Inside Space X Moon Lander

Commercial Advantages of a Reusable SLS Deployed Lunar Cargo Lander

Notional RLV-4 Cargo vehicle in a distant  Near Rectilinear Halo Orbit awaiting depot refueling before transporting a multilevel Lunar Regolith Habitat to an outpost at one of the lunar poles. 

 

 by Marcel F. Williams

Privately financing the development of a reusable SLS deployed lunar landing vehicle should be a priority for the major  Space Launch System partners: Boeing, Lockheed Martin, Aerojet Rocketdyne, and Northrup Grumman. A reusable single stage  LOX/LH2 fueled vehicle (RLV-4 Crew) could be commercially successful as a crew lander by simply adding a-- pressurized habitat module-- already being developed by Lockheed Martin for the Blue Origin National Team. 

Notional RLV-4 Crew vehicle with Lockheed Martin derived habitat module with crew deployment davit system.

 

By financing a single stage vehicle rather than a two stage vehicle, development cost could be substantially reduced by simply developing one vehicle instead of two. Further cost reductions could result from using engines and propellant tank technology that already exist. So a notional RLV-4 could use  RL-10 derived CECE engines already developed by SLS partner Aerojet Rocketdyne  and super lightweight composite propellant tanks already developed by Boeing. 

I envision the RLV-4 Crew and RLV-4 Cargo vehicles going into operation by the year 2026. If we assume a development cost of $6 billion for the RLV-4 over the course of six years, then each SLS partner would be required to supply at least $250 million a year of funding for the development of the reusable RLV-4.

Notional RLV-4 Cargo vehicle capable of being filled with up to 56 tonnes of LOX/LH2 propellant.

 

Similar to the RLV-4 Crew vehicle, I envision the RLV-4 Cargo as being launched-- in pairs-- within the 9.1 meter in diameter dynamic envelope of a 10 meter in diameter SLS payload fairing.  At its corners, the maximum diameter of the RLV-4 octagon  would be 8.44 meters with a distance between each opposite 3.23 meter side of the octagon being approximately 7.8 meters. With the legs folded during launch, the RLV-4 could easily fit within the internal  9.1 meter in diameter dynamic envelope of the 10 meter in diameter SLS  payload fairing.  

Each RLV-4 Cargo vehicle would weigh approximately 8 tonnes. The 10 meter in diameter payload fairing would add an additional 10 tonnes in weight headed for orbit.  Since an SLS Block I would be capable of deploying up to 70 tonnes to LEO, up to 44 tonnes of propellant could be added to one of the vehicles in preparation for a mission. 

Alternatively, one RLV-4 Crew vehicle could be launched with one RLV- 4 Cargo vehicle. Before launch, the crew vehicle would be filled with enough propellant to transport a crew to NRHO. The cargo vehicle would simply remain in orbit at LEO until its ready to dock with a payload and be fueled for a mission.

The reusable  RLV-4 Cargo vehicle would be able to dock securely with large payloads (up to 10 meters in diameter) subsequently deployed to LEO by the SLS. Payloads deployed to orbit by the SLS would be equipped with flat standardized docking bases configured to securely join with the octagonal payload floor of the RLV-4. Propellant depots deployed to LEO, NRHO (Near Rectilinear Halo Orbit) and eventually on the lunar surface would be used to fuel and refuel the RLV-4 Cargo vehicles.

Octagon shaped payload floor of notional RLV-4 Cargo vehicle.

 

Fueled at LEO with up to 56 tonnes of propellant, the RLV-4 could deploy up to 10 tonnes of cargo to the lunar surface. Alternatively,  the RLV-4 could transport up to 30 tonnes of cargo to NRHO where it could then be refueled to transport its 30 tonne payload to the lunar surface.

If the SLS deployed payload has an upper attachment area that could allow an additional RLV-4 to dock then two RLV-4 Cargo vehicles could be utilized for a single cargo mission.  This could allow up to 60 tonnes of payload to be transported to NRHO. A single fully fueled RLV-4 Cargo vehicle could deploy up to 50 tonnes of payload to the lunar surface. But two vehicles would be required to deliver a 60 tonne payload to the surface. One vehicle would only travel to lunar orbit and then back to NRHO while the second vehicle would travel to the lunar surface with its 60 tonnes of payload. 

So the reusable RLV-4 cargo system would be capable of delivering 10 tonnes to 60 tonnes of payload from the lunar surface from LEO. And that means the SLS   could deploy up to 60 tonnes of payload to the lunar surface with a single launch if it used a reusable RLV-4 Cargo transport system. 

Notional RLV-4 Cargo deployed lunar crane for unloading large cargo and for lunar regolith deposition. 

Large lunar cranes might be one of the most valuable initial payloads for the RLV-4 Cargo. Using a davit system, a pair of large cranes could be deployed to the lunar surface.  Such electric or hybrid electric (pressurized hydrogen fuel cell/battery) vehicles could be used to unload large and heavy payloads from a large variety of lunar landing craft. If we assume that each lunar crane weighs at least 8 tonnes, lunar regolith could be used to provide an additional 24 tonnes of counter weight. So each lunar crane should be capable of offloading more than 30 tonnes of payload. However, if the iron and other metals that inherently exist within lunar regolith are magnetically extracted to increase the counterweight capabilities of lunar regolith then payloads weighing more than 60 tonnes could be unloaded. Lunar cranes could also be used to deposit regolith within the surrounding walls of large habitats and within the foundation floor for inflatable biospheres and surrounding bio-tori.

RLV-4 Cargo vehicle carrying twin lunar regolith cranes to be deployed to the lunar surface using davit system.

 

Pressurized 8.4 meter in diameter cylinders derived from SLS propellant tank technology could provide multilevel habitats for the lunar surface up to  20 meters tall if deployed within an SLS 10 meter in diameter payload fairing. With a self deploying regolith walls, lunar cranes could provide appropriate radiation shielding by simply dumping lunar regolith within the cavity of the surrounding wall. 

Lunar regolith crane about to remove a Lunar Regolith Habitat from a RLV-4 Cargo vehicle.

But even longer 8.4 meter in diameter cylinders could be deployed to the lunar surface after being to deployed to LEO by the SLS. 40 meter habitats could be deployed to the lunar surface using the RLV-4 Cargo. Such habitats could be unloaded by large  lunar cranes and deployed horizontally to the lunar surface and then covered with lunar regolith bags. The use of the larger horizontal  habitats for agriculture could even allow for the growing of orchard trees for the production of apples, oranges, peaches, lemons, etc. The horizontal habitats could also be used for aquaculture, raising shrimp, crabs, fish, clams, etc. 

X-Ray of an SLS propellant tank technology derived Lunar Regolith Habitat

If the RLV-4 Cargo is used to deploy inflatable Kevlar biosphere and bio-tori then substantially larger habitats could be deployed. 50 meter in diameter  Kevlar biospheres that are pressurized with half the atmospheric pressure on Earth could easily be deployed to the lunar surface by an RLV-4 Cargo.  An additional SLS launch would be required to launch the surrounding  25 meter wide  bio-torus. And another SLS launch would be required to deploy the expandable connecting tunnel and regolith base for the biosphere and bio-torus on top. 

 A 15 meter high  SLS deployed lunar regolith hab might provide five spacious 8.4 meter in diameter habitat floor levels (55 square meters per floor). 

But the bottom half of a 50 meter in diameter biosphere could provide up to 9 habitat levels with each floor averaging about 25 meters in diameter (490 square meters per floor). That would be up to 16 times the floor area for just the bottom half of the biosphere. The upper half of the biosphere (the biodome) would provide the astronauts, military personal, and guest with spacious recreational area with a ceiling up to 25 meters high. Such an area could easily accommodate a large circular recreational swimming pool 30 meters in diameter. This might also be room enough to strap on a pair of wings and fly about within the 50 meter wide biodome.  The surrounding bio-torus or tori could be used for agriculture and aquaculture and storage.

Notional lunar biosphere and bio-torus covered with regolith bags and connected to twin Lunar Regolith Habitats on the sintered surface of a lunar outpost area.

 Once propellant is being produced on the lunar surface, extraterrestrial vehicles like the RLV-4 crew should make it substantially cheaper to travel to the lunar surface after departing the Earth's surface aboard a commercial crew vehicle. If a lunar habitat was deployed to the lunar surface and utilized as a hotel for astronauts, tourist, and military personal, the owners could reasonably charge its guest perhaps $10 million each for a 30 day stay. This, of course, doesn't include the cost of the round trip from Earth to the Moon. If we assumed that an individual habitat was continuously occupied by at least 4 to 8 personal (astronauts, military personal, tourist) then an individual habitat could make between  $480 million to $960 million per year in revenue. With up to 16 times the floor area for the bottom half of a biosphere, a single biosphere/bio-tori complex could make more than $15 billion a year in revenue if it were continuously fully occupied with up to 128 people.   Providing water, food, and air for the lunar guest would be insignificant if such resources are derived from ice and carbonaceous and nitrogenous resources in the lunar regolith at the poles or from similar resources deep within lava tubes. Assuming a minimum 20 year lifetime for such habitats, such SLS deployed facilities should be highly profitable.

Links and References

Commercial Advantages of a Large SLS Deployed Reusable Extraterrestrial Crew Landing Vehicle

Inflatable Biospheres and Bio-Tori for Large Outpost and Colonies on the Lunar Surface

NASA selects proposals to demonstrate in-space refueling and propellant depot tech

Delta V calculator

Blue Origin's National Team Lunar Lander

Links and References

Blue Origin: Human Landing System

Blue Origin's National Team Concept for Landing Humans on the Moon

Dynetics Lunar Landing System

Links and References

Dynetics 

NASA Awards Lunar Lander Contracts

Watch China Land their Robotic Lander on the Far Side of the Moon!

Evaluating Lockheed Martin's Reusable Lunar Lander and Orbital Propellant Depot Concept

Notional  reusable lunar landing spacecraft on the lunar surface (Credit: Lockheed Martin)

by  Marcel F. Williams 

At the 69th International Astronautical Congress held in Bremen, Germany this month,  Lockheed Martin  unveiled a new reusable lunar crew lander concept.

For simplicity,  I'll designate the notional Lockheed Martin spacecraft discussed in this article as the R-LL (Reusable Lunar Lander).   According to Lockheed Martin, the R-LL will have dry weight of 22 tonnes and be capable of storing up to 40 tonnes of LOX/LH2 propellant. The R-LL will have up to 5 km/s of  delta-v capability.

Lockheed Martin argues that the R-LL should be capable of crewed round trip  missions to any area of  the lunar surface from NASA's future Deep Space Gateway (DSG) which is to be located at a Near Rectilinear Halo Orbit (NRHO).    Such round trip missions, they argue,  would also be capable of delivering up to one tone of payload to the lunar surface in addition to a crew of four individual astronauts. 



While Lockheed Martin has been rather vague about the exact dimensions of the R-LL, they have indicated that it will consist of only two cryotanks and will be derived from the Centaur upper stage family and its descendants. They also suggest that the R-LL will have a diameter close to that of  the future Orion spacecraft.

Since Lockheed Martin's Centaur V is currently in development as the future upper stage for the ULA's future 5.4 meter in diameter Vulcan rocket, one might speculate that the diameter of the R-LL cryotanks might be the same as  and  is supposed to have the same 5.4 meter diameter as the Centaur V. Such large diameter liquid hydrogen and liquid oxygen tanks should be capable of easily accommodating the 40 tonnes of propellant required for the R-LL. So deriving the lunar vehicle from the Centaur V cryotanks might be the simplest and cheapest path towards rapidly developing the R-LL.

Lockheed Martin's Notional  Reusable Crewed  Lunar Landing Vehicle

Propellant: 40 tonnes of LOX/LH2

Inert Weight: 22 tonnes

Engines: Four RL-10 derived engines

Maximum delta-v capability: 5.0 km/s

Maximum number of crew: Four

Additional cargo capability: one tonne of additional cargo
The R-LL would use four engines to provide engine out capability. This would enhance crew safety during attempted landings in case of a serious malfunction with one of its engines. So just two counter balancing engines could be used during a landing in case of single malfunction engine.     Lockheed Martin says that engines for the R-LL  would be derived from  Aerojet Rocketdyne's  RL-10 family or from Blue Origins restartable BE-3 engine. Aerojet Rocketdyne's RL-10 derived CECE engines would be  capable of at least 50 restarts with a throttling range from 104 percent to  just eight percent of thrust. 

Departing from the Deep Space Gateway, it would take approximately 12 hours for the R-LL to reach any point on the lunar surface. Another 12 hours would be required for the R-LL to return to the  gateway at NRHO.

NRHO: (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)

Lockheed Martin says that their notional lunar spacecraft would be capable of accommodating  a crew of four astronauts on the lunar surface for up to two weeks. Such a lengthy stay would require at least four tonnes of additional shielding mass to protect astronauts from the inherently  deleterious heavy nuclei component of cosmic radiation and from a major solar flare. So one would assume that such enhanced radiation shielding would be part of the notional space vehicle's 22 tonnes of inert mass.

Lockheed Martin has also suggest that propellant depots could be co-orbited with the Deep Space Gateway so that the R-LL can be refueled at NRHO.

The simplest propellant depots would probably have to be utilized within a month after deployment to NRHO since approximately 3.81% of its liquid hydrogen and 0.49% of its liquid oxygen would boil off within a months time. For the 40 tonne LOX/LH2 requirement for the R-LL, such propellant depots would probably have to NRHO by the SLS or the BFR.

More sophisticated propellant depots could be equipped with cryocoolers and solar arrays capable of re-liquefying fuel boil-off.  Ullage gases from the boil-off of liquid hydrogen could be used to re-liquefy gaseous oxygen while 12 to 15 kWh of electricity would be needed to liquefy one kilogram of gaseous hydrogen. The 5.7 tonnes of liquid hydrogen required for a lunar mission would lose more than 217 kilograms of LH2 per month (7.2 kilograms per day).  But a 10 kWe solar  array deployed to NRHO capable of producing more than  240 kWh of electricity per day would be capable of re-liquefying 16 to 20 kilograms of LH2 per day.  The solar arrays for the Orion spacecraft will be capable of producing more than 11  kW of electric power. So it should be rather simple to deploy propellant depots already equipped with cryocoolers and and solar panels in order to prevent fuel boil-off. 

Solar powered depots that simply re-liquefied its ullage gases and powered pumps for storing and transferring liquid fueles would only  require the continuous delivery of liquid hydrogen and liquid oxygen.  Future Vulcan Heavy/Centaur rocket could deliver 7.3 tonnes of liquid hydrogen or oxygen to NRHO per launch. Monthly launches could deliver more than 87 tonnes of propellant to depots located at NRHO per year, more than enough for two R-LL missions to the lunar surface per year.

Notional propellant producing water depot (Credit: Lockheed Martin)

The most technologically complex propellant depots could use solar power to  actually  produce liquid hydrogen and liquid oxygen directly from water. This would require the addition of an electrolysis plant plus substantially more solar power.  A 375 KWE solar array proposed by Lockheed Martin could produce 40 tonnes of liquid hydrogen and oxygen propellant at NRHO per month. Such huge 375 KWE solar arrays would weigh  less than four tonnes. And two such arrays could be directly delivered to NRHO with a single SLS launch. But much smaller commercial launch vehicles could deploy 300 KWe arrays to LEO for later transport to NRHO by fueled upper stages deployed to LEO. 300 KWE arrays at NRHO could produce 40 tonnes of propellant in five or six weeks rather than just four weeks for the larger arrays.

Solar powered propellant producing water depots would make it much simpler and safer for commercial rockets to deliver fuel to NRHO since the payload would only be water. Propellant producing water depots at NRHO could eventually be supplied with water from the lunar poles.

Of course, water and propellant being produced on the lunar surface itself would dramatically reduce the amount of propellant required for   R-LL departures from NRHO. Reusable tanker vehicles directly derived from the R-LL could deliver more than 40 tonnes of lunar water  to propellant producing water depots at  NRHO per flight.  Just 12 round trips from the lunar surface could deliver enough water to NRHO to manufacture enough fuel for crewed missions to the orbits of Mars or Venus.

Lockheed Martin envisions that astronauts would be deployed to the NRHO gateway via the Orion and the Space Launch System. And then the would take the R-LL to the lunar surface and back to the NRHO gateway. And then they would take the Orion back to Earth.

However, propellant depots deployed at LEO  would make SLS crew launches of the Orion vehicle obsolete.  Refueling at LEO, the R-LL would have more than enough delta-v capability to transport crews from LEO to the  NRHO gateway. And refueling at NRHO, the R-LL would, of course, be capable of returning crews from NRHO back to LEO.  And even with  22 tonne of inert weight, a  5.4 meter in diameter R-LL could be launched to Leo aboard a Vulcan/Centaur launch vehicle within  a  6.4 meter in diameter payload fairing.

So for trips to the lunar surface, astronauts would simply take a Commercial Crew Launch vehicle (Falcon9/Dragon or Vulcan/Centaur/CST-100) to a commercial space habitat at LEO where a propellant depot refueled R-LL was already docked and ready to be boarded.  The R-LL would leave LEO with enough  propellant to take its crew on a 5 day journey to the NRHO gateway where another already depot fueled R-LL would already be docked.  The second R-LL  would take the crew for a round trip to the lunar surface, 12 hours to reach the surface and 12 hours to return to astronauts to the Deep Space Gateway.  The astronauts would return to the gateway with the first R-LL already fueled for their return to a commercial space station at LEO. The Crew would than take a Dragon or CST-100 Starliner back to the Earth's surface.

Such an architecture would, finally,  allow the SLS to be used--exclusively-- as a super heavy lift cargo transport. Such payloads could include: large and spacious microgravity and artificial gravity habitats derived from SLS propellant tank technology,  large water and propellant depots derived from SLS propellant tank technology, interplanetary spacecraft capable of accommodating at least 400 tonnes of propellant derived from SLS propellant tank technology for crewed missions to the orbits of Mars and Venus, 8 meter in diameter space telescopes exceeding the capability of the James Webb telescope,  and large inflatable microgravity and surface habitats that could make it a lot more spacious and comfortable for future astronauts and tourist to live under artificial gravity conditions in space or on the hypogravity surfaces of the Moon and Mars.


Links and References

Concept for a Crewed Lunar Lander Operating from the Lunar Orbiting Platform Gateway

Lockheed Martin unveils lunar lander concept

Cis-Lunar Gateways and the Advantages of Near Rectilinear Orbits

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

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

Notional ETLV-4 rendezvous with propellant producing water depot @ EML1 with orbiting solar power plant (where propellant depots dock when converting water into LOX/LH2) in the background.

by Marcel F. Williams

In 2018, NASA will launch the first unmanned test flight of its wide body super heavy lift vehicle, the Space Launch System (SLS). That first launch will also test the first uncrewed version of the Orion spacecraft. Coincidentally, 2018 will also be the same year that private companies, thanks to  the  financial help of NASA, will return American astronauts into orbit aboard private spacecraft. Crewed Orion/SLS missions are not scheduled to occur until at least the year 2021.

Congress has directed NASA to reveal the design of a  microgravity Deep Space Habitat (DSH)  by 2018. Unfortunately, the American space agency continues to ignore the use of a DSH as a gateway for crewed missions to the lunar surface while simply ignoring the significant  physiological problems associated with potential multiyear interplanetary missions within a microgravity environment.

Orion MPCV docked @ SLS propellant tank derived Deep Space Habitat (Credit NASA)

 The primary purposes for a  Deep Space Habitat (DSH) should be to:

1. Serve as a gateway to the lunar surface. Astronauts traveling from the Earth or from the lunar surface could dock their spacecraft at an EML1 habitat, taking temporary advantage of the more spacious accommodations before transferring to vehicle fueled destined for the lunar surface.  

2. Serve as a storm shelter during the occurrence of major solar events. This will probably require at least 30 cm of water shielding for the areas within the habitat that the astronauts will be occupying. Major solar events can last for several minutes to several hours.

3. Serve as a maintenance and repair station for reusable lunar shuttles (ETLV) and orbital transfer vehicles. Flex Craft docked at the DSH could also be utilized  for extravehicular repairs to  nearby water/propellant depots and associated solar arrays at EML1.

4. Test the effectiveness of various levels of water shielding required to mitigate cosmic radiation and potentially brain damaging heavy nuclei. In theory, 20 cm of water would be enough shielding to to stop the penetration of the heavy nuclei component of cosmic rays while 30 cm of water would reduce overall  annual cosmic radiation exposure to less than 25 Rem per year during solar minimum conditions. Solar storm events would also be significantly mitigating with 30 cm of water protection. Minimizing the mass of radiation shielding required for safe interplanetary travel would be essential for reducing the amount of propellant required for such missions.

5. Test the integrity and reliability of the pressurized habitat structures that might also be used for habitats on the surface of the Moon and Mars and for rotating  artificial gravity habitats for space stations placed in cis-lunar orbits, Mars orbit, and for crewed interplanetary journeys. 

Of course, a  DSH would be a-- destination to nowhere-- without developing vehicles capable of transporting humans and heavy cargo to the surfaces of the Moon and Mars. And, in my opinion, most Americans and members of Congress will continue to believe that  America's glory years in space are in the past until American astronauts are once again  walking on the surfaces of other worlds-- this time to stay.

NASA's beyond LEO ambitions are severely  hampered by the fact that it continues to operate a relatively expensive (~$3 billion/yr) LEO program (ISS) without a significant increase in the NASA budget for its beyond LEO program. While it has been presumed that much more funding will be provided for NASA's beyond LEO missions once the ISS program comes to an end, there are still efforts to extend the ISS program beyond 2024, again, without increasing the NASA budget in order to pay for its continuation.

Bigelow Aerospace plans to deploy its first private commercial space habitats to LEO  in 2020 aboard the ULA's Atlas V rocket. If this private space company is successful then there's really no reason for NASA to continue the ISS program beyond 2020 since private companies will be able to do  research and development at LEO.   This, of course, would allow NASA to use ISS related funds to develop the cargo and crew landing vehicles, habitats, and related infrastructure for crewed missions to the Moon and Mars.

 Allowing foreign astronauts to participate in NASA's beyond LEO program could provide additional funding for NASA. By 2018, Russia plans to charge NASA,  $81 million per astronaut for transport  to an from the ISS. NASA could charge  foreign space agencies $150 million for each astronaut participating in one of its  beyond LEO missions. The Orion MPCV is capable of accommodating as many as six astronauts. If two of those astronauts were from foreign space agencies paying NASA to join the mission then  NASA could save $300 million per crewed SLS launch.

The Center for Strategic and International Studies (CSIS) has estimated that the cost of developing a crewed two stage lunar lander  at approximately $12 billion. Former NASA director,  Charlie Bolden,  estimated the cost of developing a lunar landing vehicle at approximately $8 to $10 billion.

Neil Armstrong and Buzz Aldrin landed on the surface of the Moon just seven years after NASA invited  eleven private firms  to submit proposals for the Lunar Excursion Module (LEM) in July of 1962. So if we assume that it will take seven years to develop an extraterrestrial landing vehicle or vehicles ( using a COTS type of funding for more than one vehicle), then annual development cost over the course of seven years might range from approximately $1.1 billion  to $1.7 billion. We can also assume that an additional  $1.1 billion a year to $1.7 billion a year over the course of an additional seven years would then be needed to fund the development of a future Mars landing vehicle.  Such annual funding for  extraterrestrial landing vehicles would still leave ample funds for financing the development of lunar and martian habitats and the associated infrastructure.

Boeing Aerospace 2.4 meter Super Light Weight cryotank (Credit Boeing Aerospace)

However, the development time, cost, and recurring cost  for an extraterrestrial landing vehicle (ETLV) could be substantially reduced if: 

1.  A single stage vehicle, or vehicles,  were developed instead of a-- two stage vehicle

2. An ETLV was developed that was largely derived from technology that either already exist or is currently in development

3. An ETLV was developed that utilized LOX/LH2 common bulkhead propellant tanks instead of two different tanks for liquid oxygen and liquid hydrogen

4. An ETLV was developed that were capable of transporting cargo and crews to the surfaces of both the Moon and Mars and back to the orbits of the Moon and Mars

5.  An ETLV was  developed that had pressurized habitat and airlock areas derived from re-purposed ETLV propellant tanks. 

6. An ETLV was  developed that was  capable of being reused for at least for ten round trips to and from their destinations (the surfaces of the Moon or Mars)

7.  An ETLV was  developed that was capable of also being utilized for unmanned robotic and cargo missions

8.  An ETLV was  developed that was capable of also being utilized as a crewed orbital transfer vehicles between LEO, Low Lunar Orbit, and the Earth-Moon Lagrange points

Front view of notional singe stage reusable ETLV-4 derived from 2.4 meter in diameter cryotanks

Side view of notional singe stage reusable ETLV-4 derived from 2.4 meter in diameter cryotanks

ETLV-4 

Up to 40 tonnes of LOX/LH2 propellant in four 2.4 meter in diameter propellant tanks 

Four RL-10 derived CECE engines 

2.4 meter in diameter propellant tank derived central crew habitat area with lower heavy ion shielded storm shelter   

Twin 2.4 meter in diameter propellant tank derived airlocks 

Inert mass without heavy ion water shielded area: ~12 tonnes 

Inert mass with heavy ion water shielded area (22 cm of water): ~17 tonnes 

Gross mass: 57 tonnes 

specific impulse: 445 seconds

   
Due to reduced vehicle mass, reductions in vehicle components, and reduced vehicle complexity, Lockheed-Martin  concluded that the development  cost and recurring cost for a lunar lander could be substantially reduced if a reusable single stage vehicle were developed instead of a two staged spacecraft.   NASA reached a similar conclusion back in the late 1980s when JPL proposed its own single stage LOX/LH2 lunar landing vehicle.  

Boeing developed and tested a 2.4 meter cyrotank as a prelude to its development of a 5.5 meter in diameter, Super Light Weight Tank, that might possibly be used for the 5.5 meter LOX tank for the SLS upper stage (EUS). The 2.4 meter tank was successfully filled with liquid hydrogen chilled at  –423 °F  and cycled through-- twenty-- pressurization and  vent cycles.  If Boeing's 2.4 meter tank were utilized in a common bulkhead configuration for storing LOX/LH2 propellant in an Altair-like vehicle then such tanks could be utilized for a reusable single staged spacecraft. 

Four RL-10 derived CECE (Common Extensible Cryogenic Engine) engines, currently in development by Aerojet Rocketdyne,  could enhance vehicle safety with engine out capability and would be capable of up to 50 restarts. This should enable the vehicle to be used for at least 10 round trips from the surfaces of the Moon or Mars and to various orbital regions near each celestial body.  The CECE engines are also supposed to be designed to have a throttle capability ranging from 104% of thrust down to just 5.6%, which should allow an extraterrestrial landing vehicle to land on worlds as large as the Moon and  Mars or as small as the moons of Mars. However, thrusters near the bottom of an ETLV could also be used to land on the surfaces of the small low gravity martian moons.

Utilizing Integrated Vehicle Fluid (IVF) technology currently being developed by the ULA, helium and hydrazine would no longer be required for an extraterrestrial spacecraft with some ullage gases even being utilized for  attitude control. With the addition of  NASA emerging cryocooler technology, solar powered cryocoolers could reliquify some ullage gases, eliminating the  boil-off of hydrogen and oxygen.

Pressurized crew areas and airlocks derived from re-purposed ETLV propellant tanks, could further reduce development and recurring cost.  The twin cryotank derived airlocks allows more room within the cabin while allowing astronauts to leave the vehicle without having to decompress and then re-pressurize the crew cabin.  With the airlocks positioned just a few meters above the landing pods, pressure suited astronauts could depart the vehicle just few meters above a planetary surface, reducing the difficulty and risks associated with exiting and entering the spacecraft.   The low position of the airlocks should also make it convenient for mobile robotic vehicles to be deployed to the surface of a the Moon or Mars or the moons of Mars for robotic exploration and potential sample  returns to orbit.

NASA's ADEPT deceleration shield concept (Credit NASA)

Developing a  landing vehicle that could be used for crewed missions to both the lunar and martian surfaces would, of course, substantially reduce development cost.  A spacecraft capable of transporting astronauts from surface of Mars to Low Mars Orbit (~4.4 m/s delta-v)  would also be easily capable of transporting astronauts from the surface of the Moon to Low Lunar Orbit or to any of the Earth-Moon Lagrange points (less than 2.6 m/s delta-v).

Landing such an extraterrestrial landing vehicle on the surface of Mars, however, would require the development of a deceleration shield. NASA is currently doing research on two types of deceleration shields: HIAD and ADEPT. The rigid ADEPT deceleration shield could allow spacecraft to deploy up to  40 tonnes of payload  practically anywhere on the surface of Mars. After the ADEPT deceleration shield was discarded, a delta-v of less than 0.6 meters per second would only be required to land the vehicle on the martian surface

 

Notional ADEPT deployment of 40 tonnes of cargo to the martian surface (Credit NASA)

An extraterrestrial landing vehicle capable of transporting astronauts from the surface of Mars to low Mars orbit would also be capable of transporting astronauts from LEO to Low Lunar Orbit or to any of the Earth-Moon Lagrange points. Utilizing the ETLV in such a manner, however,  could make the Orion MPCV obsolete,  allowing astronauts to be transported into orbit by Commercial Crew vehicles and then transferred to a propellant depot fueled  ETLV  for easy access to the Earth-Moon Lagrange points and Low Lunar Orbit and to the lunar surface.

Notional CLV-7B cargo lander derived from 2.4 meter diameter cryotanks

A cargo lander (CLV) derived from the crew version of the ETLV could easily be derived using all seven 2.4 meter in diameter pressurized tanks to carry propellant. With a  diameter of at least 7.2 meters, such a cargo transport could deploy large and heavy structures as large as 8.6 meters in diameter to the surfaces of the Moon and Mars. Pressurized habitats derived from an SLS propellant tank technology with diameters up to 8.4 meters  could easily be deployed to the surfaces of the Moon and Mars by such an ETLV derived CLV. 

ATLETE robots could be used  for offloading heavy cargo to the surfaces of the Moon and Mars aboard a notional CLV-7B (Credit: NASA)

CLV-7B

Up to 35 tonnes of LOX/LH2 propellant in seven 2.4 meter in diameter propellant tanks 

Four RL-10 derived CECE engines 

Specific impulse: 445 second

Inert mass without payload: ~8 tonnes 

Gross mass without payload: ~43 tonnes 

Capable of accommodating cargo with diameters as large as 8.6 meters 

Notional SLS propellant tank derived  regolith shielded habitat for the Moon and Mars with an 8.4 meter in diameter pressurized habitat area that could be deployed to the lunar or martian surface using the CLV-7B and ATHLETE technologies. 

Once the cargo lander is  on the surface of the Moon and after its payload is deployed,  water bags could be securely attached to the top of the  CLV-7B. This could allow the CLV to be reused as a water transport tanker capable of transporting  at least 35 tonnes of water from the surface of the Moon to EML1. Using its CECE engines for ten round trips could enable the CLV to  deliver more than 300 tonnes of water to   propellant producing water depots located at EML1.

With the capability of landing crews and payloads on the Moon and Mars, the ETLV-4 crew lander and the CLV-7B cargo lander should also be capable of  someday landing crews and cargo on the surfaces of the planet Mercury and on Jupiter's moon, Callisto, two other viable worlds for potential commercialization and human settlement. Within Jupiter space, automated unmanned ETLV-4 spacecraft operated from an outpost on Callisto could transport mobile robotic vehicles to the Jovian moons within Jupiter's deadly radiation belt (Ganymede, Europa, and Io) for continuous robotic exploration and sample returns from these interesting but heavily radiation inundated  worlds.


Links and References

Composite Cryotank Technologies; Demonstration


CECE (Common Extensible Cryogenic Engine)


An Integrated Vehicle Propulsion and Power System for Long Duration Cryogenic Spaceflight (ULA)


 The SLS and the Case for a Reusable Lunar Lander

Finally, some details about how NASA actually plans to get to Mars

 

Private Space Habitat to Launch in 2020 Under Commercial Spaceflight Deal

Russia is squeezing NASA for more than $3.3 billion — and there's little anyone can do about it

Apollo Lunar Module

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

ADEPT Technology for Crewed and Uncrewed Missions to the Planets

 

Landing on Mars with ADEPT Technology

 

Inflatable Biospheres for the New Frontier 

 

Living and Reproducing on Low Gravity Worlds

Utilizing the SLS to Build a Cis-Lunar Highway

The Earth seen rising above the Lunar horizon aboard Apollo 17, the last human mission to the Moon (Credit: NASA)

by Marcel F. Williams

By 2017,  American astronauts should be back in space aboard American made and launched private commercial vehicles. 2017 will also be the year that NASA launches it first true heavy lift vehicle since the days of Apollo.

SLS crew & cargo  vehicles

Some perceive the SLS as the antithesis of Commercial Crew development. But others view the Space Launch System as complimentary to Commercial Crew development. While Commercial Crew vehicles will enable Americans to have access to orbit again, the SLS launched  MPCV (Multipurpose Crew Vehicle) will give NASA the ability to launch humans practically anywhere within cis-lunar space-- and safely back to Earth's surface.

But  the Space Launch System could also be utilized to do a lot more.  

The SLS could be used to deploy a reusable cis-lunar architecture that could give passengers aboard Commercial Crew vehicles easy access to the surface of the Moon and to other commercially viable regions within cis-lunar space.

Below is a possible scenario that could make this happen by using a standard reusable ETLV (Extraterrestrial Landing Vehicle) derived architecture, starting in the year 2021. 

Nomenclature: 

EML (Earth Moon Lagrangian point); 
LEO (Low Earth Orbit); 
SLS (Space Launch System); 
MPCV (Multipurpose Crew Vehicle); 
CM (Command Module)
ETLV-2 (crewed Extraterrestrial Land Vehicle; 
ETLV-2R (Unmanned Automated ETLV-2); 
C-ETLV-4 (cargo lunar lander); 
WFD-OTV-5 (Water- Fuel Depot Orbital Transfer Vehicle); 
WFD-LV-5 (Water- Fuel Depot Lunar Landing Vehicle); 
RWT-LV-5 (Reusable Water Tanker Lunar Landing Vehicle); 
LRH (Lunar Regolith Habitat); 
Water Bug (Robotic Microwave Water Extraction Vehicle);
ATHLETE (All-Terrain Hex-Legged Extra-Terrestrial Explorer) 

Earth-Moon Lagrangian Points (Credit: NASA)

Before manned beyond LEO cis-lunar missions can begin, a new satellite communications system must be deployed at two of the Earth-Moon Lagrange points. Under this scenario, in  2020, a Delta IV heavy or an Atlas 401 will launch two satellites to EML2 (Earth-Moon Lagrange point 2). A second launch of either or the two vehicles will deploy two more communications satellites at EML1 (Earth-Moon Lagrange point 1).  This will allow continuous communications coverage for nearly the entire lunar surface. However, there will be some brief periods at some small mid-latitude regions that will be unable to communicate with the deployed constellation of Lagrange point satellites. But the deployment of satellite pairs at EML1 and EML2 should mostly eliminate the need for Earth-based tracking.

Delta-V Budgets & Destination Travel Times
 

LEO to TLI - 3.2 km/s dv

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

LEO to LLO (~4 days) - 3.97 km/s dv

LEO to EML1 (~2 days) - 4.41 km/s dv

LEO to EML1 (~4 days) - 3.77 km/s dv

EML1 to or from LLO (~2 days) - 0.75 km/s dv

EML1 to or from  LLO (~3 days) - 0.64 km/s dv

LLO to or from the Lunar surface - 1.87 to 2.1 km/s dv

LEO: Low Earth Orbit; TLI: Trans-Lunar Injection; LLO: Low Lunar Orbit; 

EML1: Earth Moon Lagrange Point 1

(Credit John Connolly: NASA-JSC - 2012)

 

2021

Unmanned ETLV-2R docked with the WFD-OTV-5 fuel depot at ELM1

Derived from the Extraterrestrial Landing Vehicle (ETLV), the WFD (Water Fuel Depot) OTV (Orbital Transfer Vehicle) will utilize the same  cryotanks used for the ETLV-2. But these will be five in number instead of two, fixed within a higher cruciform in order to enhance the depot's ability to store the maximum amount of cryofuel. The WFD-OTV-5 would be capable of storing nearly 70 tonnes of LOX/LH2 fuel in addition to more than 100 tonnes of water. However, when the WFD-OTV-5 fuel depot is initially deployed at EML1 by the SLS upper stage, it will contain only 20 tonnes of fuel and no water because the SLS upper stage will only be able to deliver a little more than  30 tonnes to the Lagrange point.

The first ETLV-2 mission to the lunar surface under this scenario will be an unmanned mission to the South Lunar Pole. But first the SLS will launch The ETLV-2R will be launched by the SLS to the fuel depot at  EML1. Although the ETLV-2R would be nearly fully fueled, some additional fuel would be required  in order  for the vehicle's return to the Lagrange point after landing on the lunar surface.

Once on  the lunar surface, a variety of small mobile robots will be deployed to explore the polar region, test water extraction technologies, and return a variety of samples from lunar regolith. After a few days, or a few weeks, the ETLV-2R will return to L1.

A similar mission will occur with the third launch of the SLS in 2021. But the unmanned destination will be the North Lunar Pole. Again, after  a few days, or a few weeks, the ETLV-2R will return to L1.

So the end of both unmanned missions to the lunar surface will not only retrieve lunar samples from the lunar poles but will twice demonstrate the ability of the ETLV-2 vehicle to travel to and from the lunar surface from L1 on a single fueling of it's twin tanks. These two demonstrations of the ETLV-2,  to and from the lunar surface, should enhance the safety of the first crewed mission of the ETLV-2 in 2022.

MPCV (Multipurpose Crew Vehicle) Credit: NASA

The fourth launch of the SLS that same year will be the first manned mission of the MPCV. Astronauts will be sent to EML1 to dock with both  ETLV-2 vehicles in order to retrieve the lunar material for return to Earth. The SLS upper stage will also carry nearly ten tonnes of water destined for the L1 fuel depot. The WFD-OTV-5 will convert this water into liquid hydrogen and oxygen, producing more than enough fuel to replace the extra fuel extracted by a single ETLV-2 on its way towards a round trip to the lunar surface.

Astronauts will return to Earth aboard the CM of the MPCV, demonstrating the vehicle's ability to travel within cis-lunar space while also bringing back precious regolith samples from the north and south lunar poles.

2022

C-ETLV-4 and the ETLV-2 cargo and crew lunar landing vehicles

The first SLS launch of 2022 will send the C-ETLV-4 lunar cargo vehicle directly to the lunar surface. An ATLETE robot will deploy two small mobile excavators, two mobile sintering robots, and a single back hoe for depositing regolith into the walled interior of human habitat structures.

ATLETE robot for offloading cargo from the C-ETLV-4 (Credit: NASA)

The ATLETE robot will be routinely relied upon to unload habitats and machines from future C-ETLV-4 missions to the lunar surface.  

Lunar excavation robots (Credit: Astrobotic Technology and Carnegie Mellon)

The mobile excavators will be used to remove rocks and level the surface area for eventual sintering. Mobile sintering machines will move over the paved area using microwaves to melt the lunar regolith, creating a hard sintered layer approximately 0.5 meters deep and a smooth  solid surface approximately 3 to 5 cm deep.  Two widely separated  areas will be prepared by the excavators and the sintering machines. One area will be for the deployment of the Lunar Regolith Habitats. The other area will be exclusively prepared for landings by the ETLV-2, C-ETLV-2, Reusable Water Tankers, and  lunar fuel depots. Both areas will be connected to each other by a paved and sintered road perhaps a kilometer or more long.

Lunar sintering robot (Credit: Credit: Larry Taylor)

The battery powered or fuel cell powered back hoe won't be utilized until the Lunar Regolith Habitats are deployed.

An electric powered (battery or fuel cell) back hoes would have to be deployed to the lunar surface in order to deposit lunar regolith inside of the regolith walls of a Lunar Regolith Habitat (LRH) (Credit: Volvo)

The second launch of the SLS in 2022 will deploy the Lunar Regolith Habitat. The ATLETE robot will remove the habitat from the top of the C-ETLV-4 and transport it to the sintered area previously prepared for human habitat occupation.

Lunar Regolith Habitat (LRH): Lunar regolith is deposited by the back hoe within the 2 meter cavity between the pressurized SLS hydrogen tank derived habitat area and the automatically deployed exterior wall.  This will  provide micrometeorite and thermal protection in addition to protection against major solar events and a reduction of cosmic radiation exposure to below maximum levels for radiation workers on Earth. Power for the habitat is provided by the solar panel on top. And radiators on top of the habitat help to regulate and dissipate excess heat. A mobile water tanker will periodically pump lunar water into the habitat for washing, cooking, drinking, growing food, and for the production of air.

Once it is in position, the LRH-1 will automatically expand its solar panel to recharge the habitat batteries. An SLS hydrogen tank derived pressurized habitat will automatically expand its wall panels to produce a rigid and continuous wall around the pressurized area, creating a 2 meter wide cavity between the wall and the pressurized habitat. The lunar back hoe will deposit lunar regolith inside of the cavity to the top of the regolith wall which will also extend approximately two meters above the top level of the pressurized habitat. This will provide astronauts, scientist, and other visitors to the habitat with thermal and micrometeorite protection while also protecting them from the radiation of major solar events and while also reducing their annual exposure to cosmic radiation to levels below that required for radiation workers on Earth. This will allow astronauts and scientist to continuously remain at such habitats for more than a decade without coming close to their lifetime NASA limits for radiation exposure.

Within the 8.4 meter in diameter pressurized housing, there would be two levels each with approximately  55 square meters of area. So each habitat level would be about the size of a one bedroom apartment on Earth. In total, these two levels would have more floor area than the average family home in Great Britain.  Airlocks derived from the ETLV tanks would be located below the pressurized habitat area.

The last two SLS launches in 2022 will send the ETLV-2 and the MPCV to EML1. Again, the water will also be delivered to the fuel depot at L1 during the MPCV launch to EML1. After adding additional fuel, the ETLV-2 will deliver six astronauts, four Americans and two foreign guest  to the lunar surface. But they will only spend a few days or a few days on the lunar surface to inspect the lunar habitat and to collect more lunar samples.   The ETLV-2 will return the astronauts back to EML1 where it will dock with the MPCV for the crews return to Earth. The ETLV-2 will remain at L1 for future use once new fuel is being manufactured at L1 from lunar water resources. And it will be part of a fleet of three reusable vehicles starting in 2025.

2023

The solar powered WFD-LV-5 will be able to store Lunar water while also being able to  convert water into liquid hydrogen and oxygen for storage and distribution. Mobile cryotankers will extract cryofuels from the fuel depot for fueling space vehicles like the ETLV-2. Mobile water tankers supply the  fuel depot with Lunar water from the Water Bugs .

The first SLS launch of 2023  will send a solar powered water storage and cryofuel producing depot to the new lunar outpost. This will be followed just a few weeks later by the  C-ETLV-4 deployment of two mobile cryotankers derived from ETLV cryotank technology.  The mobile cryotankers will be used to extract cryofuels from the WFD-LV-5 lunar fuel depots in order to  refuel lunar landing vehicles. The mobile cryotankers will also be capable of scavenging residual fuel from the dormant C-ETLV-4 vehicles.

2023 will end with another pair of SLS launches for the ETLV-2 and MPCV  in order for another temporary human  visit to the lunar outpost . 

2024

Mobile water tanker next to a Water Bug robotic microwave water extraction vehicle. Water Bugs will recharge their batteries in the sunlight before venturing within shadowed craters for water mining. Mobile water tankers will extract the water from the Water Bugs for deposition at the fuel depot or in lunar water bags.

2024 will open with the SLS launch of a C-ETLV-4 to the lunar outpost. The ATHLETE robot will deploy two mobile water tankers plus a twin pair of Water Bug  microwave water extraction vehicles. Each Water Bugs should be able to extract as much as one to two tonnes of water from the lunar ice deposits per day. Excess water that can't be accommodated by the fuel depot, the mobile tankers, and the lunar habitats will be stored in water bags at the outpost.

A second SLS launch in 2024 will use the C-ETLV-4 to deploy a second habitat to the lunar outpost (LRH-2). The second habitat will double the area for human accommodations at the outpost. Each habitat will also serve as backup accommodations for the other in case there is a  serious malfunction at one of the habs.

Two SLS launches will end the year, bringing the first long term inhabitants to the lunar outpost. Some of these individuals will remain on the lunar surface for more than a year simply to determine if there are any deleterious physical or psychological effects for human individuals after living in a low gravity environment for more than a year. Before the first human attempts to venture to the orbit of Mars and to the Martian surface, some astronauts will have to eventually stay on the lunar surface as long as four years.  The results of these simple human test on the lunar surface could have enormous implications for humanity's future in the rest of the  solar system.

 2025

RWT-LV-5 water tanker next to the ETLV-2

A single SLS launch in 2025 will deploy two reusable lunar water tankers to the lunar outpost. Each vehicle will be capable of transporting more than 50 tonnes of lunar water to the EML1 fuel depots per flight while still being able to return to the lunar surface. With their CECE engines, each vehicle should be capable of at least ten round trips between ELM1 and the lunar surface before their engines or the entire vehicle is replaced.  

RWT-LV-5 transferring lunar water to the WFD-OTV-5 at ELM1

A single SLS launch will be used to deploy three partially fueled Orbital Transfer Vehicles (OTV-2) to LEO. Three expandable aerobrakes will accompany the three vehicles into orbit. Each OTV-2 will have enough fuel to reach the fuel depots at EML1. The OTV-2 is simply an ETLV-2 without the landing legs. So there will be minimal development cost for the vehicle. The aerobrake will be required in order to minimize fuel utilization upon returning from the Lagrange points to Earth orbit.

An OTV-2 preparing to dock with an Aerobrake Shield and another OTV-2 docked with an Aerobrake Shield

The deployment of the reusable OTV-2 vehicles will  mean that an SLS launch of the MPCV will no longer be necessary in order to transport astronauts to the Earth-Moon Lagrange points. However, NASA astronauts will still need to be able to get to LEO in order to access the OTV-2. But by 2025, NASA should have a wide variety of  Commercial Crew and foreign vehicles available to give NASA astronauts access to orbit.    

Russian Soyuz

Chinese Shenzhou

Dream Chaser (Credit: Sierra Nevada Co.)

Dragon (Credit: Space X)

CST-100 (Credit: Boeing)

SKYLON (Credit: REACTION ENGINES LTD)

 Commercial Companies could also have private commercial access to the lunar surface by simply purchasing an OTV-2 and an ETLV-2 from the American vendors that produce them. And this could allow private American companies them to provide access to the lunar surface to other nations and for wealthy space tourist and space lotto winners. So as early as 2026, reusable ETLV derived vehicles and fuel depots deployed by the SLS could allow private Commercial Crew companies to expand space tourism and other commercial enterprises all the way to the lunar surface.

OTV-2 docked with an ETLV-2 lunar landing vehicle at EML1

A single SLS launch will deploy two additional fuel depots (WFD-OTV-5) to LEO. One will use its own engines to reach EML1 while the other will remain at LEO to refuel the OTV-2 vehicles. Once a  LEO fuel depot begins to run low on fuel, it will transport itself to EML1 to be refueled with water from the lunar tankers in order to manufacture enough fuel for its redeployment back at LEO.

X-Ray of Skylab II with its SLS derived pressurized habitat at ELM1 (Credit: Griffin)

The final SLS launch in 2025 will be to deploy an SLS hydrogen fuel tank derived habitat with an internal hypergravity centrifuge to EML1. Lunar water exported to L1 will provide enough radiation shielding for the Lagrange point habitat to protect astronauts from a major solar event. The deployment of the lunar water shielded Skylab II will be first test  of a potential interplanetary habitat for possible manned missions to the orbit of Mars.

 Marcel F. Williams
© 2014 MuOmega Enterprises

Links and References

• LOW-COST LUNAR COMMUNICATION AND NAVIGATION
•  Utilizing Space Shuttle Main Engines (SSME) for Early SLS Cargo Launches and Commercial Crew Destinations
• An SLS Launched Cargo and Crew Lunar Transportation System Utilizing an ETLV Architecture
• The SLS and the Case for a Reusable Lunar Lander
• Mission and Implementation of an Affordable Lunar Return (Spudis & Lavoie) 
•  Using the resources of the Moon to create a permanent, cislunar space faring system (Spudis & Lavoie)
•  The Future of NASA and the Commercial Crew Program
• How ATHLETE Robots could Deploy Pressurized Habitats and other Large Payloads to the Lunar Surface 
• Microwave Sintering of Lunar Soil: Properties, Theory, and Practice
• Cooking Up Water From the Moon? NASA Studies Water Extraction With Microwaves