Monday, September 7, 2015

Reusable Hoppers and Orbiters for Rapid Lunar Transportation and Exploration

by Marcel F. Williams

For NASA and its future SLS program,  developing  a reusable single staged extraterrestrial  landing vehicle (ETLV) could allow America to send astronauts  to the surface of the Moon, Mars, and even to the surfaces of the moons of Mars. Such an ETLV could be used to conveniently transport astronauts from EML1 (Earth-Moon Lagrange point 1) to the surface of the Moon and back to EML1 on a single fueling of LOX/LH2 propellant. NASA astronauts could reach EML1 and return to the Earth via an SLS launched Orion spacecraft.

Eventually, by deploying ETLV derived orbital propellant depots at points of departure and destination, such a reusable spacecraft could also be used as an orbital transfer vehicle, transporting astronauts between LEO and the Earth-Moon Lagrange points. This would allow Commercial Crew vehicles to shuttle NASA astronauts to LEO to dock with an ETLV destined for EML1 or to return astronauts from an ETLV returning from EML1. 

ETLV-2 (Extraterrestrial Landing Vehicle)

Inert weight with cargo and  crew (8 passengers): 10 tonnes

Maximum amount of propellant:  24 tonnes of  LOX/LH2

Maximum fueled weight: 34 tonnes

Specific Impulse of LOX/LH2 engines: ~ 450 seconds 
Top: ETLV-2 reusable lunar crew lander and lunar hopper; Bottom: CTLV-5B reusable LOX/LH2 cryotanker.

CTLV-5B (Cryotanker Landing Vehicle)

Inert weight: 8 tonnes

Maximum amount of propellant: 30 tonnes

Maximum fueled weight: 40 tonnes

Specific Impulse of LOX/LH2 engines: ~ 450 seconds

By utilizing  ADEPT  deceleration shields, such an ETLV could also be used to transport humans from low Mars orbit to the surface of Mars and back into  Mars orbit  on a single fueling.  With an ADEPT decelerator, the delta-v requirement to land on the lunar surface from orbit is only 0.51 km/s. The delta-v to travel from the surface of Mars back to Mars orbit is 4.4 km/s. Propellant depot located in Low Mars Orbit would allow the vehicle to refuel in order to travel to orbital habitats or interplanetary vehicles located in High Mars Orbits. Traveling between High Mars Orbit and the Earth-Moon Lagrange points has the lowest delta-v requirements between Mars orbit and cis-lunar space.

A reusable  ETLV located at propellant producing  lunar outpost that utilizes a reusable CTLV (Cryotanker Landing Vehicle) could also allow humans to continuously explore practically every region on the lunar surface without the need of any additional SLS launches from Earth-- dramatically reducing the cost of the human exploration of the Moon

Once a permanent outpost is established on the surface of the   Moon, the entire lunar surface, including its craters, could be continuously explored by robotic lunar rovers tele-operated from Earth. Such solar and nuclear powered mobile robots could also retrieve regolith samples  for return to the outpost for study and, eventually, transported back to Earth. Such mobile robots could also be used to  locate interesting sites for future human exploration.

Because annual levels of cosmic  radiation on the lunar surface can range from 11 Rem during solar maximum conditions to as high as 38 Rem during solar minimum conditions, astronauts living on the Moon for several months or several years will have to minimize their radiation exposure by mostly living inside regolith shielded habitats to reduce annual radiation exposure to less than 5 Rem (the maximum level of radiation exposure for radiation workers on Earth) during solar maximum and minimum conditions. This can easily be done by landing  habitats on the lunar surface that can automatically deploy regolith walls that can be easily filled with approximately 2 meters of lunar regolith.

If astronauts spend about 10% of their time outside of their shielded habitats  (2.4 hours per day or 16.8 hours per week), their additional exposure after a year would only range from 1.1 Rem to 3.8 Rem. A 25 year old female could live and work on the Moon for a decade and still not exceed her maximum lifetime limit of 100 Rem. Astronauts minimizing their radiation exposure by  exploring the lunar surface for just  four to eight hours per week could, therefore,  explore various regions on the Moon on a weekly basis-- if they could have easy access to such regions.

Since ground vehicles transporting crews across the lunar surface are not likely to exceed 20 km per hour in average speed, the maximum area that could be explored by pressure suited astronauts is not likely to exceed a distance of more than 80 kilometers away from a shielded lunar  outpost.

However, rocket powered sub-orbital Lunar Hoppers hurtling along parabolic arcs have long been advocated as a way for humans to explore more distant regions on the Moon-- far beyond a permanent lunar outpost. But such missions would require the reusable vehicle to have-- enough propellant-- to:

1. take off from the outpost on a suborbital trajectory,

2. land at the site intended to be explored,

3. take off again on a suborbital trajectory,


4. land back at the lunar outpost.

The delta-v and travel times for possible crewed suborbital hops on the lunar surface.
David Hop, on his popular space blog, has done some interesting calculations, suggesting  that lunar hoppers could transport humans anywhere on the lunar surface in less than an hour with a maximum delta-v of only 1.68 km/s. So  transportation between lunar outpost and lunar cities could be conveniently fast and easy-- as long as every lunar outpost or  lunar city can refuel the Hopper for its next suborbital destination.  

An ETLV fueled with a maximum of 24 tonnes of LOX/LH2 propellant (originally designed for round trips between EML1 and the lunar surface) could transport astronauts within a 1300 kilometer radius from a lunar outpost and back.  Beyond 1300 kilometers (45 degrees), however, such an ETLV  would not have enough propellant for its return trip to the lunar outpost.

Since the distance from the poles to the lunar equator would be 2700 kilometers away and to  the opposite pole, more than 5400 kilometers away,  a single polar outpost would pretty much  confine  human exploration via Hoppers mostly to it's polar region.

One way to overcome such geographical limitations would be to launch crewed ETLVs to EML1.  There it would add additional rocket fuel  from a  propellant depot (WPD-OTV-5A) located at EML1 for a round trip mission from the Lagrange point to the lunar site chosen to be explored. After the completion of the exploratory mission, the ETLV would return to EML1 to add propellant for its return trip to its original lunar outpost.

Lunar Exploration via lunar outpost and EML1 propellant depot

1. Crewed ETLV-2 launched from lunar outpost to EML1 (less than 12 hours at high delta-v or two days at a lower delta-v))

2. ETLV-2 rendezvous with WPD-OTV-5A adding enough propellant for a round trip from the lunar surface and back to EML1

3. ETLV-2 travels to lunar orbit and lands at lunar site (~2 days of travel) for a few hours or a few days of exploration

4. ETLV-2 launches itself back to EML1 (~2 days of travel) and rendezvous with WPD-OTV-5A to refuel for trip back to lunar outpost

5. ETLV-2 departs from EML1 to return to lunar outpost (less than 12 hours or up to two days)

This scenario requires only one vehicle (ETLV-2). In theory, it would  allow sorties to be conducted practically anyplace on the lunar surface on a weekly basis.  This method, however,  would require at least five to eight days of travel time-- excluding the time spent exploring the region on the lunar surface. So each lunar sortie would expose astronauts to five to eight continuous  days cosmic radiation outside of a regolith shielded outpost-- for perhaps just a few hours or a few of days of exploration at a particular lunar site.

Alternatively, pre-deploying a mobile propellant depot (MCT) at the site intended to be explored could minimize astronauts radiation exposure during a lunar sortie.

 ETLV-2 lands near a pre-deployed mobile cryotanker (MCT) after it's suborbital flight to a predetermined lunar exploratory site. The MCT will provide the ETLV-2 with additional LOX/LH2 for its return flight to a polar outpost.

 Lunar exploration utilizing mobile cryotankers

1. A solar and fuel cell powered mobile cryotanker (MCT) with up to 12 tonnes of propellant is sent to a lunar exploratory site (distance traveled: 300 km/day) in less than a month

2.  Crewed ETLV-2 launched from lunar outpost to lunar exploratory site (less than an hour)  with a few tonnes of extra fuel for the return trip to the outpost. 

3. MCT adds enough additional  fuel to the ETLV-2 for it to return to the lunar outpost

4. With added fuel, the ETLV-2 launches itself back to lunar outpost in less than an hour of travel time

5. The mobile MCT returns to the lunar outpost after a few weeks of travel time.

This scenario dramatically reduces  astronaut's travel time  to less than two hours of continuous radiation exposure. Preparing for such lunar sorties, however, would require a mobile cryotanker to be deployed to the exploratory site a few weeks before the crewed mission. And then a few weeks would have to be allowed for the cryotanker's return to the lunar outpost.

However, there is another way that lunar sorties from a lunar outpost could be conducted on a daily basis while also minimizing cosmic radiation exposure. This scenario would require an ETLV to be launched in an orbital plane above the intended site to be explored  along with a reusable  CTLV (Cryotanker Landing Vehicle).

Crewed ETLV-2 rendezvous with an unmanned CTLV-5B cryotanker in the same orbital plane as the intended  lunar exploratory site and the lunar outpost. After the lunar exploratory mission is completed, both the ETLV-2 and the CTLV-5B will return to the lunar outpost to be used again for future lunar exploratory missions.

 Lunar exploration utilizing an ETLV-2 and CTLV-5B in lunar orbit

1. CTLV-5B launched from lunar outpost into an orbital plane directly above the intended landing site

2. Crewed ETLV-2 launched from lunar outpost  into the same orbital plane

3. ETLV-2 rendezvous with CTLV-5B adding enough propellant for a round trip from the lunar surface and back into orbit

4. ETLV-2 lands at lunar exploratory site for a few hours or a few days of exploration

5. ETLV-2 launches itself back into orbit along the same orbital plane

6. ETLV-2 rendezvous with CTLV-5B adding enough propellant to return to the lunar outpost

7. CTLV-5B uses the its remaining amount of propellant to land back at the lunar outpost to be eventually refueled to assist in the next sortie mission on the lunar surface

ETLV-2 at an exploratory site on the lunar surface. Distances exceeding  1300 kilometers away from a propellant producing lunar outpost will require the ETLV-2 to use its remaining fuel to launch itself back into the same orbital plane as an orbiting CTLV-5B cryotanker, in order to add the needed fuel necessary for it to return to the lunar outpost.

The CTLV is simply the CLV (Cargo Landing Vehicle) without the cargo. So no new extraterrestrial vehicle would have to be developed in order to utilize the CLV as a reusable propellant vehicle (CTLV).

While this scenario requires two reusable launch vehicles (ETLV-2 and the CTLV-5B), it has the advantage of being able to  deploy astronauts quickly to an exploration site in just a few hours. Most of the few hours of travel time for astronauts would be spent in lunar orbit while rendezvousing with the CTLV-5B propellant  depot to add more propellant.

In the early 2030s, I imagine that most of the water produced at a lunar outpost  would probably be exported to one of the Earth-Moon Lagrange points to provide water for future interplanetary missions to Mars, Venus, ESL4, ESL5, and the NEO asteroids: water for drinking, washing, the production of air, radiation shielding, and LH2/LOX propellant.

But some of the water derived from the lunar poles could also be used for the production of lunar propellant intended for the domestic human exploration of the lunar surface.  This could allow reusable Extraterrestrial Landing Vehicles to  cheaply and conveniently transport astronauts to practically every region on the lunar surface for a few hours or even a few days of exploration. So the production and export of lunar water could not only greatly enhance NASA's ability to send humans to Mars but it could also usher in a new renaissance of human exploration-- on the lunar surface.

Links and References

Trajectory Optimization for Adaptive Deployable Entry and Placement Technology (ADEPT)

Lunar Hopper

Travel on airless worlds 

Lunar pogo hopper

Drones on the Moon
Is it possible to explore the Moon with low-altitude flying spacecraft?

Lunar Lander Designs for Crewed Surface Sortie Missions in a Cost Constrained Environment

The SLS and the Case for a Reusable Lunar Lander

An SLS Launched Cargo and Crew Lunar Transportation System Utilizing an ETLV Architecture

Utilizing the SLS to Build a Cis-Lunar Highway

Cosmic Radiation and the New Frontier

Friday, July 24, 2015


From a million miles away, NASA's  Deep Space Climate Observatory has captured its first view of the entire sunlit side of Earth.

Tuesday, April 28, 2015

The Production and Utilization of Renewable Methanol in a Nuclear Economy

10.7 MWe rated methanol electric power plant at Point Lisas, Trinidad (Credit: Mendenhall Technical Services)
Terrestrial and off-shore nuclear power plants could safely and economically provide all of the base load electricity requirements for future carbon neutral  industrial economies. The additional-- peak load-- electrical demands for an industrial region could also be supplied by carbon neutral methanol electric power plants-- if nuclear electricity was also utilized to produce renewable methanol derived from biowaste and waste water resources

Methanol (CH3OH) is, of course, the simplest alcohol, producing only carbon dioxide (CO2) and water after combustion with oxygen. The production of methyl alcohol through the pyrolysis of carbon based materials and their distillation has been known since the time of the ancient Egyptians. Modern techniques of methanol production utilize pyrolysis to produce syngas (synthetic natural gas),  a gaseous mixture of consisting of carbon monoxide, carbon dioxide, and hydrogen  that is then converted into methanol.

Since approximately 65% to 75% of the CO2 content is wasted during the  synthesis of  syngas into to methanol, introducing additional hydrogen into the synthesis process could potentially increase the production of methanol by three to four times. Sources of carbon neutral hydrogen could, therefore, be produced through nuclear, hydroelectric, wind, and solar electric power through the electrolysis of water.

Plasma arc pyrolysis plants, a commercial technology that's already in existence,  could be used for the conversion of urban and rural biowaste (garbage and sewage) into syngas.  Additional hydrogen can be added to the mix through the production of hydrogen through the electrolysis of water at an electrolysis plant. The syngas and additional hydrogen can then converted into  methanol at a  alcohol methanol synthesis plant.

Diagram of a methanol biowaste complex for the production of methanol and electricity.

Carbon neutral sources of electricity could come  from nuclear, hydroelectic, wind, and solar power plants.  Because the sun doesn't always shine and the wind doesn't always blow, wind and solar facilities only offer intermittent supplies of carbon neutral electricity to the electric grid.  While hydroelectric power plants can supply carbon neutral electricity to the grid 24/7, this renewable energy source  has already reached its maximum capacity in the US and can actually supply less power to the grid during periods of drought-- as is currently the occurring in drought stricken California.

Nuclear power plants, on the other hand, can supply carbon neutral electricity to the grid 24 hours per day.  Except during periods of refueling (once every three years), current light water nuclear power plants in the US have an electrical capacity exceeding 90%. Nuclear power currently produces about 20% of America's electricity supply. But there is currently enough room-- at existing US nuclear sites--  to increase nuclear power production  in the US by at least four to five times the current nuclear capacity without the need to add new locations within the continental US. This could easily be done by gradually adding the next generation of Small Modular Reactors (SMR) to existing sites over the next twenty to thirty years.

A methanol complex using carbon neutral electricity from nuclear and renewable energy could produce methanol from the pyrolysis of urban and rural garbage and sewage-- solving the problems of urban and rural refuse while also producing clean energy. The production of hydrogen from the electrolysis of water could substantial increase methyl alcohol production. Domestic sources of carbon neutral methanol could then be used to fuel methanol electric power plants during peak load demands.  The production of electricity from a methanol electric power plant could be further increased if the waste oxygen from the production of hydrogen were  utilized during fuel combustion instead of air which contains only 20% oxygen and  80% nitrogen. 

While the CO2 produced from a methanol electric  power plant could be exhausted into the air without increasing the net amount of CO2 in the Earth's atmosphere, the waste carbon dioxide from the  flu gas could also be recycled.   Post combustion and pre- combustion CO2 capture facilities can collect 85 to 90% of CO2 from flu gas. And power plants that used oxygen can capture as much as 90 to 97% of the CO2 produced from flu gas. Pumping the waste CO2 into the methanol synthesis plants could nearly double  the production of  renewable methanol if even more hydrogen is added to the mix.

Any excess production of methanol from a methanol electric complex would be a valuable commodity that could be exported. Exported methanol could be used  for the base load production of electricity in areas with no access to nuclear power or it could be converted into gasoline or dimethyl ether for trucks and automobiles. Methanol would also be of value to industrial chemical companies.
TVA’s, Sequoyah Nuclear Plant (Credit TVA).

Despite the accidents at Fukushima and Chernobyl, terrestrially based commercial nuclear power are still the safest source of electricity production ever invented. But floating commercial nuclear reactors deployed several kilometers off marine coastlines or even deployed far out into the ocean could enhance nuclear safety even further.

The Earth's oceans, of course,  are certainly no strangers to nuclear power. There are over 140 nuclear powered ships and submarines roaming the Earth's oceans and seas  with more than 12,000 reactor years of marine operations  accumulated since 1954. 

More than 100 million Americans currently  live within 80 kilometers of a commercial nuclear reactor. But undersea electric cables more than 1000 kilometers away from coastlines  are possible.   Floating nuclear power facilities  could be deployed more than  300 kilometers from an American coastline while still being within the US's  200 nautical mile (370 kilometer) exclusive coastal economic zone.  Such floating reactors could, therefore, be deployed far beyond the 80 kilometer exclusion zone recommended by the United States during the height of the  Fukushima nuclear accident.

Of course, a Fukushima type of incident would be impossible for a floating nuclear facilities located in the open ocean since water  is a natural coolant for light water reactor fuel. Ocean waters would serve as an infinite heat sink for fissile material-- essentially making nuclear meltdowns impossible for floating reactors  placed below the water level. Floating nuclear reactors placed dozens of  kilometers offshore would also be immune to potential damage from earthquakes and tsunamis.

The safety of floating nuclear facilities from potential harm from terrorist or other hostile political groups could be enhanced by naval security from  US Coast Guard or other US government authorized security forces. Potential damage to the reactor from a  torpedo could also easily be prevented with an extensive network of  torpedo nets surround the nuclear power facilities.

But, again, even if an attack on a floating nuclear facility was successful, the ocean water would immediately prevent any melting of the nuclear material to occur.  Water also acts as a natural radiation shield. Just a few meters of water can  reduce ionizing radiation to harmless levels of exposure near the radioactive material.

Japanese Methanol Tanker (Credit: SHIN KURUSHIMA DOCKYARD CO)

Ocean Nuclear power plants could also be remotely deployed, more than a thousands of  kilometers away from coastlines for the production of electricity. Methanol powered ships could transport garbage from coastal towns and cities to floating biowaste pyrolysis, water electrolysis,  and methanol synthesis plants remotely powered by underwater electric cables from Ocean Nuclear Power plants just a few kilometers away. The methanol could then be shipped to coastal towns and cities all over the world for the production of electricity or for conversion into gasoline or dimethyl ether for diesel fuel engines.

First Methanol Fueled Ferry (Credit Stena Line)

Combined with nuclear and renewable energy, renewable methanol fueled peak load power plants  could finally end the need for  greenhouse gas polluting coal and natural gas power plants in the US and in the rest of the world.

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Destination Moon

glennwsmith said... Very nice, Marcel. This is one of the most beautifully put together, forward-looking, and yet also understated videos which I've yet seen from a major space agency -- and it just goes to show that there's a lot of good material out there if you know where to find it.

G. W. (Glenn) Smith


Stena Line to Covert Passenger Ferry to a Methanol Fueled Sea Vessel

michael jordan said...

Stena Germanica RoPax ferry is the first commercial marine vessel to run on Methanol.It is the largest ferry in the Nordic region and second biggest Ro-Pax ferry in the world.For this overall project cost comes to nearly $25.5m.It measures 240m long and 29m wide and lane metres of 3,907m.It is going to accommodate 300 cars and 1,300 passengers and freight capacity of 46,353t.