First Starliner Crew Arrives at the International Space Station

The Peregrine Lunar Mission

 

Utilizing the Centaur V and ACES 68 for Deep Space SLS Missions

by Marcel F. Williams

Artist rendition of  ULA's future upper stage precursor to the IVF modified ACES 68, accommodating 68 tonnes of LOX/LH2 propellant (Credit: United Launch Alliance)

NASA currently envisions three launches for the SLS (Space Launch System) using a Block I configuration and  consisting of an ICPS (Interim Cryogenic Propulsion Stage) for its upper stage.  The basic Block I vehicle will be capable of deploying at least 70 tonnes to LEO. However, by utilizing the ICPS as an upper stage that can accommodate  27 tonnes of propellant, the Block I configuration with an ICPS upper stage will be able to deploy at least 95 tonnes of payload to low Earth orbit.

A Block IB configuration with an EUS (Exploration Upper Stage) is expected to be introduced by 2024. The  EUS will be able to  accommodate 128 tonnes of LOX/LH2 propellant. And this will enable the Space Launch System to deploy up to 105 tonnes of payload  to LEO.  NASA currently plans to use the Block IB configuration to assemble the future Lunar Gateway at NRHO (Near Rectilinear Halo Orbit). The Lunar Gateway will serve as a bridge for Lunar and Martian operations, substantially reducing the delta v requirement to reach the orbits of the Moon and Mars.


NASA's Current  Launch Sequence for the SLS

2020:

The SLS Block I launch vehicle will deploy an unmanned Orion spacecraft to a Distant Retrograde Orbit (DRO) before returning the capsule to the Earth. DRO is interesting because of its lack of station keeping requirement. Such a distant equatorial orbit of the Moon might make  DRO  a prime location for massive rotating artificial gravity habitats perhaps sometime  in the second half of the 21st century. It might also be a good location for small asteroids imported into cis-lunar space for potential exploitation.

2022:

The second SLS  Bloch I launch is scheduled  to send a crewed Orion spacecraft around the Moon as an inaugural human occupied beyond LEO spaceflight for the SLS system.

2023: 

The third scheduled SLS Block I launch  will be used to deploy  the Europa Clipper to Jupiter orbit in order to study the surface of its icy moon, Europa.

2024:

The first launch of the SLS Block IB is scheduled for 2024. It will consist of an Orion crew of four plus a ten tonne component of the Lunar Gateway which will be assembled at NRHO . This location will eventually give crewed  vehicles weekly access to the lunar surface with as little as 12 hours of travel time to and from the surface of the Moon.

2026:

Four subsequent SLS Block IB flights will be required to completely assemble the Lunar Gateway by 2026.

SLS Block I Cargo with ICPS upper stage capable of deploying 95 tonnes to LEO (Credit: NASA)

SLS Block I without upper stage, capable of deploying 70 tonnes to LEO (Credit: NASA)

The Flaws in NASA's SLS Plans


One. Only one or two  SLS launches are required to deploy the Lunar Gateway to NRHO-- not five SLS launches. Of course, the amount of mass that can be deployed to NRHO by the SLS is substantially reduced under the NASA scenario because of the joint launch of the Orion spacecraft and Service Module. This would be  an unnecessary joy ride for NASA astronauts that would greatly inflate the cost of deploying the Gateway while also significantly delaying its full implementation.

Why spend more than two to five times as much as you have to deploy the Lunar Gateway when dollars for NASA's human spaceflight related programs are so hard to come by? Plus NASA needs more funding to help private companies develop lunar crew landing vehicles, space propellant depots, extraterrestrial habitats, and interplanetary crew transport spacecraft.

Two.  Under NASA's current scenario, the Lunar Gateway wouldn't even start to be assembled until 2024 with a completion date around 2026. Again, a totally unnecessary delay in deployment.

An SLS Block I with an ICPS upper stage could probably deploy a complete SLS derived Deep Space Habitat to NRHO as early as 2022 that weighs about 20 tonnes-- without consumables. Food and water could subsequently be launched to the Gateway by commercial launch vehicles.

An SLS Block IB, would be able to deploy SLS derived Deep Space Habitat concepts weighing  22 tonnes for 353 cubic meters of habitable pressurized volume and 28 tonnes for 519 cubic meters of habitable pressurized volume with a single launch in 2024. That would still be two years earlier than NASA's current Lunar Gateway completion plans.

However, a large private commercial upper stage is currently being developed by the ULA (United Launch Alliance) that will be used to deploy payloads for the Air Force (Space Force?). And the ULA's Centaur V could be certified for military payloads in 2021 and ready for utilization in 2022.

If  the SLS was used to deploy a large commercial upper stage (Centaur V) to LEO, NASA could deploy a 28 tonne SLS derived Deep Space Habitat to NRHO with just two launches.  Assuming a maximum dry weight of no more than seven tonnes for the Centaur V, an SLS Block one launch could deploy the Centaur V to orbit with at least 63 tonnes of propellant. An SLS Block I with an ICPS upper stage could deploy the Centaur V with 68 tonnes of propellant to LEO plus 20 tonnes of additional payload for, perhaps,  another ICPS with at least 16 tonnes of additional propellant. 

After docking with an SLS payload deployed to LEO by a previous SLS launch, the Centaur V should be easily capable of transporting more than 30 tonnes of payload to NRHO.

However, the preceding SLS Block I launch would be able to deploy up to 70 tonnes of payload to LEO. So you could actually  deploy two 28 tonne habitats to LEO (just 56 tonnes) with one destined for NRHO after the next SLS upper stage launch-- while the other 28 tonne habitat remains at LEO as a potential replacement for the ISS.

Replacing the ISS with a new space station would possibly save NASA up to $4 billion a year!

An SLS derived LEO habitat wouldn't be a space laboratory, it would simply be a habitat used for NASA and Space Force astronaut training and for the training of astronauts from foreign space agencies. It could also be a used as a destination for wealthy space tourist and space entrepreneurs.  Small commercial launched space laboratories could be co-orbited near the LEO habitat while lab specialist use the SLS derived habitat as a hotel, visiting their floating laboratory only when necessary to add or retrieve materials.

Alternatively, NASA could deploy three 22 tonne SLS derived habitats to LEO with one destined for NRHO with the other two remaining at LEO. One could be used exclusively for NASA and the Space Force with the other being auctioned off to a private space company for space tourism or to accommodate the needs of foreign space agencies.

While the above scenario might delay the first crewed flight of the SLS until 2023 (just one year), it would actually give astronauts a place to go on their first SLS flight in 2023. Of course, NASA could still have a  test flight of a crewed Orion in 2021 instead of 2022.  NASA astronauts could use commercial crew vehicles to travel to LEO to inspect the Gateway habitat before its deployed to NRHO.

Three.  There's no logical reason to waste an SLS launch for a flyby mission of Europa. The Europa Clipper can probably be deployed by commercial launch vehicles. However, an orbital mission to Europa is questionable since the moon Callisto would be much easier to access. Callisto is the only place in Jupiter space where human outpost could be set up for  potential colonization.  A human outpost on the surface of  Callisto would make it substantially  easier to  explore  Europa, Ganymede, and Io (all within Jupiter's deadly radiation belt) with robots remotely controlled from the surface of Callisto. A better near term use for a non human spaceflight related launch of the SLS would be the deployment of space telescopes with mirror diameters even larger than the James Webb.

16.5 meter long 8.4 meter in diameter SLS derived orbital habitat (Credit: NASA)

13.5 meter long 8.4 meter in diameter SLS derived orbital habitat (Credit: NASA)

Propellant Depots and the Future of the Orion

The utilization of reusable vehicles for the human exploration, pioneering, and exploitation of the lunar surface is one of the primary reasons for having a Lunar Gateway at NRHO.  Reusable spacecraft will, of course, require propellant depots.

Once the Lunar Gateway is deployed, co-orbiting propellant depots can also be deployed to NRHO by private commercial launch companies. NASA breakthroughs in zero boil off (ZBO)  liquid hydrogen storage should make it possible for commercial launch companies to deploy propellant tank derived  LH2 (liquid hydrogen) and liquid oxygen (LOX) storage tanks to NRHO that don't leak any hydrogen or oxygen. More sophisticated technologies could allow the solar power production and liquefaction of  hydrogen and oxygen from water in space which could substantially reduce launch complexity and cost for commercial launch companies.

The SLS propellant tank technology derived EUS might have questionable utility if NASA is already using the Centaur V and, subsequently, the ACES-68 to deploy heavy payloads to deep space locations.

Notional ACES 68 with BE3 Engine (Credit: ULA)

With its Integrated Vehicle Fuel (IVF) technology, the ULA's ACES-68 successor to the Centaur V could be in operation as early as 2023 but is currently planned to go into operation within the 2024 to 2025 time frame. It now seems likely that the ULA will allow Lockheed Martin, one of its parent companies, to be first to develop IVF technology for its future reusable crewed lunar landing vehicles. In tandem (on either side of an orbiting payload) two such ACES vehicles could transport payloads exceeding 70 tonnes from LEO to NRHO or to Low Lunar Orbit. A single ACES 68 could deploy an equal amount of payload to Mars orbit from NRHO; so massive amounts of water or propellant deployed to NRHO could easily be later deployed to Mars orbit from NRHO.

If propellant depots are deployed at LEO and NRHO, the ACES-68 could replace the ICPS and the Service Module for the Orion space capsule. This would make the Orion a completely reusable vehicle for transporting astronauts between LEO and NRHO. So no longer would the Orion spacecraft have to be deployed by the SLS for deep space missions.    The ULA's Vulcan spacecraft could deploy the reusable Orion/ACES to LEO, fueling the ACES 68 booster at a LEO propellant depot before heading for NRHO or Low Lunar Orbit.

So, in theory,  astronauts could board a commercial launch vehicle (Falcon 9/Dragon, Atlas V/Centaur/CST-100, etc.) that transports them to LEO. The could then dock with an already propellant depot fueled  Orion/ACES vehicle for transport to the Lunar Gateway or to Low Lunara Orbit. Again, no SLS launch would be required which means that the heavy lift vehicle could be more properly used to transport heavy payloads to LEO.

Notional Orion/ACES reusable shuttle with crew hab approaches  SLS derived Lunar Gateway at NRHO (Near Rectilinear Halo Orbit). (After NASA and ULA)

The Future of the EUS

If NASA eventually uses commercial upper stages such as the Centaur V and the ACES 68  to transport large and heavy payloads initially transported to LEO by the SLS then the space agency could delay the deployment of the EUS and focus on developing a far more enhanced orbital transfer vehicle. An SLS derived EUS  equipped with IVF and cryocooler technologies could make such a vehicle reusable. Such a vehicle could simply use the SLS core stage liquid oxygen tank as a liquid hydrogen tank while also deriving a smaller oxygen tank from the same technology.

Such a reusable vehicle  could accommodate more than 345 tonnes of LOX/LH2 propellant. And it could be used to transport large habitats and their crews  to the orbits of Mars, Venus, and to the NEO asteroids from NRHO. The performance of such a reusable interplanetary crew transport could also be greatly enhanced by coupling it with a  twin transport or just a reusable ACES booster with 68 tonnes of propellant. Propellant depots in Mars orbit would be required for the the return journey to Earth. But, again, the water or propellant could be routinely transported to Mars orbit from water or propellant transported from the lunar surface to NRHO. Eventually, however, propellant depots in Mars orbit could be routinely supplied with water or propellant extracted from the regolith of the martian moons, Deimos and Phobos. And it might even be economical to transport liquid hydrogen from the surface of Mars from reusable spacecraft to orbiting depots to be used with liquid oxygen extracted from the martian moons for propellant. 


An Alternate SLS Launch Scenario 



2020:

SLS 1: Unmanned SLS Block I launch of  Orion/SM/ICPS to DRO (Distant Retrograde Orbit)


2021:

SLS 2: Crewed SLS Block I launch of  Orion/SM/ICPS to TLI (Trans Lunar Injection) around the Moon

(Beginning of deployment of small mobile robots to the lunar surface by commercial launch companies) 


2022:

SLS 3: Unmanned SLS Block I launch of two 28 tonne  SLS derived microgravity habitats to LEO.

(Two Commercial Crew launches to LEO to inspect the twin microgravity habitats.)

SLS 4:  SLS Block I launches Centaur V to LEO. Centaur five docks with Lunar Gateway at LEO and transports the fully complete deep space habitat to NRHO (Near Rectilinear Halo Orbit)


2023:

SLS 5: Crewed SLS Block I launch of  Orion/SM/ICPS  to Lunar Gateway at NRHO.

SLS 6:  SLS Block I with ICPS upper stage launches a Centaur V with an 8 meter class space telescope to ESL2 (Earth-Sun Lagrange Point 2).  The new space telescope will have an 8 meter plus monolithic primary mirror housed within a 12 meter in diameter payload fairing. And it will join the with join the 6.5 meter in diameter James Webb telescope at  ESL2. The diameter for the mirror for the Hubble Telescope was 2.4 meters.  The development of such a enormous fairing size for the SLS will  greatly enhance the launch vehicles unique ability  to accommodate exceptionally large payloads. NASA needs to stop entertaining smaller payload shrouds for the SLS that could nullify its advantage over other launch systems.   

(Commercial launch companies begin the continuous deployment of tanks of LOX and LH2 to depot clusters at  LEO and NRHO)

{NASA begins using new RS-28 engines for the SLS core vehicle. Hopefully, some meager funding to develop an SLS-B (the SLS without  Solid Rocket Boosters) with a commercial Centaur V or ACES upper stage and a commercial CST-100, Dream Chaser, Dragon, or maybe even an Orion as the crew capsule. This would allow more frequent use of the SLS core stage and its RS-25 engines which should help to substantially reduce the overall cost of SLS launches.}   


2024:

SLS 7: SLS Block I launches two reusable Lockheed Martin Lunar Crew Landing Vehicle (LCLV) equipped with advanced IVF and cryocooler technology. One LCLV will be launched with enough fuel to self deploy itself to the Lunar Gateway at NRHO. The LCLV already fueled with LH2,  will utilize a LEO orbiting LOX depot in order to fuel itself for self deployment to NRHO.

Both Lunar Crew Landing Vehicles  will be fueled and tested (unmanned) at NRHO with each traveling to opposite lunar poles to deploy mobile robots to the surface via their lift elevators.  Some of the mobile robots will collect regolith samples for return to the Lunar Gateway and eventually to Earth. A few weeks later, one LCLV will be deployed to the surface of the far side of the Moon to collect regolith more lunar regolith samples while proving the vehicle's reusability.

{First NASA /ULA funded unmanned test of a reusable Orion/ACES to NRHO followed by the first crewed Orion/ACES to the Lunar Gateway at NRHO. The reusable vehicle will be launched into orbit by the ULA Vulcan rocket. The success of  reusable Orion/ACES spacecraft and reusable Lockheed Martin Lunar Landing Vehicle (used for crew transport between LEO and NRHO) should end the necessity of using the SLS to deploy astronauts to NRHO Gateway}

SLS 8: Last crewed SLS Block I launch of  Orion/SM/ICPS to Lunar Gateway at NRHO.  

After the six member crew arrives at NRHO, four astronauts will climb aboard one of the Lunar Crew Landing Vehicles to travel to one of the lunar poles (The first Americans to land on the lunar surface since 1972). If the crew on the lunar surface should have some serious difficulties attempting to return to the Lunar Gateway, the remain astronauts at NRHO will use the second LCLV to rescue the astronauts from the lunar surface, returning them safely to the Lunar Gateway.

So under this SLS launch scenario (before the end of 2024),  NASA would have a new simpler and cheaper (and possibly money making) space station at LEO, a new Lunar Gateway at NRHO, plus American astronauts and hopefully, guest astronauts from foreign space agencies, routinely traveling to and from the lunar surface from the Lunar Gateway on private commercial landing vehicles.


Links and References


Space Launch System Lift Capabilities

“Plan D for Outer Space” — NASA updates EM-2 mission baseline

Navigating the twists and turns steering SLS Development

Getting Vulcan up to speed: Part one of our interview with Tory Bruno

NASA updates Lunar Gateway plans

Space Launch System

Deep Space Habitats

Habitat Concepts for Deep Space Exploration


Ares V Launch Capability Enables Future Space Telescopes

ACES Stage Concept: Higher Performance, NewCapabilities, at a Lower Recurring Cost

ULA’s Vulcan Rocket To be Rolled out in Stages

ULA's Tory Bruno (Twitter)

A Commercially Based Lunar Architecture

Evolving to a Depot-Based Space Transportation Architecture

A Study of CPS Stages for Missions beyond LEO

LARGE SCALE CRYOGENIC STORAGEWITH ACTIVE REFRIGERATION

Transient Modeling of Large Scale Integrated Refrigerationand Storage Systems

 

 

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

A Commercially Based Lunar Architecture

Robust Lunar Exploration Using an Efficient LunarLander Derived from Existing Upper Stages

ACES Stage Concept: Higher Performance, New Capabilities, at a Lower Recurring Cost

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

 

America's Future in the New Frontier (April Congressional Hearing)

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

The ULA's Cis-Lunar Economy

Cis-Lunar Panel

The ULA's Future ACES Upper Stage Technology

Part 1




Part 2




Links and References

ULA's Cis-Lunar 1000 Concept

Transportation Architecture for Cislunar Space

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

Left: Orion space capsule with hypergolic fueled Service Module; right:  notional Orion spacecraft with a reusable EUS derived orbital transfer vehicle.  

It now appears that Congress will direct NASA to return Americans to the surface of the Moon in order to prepare for future crewed journeys to the surface of  Mars. But the Moon could prove to be much more than just a beyond LEO testing ground for astronauts and components.

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

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

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


Delta-v to important destinations within cis-lunar space

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

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

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

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

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

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

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


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

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

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

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

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

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

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

Expendable EUS for SLS launch vehicle (Credit: NASA)

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

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

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

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

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

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

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

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

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


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

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

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

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

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

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

SLS propellant tank derived habitat (Credit: NASA).

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

Links and References

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

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

Lori Garver Questioned Astronauts about NASA's Next Destination?

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

What about Mr. Oberth

Human Lunar exploration architectures

Earth Departure Options for Human Missions to Mars

A Study of CPS Stages for Missions beyond LEO

Deep Space Habitats

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

Congress Requires NASA to Develop a Deep Space Habitat

UltraFlex Solar Array Systems

The ULA's Role in Commercial Crew Launches

ULA's Cis-Lunar 1000 Concept

Links and References

Transportation Architecture for Cislunar Space

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

Originally utilized for human operations withing cis-lunar space in the 2020s, the reusable LOX/LH2 fueled ETLV-2 now heads towards its first crewed rendezvous and landing on the surface of the martian moon, Phobos, in 2031.

by Marcel F. Williams

NASA suggest that the first human missions to Mars will occur sometime in the 2030s. While the Obama administration has merely suggested a  Mars flyby  for the first crewed interplanetary voyage,  others have proposed much more ambitious early human missions near the vicinity of the Red Planet. One frequent proposal is for a crewed journey  to the orbit of  Mars. Such an orbital mission could also include landings on at least one or both of the martian moons: Phobos and Deimos.

However,  any serious efforts to transport humans on multi-year interplanetary voyages has to resolve the inherent problems of enhanced exposure to cosmic radiation  and major solar events.  Also, the deleterious effects of long term exposure to a microgravity environment over the course of several months and even years has to be resolved.

Mass shielding habitat areas with at least 30 centimeters of water could protect astronauts from the dangers of major solar storms while also enabling multiyear round trip missions to Mars and Venus without excessive exposure to cosmic radiation-- even during solar minimum conditions.  The deleterious effects of microgravity on the human body could also be eliminated or, at least, substantially reduced  by transporting astronauts aboard  rotating interplanetary vessels with twin counterbalancing habitat modules.

However, a water shielded spacecraft with rotating habitat modules  would substantially increase the mass of a crewed interplanetary vessel. One way to compensate for the increase in vehicle mass would be to launch the interplanetary vessel from one of the Earth-Moon Lagrange points-- instead of from LEO. This could shave off at  least 2.8 km/s of delta-v requirement for an interplanetary mission. Dumping the water shielding for the twin habitat modules just a few hours, or a few days,  before  final trajectory burns into  orbit could also substantially reduce the propellant requirements for an interplanetary vehicle.  Finally, utilizing pre-deployed propellant producing water depots supplied with water from the Moon's low gravity well  could also substantially  reduce the propellant requirement for a reusable  interplanetary vehicle.

The crewed interplanetary mission to Mars orbit presented in this article, combines Boeing's SLS propellant tank technology with the ULA's (United Launch Alliance)  emerging IVF (Integrated Vehicle Fluid) technology to create reusable interplanetary spacecraft and  propellant producing water depots for human interplanetary missions to the orbits of Mars and Venus.

In 2030, under this scenario,  eight American astronauts and four foreign astronauts will depart from Earth-Moon Lagrange point four (EML4) towards a flyby of the planet Venus and then, a few months later,  into high Mars orbit. During the interplanetary mission, astronauts will visit both of the martian moons, Phobos and Deimos, returning to Earth after the 22 month mission with a significant tonnage and variety of regolith samples from the moons of Mars. Water exported from the surface of the Moon from one of the  lunar poles will be used to provide the water and propellant needed for the interplanetary mission.

Propellant producing water depot (WPD-LV-5A) on the lunar surface next to a mobile water tanker, LOX/LH2 cryotanker, and a Water Bug mobile microwave water extraction robot.

Nomenclature:

ETLV-2 (Extraterrestrial Landing Vehicle): Reusable LOX/LH2 vehicle capable of landing crews on the surface of the Moon or on the moons of Mars.

LWS (LEO Way Station): Large pressurized microgravity habitat (8.4 meters in diameter) in low Earth orbit derived from SLS hydrogen propellant tank technology.

CLV-5B: Cargo landing vehicles originally utilized to land large payloads on the lunar surface but  that are later utilized as reusable water tankers by latching a water bag to the top of the spacecraft. 

CLV-5A: Reusable cargo landing vehicle specifically designed to transport water,  regolith, or other heavy cargo from the lunar surface to the Earth-Moon Lagrange points.

OTV-400: Reusable SLS hydrogen tank derived orbital transfer vehicle capable of storing up to 400 tonnes of LOX/LH2 propellant. It uses IVF technology to power thrusters for attitude control.

WPD-OTV-400: OTV-400 derived water storage and propellant manufacturing and storage depot capable of storing up to 1000 tonnes of water and up to 400 tonnes of LOX/LH2 propellant.

AGH (Artificial Gravity Habitat):  rotating  pressurized  artificial gravity habitats derived from   SLS hydrogen propellant tank technology. 

Odyssey: Crewed interplanetary vehicle with OTV-400, AGH, and ETLV-2 components  capable of transporting 8 to 16 astronauts  to the orbits of Mars and Venus.


Mars Mission Scenario:

February 2030: OTV-400 trajectory burns transports Odyssey interplanetary spacecraft from EML4 into a Venus-Mars Transfer Orbit.

July 2030: Odyssey spacecraft flyby of Venus with minor OTV-400 trajectory burn (`80 m/s delta-v)

February 2031: OTV-400 trajectory burn places Odyssey into a high Mars orbit.

February, March, and April of 2031: Two crewed  ETLV-2 missions to the martian moon, Deimos and two crewed missions to the surface  of Phobos

April 2031: OTV-400 trajectory burns transports Odyssey spacecraft from high Mars orbit into an Earth transfer orbit.

December 2031: OTV-400 trajectory burns places the Odyssey spacecraft back into a halo orbit at EML4.

Maximum radiation exposure during the 18 month mission during solar minimum conditions (under 30 cm of water shielding aboard the Odyssey and  including 10 days of temporary full exposure during orbital insertion and ETLV-2 visits to Phobos and Deimos): less than 50 Rem.

CLV-5A water tanker capable of  transporting more than 50 tonnes of lunar water to the Earth-Moon Lagrange points. Mobile water tanker and a mobile LOX/LH2 cryotanker are near the shuttle spacecraft.

Cis-Lunar Space

During the early 2020s, a series of SLS cargo launches will be utilized to deploy a water and propellant producing and exporting infrastructure at one of the lunar poles .  So starting in 2026, this will allow NASA to   to focus its priorities  on  deploying the interplanetary infrastructure that will be necessary to take humans to the orbit of Mars in 2031-- and eventually to the surface of Mars in 2036.  Under this scenario, the interplanetary infrastructure needed to accomplish these goals will mostly be derived from the technology and infrastructure developed for the cis-lunar program.

CLV-5A   rendezvous with WPD-OTV-400 at EML4 to transfer more than 50 tonnes of  lunar water. The orbiting depot will be capable of storing up to 1000 tonnes of water and up to 400 tonnes of LOX/LH2 propellant.

2030

Access to Orbit

In February of 2030, three American Commercial Crew vehicles will launch eight American astronauts plus four foreign astronauts from terrestrial launch facilities to low Earth orbit (LEO).  All three of the Commercial Crew vehicles will dock at LEO  Way Station (LWS) that was originally deployed to LEO back in 2020. Simply derived from SLS hydrogen propellant tank technology and deployed by a single SLS launch,  the LWS will be substantially cheaper than the hyper expensive ISS laboratory.

Rather than outsourcing technological participation from foreign space agencies, NASA will charge foreign  space agencies  $150 million  for each foreign astronaut trained to  participate in NASA's first interplanetary mission.  So the inclusion of four foreign astronauts in the interplanetary mission will shave off $300 million in cost to NASA-- and the tax payers. Foreign space agencies whose astronauts are participating in the Mars orbital mission will  receive up to 10 kilograms of material retrieved by astronauts and robots  from the surfaces of the martian moons, Deimos and Phobos.

An OTV-400 interplanetary booster rendezvous with a WPD-OTV-400 at EML4 to receive up to 400 tonnes of LOX/LH2 propellant. The WPD-OTV-400 produces propellant from lunar water when it is docked to a 1.2 MWe solar array (seen in the background) which is also located at EML4.

EML4

Docked at the LEO Way Station will be two reusable ETLV-2 vehicles.  Originally deployed by the SLS during the lunar outpost  program of the early 2020s, each ETLV-2 vehicle will perform orbital transfer duties, transporting the international crew of 12 from LEO to EML4 ( Earth-Moon Lagrange Point Four) in approximately two days at a slightly higher and more propellant expensive delta-v.

The LOX/LH2 propellant needed to fuel the ETLV-2 vehicles will come from a LEO orbiting   propellant producing water depot (WPD-OTV-400). The LEO orbiting WPD-OTV-400 was  originally deployed by the SLS in the 2020's for cis-lunar operations.

 WPD-OTV-400 depots will be capable of storing up to 400 tonnes of LOX/LH2 propellant and up to 1000 tonnes of water. Some of the water for the orbital  depot  will arrive as additional payload  from Earth aboard SLS and other launch vehicles with some extra payload availability beyond the regular payloads that they will be deploying.  But most of the water for the LEO water/propellant depot will originate from the surface of the Moon.

When running low on water and propellant, the LEO orbiting WPD-OTV-400  uses the remaining 50 tones of stored propellant to transport itself  to EML4.  There  it is supplied with water and propellant from another WPD-OTV-400 that is continuously being supplied with lunar water from the lunar   poles from reusable CLV-5A and CLV-5B water shuttles. Once the WPD-OTV-400 filled with 240 tonnes of water in addition to being fully fueled with 400 tonnes of LOX/LH2 propellant, it will redeploy itself back to LEO where most of the 240 tonnes of water will be converted into LOX/LH2 propellant. Large  solar arrays deployed by previous SLS launched at both LEO and EML4 will provide all of the electricity necessary to power the depot  electrolysis plants and cryocoolers for converting water into liquid hydrogen and oxygen. 



The Odyssey

Once at EML4, the two ETLV-2 vehicles with dock at the twin AGH ports for the Odyssey interplanetary vehicle, transferring the 12 astronauts to the vessel  destined for Mars. The Odyssey interplanetary vehicle consist of an OTV-400 orbital transfer vehicle capable of storing up to 400 tonnes of LOX/LH2 propellant; an AGH artificial gravity habitat shielded with 30 cm of lunar water; and two ETLV-2 crew transport vehicles with only 6 tonnes of propellant within each vehicle. These Odyssey components will be deployed to EML4 by three separate  SLS launches the previous year (2029). 

Inside of the Odyssey, the 12 astronauts will  be greeted by six others astronauts who are permanently stationed at an EML4 AGH (Artificial Gravity Habitat) space station.   The permanent artificial gravity space station is protected from dangerous levels of cosmic radiation and major solar events with a shielding of lunar iron slabs that were manufactured by 3D printers on the surface of the Moon and exported to EML4 by reusable CLV-5A cargo landing vehicles.  The EML4 stationed astronauts will return to their AGH space station after helping to prepare the crew of the Odyssey for their interplanetary launch.

Top: Odyssey trajectory burn configuration. 2nd from top: After the trajectory burn the OTV-400, AGH, and twin ETV-2 shuttles separate in preparation for vehicle reconfiguration. 3rd from top: After AGH shifts 90 degrees and then commences to rotate along an axis between the separated OTV-400 and the ETLV-2 vehicles. 4th from the top: AGH internal cables and external  retractable booms expand to produce 0.5g of simulated gravity. Bottom: The two ETLV-2 vehicles rotate to match the rotation of the AGH before they dock with the structure at the pressurized  central docking module.   

Interplanetary Space
 

Since the Odyssey mission will take a longer route to Mars that will  allow it to also fly past the planet Venus, the OTV-400 will require maximum amount of propellant. But launching from EML4 instead of LEO will still shave off nearly 2.8 km/s of its delta-v requirements. The WPD-OTV-400 will fill the Odyssey's  OTV-400  with nearly 400 tonnes of LOX/LH2 propellant and its twin  AGH habitat modules with more than 200 tonnes of water for radiation shielding (142 tonnes) plus water for  drinking, washing, food preparation, and the production of air.  

Initially, the Odyssey will be in a linear configuration when it departs from cis-lunar space. But after the Mars Transfer Orbit  trajectory burns, the Odyssey components will separate in order to   reconfigure itself so that the AGH can rotate and expand the light weight retractable booms surrounding the cables connecting its twin habitat modules. Extending about 112 meters away from the central axis while rotating at 2 rpm, each of the twin modules will experience a simulated gravity of approximately 0.5g.  The astronauts within each habitat module would, therefore, feel a simulated gravity half that of being on the surface of the Earth but still significantly higher than the gravity experienced on the surface of the Moon or Mars.  In theory, the artificial  gravity environment should  substantially reduce and possibly  even eliminate the deleterious effects associated with   microgravity environments. Artificial gravity should also create a much more  comfortable and familiar physical and psychological  environment during their 22 month mission.

In a trajectory configuration, the Odyssey flies past the plant Venus on its way to Mars.

Venus

 In July of 2030, after nearly five months of interplanetary travel, the Odyssey will reconfigure itself into a linear configuration just a few days before it nears the planet Venus. This will allow the OTV-400  to make some minor trajectory burns as they Odyssey flies past Venus on its way to Mars.  During the flyby,  the astronauts aboard the Odyssey could utilize one of the ETLV-2 vehicles to get a better look at Venus during the flyby,  taking photographs and videos of the veiled planet.  After the trajectory burns, the Odyssey will once again reconfigure itself so that the AGH can once again produce an artificial gravity environment for the astronauts.

After the AGH habitats dump their water shielding, the Odyssey reconfigures to a linear position in order to enter   high Mars orbit.

2031


High Mars Orbit

Before the arrival of the Odyssey, two  WPD-OTV-400 water/propellant depots will already be in high Mars orbit along with a pair of large solar electric arrays, originally launched to high Mars orbit during the previous launch window in 2028.

In February of 2031, several hours to a few days before the Odyssey’s rendezvous with Mars, the rotating AGH modules  will dump their 142 tonnes of water shielding.   This will cut the total inert mass of the Odyssey nearly in half which will substantially reducing the amount of propellant required to place the interplanetary vessel into a high Mars orbit. After the final trajectory burn places the Odyssey into orbit, the AGH will separate from the Odyssey to rendezvous with one of the WPD-OTV-400 water/propellant depots  to replace the water shielding for its habitat modules. 

Once the AGH modules are fully water shielded again, the Odyssey will  reconfigure itself so that the AGH can produce 0.5 g of simulated gravity and so that the crew can begin to conduct their exploration of the two martian moons.

The WPD-OTV-400, in high Mars orbit,  rendezvous with the AGH to replenish the 142 tonnes of water for radiation shielding the habitat modules.

Fully water shielded again, the AGH begins to rotate again at 0.5 Gs, expanding its retractable boom and twin habitat modules.

Deimos

One of the ETLV-2 vehicles will dock with one of the orbiting water/propellant depots in high Mars orbit,   accessing the amount of propellant needed for its crewed mission to the surface of Deimos and back to the Odyssey. Six astronauts will participate in the three day exploration of  the outer martian moon. After the astronauts land on the surface of Deimos, a few  mobile robots will be deployed  that will be teleoperated by astronauts still remaining at the  AGH. For over a month, these robots will explore various regions on the surface of Deimos, taking videos and photographs and collecting samples.  These samples will be retrieved a month later by the second six person crew from the Odyssey to land on the surface of Deimos.

 ETLV-2 on its way towards the first crewed landing on Deimos.

Phobos

After the first crewed mission to Deimos, Phobos will be the next destination for a crewed ETLV-2.
Again,  six astronauts will participate in   three days of  exploration. After the astronauts land on Phobos,  mobile robots will be deployed  to explore various regions on the surface of of the inner moon, taking videos and photographs and collecting samples.  These samples will also be retrieved, a month later, by the second six person crew from the Odyssey sent to  the surface of Phobos


Preparations for Departure

After two months in orbit around Mars, the OTV-400 will   fill its tanks up with more than 300 tonnes of LOX/LH2  propellant from one of the WPD-OTV-400 water/propellant depots. 

Reconfigured into a linear configuration, the Odyssey will depart from Mars in April of 2031. After the trajectory burns that launches the Odyssey into an Earth Transfer Orbit, the Odyssey will, once again,  transform into  an artificial gravity producing configuration.

One of the nearly depleted WPD-OTV-400 water/ propellant depots will also leave Mars for cis-lunar space in order to resupply itself with lunar water and propellant for a return to Mars orbit in 2033. 

With the  solar power plant for the WPD-OTV-400 in the background, the OTV-400 rendezvous with the propellant depot to add LOX/LH2 for the Odyssey's return journey to cis-lunar space. 

The Return to  Cis-Lunar Space


In December of 2031, the AGH will once again dump its water shielding as it nears its rendezvous with cis-lunar space.   Once it is linearly reconfigured, the final trajectory burns will place the Odyssey and its crew back in halo orbit at EML4.

The crew will then be transferred by two ETLV-2 shuttles to the EML4 AGH space station for a few days before being transferred again  by two ETLV-2 shuttles to LEO. Commercial Crew vehicles will then transport the astronauts to the Earth's surface, pioneers and heroes  to be welcomed back by the cheering crowds on  Earth. 

The Odyssey interplanetary spacecraft returns to  EML4. Two ETLV-2 shuttles docked at a permanent AGH space station at the Earth-Moon Lagrange point will transport the crew back to the EML4 space station for a few days before the 12 person crew is eventually transported to LEO and then back to the surface of the Earth aboard  Commercial Crew vehicles. 

The Next Interplanetary Mission

NASA, on the other hand, will be preparing for the next crewed mission to Mars orbit which will be launched from EML4 in 2033. The 2033 mission will deploy the first permanent iron shielded AGH space station into high Mars orbit.   The 2033 mission will also deploy the first unmanned ADEPT protected ETLV-2 vehicles to the surface of Mars to test ETLV-2 s ability to land large masses on the surface of Mars while testing the ability of the ETLV-2 to return to orbit from the surface of Mars.   Tele-operated robots will also be deployed by the ETLV-2 vehicles to retrieve regolith samples to be transported to Mars orbit and eventually back to Earth.


Links and References


Comparison of Deimos and Phobos as Destinations for Human Exploration and Identification of Preferred Landing Sites

Deimos and Phobos as Destinations for Human Exploration

Phobos and Deimos: The Moons of Mars

Mining the Moons of Mars

Cosmic Radiation and the New Frontier

A Cryogenic Propellant Production Depot for Low Earth Orbit

Evolving to a Depot-Based Space Transportation Architecture

A Study of CPS Stages for Missions beyond LEO

A Study of Cryogenic Propulsive Stages for Human Exploration Beyond Low Earth Orbit

Ames Research Center Mission Design Center Trajectory Browser 

Delta-v budget

Establishing a Permanent Human Presence on Mars with a Lunar Architecture

Utilizing Lunar Water Resources for Human Voyages to Mars

Utilizing the SLS to Build a Cis-Lunar Highway

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

SLS Fuel Tank Derived Artificial Gravity Habitats, Interplanetary Vehicles, & Fuel Depots

The SLS and the Case for a Reusable Lunar Lander



© Marcel F. Williams
New Papyrus Magazine
11/25/15