Tuesday, December 20, 2016

Siting Ocean Nuclear Power Plants in Remote US Territorial Waters for the Carbon Neutral Production of Synfuels and Industrial Chemicals

US island territorial waters most suitable for floating nuclear synplexes:

Uninhabited islands: Jarvis Island, Palmyra Atoll and Kingman Reef, Johnston Atoll, Howland and Baker Islands, Aleutian Islands (Near Islands, the Rat Islands, Buldir Island and the Island of the Four Mountains)

Islands exclusively occupied by the US military: Wake Island, Midway Atoll

by Marcel F. Williams

The fossil fuel dominated energy economy of modern human civilization has now pushed the carbon dioxide (CO2)  component of our atmosphere above 400 parts per million. This is a 40% increase in carbon dioxide levels in the atmosphere since the start of the industrial revolution.  The Pliocene epoch was last time CO2 levels in the atmosphere were as high , the geologic period that preceded the Pleistocene and the emergence of our genus (Homo). So modern humans are currently living within an atmosphere that is not only alien to our species but also to are genus.    

The enhanced greenhouse effect resulting from the ever increasing amounts of  carbon dioxide being  put into the atmosphere by human activity  is already starting to melt the  the polar icecaps. And melting icecaps are  gradually increasing global sea levels. Rising sea levels caused by increased amounts of atmospheric CO2 is nothing new in the natural history of the Earth.  But the deposition of carbon dioxide into the atmosphere by human activity is something new. And it threatens to  rapidly expose our species and the other plant and animal species currently living on our planet to higher global temperatures and sea levels not seen in millions of years. In the decades and centuries to come, the results of global warming from human activity could drown our coastlines and our coastal cities while causing the mass extinction of many, if not most, of the plant and animal species on our planet.

Politicians have tended to expressed concern about the long term consequences of  carbon dioxide induced climate change from human civilization. But in reality,  there has actually been very little serious pressure placed on  the global  energy companies to shift from a fossil fuel economy to a carbon neutral energy economy. Fear that a shift from fossil fuels could threaten economic prosperity has often been expressed by the global energy companies. And some politicians beholden to the economic might of the energy companies have even denied that CO2 induced global warming is a problem at all.  Of course, since the energy companies have trillions of dollars invested in the fossil fuel economy, they really have no  incentive to move away from a fossil fuel economy.

Top Ten Greenhouse Gas Emitters in 2014 

China - 29.55%

USA - 14.95%

European Union - 9.57%

India - 6.56%

Russia - 4.95%

Japan - 3.58%

Iran - 1.73

South Korea - 1.71%

Canada - 1.58%

Brazil - 1.40%

Fortunately, we Americans and other democratic republics around the world do have an interest and the power  to do what's best for humans and for the Earth's environment. And countries that tend to care about the quality of their environment  also tend to develop economies with the most  prosperity.  And it is in the long term  interest of human society to move towards a carbon neutral economy as rapidly as possible in order to protect the Earth's environment and the quality of human life and economic prosperity.

World Energy Consumption

China - 20.2%

USA - 19.0%

Russia - 5.8%

India - 4.4%

Japan - 4.3%

Germany - 2.7%

Canada - 2.6%

France - 2.1%

No Shortage of Uranium

Despite the phobia that surrounds the industry, nuclear energy would seem to be the simplest and the  most rapid way to deal with the threat of human greenhouse gas induced climate change. Nuclear power produces nearly 20% of the electricity in the US and nuclear energy represents approximately 6% of the world's energy consumption.

The current world demand for uranium is over  70,000 tonnes per year. Terrestrial uranium resources exists in ore reserves that are economically viable at $59 per pound in US dollars.  But it is estimated that there are approximately 5.5 million tonnes of proven uranium reserves at a cost below $130 per kilogram. With the resurgence of nuclear power, the exploration for new uranium sources could increase total terrestrial uranium reserves to more than 16 million tonnes. So there should be enough uranium to supply current global nuclear power demand for at least 200 years. But this is clearly not enough provided electric power and synthetic fuels and industrial chemicals for all of civilization.

Nuclear breeding technologies such as fast neutron reactors or ADS accelerator reactors could increase fuel supplies by a factor of 140 since fissile uranium 235 only represents about 0.7% of natural uranium. But terrestrial reserves of fertile thorium are even more plentiful. There is at least 3 times as much terrestrial thorium 232 as there is uranium 238. Thorium would be one of the easiest ways to recycle the plutonium produced from the fission of  uranium 235  within fertile uranium 238. So nuclear technologies that also utilize fertile uranium and thorium supplies in breeding technologies could provide civilization with all of the electric power, fuel, and chemicals that it needs. 

While terrestrial deposits rich in uranium and thorium are relatively  limited, the Earth's oceans contain about 4.6  billion tonnes of uranium. That's also  enough nuclear fuel to provide electric power and synthetic fuels and industrial chemicals  for human civilization for at least a few thousand years without the need for breeding technologies.

However the uranium content of the oceans is naturally replenished by a natural equilibrium between the hydrosphere and the terrestrial environment. And the rocks that chemically interact  with the Earth's hydrosphere contain nearly 100 trillion tonnes of uranium.  So whenever uranium is extracted from seawater, it is replenished by is chemical interaction with the Earth's rocks and soil, leaching their uranium content into the rivers and oceans. Marine uranium, therefore, is a renewable resource that could provide all of humanity's energy needs for the next billion years, about the time when the Earth's oceans will probably disappear because of the continuing natural increase in the sun's luminosity.

Current technology can extract uranium from seawater at a price of $200/lb of U3O8. Nuclear fuel, however, only represents less than 12% of the total cost of electricity from nuclear power plants and the  uranium ore itself, only represents about 46% of the total  cost of the fuel before it is enriched and fabricated for use in a nuclear reactor.   So even at quadruple the current price of uranium, marine uranium would only increase the cost of electricity from nuclear power by a meager 15%.

Environmentally Safest Commercial Energy Technology on Earth

Despite a few serious accidents in Japan, the Ukraine, and in the US, commercial nuclear power is still statistically the safest form of electric energy production. Unfortunately, we live in a global society that still has an inordinate  fear of ionizing radiation. This is despite the fact that  humans and all other plant and animal species on this planet live on a world and within a universe that is naturally radioactive-- and always has been! 

Global Mortality Rate related to commercial energy production (deaths/trillion kWhr)

Coal (global average) 170,000

Oil - 36,000

Biofuel/Biomass - 24,000

Natural gas - 4000

Hydroelectric (global average) - 1400

Solar panels (rooftop) - 440

Wind - 150

Nuclear (global average) - 90

Wind and solar energy have long been touted as-- safe long term solutions-- to climate change. But such renewable systems are extremely land intensive and  only produce energy when the wind is blowing or when the sun is shining. While the storage of wind and solar energy would solve this problem, it would also require a substantial  increase in the number of wind and solar power facilities in order to make up for the majority of time when energy is not being produced and the lowered efficiency of energy storage and power production from stored energy.  Wind and solar power plants  also have significantly shorter lifespans than commercial nuclear power plants that can last at least 60 years or longer.  So replacing old wind and solar power plants with new facilities could double or even quadruple the number of units required to produce the same amount of energy as nuclear power plants could.

Solar power currently produces less than 0.1% of the energy consumed in the US. So even if solar energy production were increased by 100 times, it would still produce less than 10% of America's current energy needs-- and even less for the even larger American populations thirty to forty years from now.

The manufacture of solar panels produces at least 10,000 times as much toxic waste as nuclear power plants. The spent fuel from commercial nuclear power plants is so tiny that all of the spent fuel ever produced by the commercial nuclear industry in the US could be housed in an area the size of a football stadium only a few meters high. Of course, most of the content from spent fuel could be recycled to produce even more carbon neutral electricity.

Environmentally, wind power plants are well known to be deleterious to predatory birds and bats that feed on pest that either harmful to humans or their food supplies.  And while some find them aesthetically beautiful, others find them eyesores the destroy the beauty of the local landscape. 

No American lives have ever been lost as the result of exposure to excessive amounts of radiation from the commercial nuclear industry. and America currently has the most  commercial nuclear reactors currently operating. But as remarkably safe as nuclear power plants are today, they would be even safer if they were deployed on the Earth's oceans.

MIT floating nuclear reactor concept (Credit: MIT)

Lack of coolant (water) caused the partial  meltdowns at the Light Water reactors at  Fukushima in Japan and at Three Mile Island in the US. However, the deployment of light water nuclear reactors out to sea could offer the commercial nuclear industry an inherently safe environment for producing carbon neutral energy.  The ocean's almost infinite heat sink of seawater would  completely eliminate the possibility of nuclear fuel meltdowns for light water reactors deployed out at sea.

Most proponents of floating nuclear reactors would like  to moor such power plants just 10 to 20 kilometers offshore. While this might be convenient for supply electric power to coastal towns, cities, and industries, it might also leave such facilities easily vulnerable to attacks from both the sea and air by hostile entities.   While such attacks on a floating nuclear facility would probably pose little danger to the public and to the environment,  the resulting sociological and political  effects could be  financially devastating for companies that own or who manufacture such facilities.
US Navy floating modular platform concept (Credit: US Navy)

Deploying a floating nuclear reactor within the cavity of a pair of  floating storm shelters, cement barriers designed to enclose and shield the facility from severe weather and from potential aerial and ocean attacks,  could greatly enhance the protection of floating nuclear reactors.  Such floating barriers could easily be derived from the US Navy's modular floating platform concepts.  They could completely envelope a floating reactor by simply using tugs to pull the larger half of a shelter over the smaller half of the shelter. While such barriers wouldn't make it absolutely impossible for floating nuclear power plants to be seriously damaged, they  would  make it very difficult and extremely expensive for potential terrorist to damage a floating nuclear facility.
Floating storm shelters derived from the US Navy floating platform concepts. Under this concept, the floating reactor would mostly be housed within the smaller shelter.  Normally, the cavity of the larger shelter would face the cavity of the smaller shelter less than 100 meters away.  This would allow sea vessels to easily arrive and depart from the floating reactor. During a major storm, tug boats would move the larger shelter over the smaller shelter, completely enclosing the floating reactor within the two storm shelters. This would also be the configuration in case some entity attempts to damage the floating reactor by air or by ship.    

How Many Reactors? 

US Energy Consumption in 2015
(Credit: Lawrence Livermore National Laboratory):

39.0% - Electricity 

28.4% - Transportation

21.8% - Industrial chemical and other  processes (minus the electricity utilized)  

  6.7% - Non-electrical residential heating and cooking

  4.1% - Non-electrical commercial heating, cooking, and other processes

About  409 1.1 GWe (1100 MWe)  terrestrial nuclear reactors would be required to completely replace all of the electricity currently produced in the US by other sources of electricity (coal, natural gas, hydroelectricity, wind, solar, etc.). That would require a five fold increase in current nuclear electric power production.  Some of the electricity could be used to convert urban and rural biomass into methanol for the production of electricity during  peak load hours. Such a substantial increase in  nuclear electric power production  in America could easily be accomplished by simply accommodating up to eight 1.1 GWe nuclear reactors  at every existing site in America.

A five fold increase in terrestrial nuclear power  would still only meet about  39% of America's total energy needs. And, of course, these figures don't even account for future American electricity demand 30 to 40 years from now due to simple population growth. This figure also doesn't  include the probable increase in electricity demand from the growth in the number of  automobiles that either partially or totally use electricity. This figure also doesn't include the increase in domestic electricity demand if all Americans switched from using natural gas to electricity for cooking, space heating, and water heating.

Even with a shift towards electric vehicles, the demand for transportation fuel for planes, ships, and ground vehicles is still going to be enormous. And huge amounts of energy will also be required for the production of industrial chemicals and fertilizers.

Major carbon neutral synthetic fuels and industrial chemicals that could be manufactured at remotely sited floating nuclear synplexes

1. Methanol

2. Gasoline

3. Diesel Fuel

4. Jet fuel

5. Dimethyl ether 

6. Liquid hydrogen

7. Liquid oxygen

8. Fresh water

9. Sodium Chloride

10. Ammonia

11. Urea

12. Formaldehyde

13.  Chlorine

14. Uranium

It would require at least 964 synthetic fuel producing nuclear reactors (1100 MWe each) to replace America's current gasoline needs.  441 reactors would be required  to replace America's diesel fuel demand.  152 reactors would be needed to replace current civilian and military jet fuel demand. These figures, of course, don't account for future demand over the next 30 or 40 years due to population growth. So 1557 1.1 GWe floating nuclear reactors would be needed to provide the carbon fuels for all of America's-- current transportation needs.

Number of 1.1 GWe (1100 MWe) nuclear reactors needed to annually supply all of America's current transportation fuel needs:

964 floating reactors -  carbon neutral gasoline production

441 floating reactors - carbon neutral diesel fuel production

137 floating reactors - carbon neutral  production of civilian jet fuel

15 floating reactors - carbon neutral production of military jet fuel

An additional 1195 floating reactors would be needed to meet America's industrial chemical and fertilizer needs. So just to replace fossil fuels for transportation, industrial chemicals and chemical fertilizers would require 2752 1.1 GWe floating nuclear reactors.

And, again, these figures don't include the inevitable increase in energy demand due to population growth. And there's also the daunting reality that America only consumes about 20% of the world's energy needs. Could America or other nations provide for the rest of the world's clean energy needs?

Exclusive Economic Zones

America is a nation that's still finding it politically difficult to keep a little more than 100  nuclear reactors currently operational within the US.  And with only four new nuclear reactors (~4.4 GWe) currently under construction, its rather difficult to imagine Americans adding more than 3000 terrestrial nuclear reactors to the continental United States--  over the next 30 to 40 years.

It would be equally as politically daunting, in my opinion, to  attempt to deploy thousands of floating nuclear  reactors along the coastlines of the United States over the next 30 to 40 years. So why even go through the process of  attempting to deploy floating nuclear power plants near any populated American coastline at all when its totally unnecessary!  

Public and environmental  fears about deploying floating  nuclear facilities and floating synthetic fuel producing facilities off the populated coast of continental North America could be completely eliminated by simply transporting such facilities-- far out to sea.

America has economic control over vast amounts of ocean territory thousands of kilometers away from populated coastlines. Some of these Exclusive Economic Zones surround uninhabited islands or islands exclusively occupied by small numbers of  US military personal.

Wake Island, for instance, has about 7.1 square kilometers of land area surrounded by a US   Exclusive Economic  Zone (EEZ) of over 407 thousand square kilometers. Administered by the  United States Air Force, the island is only occupied by 94 US personal. The airfield on Wake Island is currently  used as a mid-Pacific refueling stop for US military aircraft.

The US territory of Wake Island.

If just  one quarter of the Wake Island EEZ territory that is at least 50 kilometers away from the island's land and lagoon area were allowed to be utilized for the deployment of floating nuplexes and synplexes, nearly  100,000 square kilometers of territorial waters would be available. This region could be used to produce carbon neutral synthetic fuels and industrial chemicals. Another 100,000 square kilometers of territorial water on the opposite side of the island could be exclusively used for potential Seasteading, aquaculture, and floating farms  while the rest of the territorial water (more than half) would be under conservation including the 50 kilometer stretch of water encircling the island.

Floating nuplexes could  consist of eight to sixteen 1.1 GWe nuclear reactors floating along the arc of a circle four kilometers in diameter.   A cruise ship could be placed at the center of the circle, to kilometers away from each floating reactor,  to house the nuclear workers when they're off duty and may also serve as a floating home for their families.

Each floating nuplex would provide between  8.8 GWe to 17.6 GWe of power (more than four to eight times more power than the typical two unit nuclear plants in the continental USA). 

The fuel and industrial chemical producing  synplexes could be positioned between five to ten kilometers away from the nuclear facilities to ensure that any accidental chemical explosions can't potentially damage any of the nuclear facilities or to their protective storm shelters.

Power to the floating synplexes would come from submarine cables connecting them to the floating nuplexes. So the entire   8.8 GWe to 17.6 GWe nuplex  and surrounding synplexes could be deployed within a circle up to 24 kilometers in diameter. In reality, of course, the floating nuplexes and synplexes would physically only occupy an extremely tiny fraction of this 452 square kilometer area.

Within the proposed 100,000 square kilometer area,  more than 221 nuplexes and their surrounding synplexes could be produce between 1945 GWe to 3890 GWe of electric power.  So this one remotely sited region alone could potentially provide the United States will all of its energy needs.

But if we add a quarter of the EEZ waters surrounding the remote uninhabited islands of the Johnston Atoll, Palmyra Atoll, Jarvis Island, and Baker Island and the US Navy occupied Midway Island Atoll then more than 23 TWe of electric power could be produced, more than enough to provide all of the energy needs for the entire planet!

Beyond the tropical Pacific islands, Alaska might be the only State in the Union that might be willing to accommodate thousands of floating nuclear reactors with its Exclusive Economic Zone. This might be particularly true in the vast  EEZ waters both north and south of the Aleutians. Less than 8500 people live on a few of the Aleutian islands with more than half living on the island of Unalaska. But Alaska has more than 3.7 million square kilometers of EEZ territory. So just a quarter of Alaska's EEZ territory could provide energy for the entire planet.

Of course, the US shipyards could  manufacture and deploy floating nuclear reactors to  some of the vast  remote EEZ areas controlled by other nations. It might be in the interest of the United States to deploy at least some of their Ocean Nuclear assets in the Atlantic within the remote and  EEZ areas of strategic allies such as Europe.  The UK Ascension Island EEZ in the South Atlantic might be a particularly suitable for for the deployment of American and possibly British Ocean Nuclear facilities and synplexes.

Using Renewable Methanol in Natural Gas Power Plants and Methanol Power Barges

Beyond the ocean production of transportation fuels and industrial chemicals, remotely sited synplexes could also  easily supply all of the world's electricity needs by simply producing methanol. Remotely sited nuclear synplexes could produce methanol by importing biowaste and other carbon waste imported from coastal towns and cities. Coastal communities would probably pay to have their garbage towed away, reducing or eliminating the cost of ocean transport. A floating plasma arc pyrolysis plant could convert the imported garbage into syngas which could then be converted into methanol. However, since approximately 66% of the carbon in this process is CO2 waste , substantially more methanol could be produced through the production of hydrogen through the electrolysis of water distilled from seawater. 

The US Navy's new synfuel from seawater technology could also be used to produce carbon neutral synthetic fuels and industrial chemicals. 

Ironically, the infrastructure for utilizing methanol for electric power use on continental America already exist thanks to some of the fossil fuel utility companies.   Only minor modifications are required to covert natural gas turbine electric power plants into turbines capable of using methanol to produce electric power. This was demonstrated decades ago.  So the rapid growth of natural gas power plants could be a back door for the emergence of nuclear power in the form of methanol remotely produced far out to sea at floating synplexes.  And the tankers that could ship methanol to continental America could also be powered by methanol as a growing number of vessels are today.

Existing  cryogenic carbon capture technology, could   liquify up to 99% of the CO2 produced from the  flu gasses of methanol power plants. That CO2 could then be transported by tankers back to the floating nuclear synplexes for the production of more methanol. Such a fuel cycle could make methanol from nuclear energy, carbon negative (permanently extracting CO2 from the atmosphere as the number of methanol power plants grow). So if floating nuclear synplex are used to replace existing fossil fuel power plants and even carbon neutral nuclear and renewable power plants, floating nuclear synplexes for electricity production would actually be carbon negative-- gradually reducing the amount of CO2 in the atmosphere until such facilities finally reach the point where they completely replace other forms of electricity production. So while the growth of terrestrial nuclear reactors would be carbon neutral, the growth of Ocean Nuclear Power plants exporting methanol for electricity production and recycling the CO2  would be carbon negative

106 MWe natural gas powered electric energy barge (Credit: Wartsila Corporation)

Electricity from methanol for coastal towns and cities that don't have existing natural gas power plants could could be quickly deployed through methanol power barges. The US  could   manufactured and deployed such power barges to coastal towns and cities with the US and  around the world. In the US, methanol power barges could also be deployed inland via the Saint Lawrence Seaway to the Great Lakes States or inland states adjacent to the Mississippi and Ohio Rivers with methanol tankers entering the Mississippi River via the Mississippi River Delta.

The waste heat from the methanol power barges could also be used to desalinate seawater, providing both electricity and palitable water to coastal towns and cities. Such electricity and freshwater producing barges might be particularly attractive to states like California which is currently in the middle of a multi-year drought.

Jobs, the Reindustrialization of America, and Seasteading

States with active Shipyards (Credit: MARAD).

Employment related to shipbuilding and repair (Credit: MARAD)

If natural gas is eventually banned in the US for domestic and commercial use for heating and cooking then there will probably be a dramatic increase the use of electricity. And that would probably require an additional 100 land based nuclear power plants.

Replacing the additional 100 land based nuclear reactors with synfuel from Ocean nuclear reactors would require 400 floating reactors. If all 500 land based nuclear power plants were replace by synfuel from Ocean Nuclear power plants then  at least 2000 reactors would be required. This is  because of the substantial  inefficiency of converting electricity into to carbon fuels, transporting the fuel to coastal towns and cities  and then converting those carbon fuels back into electricity again.

However, the cost of electricity at ocean nuclear sites should  be dramatically lower than that of land based nuclear sites because Ocean Nuclear reactors are likely to be centrally mass produced. And most of the cost of nuclear electricity is due to it high  capital cost.  The recycling of flu gases from power plants using fuels from Ocean Nuclear technology could also significantly increase the fuel production since electricity wouldn't have to be used to for the extraction of CO2. 

The deployment of floating nuclear reactors, floating protective structures, floating synplexes, cruise ships, methanol tankers, methanol power barges and methanol powered tankers for the transport of other synthetic fuels and industrial chemicals will, of course, require a resurgence of the US shipbuilding industry. And that would mean a resurgence of hundreds of thousands of new jobs at shipyards in States along the Atlantic and  Pacific Coast and the Gulf Coast  and even within the Great Lakes region. 

Major shipbuilding activities in an Ocean Nuclear economy

Floating nuclear power plants

Floating nuclear storm shelters 

Methanol fueled tankers:

Methanol tankers

Gasoline tankers

Diesel fuel tankers

Jet fuel tankers 

CO2 tankers

Industrial chemical tankers


Methanol electric power barges

Synfuel production barges

Biowaste transport barges 

Cruise ships designed to house floating nuclear power plant workers and synplex personal

Artificial islands and breakwater structures  for ocean nuplex and synplex workers (Seasteading)

But millions of jobs would be created for US citizens operating far out to seas at  ocean nuclear synplexes. And this might well be the beginning of still another major ocean oriented shipyard industry, the creation of artificial residential islands for all of those millions of Americans working far out at sea! Ocean Nuclear and Ocean Synplex workers may end up being the first large group of American Seasteaders.

There should still be a place for terrestrial nuclear reactors in the US, in my opinion. But the future of terrestrial nuclear power is in the mass production of small nuclear reactors that are placed underground for enhanced safety. But most of the energy for electricity, synfuels, and industrial chemicals in the 21st century will probably be produced by floating synplexes powered by remotely sited floating nuclear power plants.

Links and References

Uranium (Wikipeidia)

Advances in extracting uranium from seawater announced in special issue

Uranium Seawater Extraction Makes Nuclear Power Completely Renewable

Fueling our Nuclear Future

The Economics of Nuclear Power

How deadly is your kilowatt?

Solar industry grapples with hazardous wastes

Jinko Solar Apologizes for Pollution


Will Russia and China Dominate Ocean Nuclear Technology?

The Future of Ocean Nuclear Synfuel Production

The Floating Stable Platform: Office of Naval Research

Methanol to Power Demonstration Project

Simple Cycle Methanol Power Plant

Methanol Economy

 The Production and Utilization of Renewable Methanol in a Nuclear Economy

The feasibility and current estimated capital costs of producing jet fuel at sea using carbon diox-ide and hydrogen

Market and Economic Assessment of Using Methanol for Power Generation in the CaribbeanRegion 

Exclusive Economic Zones 

What is the EEZ

U.S. Maritime Limits & Boundaries

Plasma arc gasification

Power Barges around the world 

Waller Marine Power Barges

Tuesday, October 18, 2016

Inflatable Biospheres for the New Frontier

X-Ray of a notional regolith shielded 16 meter in diameter biosphere (Credit: NASA)
by Marcel F. Williams 

At least 0.1 g is required for  unaided human traction when walking  on a low gravity world. And some studies suggest that some individuals may have difficulty-- non-visually-- perceiving up and down under a gravity that is less than 1.5 g. There are also some questions as to whether rigorous exercise will be enough to prevent human bones from losing  significant amounts of calcium  under low gravity environments that could cause bone fractures-- especially when returning to Earth.

Planets and Moons within the solar system that are potentially suitable for human colonization:


surface gravity relative to the Earth: 0.17g

diameter relative to the Earth: 27.3%

surface area relative to the Earth: 7.4%


surface gravity relative to the Earth: 0.38g 

diameter relative to the Earth: 53.1%

surface area relative to the Earth: 28.4%


surface gravity relative to the Earth: 0.38g 

diameter relative to the Earth:  38.3%

surface area relative to the Earth:  14.7%


surface gravity relative to the Earth: 0.13g 

diameter relative to the Earth:  37.8%

surface area relative to the Earth:  14.3%

Note: Land area comprises ~ 29% of the Earth's surface with ~71% covered by water

But even if future human colonist  can physically and psychologically  adjust to living and reproducing  on the surfaces of low gravity worlds, its  unlikely that such individuals would spend more than ten percent of their time outside of the protective envelope of their pressurized habitats. Even on the surface of Mars, during solar minimum conditions, cosmic rays could expose colonist to levels of radiation exceeding that legally allowed for radiation workers on Earth in just two months. And on extraterrestrial worlds without atmospheres such as the Moon, Mercury, and Callisto,   pressure suits with more massive radiation shielding would be required to protect the human brain and cardiovascular system from the enhanced dangers of  heavy ions.

Radiation levels on the Moon and Mars

Surface of the Moon:

38 Rem - annual amount  of cosmic radiation on the Lunar surface during the solar minimum

11 Rem - annual amount of cosmic radiation on the Lunar surface during the solar maximum

Surface of Mars:

33 Rem - annual rate of cosmic radiation on the surface of Mars beneath 16 gm/cm2 of Martian atmosphere during the solar minimum

8 Rem - annual rate of cosmic radiation on the surface of Mars beneath 16 gm/cm2 of Martian atmosphere during the solar maximum

Pressurized habitats in extraterrestrial environments can easily be protected from dangerous levels of cosmic radiation and their  heavy nuclei component with just a few meters of  regolith or several meters of water.  However, the fetuses of pregnant women and children growing up on   extraterrestrial  worlds are substantially more vulnerable to higher levels of  radiation exposure and will probably have to spend a lot more time within the protective confines of pressurized habitats.  

Internal configuration of a  lunar habitat derived from  SLS propellant tank technology. A  regolith wall composed of kevlar sandwiched between eight rigid aluminum panels is deployed around the habitat cylinder and filled with regolith to protect astronauts from cosmic radiation, micrometeorites, and fluctuating temperatures on the lunar surface. The airlocks are derived from ETLV propellant tank technology.

So it appears likely that future colonist  living on the surfaces of extraterrestrial worlds will  probably have to spend at least 90% of their time inside of radiation protected pressurized  habitats. Therefore, pressurized habitats that are spacious enough  and aesthetically comfortable enough for people not to mind spending  90% of their lives living and raising their families in indoor environments will probably be necessary.

The deployment of huge— inflatable biospheres— could provide a large variety of aesthetically spacious and comfortable environments for colonist on extraterrestrial worlds-- especially if the upper half of a biosphere is utilized to provide open spaces for parks and recreational activities. 

NASA researchers have previously proposed deploying a 16 meter  biospheres to the lunar surface weighing 2.2 tonnes with a safety factor of five. The mass of the inflatable material increases in proportion to the mass of the atmosphere that it envelopes.   Here, I propose using the SLS in combination with large cargo landing vehicles to deploy 28 tonne Kevlar-29 biospheres to the surfaces of the Moon and Mars  with an inflated  pressurized volume of 33,510 m3 and a diameter of 40 meters.  Nitrogen and oxygen environments could be provided in such pressurized biospheres with an Earth-like  14.7 psi (101.3 kPa) of pressure similar to atmosphere aboard the ISS— with a safety factor of four.

Notional Lunar Cargo landing vehicle that could transport regolith habs and deflated Kevlar biospheres to the lunar surface.

An extraterrestrial cargo landing vehicle with 30 tonnes of LOX/LH2 propellant could deploy a deflated 28 tonne biosphere to the surface of the Moon from EML1. Similar biospheres could be deployed to the surface of Mars using lunar landing vehicles coupled with  ADEPT deceleration shields currently being developed by NASA. An ADEPT deceleration shield would be capable of deploying up to 40 tonnes of cargo to the Martian surface.

Notional ADEPT deceleration shield for deploying payloads to the Martian surface. (Credit: NASA)

Possible ADEPT architectures that could deliver up to 40 tonnes of cargo to the Martian surface. (Credit: NASA)

On Mars, the nitrogen component for the pressurized atmosphere of the biosphere could be extracted from the Martian atmosphere which contains nitrogen at  approximately 1.89%. On the moon, nitrogen would have to be derived from possible ammonia deposits at the lunar poles or exported from Earth.

The oxygen component of the biosphere's pressurized atmosphere could be derived from the electrolysis of water extracted from ice deposits from the lunar poles or directly derived from the pyrolysis of lunar regolith. Oxygen derived from water on Mars could be derived from various regions on Mars that are rich in water ice.

Notional 40 meter in diameter regolith bag shielded Lunar biosphere connected to two Lunar Regolith habs
Since the top half of a Lunar  biosphere would be above the surface,   the upper hemisphere would be protected from micrometeorites and extreme temperature fluctuations by covering the upper exterior dome with regolith bags. Regolith bags would also protect humans inside from heavy nuclei while reducing overall cosmic radiation exposure to appropriate levels. Constructing a supporting geodesic dome inside of the upper dome area of the biosphere   could be  protected from a rapid collapse if the Kevlar walls are punctured.   Light fixtures could even be placed on the internal geodesic dome for internal illumination.

Notional 40 meter in diameter biosphere covered with a water filled biodome to protect inhabitants from cosmic and UV radiation. Since there would be no danger from micrometeorites on Mars, regolith shielding the upper dome would be unnecessary.
On Mars, a transparent water filled biodome could be placed on top of the top hemisphere of a transparent Kevlar biosphere to protect the inhabitants from radiation while still allowing in sunlight.  The transparent water filled biodome could be embedded a transparent UV protective film to shield inhabitants from ultraviolet radiation.  This would allow inhabitants occupying the top half of the biosphere to enjoy the Martian sunlight during the day and to view the stars at night. Since the atmosphere of Mars is so thin (~ one percent of the Earth’s atmosphere) the high heat conductivity from the thick Earth-like pressurized biosphere would keep the liquid water in the external water dome from freezing. The water dome could be  replaced if it becomes  soiled with dust from periodic dust storms on Mars or an enormous tent could be  temporarily placed over the water dome to   protect it from being soiled during dust storms. 

The upper half of a biosphere could be used for open space recreational activities and sports while the lower, underground, half of the biosphere could be used for housing and commercial structures.  But,  homes and apartment buildings similar to those found on Earth could also be assembled and  placed on the bottom surface of the top half of the biosphere, if desired,  along with grass and trees and other foliage to enhance the aesthetic environment.
X-ray of a 40 meter in diameter lunar biosphere with a 20 meter circular swimming pool. Multiple levels of habitats could be constructed in the bottom half of the biosphere with some base support by lunar regolith. A central area could utilize scissor elevators to access different floor levels. 

Some biospheres could be specifically dedicated for agriculture, providing space in the upper half for grazing animals used for milk and meat and cheese while the lower half could provide compartments for hen houses and aquaculture. For growing crops, the top half could be used grow fruit trees: apple trees, orange trees, cherry trees, peach trees, pear trees, lemon trees, etc. while underground compartments in the bottom half of the biosphere could be used for growing corn, potatoes, wheat, rice, tomatoes, lettuce, yams, sugar beets, etc.

Much thinner but larger  biospheres could also be deployed to the surfaces of extraterrestrial worlds. But once they are inflated, they would have to be internally thickened with additional adhesive layers of Kevlar in order to provide the same safety factor as the smaller domes. This would probably require the deployment of modular Kevlar manufacturing factories on the surface of these worlds by cargo landing vehicles. But this would make it possible to deploy biospheres that are 100 to 200 meters in diameter in the near future. Once the Moon and Mars become fully industrialized worlds with significant populations then  Kevlar biospheres that are 300 meters to 1000 meters in diameter might eventually be deployed. 

Mass of a Kevlar-29 biosphere for an atmospheric pressure of of  14.7 psi (101.3 kPa) with a structural safety factor of four.

40 meters in diameter - 28 tonnes

100 meters in diameter - 430 tonnes

200 meters in diameter - 3438 tonnes

300 meters in diameter - 11,600 tonnes  

1000 meters in diameter - 430,000 tonnes 

Biospheres as large as 200 meters in diameter could allow colonist to enjoy familiar sporting activities such as America football and baseball and international soccer. Some biospheres could be specifically designed for sporting activities, allowing baseball, American football, and international soccer to be played on the bottom surface of the top half of the biosphere while the bottom half, extending nearly 100 meters below, could easily accommodate large variety of  underground stadiums for playing basketball,  hockey, volleyball, and  tennis while also being able to accommodate a few  Olympic sized swimming pools.

Dimensions for professional sporting activities

Volleyball Court - 9 meters by 18 meters

Doubles Tennis Court - 10.97 meters by 23.77

Basketball Court -  15 meters by 29 meters

Olympic sized swimming pool - 25 meters by 50 meters

International Hockey Rink - 30.5 meters by 61 meters

NFL Football field 48.76 meters  by 110 meters (110 m)

Baseball outfield fence from home plate -  91 meters  to 128 meters

But biospheres that are only 100 meters in diameter on the Moon could be spacious enough to allow people to don wings to fly within the upper biodome or even withing the entire biosphere.  This could perhaps initiate of a new era of aerial extraterrestrial sports! Who knows! Someday flying inside of  Lunar biospheres or watching Lunar Aeroball could be a major attraction for space tourist from Earth!

Links and References

Inflatable Habitation for the Lunar Base

The Economic Viability of Mars Colonization

The Architecture of Artificial-Gravity Environments for Long-Duration Space Habitation

Protecting Spacefarers from Heavy Nuclei

Landing on Mars with ADEPT Technology

ADEPT Technology for Crewed and Uncrewed Missions to the Planets

Living and Reproducing on Low Gravity Worlds

Cosmic Radiation and the New Frontier

Pioneering and Commercial Advantages of Permanent Outpost on the Moon and Mars

Monday, August 29, 2016

Protecting Spacefarers from Heavy Nuclei

Buzz Aldrin on the surface of the Moon (Credit: NASA)
by Marcel F. Williams

In July of 2016, researchers on the health of NASA astronauts dropped a bombshell concerning the cardiovascular mortality of the Apollo Lunar astronauts. Despite the enhanced levels of radiation exposure by astronauts at LEO and beyond LEO, there were no indications of increased levels of cancer for space faring astronauts relative to people living on Earth. The research also showed no significant increase in cardiovascular deaths (the leading cause of death for Americans) relative to people living on the Earth's surface. Surprisingly, the research did reveal that the  frequency of  cardiovascular deaths of Apollo Lunar astronauts was four to five times higher than in LEO astronauts and in NASA astronauts that have yet to have the opportunity to fly into space.

Although astronauts are exposed to enhanced levels of radiation beyond the Earth's magnetosphere, astronauts at LEO are completely shielded from the most lethal component of cosmic radiation, heavy nuclei (heavy ions), most of the time.

Cosmic radiation beyond the Earth's surface (Annual levels)

Low Earth Orbit (LEO): 20 Rem (solar maximum) to 40 Rem (solar minimum) 

Interplanetary Space: 28 Rem (solar maximum) to 73 Rem (solar minimum)

Surface of the Moon: 11 Rem (solar maximum) to 38 Rem (solar minimum) 

Surface of Mars: 8 Rem (solar maximum) to 33 Rem (solar minimum) 

Cosmic rays are relativistically accelerated particles  resulting from the  explosions of ancient super nova mostly within the galaxy. Approximately 87% of cosmic radiation particles are composed of  protons;  12% are alpha particles derived from helium atoms.  But approximately, 1% of the population of cosmic rays are composed of heavy nuclei, large ionized accelerated particles derived from heavier nuclei such as carbon, oxygen, silicon, and iron.

Most of the protons and alpha particles from cosmic radiation pass harmlessly though the vacuous space between the atoms of the human body. But the relentless rain of cosmic radiation inevitably results in impacts upon our corporeal components. Heavy nuclei, on the other hand,  have relatively-short interaction lengths when encountering matter. Such interactions with human tissue can be significantly deleterious DNA molecules and can pose a challenge to cellular repair. 

It has been estimated that during a future-- 6 month-- journey to Mars, the nucleus of  one out of every three  cells in the human body would receive at least one hit from a cell damaging heavy ion. With the inability of neurons to repair themselves, it has been predicted that a mere six months of heavy nuclei exposure could potentially destroy a third of the total neurons in the central nervous system.

Approximately, 15 to 20 g/cm2 of mass is required to effectively stop the penetration of heavy ions. However, its estimated that Astronauts aboard the Apollo Command Module (CM), were only provided with about 10 g/cm2 of radiation shielding. And some parts of the Command Module were more heavy shielded than other areas of the CM. The window areas were particularly thinly shielded which would have allowed heavy nuclei to easily penetrate into the CM interacting with the body tissues of the astronauts. 

Astronauts on there way to and from the Moon experience retinal flashes aboard the CM when they were outside of the Earth's magnetosphere. And NASA believes that this was the result of heavy nuclei traversing the human retina. Retinal flashes occurred at an average frequency of every 2.9 minutes which sometimes made sleeping a challenge for the astronauts.  At least 90% of the Apollo astronaut's exposure to heavy nuclei bombardment occurred during their voyage to and from the lunar surface and not on the lunar surface itself.  

But there was even less shielding against heavy nuclei for astronauts when the were aboard the Lunar Module (LM) and when they were on the surface of the Moon. However, half of the heavy nuclei would have been blocked by the mass of the Moon when astronauts were on the lunar surface.

 Since the cardiovascular health of  Apollo Lunar astronauts relative to humans on Earth has now been shown to be significantly effected after less than two weeks beyond the Earth's magnetosphere, its now clear that astronauts in the future will have to be adequately protected from heavy nuclei when traveling beyond the magnetosphere to the Earth-Moon Lagrange points, the lunar surface and on interplanetary journeys to Mars. 

Since there is virtually no atmosphere on the surface of the Moon, lunar astronauts venturing outside of their regolith shielded habitats would be exposed to the relentless penetration of heavy nuclei. Lunar astronauts would, therefore, have to wear pressure suits with enhanced shielding (~ 20 g/cm3). Helmets could easily be shielded with iron 2.6 cm2  thick.  But the helmet visor for lunar excursions would probably have to be composed of lead iron glass nearly 5 centimeters thick. Thickening the rest of the lunar pressure suit with 2.6 centimeters of iron shouldn't be too difficult. The increased weight of the iron shielded pressure suit should be easily mitigated by the Moon's 1/6 gravity. 

On the surface of Mars, the thin carbon dioxide atmosphere is still thick enough (~ 15 g/cm2) to shield astronauts on the surface from any direct interaction from most heavy nuclei. So enhanced shielding of pressure suits on the surface of Mars will probably not be required. 

Notional reusable EUS with an internally water shielded  Cygnus habitat module rendezvousing with an EUS derived  propellant producing water depot at LEO
Since traveling from LEO to other important regions within cis-lunar space can take several days, its pretty obvious that crewed spacecraft traveling within cis-lunar space will have to be  appropriately shielded against heavy nuclei. However, substantially increasing the shielding requirements of the Orion spacecraft to protect against heavy ions  could make it to heavy for the   ATV derived  Service Module (SM) to push the Orion capsule on a trajectory return to Earth. 

Delta-v to important destinations within cis-lunar space

Earth surface to LEO - 9.3 km/s to 10 km/s

LEO to EML1 - 3.77 km/s (~3 days)

LEO to EML1 - 4.5 km/s (~2 days)

LEO to EML2 - 3.43 km/s (~8 days)

LEO to EML2 - 3.95 km/s (~4 days)

Lunar surface to EML1 - 2.52 km/s (~3 days)

Lunar surface to EML2 - 2.53 km/s (~3 days)  

Notional ETLV-2 crew landing vehicle with internal radiation water shielding compartment.

However, if the ATV derived SM is replaced with a reusable EUS that uses IVF technology and orbiting water/propellant depots, then the Orion capsule  could be coupled with an appropriately water shielded Cygnus habitat.  The water shielded (20 cm thick) area within the Cygnus habitat could be dumped just before the final trajectory burns into the desired cis-lunar destinations. Water could be replenished for the Cygnus habitat for return trips at the water/propellant depots. 

Notional reusable ETLV rendezvousing with an EUS derived  propellant producing water depot at LEO

In the long run, however, it would be even more fuel efficient if an Extraterrestrial Landing Vehicle (ETLV) were also used as an orbital transfer vehicle between LEO and the Lagrange points. Again, 20 centimeters of water shielding could be provided with an designated area of the ETLV and then dumped before the final trajectory burns to the Lagrange points, Low Lunar Orbit, or to LEO. While water shielding  the ETLV crew transport area before its departure from the lunar surface would require more propellant at take off, there should be no shortages of lunar derived oxygen and hydrogen propellant on the lunar surface. 

Notional reusable ETLV rendezvousing with an EUS derived  propellant producing water depot at EML-1.

And ETLV using a ADEPT or HIAD deceleration shield could dump its water shielding just before entering Mars orbit or descending from from Mars orbit to the surface of Mars. Returning to Mars orbit, an ETLV could dock with a Mars orbiting water/propellant depot at Low Mars Orbit to add water shielding and propellant to the vehicle in order for it to return its astronauts to an interplanetary spacecraft parked in High Mars orbit.

Notional reusable ETLV returning from the martian surface rendezvousing with an EUS derived  propellant producing water depot at Low Mars Orbit before returning to High Mars Orbit. 

Protecting astronauts from the deleterious effects of heavy ion bombardment beyond the Earth's magnetosphere will increase mass shielding and propellant requirements for crewed spacecraft. But  the utilization of extraterrestrial water and regolith resources should make it easy and affordable to protect the health of astronauts from the dangers of heavy nuclie in the New Frontier.  

Links and References

 The SLS and the Case for a Reusable Lunar Lander

Monday, July 11, 2016

Substantially Enhancing the Capability of the SLS Architecture by Utilizing EUS Derived Propellant Depots and Reusable Orbital Transfer Vehicles

Left: Orion space capsule with hypergolic fueled Service Module; right:  notional Orion spacecraft with a reusable EUS derived orbital transfer vehicle.  
It now appears that Congress will direct NASA to return Americans to the surface of the Moon in order to prepare for future crewed journeys to the surface of  Mars. But the Moon could prove to be much more than just a beyond LEO testing ground for astronauts and components.

At minimum, an interplanetary round trip to the Red Planet would require several hundred tons of  water for drinking, washing, food preparation, radiation shielding, the production of air, and for the production of liquid oxygen (LOX) and liquid (LH2)  for rocket propellant.

Supplying the water needed for an interplanetary spacecraft parked at LEO  would require a delta-v ranging from  9.3 km/s to 10 km/s from the Earth's surface. Minimum energy launch windows during the 2030s would require an additional delta-v ranging from 3.59 km/s to 4.81 km/s for Trans Mars Injections (TMI)  that could send humans to Mars in less than a year.

But at different locations within cis-lunar space, substantially lower levels of delta-v could be taken advantage of in order to launch cargo and crew into a Trans Mars Injection. And these interplanetary launch points within cis-lunar space are most easily accessible from the lunar surface rather than from within the Earth's deep gravity well. So utilizing lunar ice resources could greatly reduce the cost and the complexity of sending humans to Mars.

Delta-v to important destinations within cis-lunar space

Earth surface to LEO - 9.3 km/s to 10 km/s

LEO to EML1 - 3.77 km/s (~3 days)

LEO to EML1 - 4.5 km/s (~2 days)

LEO to EML2 - 3.43 km/s (~8 days)

LEO to EML2 - 3.95 km/s (~4 days)

Lunar surface to EML1 - 2.52 km/s (~3 days)

Lunar surface to EML2 - 2.53 km/s (~3 days)

Delta-v from cis-lunar space to Trans Mars Injection

LEO to TMI (2030s) - 3.59 km/s to 4.81 km/s

EML1 to TMI (2030s) - 1.04 km/s to 1.3 km/s

Because of its shorter travel times from Earth orbit,  EML1 would appear to be the optimal region for locating Deep Space Habitats (DSH), reusable lunar shuttles,  propellant manufacturing water depots that receive water from the lunar surface and for launching cargoes and crew on interplanetary journeys to the orbits of Mars and Venus.

A delta-v of   3.77 can transport crews to EML1 in approximately 4 days. It would require 3.95 km/s to travel to EML2 in 4 days but 8 days of travel and radiation exposure would be required to take advantage of a lower delta-v to EML2 at 3.43 km/s. A delta-v of 2.52 km/s would be required for a 3 day journey between EML1 to the lunar surface. 2.53 km/s would be required for a similar journey between EML-2 and the lunar surface. The significant presence of habitats and depots and reusable vehicles at EML-2 could also interfere with future radio astronomy on the back side of the Moon.

Taking full advantage of polar ice resources on the Moon would require a space architecture that utilizes orbiting depots to supply water and propellant to reusable interplanetary spacecraft and landing vehicles. Some space advocates have argued that propellant depots make heavy lift vehicle's an unnecessary expense. However, heavy lift vehicles would make it possible to easily deploy propellant manufacturing water depots to  EML1  for crewed interplanetary journeys to the orbits of Mars and Venus.

Similar depots located at LEO could also enable large payloads  originally deployed  to LEO by heavy lift vehicles to be later  deployed by reusable orbital transfer vehicles practically anywhere within cis-lunar space.

Expendable EUS for SLS launch vehicle (Credit: NASA)

In 2018, NASA will launch the first SLS heavy lift vehicle with an unmanned Orion space capsule and a hypergolic fueled Service Module and an interim upper stage. But NASA currently envisions crewed SLS launches in the 2020s to include an Orion space capsule with a hypergolic fueled Service Module and a large LOX/LH2 fueled Exploratory Upper Stage (EUS). 

But two of the principal companies (Boeing and Lockheed Martin) currently developing the SLS/Orion architecture are also--  privately developing-- an alternate space architecture through their joint company, the  ULA (the United Launch Alliance). In this alternate architecture, the ULA  will utilize their emerging  IVF (Integrated Vehicle Fluids ) technology to deploy a reusable ACES upper stage that could eventually utilize LOX/LH2  propellant depots for travel within cis-lunar space during the 2020s. IVF technology allows a spacecraft to utilize hydrogen and oxygen ullage gases for attitude control, power production, and for autogenously pressurizing propellant tanks, eliminating  the need for hydrazine and liquid helium. 

NASA could greatly enhance the capability, efficiency, and the safety of the SLS/Orion architecture by taking full  advantage of the ULA’s  emerging IVF  technology. While there's no reason to stop Boeing from developing the EUS as an expendable upper stage for the SLS, it would still be technologically advantageous for NASA to commission the ULA to use its IVF technology to convert some EUS vehicles into  reusable orbital transfer vehicles and others into propellant depots.

EUS derived propellant manufacturing water depot and reusable Orion orbital transfer vehicle.

 An SLS/Orion architecture utilizing EUS derived Orbital Transfer Vehicles (OTV-125) and EUS derived propellant producing water depots (WPD-OTV-125) would no longer require the expense and the enhanced risk of launching astronauts on top of a super heavy lift vehicle. So for beyond LEO missions in the 2020s, under this scenario, astronauts would simply be transported to LEO by Commercial Crew vehicles that would have already been in operational service since 2018.

Once in orbit, the commercial crew capsule would dock directly with the Orion-OTV-125 reusable spacecraft, transferring its crew aboard the Orion for its beyond LEO mission. Alternatively, a crew capsule could dock at the port of  a space station where the Orion-OTV-125 would also be docked at a different port. Both scenarios would mean that the ATV based hypergolic Service Module being manufactured by the Europeans would not be required for crewed beyond LEO missions, and would only be used once during the 2018 test mission. So only  the domestically manufactured Orion capsule being developed by Lockheed Martin would be preserved in this architecture.

A single SLS Block I cargo launch could be used to deploy two WPD-OTV-125 depots to LEO plus a two 1 MWe solar arrays. With at least 35 tonnes of propellant, one of the water/propellant depots could self deploy itself to EML1 along with its 1.4 to 2.8  MWe solar array. Another basic SLS Block I cargo launch could be used to deploy two reusable Orion-OTV-125 vehicles to LEO. But once this reusable depot based extraterrestrial architecture is deployed by the SLS,  private commercial launch vehicles will only be required to conduct crewed beyond LEO missions. This will allow the SLS to be used exclusively as a cargo launcher for the deployment of large and heavy spacecraft and habitats and other large and heavy structures.

Notional lunar water ice extraction, storage, and LOX/LH2 manufacturing facility.

Water for the propellant manufacturing orbital depots could be regularly supplied to LEO and to EML1 from commercial launch vehicles (Atlas V, Delta IV heavy, Falcon 9, and the future Falcon Heavy, Vulcan, and Vulcan Heavy vehicles).  However, once water is being manufactured on the lunar surface, water transported to EML1 would be supplied  exclusively from the lunar surface.

Since the  Orion-OTV-125 would derived from the EUS, it would be capable of accommodating up to 125 tonnes of propellant. But less than 35 tonnes of propellant would be required for an Orion-OTV-125 to transport its crew to EML1. And an equal amount of fuel would be needed to return astronauts to LEO. No aerobraking would be required.

A reusable Extraterrestrial Landing Vehicle (ETLV) would transport astronauts from EML1 to the surface of the Moon and back  to EML1 with a single fueling of LOX/LH2. A single SLS Block I cargo launch could deploy three ten tonne ETVL-2 vehicles to LEO, each with enough propellant to travel to EML1. The ETLV-2 could also serve as an back up OTV in case one or both of the Orion-OTV-125 vehicles becomes inoperable.

Until new RS-25 engines are in production, perhaps by 2021 to 2023, NASA will only be able to launch four SLS vehicles. And one of those launches will be an unmanned test launch in 2018. So after 2018, only three SLS launches will be possible before the RS-25 engines go into production.

Notional EUS derived propellant manufacturing water depot @ EML1 after refueling a reusable Extraterrestrial Landing Vehicle.

But  just three basic  SLS Block I cargo launches would be required to deploy a reusable EUS derived cis-lunar transport architecture (WPD-OTV-125, Orion-OTV-125, and the ETLV-2) capable of transporting humans to EML1 and to the lunar surface and back.

However, the deployment of the lunar landing vehicles could be delayed until the new RS-25 engines are in production. This would allow NASA to use their last four Space Shuttle Main Engines to be used to launch a DHS (Deep Space Hab) to EML1. An SLS propellant tank derived habitat with over 510 cubic meters of pressurized habitable volume would have a dry weight of 22.4 tonnes. So in theory,  a single SLS Block I cargo launch could be used to deploy two or three pressurized habitats to LEO. A partially fueled Orion-OTV-125 could then be used to transport one of the pressurized habitats to EML1.
SLS propellant tank derived habitat (Credit: NASA).

This would leave one or two pressurized habitats at LEO with a combined pressurized habitable volume exceeding that of the ISS! All of that would be achieved with  a single SLS launch and a reusable propellant producing water depot architecture routinely and sustainably  supplied with water from commercial launch vehicles.

Links and References

Moon first, then Mars? Congress moves to shift space priorities

The return to the moon, Lori Garver, and the price of ambition

Lori Garver Questioned Astronauts about NASA's Next Destination?

Seeing the end of Obama’s space doctrine, a bipartisan Congress moves in

What about Mr. Oberth

Human Lunar exploration architectures

Earth Departure Options for Human Missions to Mars

A Study of CPS Stages for Missions beyond LEO

Deep Space Habitats

First Human Voyages to the Martian Moons Using SLS and IVF Derived Technologies

Congress Requires NASA to Develop a Deep Space Habitat

UltraFlex Solar Array Systems

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