Tuesday, June 5, 2018

Cis-Lunar Gateways and the Advantages of Near Rectilinear Orbits

Computer illustration of Near Rectilinear Orbits between EML1 and EML2 (Credit: NASA).

NASA appears to have settled on a Near Rectilinear L2 Halo Orbit (NRO) for its future Deep Space Habitat (DSH).  NROs are a subset of of L1 or L2 halo  orbits. NRO's have  large amplitudes over either the north or south lunar poles with shorter periods that pass closely to the opposite pole. Station keeping at an NRO would require a delta-v of only 5 m/s per year. With an impulsive departure from LEO at about 3.124 km/s, a crewed spacecraft would reach an L2  NRO in about 5.33 days. Orbital capture would require a delta-v of 0.829 km/s. 

An  EML1 location for a DSH  would only require a delta-v of  3.77 km/s and four days of travel time. But 2 days of travel time would be required for a journey from EML1 to Low Lunar Orbit (LLO). An NRO location, however, would only require 12 hours of travel time to LLO. So the surface of the Moon could be accessed from a NRO located Deep Space Hab in just 12 hours.

Possible Cis-Lunar Locations for a DSH (Deep Space Habitat)

EML1(Earth-Moon Lagrange Point One):

Travel time to and  from LEO:  ~4 days (3.77 km/s)

Station keeping: < 10 m/s per year

Travel time to and from LLO: ~ 2 days (0.750 km/s)

EML2  (Earth Moon Lagrange Point Two):

Travel time to and  from LEO:~ 8 days from LEO (3.43 km/s)

Station keeping < 10 m/s per year

Travel time to and from LLO:~ 3 days to LLO (0.8 km/s)

DRO (Distant Retrograde Orbit):

Travel time to and  from LEO: ~ 6 days

Station keeping: 0 m/s per year

Travel time to and from LLO: ~ 4 days  (0.83 km/s)

NRO: (Near Rectilinear Halo Orbit):

Travel time to and  from LEO:~5 days from LEO (3.95 km/s)

Station keeping: 5 m/s per year
Travel time to and from LLO:~ 12 hours to LLO (0.730 km/s)

Significantly shorter flight times from LEO to NRO could be achieved with higher delta-v levels that could easily be achieved by future reusable LOX/LH2 fueled spacecraft such as the ULA's XEUS and Lockheed Martin's MADV which could be used for round trip journeys to the lunar surface from a NRO and for transporting crews between LEO and NRO.

Links and References 

Thursday, May 10, 2018

The Mighty XEUS

ACES derived XEUS DTAL lunar crew lander (Credit: ULA)
The United Launch Alliance's (ULA) reusable XEUS vehicle would use ACES cryotanks capable of storing up to 68 tonnes of LOX/LH2 propellant. Filling up with liquid hydrogen and oxygen at a LOX/LH2 propellant producing water depot located at EML1, the XEUS could be used to transports astronauts, round trip,  between EML1 and the surface of the Moon.

The XEUS  could also be used to transport astronauts between propellant depots located at  LEO and EML1 or EML2. 

 Beyond cis-lunar space, the XEUS vehicle could be used to access the surfaces of Mercury, asteroids in the asteroid belt such as Ceres, Vesta, and Psyche,  Jupiter's moon, Callisto,  and also the moons of Mars, Phobos and Deimos.

As a cargo transport operating out of EML1, the XEUS could deliver more than 50 tonnes of cargo to the lunar surface or transport more than 50 tonnes of water extracted from the lunar ice back to propellant producing water depots located at EML1 or EML2. 

Deployed into Earth orbit by a  Vulcan/ACES 68 launch vehicle in the early 2020s, the XEUS could give NASA, the DOD, other government space agencies, and even space tourist easy access to the surface of the Moon and back while helping to give humans access to other regions of the solar system.

Marcel F. Williams

Links and References

Efficient Utilization of the Space Launch System in the Age of Propellant DepotsThe ULA's Future ACES Upper Stage Technology


Friday, May 4, 2018

The Swamp Ape's Pad-to-Pad Precision Grip

by Marcel F. Williams

Skull of Oreopithecus (Credit: After Szalay and Berzi, 1973)
Primates, of course, are generally characterized by their grasping  hands and feet. While the toes of  human feet have lost their prehensile capability, the fingers of human hands have the most sophisticated manipulative ability of any primate. Humans are the only hominoid (humans and apes) primate  capable of supplying the substantial force necessary for holding objects steadily and securely between the pads of the thumb and one or more fingers. This is called a pad-to-pad precision grip.

Fossil evidence suggest that early hominins (humans and their ancestors) such as Australopithecus also possessed a pad-to-pad precision grip.

In 1970, Clifford Jolly suggested that human manipulative capability may have paralleled those of the small object feeding gelada baboon (Theropithecus), a largely terrestrial East African primate that uses its pad-to-pad precision grip to feed on grasses and the seeds of grasses. Jolly suggested that such a folivorous diet in early hominin ancestors might also explain the reduction in hominin canine size.

But in 1977, marine biologist, Alister Hardy proposed an alternative hypothesis for the origin of the human pad-to-pad precision grip. He hypothesized that the  hominin  precision grip was originally an adaptation for the intensive exploitation of benthic invertebrates while wading bipedally in shallow water. In 1960, Alister Hardy suggested that the sensitive probing fingers of humans may have evolved in human ancestors adapted for the exploitation of shelfish and other benthic organisms. Hardy also proposed that bipedal wading for benthic organism was the selective reason for the evolution of  obligatory bipedalism in the earliest hominins.
In 1999, Salvador Moyà-Solà, Meike Köhler, and Lorenzo Rook presented evidence for the possession of a pad-to-pad precision grip in the 7.6 million fossil hominoid, Oreopithecus bambolii. 
Oreopithecus has been vernacularly called the 'Swamp Ape' because of its apparent preference for swampy wetland environments. This late Miocene hominoid was also the earliest bipedal ape and  lived in isolation from the European and African continents on an ancient Mediterranean island known as Tuscany-Sardinia.  Rather abundant oreopithecine fossils have been found in lignite layers along with the fossil remains of freshwater mollusk, turtles, otters, and crocodiles (the possible predators involved in the deaths of the oreopithecine remains).

Paleontologist such as Birdsell, Harrison, and Rook have suggested that Oreopithecus may have exploited these aquatic plants as a food resource. And sedges, water lilies, reeds, cattail, pond- weeds, horestails, and stoneworts, and other wetland plants which were also abundantly represented in the fossil pollen spectrum.

Feeding on aquatic vegetation is certainly not unusual in modern primates and has been observed in lemurs, chimpanzees, gorillas, baboons, the Colobus monkeys and, of course, in humans.  Groups of Colobus monkeys have been known to descended from trees and to travel to pools of open water in swampy areas in order to feed on aquatic vegetation.  Western Gorillas are also known to wade bipedally into swamps to feed on aquatic plants, sometimes even using walking sticks to stay erect.

Human pad-to-pad precision grip (Credit: Alister Hardy, 1977)

The short legs of Oreopithecus along with its peculiar feet which exhibit a widely abducted hallux suggest that the swamp apes were less adapted for terrestrial locomotion than in the early African hominins. The short hindlimbs and the pedal tripod formed by widely abducted hallux and the deviated metatarsals of Oreopithecus appear to be designed as a stable platform for efficient postural harvesting which would have been advantageous for wading for food items in shallow aquatic environments.

While the cranio-dental evidence strongly indicates that Oreopithecus was intensely herbivorous, the unusual amount of wear on the canines and incisors in addition to the thickness of the central incisors which bear a number of small mammelons, may suggest that aquatic vertebrates were also included in their diets. As earlier noted, freshwater mollusks were abundant in the ancient wetland environments that Oreopithecus frequented. Oreopithecus also possessed a hominin-like pad-to-pad precision grip which they could have utilized to apprehend aquatic invertebrates while using their fingers, canines and central incisors to pry open and scrape out the edible flesh of the hard shelled freshwater bivalves.

Sometime after 7.4 million years ago, sea levels began to fall in the Mediterranean creating land bridges to North Africa.  Global sea levels fell to such an extent that eventually the Mediterranean Sea became completely isolated from in the inflow of marine waters from the Atlantic Ocean 6.1 million years ago.

 The  earliest African hominin,  Sahelanthropus, appeared in the fossil record in North Africa sometime between 6.8 and 7.2 million years ago. While not much is known about the postcranial remains of Sahelanthropus, its craniodental morphology is remarkably similar to that of Oreopithecus bambolii.

Aquatic foraging in the wetland swamps of Tuscany-Sardinia would, therefore, explain the adaptive value of bipedal behavior, pad-to-pad precision grips and intense folivory in Oreopithecus and the origins of obligatory bipedalism, precision grips, and hyper-mastication in hominin evolution. And this would appear to be further evidence that Oreopithecus was the earliest bipedal human ancestor.

Links and References

Was the Swamp Ape Bipedal?

Our Earliest Ancestor

Evidence of hominid-like precision grip capability in the hand of the Miocene ape Oreopithecus

The morphology of Oreopithecus bambolii pollical distal phalanx.

Oreopithecus was a bipedal ape after all: evidence from the iliac cancellous architecture.

Ape-like or hominid-like? The positional behavior of Oreopithecus bambolii reconsidered.

Cranio-dental evidence of a hominin-like hyper-masticatory apparatus in Oreopithecus bambolii. Was the swamp ape a human ancestor?

Monday, March 26, 2018

The Case for Remotely Sited Underwater Nuclear Reactors

FlexBlue subsea nuclear reactor being deployed by vessel (Credit: DCNS)
by Marcel F. Williams

Within the Exclusive Economic Zones (EEZ) of remote US island territorial waters, centrally  mass produced subsea commercial nuclear reactors could be safely deployed and utilized to provide all of America's energy and industrial chemical needs.   In fact,  remote US territorial waters alone, could provide the American continent  and the rest of  the world with all of the  electricity,  transportation fuel, industrial chemicals, and fertilizers needed to sustain human civilization.

United States Exclusive Economic Zones (Credit: NOAA)

Anchored and moored above the seabed, approximately 100 meters below the water's surface, subsea nuclear power plants would be safe from damage from extreme temperatures,  hurricanes, earthquakes, and tsunamis, plane crashes and ship collisions.  And even if a subsea reactor is seriously damaged, no electricity is need for the reactor to passively shut down since it allows the natural cooling ability of the ocean to keep its fuel from melting.

Notional FlexBlue reactor farm at the bottom of a sea bed (Credit: DCNS) 
Under this scenario,  subsea nuclear reactors, similar to the 250 MWe FlexBlue reactors proposed by France, could be clustered in groups of eight (2000 MWe) and under the control of a floating Control Center barge. Up to eight such nuclear complexes (nuplexes) would be placed along a circle four kilometers in diameter, producing as much as 16 GW of electric power.  Power plant employees living alone would be comfortably housed at one of two cruise ships positioned at the center of the surrounding circle of nuplexes (nearly two kilometers away) when they're not working. 

Floating Control Center connected to subsea nuclear reactors floating above the seabed.

Five to ten kilometers distant from the nuplexes, a variety of floating barges designed to produce carbon neutral synthetic fuels, industrial chemicals, and fertilizers would be deployed to utilize the nuclear electricity provided through submarine cables. Synplex and nuplex workers and their families could be housed in cruise ships positioned at least ten to twenty kilometers away from the nuclear synplex zones.

Ocean Nuclear Zone and surrounding Synplex Zone
While the subsea reactor wouldn't be vulnerable during a hurricane, the Control Center barge floating on the surface above could disconnect from the under water reactors and easily towed to a safe region until the tropical storm has passed. That could also apply to the floating assets within the synplex zones, returning to reconnect with the nuclear grid once the hurricane has passed. Once a hurricane has formed, it can be tracked and scientists can usually predict its path 3 to 4 days in advance.

The security of the nuplex zone would be provided by the US Coast Guard, under this scenario, put payed for by the private nuplex company or companies. Security for the surrounding synplex zone would be provided by private security companies paid for by the synplex companies.

So any attempt at terrorism against a subsea reactor would require terrorist to pass through a privately protected synplex zone five kilometers wide and then pass through an inner Coast Guard protected area that's an additional five kilometers wide-- areas where ships not related to the synplexes or nuplexes would be forbidden to enter.  And if a subsea reactor somehow became extensively damaged, it would still be surrounded by the virtually infinite heat  sink of the ocean which would make the meltdown of its nuclear fuel-- impossible. 
Island EEZ with designated areas for seasteading and nuclear synplex zones

If such nuclear synplexes were confined to a quarter of the EEZ  area at least 100 kilometers  away from a natural island or atoll, less than half of the nuclear synplex zone could produce more than 1.7 Terrawatts of electricity.  So the synplex zones within the EEZ areas of just three different remote US island territories could, in theory,  provide all of America's energy and industrial chemical needs. But such nuclear synplex zones could be deployed in the remote  EZZ areas of: Wake Island, the Midway Islands, the Northern Mariana Islands, the Palmyra Atoll, the Johnston Atoll, Jarvis Island, and the Howland and Baker Islands. The vast and remote Aleutian Island chain would also be an excellent location for nuclear synplex zones.

The opposite quarter of the island's  EEZ would be for a aquaculture and seasteading (inhabited artificial islands). While no one has ever been killed or even harmed from radiation from commercial nuclear power plants within the US, more than 116 million people on the continental US live within 80 kilometers of a commercial nuclear power plant.  So the closest seasteaders under this scenario would be more than 200 kilometers away from ocean synplexes and  nuplexes  that would already be substantially safer than terrestrial commercial nuclear power plants that are already incredibly safe.

The deployment of specialized barges into Synplex Zones powered by Ocean Nuclear power plants could be used to produce:  

1. Methanol

2. Gasoline

3. Diesel Fuel

4. Jet fuel

5. Kerosene

6. Dimethyl ether

7. Liquid hydrogen

8. Liquid oxygen

9. Potable water

10. Sodium Chloride (salt)

11. Ammonia

12. Urea

13. Formaldehyde

14.  Chlorine

15. Uranium

Synplex zones could also be used to locate floating factories that could export their manufactured goods to ports located around the world.

Methanol manufactured from Ocean Nuclear Synplexes could use  methanol powered tanker ships to export methanol to coastal cities and towns around the world for the production of electricity.  Greenhouse gas polluting natural gas power plants can be easily and cheaply converted to burn carbon neutral methanol. Floating methanol energy barges could be used to quickly deployed to provide electricity to coastal towns and cities around the world. Such energy barges and methanol tankers could also be transported into the Great Lakes area of the US to provide carbon neutral electricity to interior states such as Ohio, Indiana, Illinois, Michigan, Wisconsin, and Minnesota plus the Canadian province of Ontario.   

And if the CO2 from the flu gasses from methanol power plants are recovered and exported back to Ocean Nuclear Synplexes for the production of even more methanol, methanol power plants would be carbon negative (extracted carbon dioxide from the atmosphere for each new plant that is either deployed or converted to use methanol).

Since sunlight only provides 8 hours a day of useful energy for solar power plants, methanol electric power plants using synthetic methanol could be used as backup power, replacing greenhouse gas polluting natural gas power plants.

In the near future, a US state like California could export its urban and rural biowaste to a remote nuclear synplex located in the EEZ area of Wake Island. Nuclear electricity could be used to convert the  biowaste  into syngas through plasma arc pyrolysis. The syngas would be enriched with hydrogen produced from the electrolysis of water extracted from seawater in order to triple the production of carbon neutral methanol.  The methanol could then be exported to back to coastal cities and towns in  California to produce back up electricity for its future solar electric power plants. The recaptured CO2 from the flu gasses from the methanol power plants could be exported back the the Wake Island EEZ for the production of more methanol.  So methanol produced from nuclear electricity from the remote Wake Island EEZ could provide at least 70% of California's electric power needs while inland solar energy could provide the rest of California's electricity needs during the daylight hours when the skies are not significantly overcast. Carbon neutral methanol, gasoline, jet fuel, diesel fuel, and dimethyl ether produced from the Wake Island EEZ nuclear synplex zone could also provide California with all of its transportation fuel needs.

Links and References

Flexblue: A Subsea Reactor Project

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

Will Russia and China Dominate Ocean Nuclear Technology?

FlexBlue Underwater Commercial Nuclear Reactor

The Future of Ocean Nuclear Synfuel Production

Fueling Our Nuclear Future

Sunday, March 4, 2018

The Commercial Case for an SLS-B

by Marcel F. Williams
SLS core vehicle and EUS without SRBs (Modified after NASA)
The Space Launch System (SLS) will only  be truly successful as a government and commercial heavy lift vehicle if its utilized in  a manner that takes full advantage-- of its inherent advantages. As a super heavy lift vehicle of the SLS should be capable of deploying  70 tonnes to 130 tonnes of payload to LEO (Low Earth Orbit). However, much simpler and cheaper SLS configurations could still  deploy at least 20 tonnes to 50 tonnes to LEO. In this article, I'll refer to a simpler and cheaper version of the SLS-- as the SLS-B.

The SLS-B would only consist of the SLS core vehicle plus the Exploratory Upper Stage (EUS).  Five expendable RS-25 engines would  be used for the SLS-B, one more than is utilized for the SLS heavy lift vehicle.   And such a basic SLS configuration should be  capable of deploying at least 20 tonnes of payload to LEO.

Twenty tonnes of payload capability would, of course, make the  SLS-B   fully capable of launching a variety of crew modules into orbit such as: Boeing's CST-100 Starliner, Space X's Dragon, and possible future crewed spacecraft such as Sierra Nevada's Dream Chaser. Such crew modules on top of the SLS-B would also allow several tonnes of additional payload within an expansive payload fairing with a maximum payload diameter of 7.5 meters, much larger that the 4.6 meter internal fairing diameter you'd get aboard the Falcon Heavy or the Atlas V.

The SLS-B could, therefore,  add an additional crew launch vehicle to America's fleet of Earth to LEO spacecraft, competing with the Falcon 9, the Atlas V, and the future Vulcan and Glenn launch vehicles.

A cluster of small solid rocket boosters currently used to enhance the payload capability of the Atlas-V could also be used to increase the payload capability of the SLS-B up to 50 tonnes to LEO. This would give the SLS-B a payload capability close to that of the Falcon Heavy while offering a substantially  larger internal payload fairing diameter.

As a purely liquid hydrogen and liquid oxygen fueled vehicle, the SLS-B  would have the environmental advantage of being  carbon neutral-- if its fuel is exclusively derived from nuclear or renewable electrolytically produced hydrogen and oxygen. The the SLS-B would, therefore,  be one of the most environmental benign launch vehicles in operation by not contributing to global warming, ocean acidification,  and global sea rise.

The increase in the demand for the SLS EUS, core stage, and RS-25 engines for sub-heavy lift flights should help to significantly reduce the vehicle cost for the SLS super heavy lift vehicle.

Of course, there is still the question as to whether  there will be enough launch demand for so many launch vehicles.

As far as crew launches are concerned, current demand by government agencies is relatively meager, with only four crew launches in 2017.  However, the potential passenger demand for space tourism could be substantial once private spacecraft of crew launch capability. There are currently more than 50,000 people in the world wealthy enough to afford a $20 million to $50 million ticket to orbit. If just 1% (500 individuals) of such individuals traveled into orbit every year, the demand would require at least 100 to 125 crew launches annually.

Commercial launch demand could be further enhanced by:

1. Starting a space lotto system: allowing adults to purchase dollar tickets for a trip to a private space station in orbit.

2. Deploying propellant producing water depots at LEO and EML1 (Such depots would require hundreds of tonnes of water to be launched from the Earth's surface annually)

3. Creating an international space agency that requires only $50 million in annual  dues from its member nations (If such an international agency only had twenty members and spent only half of its revenue on purchasing crew flights into space then ten to twenty people could be annually launched to LEO)

4. Allowing the US military to deploy astronauts from the armed services into space aboard facilities owned and operated by the DOD (Department of Defense): A mere $1 billion a year could allow ten to twenty military personal to fly into orbit annually.

5. Starting a guest astronaut program for deep space missions that charges foreign astronauts $150 million for participating in a deep space mission. So two foreign astronauts participating in a deep space mission could cut NASA's cost per mission by $300 million, allowing more missions to be funded. 

Private operation and commercial utilization  of the SLS and SLS-B (Boeing, Orbital ATK, and Aerojet Rocketdyne?) would allow both vehicles to compete with launch vehicles deployed by Space X, the ULA, and other countries around the world.

Links and References

 The Case for an International Space Agency

Boeing's New HLV Concept could be the DC-3 of Manned Rocket Boosters

Space Commercialization and the Lunar Lotto

The Case for a US Miltary Presence at LEO and Beyond

Thursday, February 8, 2018

Efficient Utilization of the Space Launch System in the Age of Propellant Depots

by Marcel F. Williams 

SLS Block I and Block IB (Credit: NASA)

With the successful test launch of Space X's  Falcon Heavy, some have questioned why NASA continues to support the development of the Boeing/Orbital ATK Space Launch System (SLS). The Falcon Heavy is now the most powerful rocket in operation with the capability of deploying up to 63 tonnes of payload to Low Earth Orbit (LEO). But next year,  NASA will test launch an even more  powerful heavy lift vehicle.  In its earliest incarnation, the SLS will be capable of deploying at least 70 tonnes of payload to LEO. By the time its Exploratory Upper Stage (EUS) is developed in the early 2020s, the SLS will be capable of deploying more than 105 tonnes of payload to LEO. Future advances or alternatives to the SLS solid rocket boosters also promise to enable the SLS to  deploy more than 130 tonnes of payload to orbit.

Maximum payload deployment to LEO:

SLS Block 2: 130 tonnes

SLS Block 1B: 105 tonnes

SLS Block 1: 70 tonnes

Falcon Heavy: 63 tonnes

Delta-IV Heavy: 28.8 tonnes

Falcon 9: 22.8 tonnes

Atlas-V: 20.5 tonnes

But  the Space Launch System will have an additional advantage over other launch vehicles in its ability to also accommodate  payloads with substantially larger dimensions. While the Falcon Heavy and most other launch vehicles will continue to be  limited to housing payloads within a maximum diameter of 4.6 meters, the SLS will be capable of deploying payloads within its  fairing up to 9.1 meters in diameter.

NASA's Hubble space telescope has a 2.4 in diameter mirror. The SLS would be the only vehicle capable of  accommodating space  telescopes with a single mirror  8 meters in diameter mirror or  segmented mirrors up to 16.8 meters in diameter.  The SLS would also be only launch vehicle with a fairing size capable of deploying Bigelow's 65 to 100 tonne BA-2100 Olympus space station which requires a fairing diameter of at least 8 meters.

Beyond the payload fairing dimensions, the SLS would also be the only rocket capable of deploying  Lockheed-Martin's reusable Mars landing vehicle (MADV) to orbit.
Notional  MADV on to of SLS (Credit: Lockheed Martin)

Maximum (internal) payload fairing diameter:

Space Launch System (SLS): 9.1 meters

Falcon Heavy: 4.6 meters

Falcon 9: 4.6 meters

Atlas-V: 4.6 meters

Delta-IV: 4.6 meters

The cost of an SLS launch will largely depend on how frequently the heavy lift vehicle is launched. NASA launched as many as eight space shuttle (a heavy lift vehicle) missions in one year. But since the expendable RS-25 engines for the core vehicle won't be ready until the early 2020s, the SLS can't be routinely launched into space until that time. However, sixteen RS-25 engines derived from the old Space Shuttle program are available for four SLS launches until the new expendable engines are ready.

But the success of the SLS will depend on how efficiently and frequently it is utilized. Once the new RS-25 engines are in production, it will be essential for NASA to launch the SLS at least twice per year during the 2020's and a lot more frequently during the 2030s. 

Propellant producing water depots are still the key to opening up the rest of the solar system for eventual commercialization and colonization of the rest of the solar system. Since most propellant depots concepts utilize existing propellant tanks or existing propellant tank technology, the SLS would have a distinct advantage over other launch technologies because of the size and volume of its propellant tanks.

An EUS modified with the ULA's Integrated Vehicle Fuel ( IVF) technology (WPD-OTV-128) could be deployed by the SLS to LEO or EML1 with a LOX/LH2 storage capacity of 128 tonnes with a 450 Kwe solar power plant. At EML1, such a propellant producing water depot would be capable of producing approximately 45 tonnes of LOX/LH2 propellant per month plus an additional 12 tonnes of LOX per month. The notional WPD-OTV-128 would also be capable of redeploying itself in orbit around Mars or Venus to enable crew returns to cis-lunar space from those worlds. Propellant producing water depots (WPD-OTV-128) at LEO and EML1 could be supplied with water from private commercial launch vehicles such as the Falcon Heavy.

Notional solar powered propellant producing water depot (WPD-OTV-128) at EML1.

An SLS Block IB might be capable of deploying up to 35 tonnes of payload to EML1. An IVF modified EUS utilized as a reusable OTV (Orbital Transfer Vehicle) would be capable of transporting at least 70 tonnes of payload from LEO to EML1. Two such OTVs (positioned on opposite sides of the cargo) would be capable of transporting at least  140 tonnes of payload from LEO to EML1. So by utilizing propellant depots, anything the SLS can launch to LEO could also be transported practically anywhere within cis-lunar space.

A larger orbital transfer vehicles (OTV-400) and propellant depots (WPD-OTV-400) could also be derived from SLS propellant tank technology and  used for crewed missions to the orbits of Mars and Venus.
Notional OTV-400 orbital transfer vehicle for crewed interplanetary missions

 Reusable LOX/LH2 spacecraft deployed by the SLS or by private commercial launch vehicles could be utilized for cargo and crew missions between EML1 and the lunar surface and between EML1 and LEO. Lockheed-Martin's reusable MADV could be used to land astronauts on the Moon and Mars or  transport them between LEO and EML1.   Reusable vehicle concepts such as the XEUS spacecraft or a notional Altair-like reusable vehicle (ETLV-4) utilizing Boeing's 2.4 meter in diameter cryotanks could be used to transport astronauts to and from the lunar surface to EML1 or between LEO and EML1.

XEUS lunar lander (Credit: ULA)

NASA plans a crew launch of the SLS in the early 2020s with a plan to deploy the Orion Multipurpose Crew Vehicle (MPCV) to the vicinity of the Moon. But reusable spacecraft using propellant depots would make Orion's European manufactured Service Module (SM) obsolete. The Service Module could be replaced by a reusable LOX/LH2 ACES 68 which could also be utilized with  the ULA's future Vulcan spacecraft to deploy the Orion to LEO.

Notional ETLV-4 lunar lander

Notional CLV-7 lunar cargo lander

Another SLS advantage over other launch vehicles would be the inherent  ability to use SLS propellant tanks or SLS propellant tank technology to deploy large habitats into orbit and to the surfaces of extraterrestrial worlds.

SLS propellant tank derived 8.4 meter in diameter microgravity habitats would have enough internal space to easily accommodate 20 centimeters or more of water shielding to protect astronauts from the deleterious effects of heavy nuclei and major solar events while still providing enough room to accommodate hypergravity centrifuges up to 6 meters in diameter that could be used to mitigate some of the deleterious effects of microgravity on human physiology. At least two SLS propellant tank derived microgravity habitats with 662 m3 of internal volume (more than twice the internal volume of Bigelow's BA-330) could be deployed to LEO-- with a single SLS launch. 

Notional SLS propellant tank derived microgravity habitat (Credit: NASA)

8.4 meter in diameter  SLS propellant tank habitats designed for the lunar and Martian surfaces could be easily placed with the SLS  payload fairing for deployment to the surfaces of the Moon or Mars.
 Such SLS propellant tank derived habitats could provide spacious multi-level habitats for the surfaces of the Moon and Mars that can be easily protected from the dangers of excessive cosmic radiation, major solar events, micrometeorites, and extreme thermal fluctuations by dumping regolith into an automatically deployed regolith wall that could allow up to two meters of regolith shielding, reducing radiation exposure well below that of radiation workers on Earth. 
X-Ray of notional Lunar Regolith Habitat
Notional twin Lunar Regolith Habitats on top of a sintered regolith

Three 8.4 meter in diameter SLS  propellant tank derived habitats joined together by cables and a retractable boom. When rotating at 2rpm, the cylindrical rings of the telescoping booms would expand the AGH approximately  224 meters in diameter, producing a simulated gravity up to 0.5 g within the counter balancing habitat modules. For crewed interplanetary missions, the booms could be easily retracted so that the AGH can be re-docked with an Orbital Transfer Vehicle for trajectory burns during the beginning or end of any interplanetary mission. The 0.5g simulated gravity aboard an AGH would be higher than on the surface of the Moon (0.17g) or Mars (0.38g). Appropriate radiation shielding against the heavy ion component of cosmic rays could be internally provided by water. Permanent internal shielding against excessive levels of cosmic radiation exposure could be provided by iron extracted from lunar regolith. 
X-Ray of notional SLS propellant tank derived artificial gravity habitat
Notional rotating artificial gravity habitat at EML1

While the Falcon Heavy wouldn't even come close to the launch capabilities of the SLS, Space X is currently working on a Super Heavy Lift vehicle that could.  The two stage methane fueled  BFR would be 9 meters in diameter (0.6 meters wider than the SLS) and be capable of deploying up to 150 tonnes to orbit (20 tonnes more than the SLS Block 2. Clearly, Elon Musk understands the value of large super heavy lift space rockets.

Links and References 

Lockheed Martin's Reusable Extraterrestrial Landing Vehicle Concept for the Moon and Mars

(Part II) Practical Timelines and Funding for Establishing Permanent Outpost on the Moon and Mars using Propellant Producing Water Depots and SLS and Commercial Launch Capability

Reusable Heavy Cargo and Crew Landing Vehicles for the Moon and Mars

The ULA's Future ACES Upper Stage Technology

SLS Derived Artificial Gravity Habitats for Space Stations and Interplanetary Vehicles

Space X BFR (Rocket)

Blog Archive

Popular Posts