysis unit to make oxygen and rocket fuel.  Here's how to accomplish the task without having to gather ice on Mars.  You use two mini-Moxies to convert CO2 to oxygen, no rocket fuel needed.  The crew, instead of risking their lives to drive all over Mars collecting dirty salt water to try and make some oxygen, would maintain the life support equipment and grow food. 

The goal of self sufficiency is great if it were as easy as having a small forge.  It's not that easy.  It's way, way, way more complicated than that.  It takes many machines to make all the components of one complicated machine.  You can't do it with just a forge or a 3D printer. 

Please list all the life support components you can make with a forge.  I'm still waiting. 

I'm not talking about a science mission.  I'm talking about settlement.  I would have three exploration missions, all to different places on Mars, then land a tuna can and start the base. 

You want apartments on Mars?  I know, I've seen the pictures.  That might happen in about 500 years.

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#92 2017-05-03 19:25:10

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Air. Shelter. Water. Food.

Oldfart1939 wrote:

Robert-

Do ever get the feeling that Dook is simply Trolling us here? We've responded many times to the same inane questions/comments, but he keeps returning to the same assumptions not based on fact, but based on opinion.

Your post does not address the topic. 

Seems you're the one who is the troll.

Perhaps you could provide the facts that explain your idea to have a "thousand gallon a day" water treatment plant on Mars.  Or maybe give us all your facts on how your sewage treatment plant on Mars is going to work?

Last edited by Dook (2017-05-03 19:25:25)

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#93 2017-05-03 20:40:03

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 26,803

Re: Air. Shelter. Water. Food.

Oldfart1939 wrote:

Robert-

Do ever get the feeling that Dook is simply Trolling us here? We've responded many times to the same inane questions/comments, but he keeps returning to the same assumptions not based on fact, but based on opinion.

Say its not so not another.....

I think part of the issues that we are seeing is via shifting scale of ideas as we try to move forward past a day where we can transport and land something more than the small 2mT dragon crafts to something that can be factor of 10 greater with moving up the scale in ideas to what we want for mars as we leap into a future state not taking the time to indicate time scale or timeline to when we arrive to the events to which we are forecasting to...

I think infleatables do have a place in early mars colony developement as under ground units that are to be a sealed structure with the regolith supporting its self and not trying to hold down the inflateable.

I think that a structure that has windows will not be a full structure of windows but one that is mostly under the mars regolith with select location having a southern exposure for the windows to which they will cover maybe only about 20% of that side for natural lighting and for sanity of being able to look upon the Mars surface.

I think we will grow some plants and possibly food in such lighted areas but mostly we will once we can stay in the subsurface inflateables be using hydroponic gardening techniques with LED grow lights.

As the titles starts we have 4 if we lack any of these is a final curtain call but without power to make the 5th we are surely sunk as well. We take for granted here on Earth how lucky we are to have a planet that recieves about 1,000 watts of energy for each square meter where it counts at the temporate zone and for that same zone on mars we are only at 430 watts which tells just how far down the energy well we are starting at mars. So lucky that we have air to breath without using any energy to create it. That plants grow readily and that there is water for the most part all over this great planet and that what grows can be turned in to shelter.

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#94 2017-05-04 03:09:00

Terraformer
Member
From: Ceres
Registered: 2007-08-27
Posts: 3,560
Website

Re: Air. Shelter. Water. Food.

To be honest, I've just been skipping over most of Dook's posts, and most of the replies to them. He's operating on completely different assumptions to everyone else, basing his posts on the assumption that in-situ resources won't be used, therefore one shouldn't plan to use them.


"I'm gonna die surrounded by the biggest idiots in the galaxy." - If this forum was a Mars Colony

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#95 2017-05-04 03:53:22

Antius
Member
From: Cumbria, UK
Registered: 2007-05-22
Posts: 1,003

Re: Air. Shelter. Water. Food.

Most plants suffer frost damage if temperature drops beneath zero Celsius.  A radiation temperature of zero C corresponds to a solar flux of 316W/m2.  If maximum solar constant on Mars is 430W/m2, this suggests that it will be difficult to grow plants on Mars without some substitute heating.  Close to the equator, it may be possible to keep a greenhouse sufficiently warm without substitute heating if it is covered with insulation at night and when the sun is low in the sky.  We do not need to go to such lengths at high latitudes on Earth because the atmosphere is thick enough to maintain a warm outside temperature at night.

One way of trapping heat is to build the greenhouse in a shallow pit with reflective walls.  That way, the heat capacity of the walls provides thermal inertia that will assist in keeping the greenhouse above freezing at night.  Also, the ground around the greenhouse could include a network of hoses that will transfer solar heat into the greenhouse during the day, where it could be stored within a body of water.  One could incorporate heat pumps at higher latitudes.

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#96 2017-05-04 05:16:36

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Air. Shelter. Water. Food.

I think you're right there SpaceNut. The constraints have been relaxed somewhat, meaning we can move much more quickly towards Mars ISRU using a range of imported (mostly automated) machines, rather than having to focus purely on immediate life support.


SpaceNut wrote:
Oldfart1939 wrote:

Robert-

Do ever get the feeling that Dook is simply Trolling us here? We've responded many times to the same inane questions/comments, but he keeps returning to the same assumptions not based on fact, but based on opinion.

Say its not so not another.....

I think part of the issues that we are seeing is via shifting scale of ideas as we try to move forward past a day where we can transport and land something more than the small 2mT dragon crafts to something that can be factor of 10 greater with moving up the scale in ideas to what we want for mars as we leap into a future state not taking the time to indicate time scale or timeline to when we arrive to the events to which we are forecasting to...

I think infleatables do have a place in early mars colony developement as under ground units that are to be a sealed structure with the regolith supporting its self and not trying to hold down the inflateable.

I think that a structure that has windows will not be a full structure of windows but one that is mostly under the mars regolith with select location having a southern exposure for the windows to which they will cover maybe only about 20% of that side for natural lighting and for sanity of being able to look upon the Mars surface.

I think we will grow some plants and possibly food in such lighted areas but mostly we will once we can stay in the subsurface inflateables be using hydroponic gardening techniques with LED grow lights.

As the titles starts we have 4 if we lack any of these is a final curtain call but without power to make the 5th we are surely sunk as well. We take for granted here on Earth how lucky we are to have a planet that recieves about 1,000 watts of energy for each square meter where it counts at the temporate zone and for that same zone on mars we are only at 430 watts which tells just how far down the energy well we are starting at mars. So lucky that we have air to breath without using any energy to create it. That plants grow readily and that there is water for the most part all over this great planet and that what grows can be turned in to shelter.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#97 2017-05-04 07:27:56

Oldfart1939
Member
Registered: 2016-11-26
Posts: 2,306

Re: Air. Shelter. Water. Food.

One of the features of the hillside greenhouse as described by Robert is an ability to capitalize on some passive solar heating; as a result of having some structure (terraces) within, there will be more exposure to solar gain by the regolith sidewalls of the terraces. Even adding some big rocks painted black will assist. Some additional heating will undoubtedly be required, though.

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#98 2017-05-04 08:21:07

Dook
Banned
From: USA
Registered: 2004-01-09
Posts: 1,409

Re: Air. Shelter. Water. Food.

Terraformer wrote:

To be honest, I've just been skipping over most of Dook's posts, and most of the replies to them. He's operating on completely different assumptions to everyone else, basing his posts on the assumption that in-situ resources won't be used, therefore one shouldn't plan to use them.

We will absolutely use Mars in-situ resources to make oxygen, get water from the atmosphere, and regolith to grow plants.

The first settlers won't be driving around Mars gathering blocks of salty ice or buckets of regolith to bring back to the base and attempt to process it for tiny amounts of water or sulfur or iron oxide. 

Producing steel on Mars with a small forge, or having a 3D printer, does not increase the settlements oxygen, food, or water and those are the things that limit your population level.

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#99 2017-05-04 08:53:03

Antius
Member
From: Cumbria, UK
Registered: 2007-05-22
Posts: 1,003

Re: Air. Shelter. Water. Food.

A quick energy analysis: The average human being doing light work will consume 2300 Calories per day.  That’s about 10MJ of food energy, or an average power of 116 watts.  Food crops are about 1% efficient at fixing calories in natural sunlight, but only about 40% of sunlight is photosynthetically available.  So with a light spectrum tailored to plant photosynthesis, efficiency would be 2.5%.  Red light LEDs are now up to 50% efficient (See below).  So electricity to food efficiency is 1.25% for common food plants.  Some types of algae and C4 plants can do better, maybe double.  If meat is part of diet, it would bring efficiency down some.  So let’s say 1.25% efficient overall.

http://www.candlepowerforums.com/vb/sho … y-at-350mA

To cover food energy for one person would require a constant electric input 9.28kW per person, about 80,000kWh per person per year.  That is quite a lot.  To put it another way, a 1GW standard size nuclear reactor would feed 100,000 people if none of the electric power went anywhere else.  At a power cost of $0.1/kWh, the annual energy bill for food alone would be $8000 per person.  So for hydroponics to work well, the base / colony would need to prioritise cheap electric power.  That means lots of nuclear power.

On the plus side, hydroponic food production areas could be much more compact than any greenhouse arrangement and do not require windows.  So whilst energy costs are higher, construction costs are substantially lower.  Also, the hydroponics would generate most of the oxygen a colony would need and would produce a great deal of low and medium quality waste heat for space heating, water heating and desalination.  But it places a lot of emphasis on cheap energy.  That means nuclear energy, almost certainly using nuclear reactors that are built on Mars using native resources.  A solar power plant capable of generating sufficient power for one person would cover at least 600m2 even at the equator.  That’s a lot of infrastructure.

Last edited by Antius (2017-05-04 08:55:28)

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#100 2017-05-04 08:56:56

louis
Member
From: UK
Registered: 2008-03-24
Posts: 7,208

Re: Air. Shelter. Water. Food.

I agree we'll start with water extraction from the atmosphere - much more dependable and it can be commenced prior to the human landing.

But why would you stop at oxygen, water and farming? 

Why wouldn't you rapidly develop an industrial infrastructure using robots, automated machines and 3D printers? Per capita energy is certainly not an issue.  The early settlement will have available many times more energy per capita than is available in human communities on Earth.

Why wouldn't you use small "rocket hoppers" for exploration of the area around your landing point?  Why wouldn't robot rovers travel to areas of interest and bring back samples (maybe under human remote control)? 

I don't think these things are too difficult - with the right equipment of course. 

Dook wrote:
Terraformer wrote:

To be honest, I've just been skipping over most of Dook's posts, and most of the replies to them. He's operating on completely different assumptions to everyone else, basing his posts on the assumption that in-situ resources won't be used, therefore one shouldn't plan to use them.

We will absolutely use Mars in-situ resources to make oxygen, get water from the atmosphere, and regolith to grow plants.

The first settlers won't be driving around Mars gathering blocks of salty ice or buckets of regolith to bring back to the base and attempt to process it for tiny amounts of water or sulfur or iron oxide. 

Producing steel on Mars with a small forge, or having a 3D printer, does not increase the settlements oxygen, food, or water and those are the things that limit your population level.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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