. Cislunar Space Economy - United Launch Alliance (ULA) & Evolvable Lunar Architecture





This study publied in July 13, 2015, by NexGen Space LLC (NexGen) was partly funded by a grant from NASA’s Emerging Space office in the Office of the Chief Technologist. The conclusions in this report are solely those of NexGen and the study team authors.  LEARN MORE SOON

NexGen Space LLC has assembled a team of former NASA executives and engineers who assessed the economic and technical viability of an “Evolvable Lunar Architecture” (ELA) that leverages commercial capabilities and services that are existing or likely to emerge in the near-term.

The ELA concept evaluated was designed as an incremental, low-cost and low-risk method for returning humans to the Moon in a manner that directly supports NASA’s long-term plan to send humans to Mars. The ELA strategic objective is commercial mining of propellant from lunar poles where it will be transported to lunar orbit to be used by NASA to send humans to Mars. The study assumed that, the United States is willing to lead an international partnership to leverages private industry capabilities and, public-private-partnership models proven in recent years by NASA and other government agencies.

Their analysis concludes that:

  • Based on the experience of recent NASA program innovations, such as the COTS program, a human return to the Moon may not be as expensive as previously thought.

  • America could lead a return of humans to the surface within a period of 5-7 years at an estimated total cost of about $10 Billion (+/- 30%) for two independent and competing commercial service providers, or about $5 Billion for each provider, using partnership methods.

  • America could lead the development of a permanent industrial base of 4 private-sector astronauts in about 10-12 years after setting foot on the Moon that could provide 200 MT of propellant per year in lunar orbit for NASA for a total cost of about $40 Billion (+/- 30%).

  • Assuming NASA receives a flat budget, these results could potentially be achieved within NASA’s existing deep space human spaceflight budget.

  • A commercial lunar base providing propellant in lunar orbit might substantially reduce the cost and risk NASA of sending humans to Mars. The ELA would reduce the number of required Space Launch System (SLS) launches from as many as 12 to a total of only 3, thereby reducing SLS operational risks, and increasing its affordability.

  • An International Lunar Authority, modeled after CERN and traditional public infrastructure authorities, may be the most advantageous mechanism for managing the combined business and technical risks associated with affordable and sustainable lunar development and operations.

  • A permanent commercial lunar base might substantially pay for its operations by exporting propellant to lunar orbit for sale to NASA and others to send humans to Mars, thus enabling the economic development of the Moon at a small marginal cost.

  • To the extent that national decision-makers value the possibility of economical production of propellant at the lunar poles, it needs to be a priority to send robotic prospectors to the lunar poles to confirm that water (or hydrogen) is economically accessible near the surface inside the lunar craters at the poles.

  • An affordable commercial industrial base will provide economic growth, national security, advances in select areas of technology and innovation, inspiration, and a long-term future of democracy and free markets.


The "Evolution" of United Launch Alliance (ULA)

Atlas to Vulcan Vehicle Evolution.


Centaur Atlas Second Stage. Credit: ULA 


Multiple Stages of ULA.


Tank's stocks, Alabama, USA. Credit: ULA


For now, the Russian RD-180 Engine is used on ULA's Booster


U.S. Blue Origin BE-4 Engine will probably go under Vulcan's Booster!

Aerojet Rochetdyne AR-1 engine is also considered by ULA!


ACES can accommodate one 100-150 klb, two 50-75 klb, or four 25-35 klb engines, obviously with differences in thrust structures and feed lines resulting.  ULA will choose between the Aerojet Rocketdyne RL-10, a Blue Origin BE-3 derivative, and an XCOR engine.



REF 10


In 2015, United Launch Alliance (ULA) announced its Sensible Modular Autonomous Return Technology (SMART) re-use plan to recover the booster module of its Vulcan. The plan employs the non-propulsive atmospheric entry, descent and landing (EDL) technologies.

ULA set out to develop an approach that can show benefit to both spacecraft operators and shareholders for the expansive's costs of launching rockets. Its Sensible Modular Autonomous Return Technology (SMART) re-use concept sought to minimize the performance penalty while maximizing the dollar value of the elements returned, the booster engines.

The Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology use a flexible thermal protection system to protects the Bue Origine BE-4 Vulcan Engines for the atmospheric re-entry. At some level, a drogue and parafoil system is deployed and the HIAD system is jettisoned. The guided parafoil allows the system to steer toward a capture zone where a helicopter has been proceeding. The two vehicles converge to perform a Mid-Air Retrieval allowing delivery to a waiting ship.

ULA has been working with NASA Langley Research Center on maturing the HIAD concept for SMART Re-use and have honed on a 12 m implementation for the system. The company had also working with NASA Armstrong Flight Research Center and Airborne Systems to refine the Mid-Air Recovery (MAR) elements. 

Inflatable Heat Shields Could Drop-Ship Bigger Robots 

In the Picture below, we see the installation of the Delta Cryogenic Second Stage (DCSS) inside the Delta IV Heavy Rocket. It will be used in EFT-1.

Orion EFT-1 re-entry and splash down.

ULA have BIG plans for the Moon!

Already very prolific launcher of payloads in space with its Atlas and Delta families, United Launch Alliance (ULA) wants the Moon more accessible for every one. It will be not easy, but very, very possible because its determination and skills are there.

The cis-lunar econosphere is a territory that includes trade routes of business between LEO and GEO orbits, Lunar orbit, Earth/Moon Lagrange Points, and near Earth objects (NEO). These routes permit water and raw material mining, propellant refining and storage, and in-space manufacturing.

Transfer vehicles traveling along these routes will be self-sufficient because of a near endless supply of liquid oxygen (LO2) and liquid hydrogen (LH2) propellants, mined and refined from water on the Moon and asteroids.

Transporting goods and people from the Moon to the Geosynchronous-Earth Orbit (GEO) takes less than 10% of the propellant needed for their transport from the Earth's gravity to the Orbit.

The Lunar Poles are the perfect locations to extract resources because the moon’s rotation axis is nearly perpendicular to the ecliptic, providing almost 100% of sunlight on some regions while others are in a permanent shadow.

One big advantage to extracting resources where the sunlight is always present is that it gives an unlimited solar power energy and eliminates the 14-day night of equatorial. This is very interesting because, just next to it, in the permanently shadowed regions, an estimated 10 billion tons of water-ice per polehas been confirmed.

View of aLunar Crater 

How does ULA want to proceed?

To make cis-lunar economy self-sufficient, the cost of transportation needs to be reduced drastically. And, the way to lowering that cost, is through the use of space resources. 

Cis-lunar econosphere. Credit: ULA

The major reason for the high cost of travelling is the large amount of fuel required to escape the Earth's gravity to reach the LEO. Once there, much less fuel is necessary to go anywhere in cis-lunar space. 

Until today, the market for satellites is provided by many transportation systems using variations of multi-stage chemical rockets. All are actually expendable, although several companies are experimenting with various forms of partial or full re-usability, as SpaceX does.

Example of Energy (Propellant mass) used by each stage of an Atlas V. Credit: FAA Office of Commercial Space Transportation

As we see in the diagram, once in orbit, the energy levels to be managed are much reduced and there are no aerodynamic forces to contend with. At that point, the challenges are getting the system elements into cis-lunar space, the re-usability of stage, finding fuel, the thermal environment and the time of the mission.

Water can be easily electrolyzed into hydrogen and oxygen using solar power which can then be used for rocket propellant. Hence, it makes sense to base the cis-lunar transportation system on liquid hydrogen (LH2) and liquid oxygen (LO2), the constituents of water and the highest energy chemical propellant known.

United Launch Alliance (ULA) has most of the world’s experience operating LO2/LH2 propulsion systems in space with more than 100 rockets'launches. Its second stage of Atlas V (REF 1) and Delta IV launch systems utilize LO2/LH2 as propellant. Furthermore, the functionality of these stages is largely what is needed for the cis-lunar transportation system.

The Evolution of the family 

Atlas V 

New Vulcan

The development of the Vulcan booster, the Advanced Cryogenic Evolved Stage (ACES), and theSMART Re-use concept enhances the current capabilities towards a single launch system. With the next generation in avionics and the advancements in Guidance, Navigation & Control (GN&C) systems, ULA has a new and more capable concept of  launch service.

ULA is presently working on the Booster Stage Vulcan that will increase its capacity in numerous space launch markets, such as National security, scientific exploration, human spaceflight, and communications. Also, with its goal to have a competitive All-American Enginethe company has tested the methane-fueled BE-4 of Blue Origin (REF 5)  and, the kerosene-fueled AR-1 of Aerojet Rocketdyne (REF 6)

For now, ULA's prime candidate to replace the Russian RD-180 Engine (REF 4) is the high-performance, oxygen-rich staged combustion BE-4 engine because it can provide a combined thrust of about  5 million N (1.1 million lbf) to the booster.

Concept of Vulcan 561

ULA will add up to six Solid Rocket Boosters (SRBs) to the main Vulcan's booster. These SRBs, developed by Orbital ATK, will give the impulse needed for the heavy payloads, or for cis-lunar missions.

ULA has strategic partnerships with Blue Origin and Orbital ATK to improve efficiency and performance at lower costs.

Step by step

With the goal of having only one launcher by 2023, ULA is introducing its innovative technologies gradually to improve them before their finale implementation.

For now, the Vulcan will be matched to the Centaur second stage in 2019, either to the 4 or 5 m payload fairings, and launched to test its capabilities. During these tests, the total impulse of the 4 and 5 m fairings will be increased with up to four and five SRBs respectively, that will surely exceeds the power of the Atlas V's rocket.

When the main Vulcan booster is available as Provider, ULA will have a family of three launchers with its Atlas and Delta.

During the transition to eliminate Atlas, the work will continue to provide a common flight software, avionics, simulation suite, and processes. 

Before the switch of the Centaur second stage with the powerful Advanced Cryogenic Evolved Stage (ACES) in 2023, Atlas will continue to fly until the couple Vulcan-Centaur is certified for missions to the U.S. government.

When the finale implementation will be done with the Vulcan booster and the second stage ACES, the prolific Delta IV Heavy will be retired. A this time, ULA will have a single and definitively more affordable launch system.

Credit: FAA Office of Commercial Space Transportation

What is the new upper stage ACES?

The Advanced Cryogenic Evolved Stage (REF 6) is a 5.4 m diameter second stage of about 15 meters long. It utilizes almost 68 tons of LO2/LH2 propellants and has a propellant to dry mass fraction of 0.92, while exceed the mass fraction of Centaur, the upper stage of the Atlas.

Current cryogenic upper stages Delta IV Cryogenic Second Stage (DCSS) or Centaur (REF 2),  does only about twelve hours maximum of missions in space because they loose propellants via the Boil Off provided by the sun radiation.

At atmospheric pressure, Liquid Hydrogen (LH2) boil at -253⁰ C and Liquid Oxygen (LO2) at -183⁰ C.

With its long experience in cryogenic upper stages, ULA has overcome these critical problems by the development of technologies that can eliminate and reduce drastically the Boil Off of LO2 and LH2, respectively.

Solutions for the Boil Off problems 

By earlier tests with the CRYogenic Orbital TEstbed (CRYOTE), ULA has discovery that, boiling hydrogen is almost 10 times more efficient to remove the heat than boiling the oxygen. With these results, ULA has developed a system using the hydrogen Boil Off to vapor warm spots of oxygen. 

ULA has also built a new tank with a multi-layer insulation improved and an architecture with less attachments to provide a minimum contact between the tanks of hydrogen and oxygen. 

Today, all the time of space missions of second stage are limited because the constraints of utilization of battery power, and Helium and Hydrazine supplies tanks.  With IVF, it is not necessary to uses these costly equipment.

IVF is a powerful auxiliary engine unit using free Boil Off of hydrogen and oxygen to generate electricity, to pressurize tanks for engine starts, and to provide attitude control thrust by their gas. All IVF'components reside in a module located on the aft end of the second stage (REF 8 & 9).  So long LH2 and LO2 remains in the tanks, the power is provided and extends the time of missions from hours to weeks, even months. This is the reason why a Fuel Gas station in space is now very possible. (REF 10)

The new ACES stage will includes two IVF for redundancy.

So, IVF consumes hydrogen and oxygen to power a small internal combustion engine that drives an alternator to provide power. More flexible, IVF allows the Payload upper stage to maneuver and rendezvous with a 80 foot Drop Tank (DT). Once the payload is approaching, the DT will initiate axial settling powered by its IVF GH2/GO2 thrusters and terminate its transverse roll. Axial settling at 10-3 g’s will support cryogenic fluid management during the rendezvous maneuvers.

During the process, the Payload upper stage will maneuver alongside the DT in low settled acceleration formation. The DT robotic arm will connect the flexible LO2 and LH2 transfer lines at the Payload to make the transfer of the pressurized cryogenic propellant. Flying in formation will prevents for any possible damages. 

Once the propellant has been transferred, the coupling line will be released and the two systems will slowly maneuver away from each other. Following separation, the Payload upper stage system will align for the Earth departure burn. Depending on mission needs, the Payload upper stage may continue to operate to perform mid-course corrections and deliver the payload, such as Cygnus cargo, to any location in cis-Lunar space. That could be, in example, the Bigelow Earth Moon-LaGrange Point space station!

These technologies combined enable ACES missions of up to a week without refueling, more than enough time to transit from EM-L1 to LEO and return. When these technologies are implemented into a dedicated long duration storage vessel (not a stage) and equipped with a sun shield, storage times of years can be achieved. (REF 10)

Credit: Lunar Exploration Analysis Group (LEAG)


Credit: United Launch Alliance

The innovative Next Generation Launch System will provide the U.S. most reliable, affordable, and accessible launch service.

ULA Innovation: Advanced Cryogenic Evolved Stage-ACES, Part 1

ULA Innovation: Advanced Cryogenic Evolved Stage, Part 2

Cis-lunar 2017: A Vision for a Self-Sufficient Space Economy

The current space launch market has few profitable business sectors, such as National security, scientific exploration, human spaceflight, and communications.

ULA launch national security payloads that provide critical support to the war-fighter as weather, mapping, military communications, intelligence and surveillance. Also, it provide launch NASA scientific missions to low Earth orbit, Pluto and beyond. To support NASA human spaceflight activities on the International Space Station, the Company make partnership with Boeing to launch astronauts on the CST-100 Starliner and Orbital ATK and Sierra Nevada to launch the Cygnus and DreamChaser cargo resupply spacecraft. Finally, it launch commercial communications satellites for U.S. and international customers.

A self-sufficient economy in cis-lunar space can significantly reduce transportation costs while growing the market and increasing launch rate for all Providers.

Cis-lunar Space Habitation – Paving the Way to Mars

Credit: Orbital ATK

Note: the Orbital ATK spacecraft arrived at the International Space Station (ISS) on Nov. 14, 2017 to deliver acargo to the Expedition's 53 astronauts. Credit: Ultimate Military Channel

VULCAN Booster's  roadmap

Formerly named the Next Generation Launch System (NGLS), the Vulcan booster will be available in 2019. Leveraging technologies and processes accumulated since 2002 from the Atlas V and Delta IV programs, the Vulcan will feature a couple of unique capabilities.

As engines are the most expensive element in the rocket'architecture, ULA works to develop the capacity to re-use the BE-4 of Blue Origin that will powered the Vulcan's first stage.  To do it, once the first stage is spent on orbit, the engine's subsystem will separate from the stage, deploy a reentry shield and a parachute. In an specific area, an aircraft recovered it. (More details below

Also, like say before, ULA will use the Advanced Cryogenic Evolved Stage (ACES) as an upper stage, while will dramatically increase the vehicle’s capacity to orbit in deep space. 

To introduce its new transportation system, ULA will first retired the Delta IV Medium vehicles in 2018, except the Delta IV Heavy. And, like say earlier , in 2019, Vulcan will fly concurrently with the Atlas V for an undisclosed period of time. 

The Delta IV Heavy and the Atlas V will be retired following successful deployment of the Vulcan-ACES combination in 2023.

ULA's distributed launch concept

The concept is to launch a disposable Drop Tank within cryogenic propellant and storing it for weeks or months.  Because, most of the propellant used to put payload in orbit is burned to escape the Earth' gravity, it is necessary to re-fuel the upper stage to go further in space.

ULA has overcome this problem in making the concept to transfer the propellant's Drop Tank into a cryogenic upper  stage  such  as  Centaur,  the Delta  Cryogenic  Second  Stage (DCSS),  or the Advanced  Cryogenic Evolved  Stage  (ACES). 

The current larger vehicle can lift payload of only about 25 mT to LEO, 12 mT to Geostationary Transfer Orbit (GTO) or 9 mT to Earth escape. So, what happens if a mission requires more performance?

With a larger rocket on orbit, it is possible to use propulsion like nuclear thermal or solar electric to reduce the required Initial Mass in Low Earth Orbit (IMLEO). Another option is to assemble the mission on orbit, helped by many launches.


Distributed launch

So, the cryogenic propellant is the Liquid Oxygen (LO2) and Liquid Hydrogen (LH2) launched  in a disposable “Drop Tank” on the first launch. Days, weeks or months later, the second launch will be made with the payload. The long waiting time in the vacuum of space will give some challenges to the propellant, notably the Boil Off.

Also, some to all of the propellant used from the payload launchers’ upper stage is consumed to achieve the orbit-target. Once in LEO, the upper stage/payload (Centaur) have to make some orbit phasing maneuvers for its rendezvous with the Drop Tank.

Currently, these phasing maneuvers are not possible with any upper stage. The ULA's Integrated Vehicle Fluids (IVF) has been conceived to enables these problems.

Existing cryogenic stages are limited to hours of operation because its power is provided by heavy batteries. Also, their maneuverability is limited by the available hydrazine or reaction control propellant's reserve. Finally, to maintain the pressure in the propellant's tank, the main engine burn is limited at two or three, provided by the helium's tank.

Once rendezvous, the Drop Tank and payload/upper stage fly in formation. To enabling the exchange of LH2 and LO2 propellants, a robotic arm will connect the transfer plumbing from the Drop Tank with the payloads upper stage and associated avionics.

Centaur, an example of Drop Tank. Credits: ULA, Cygnus Payload, and Allan Walters

Example of an orbit transfer.

When all of the propellants have been transferred, the two systems separate. The upper stage/payload perform one or more main engine burns to achieve  the  desired  trajectory, like cis-lunar orbit. The disposition of the Drop Tank is done by its entry in the Earth's atmosphere or a future's re-use in orbit. 

Minimizing the boil-off is critical 

First, the Drop Tank orbit altitude must be sufficiently high to avoid atmospheric drag when it wait. Also, the tank need to be not too heavy. Then, it have to be constructed of thin stainless steel and its pressure stabilized like ULA's Centaur tank.

For a 20 mT class propellant load (Atlas 552 launch), the Drop Tank is a simplified Centaur tank of 10 feet in diameter and 30 feet long, built on Centaur tooling.

For the 30 mT propellant load (Vulcan 564A launch), the Drop Tank  will  be   built  using  the  17   foot  diameter Advanced Cryogenic Evolved Stage (ACES) tooling. 

Shrouded in a 40 Multi-Layer-Insulation (MLI) blanket, the Drop Tank is separated by a common bulkhead constructed from two nested domes held apart with structural insulation. Between, a thin stainless steel tank walls, that provide a low structural heat conduction, connect the two tanks of LH2 and LO2. 

The common bulkhead permit a passive transfer of about 80% of the LO2 thermal load to the hydrogen tank. The cold hydrogen is used to vapor cool the exterior of the LO2 tank to control its heating for a net zero boil-off.

Once on orbit, the Drop Tank remains attached and is placed in a slow (1⁰/sec) transverse spin. This transverse spin provides centrifugal acceleration during the multi-week LEO loiter that allows settled Cryogenic Fluid Management (CFM) of the LH2. By the past, settled CFM has been successfully used on all of the over 300 cryogenic upper stage missions flown of ULA.

By isolating elements at different temperatures, ULA minimize LH2 Boil Off and make the storage of LO2 without any boil-off in its Drop Tank. Because the LH2 tank is the coldest element (36⁰ R), it is placed at the top of the Drop Tank system stack and by its structural connection, moderate warm LO2 tank at 180⁰ R. The LO2 tank is connected to the  hot  (~500⁰  R)  spent  second  stage  using  low conductivity struts.

Example. If we launch 20 mT by Atlas Centaur and 35 mT with the Vulcan ACES, after one month of LH2 Boil Off, the usable transfer propellant will be 18.1 mT and 30.5 mT, respectively.

So, the net heating of the LH2 tank give a Boil Off under 0.1% per day  or 900 kg per month for a 30 mT of propellant loaded in the Vulcan'ACES stage.

Sources & References

.Distributed Launch - Enabling Beyond LEO Missions / Bernard Kutter1, Eric Monda, and Chauncey Wenner-United Launch Alliance, Centennial, CO 80112, USA & Noah Rhys-Yetispace, Huntsville, AL 35802, USA

.VULCAN, ACES AND BEYOND: PROVIDING LAUNCH SERVICES FOR TOMORROW’S SPACECRAFT/ Rich S. DeRoy,* Engineer, Mission Design, United Launch Alliance, 7858 S. Chester St., Centennial, CO. & John G. Reed† Sr. Technical Fellow, Mission Design, United Launch Alliance, 7858 S. Chester St., Centennial, CO.

.Cislunar-1000: Transportation supporting a self-sustaining Space Economy / Bernard F. Kutter1 - United Launch Alliance, Centennial, CO 80111

.The Annual Compendium of Commercial Space Transportation: 2017 / Federal Aviation Administration (USA)

.Building an Economical and Sustainable Lunar Infrastructure to Enable Lunar Industrialization/ Dr. Allison F. Zunigai, Mark Turnerii and Dr. Daniel Raskyiii-NASA Ames Research Center, Moffett Field, CA 94035, and Mike Loucksiv, John Carricov and Lisa Policastrivi- Space Exploration Engineering Corp, Friday Harbor, WA 98250


.Launch Vehicle Recovery and Reuse / Mohamed M. Ragab1, United Launch Alliance, Centennial, CO 80111 / F. McNeil Cheatwood and Stephen J. Hughes, NASA Langley Research Center, Hampton, VA 23681 and, Allen Lowry, Airborne Systems, Santa Ana, CA 92705

.ACES Stage Concept: Higher Performance, New Capabilities, at a Lower Recurring Cost / Jonathan Barr - United Launch Alliance, Centennial, CO, 80112, USA

Learn More About Lunar Development

After the Soviet Union’s Luna 24 mission in August 1976, there were no more surface missions until China’s Chang’e 3 mission landed successfully on December 14, 2013 which was 37 years later. The Chang’e 3 mission successfully delivered the lunar rover, Yutu16, to Mare Imbrium. The rover was designed to explore an area of 3 square km with a maximum traveling distance of 10 km.

Except for the Surveyor missions, all of these surfaces missions used radioactive power sources to provide sufficient long-term power and heat to maintain its subsystems above freezing temperatures through several lunar nights. These RHUs and RTGs are small devices that provide heat through radioactive decay of a radioactive isotope, such as plutonium or polonium. Although these units provide good thermal performance for many years, they severely add cost and complexity to its deep space missions.

Consequently, these RHUs and RTGs are highly undesirable for low-cost commercial missions. Therefore, our reference architecture for the lunar infrastructure system focused on power stations based solely on solar power and batteries to maintain an economical approach to infrastructure development.


SOON - Learn More About Business cases of Economics benefits of Cislunar and Lunar surface Economy

Having established that the technology for a cis-lunar transportation system will exist early in the next decade, we now turn to consider the business case of resourcing propellant from the moon. Once the transportation infrastructure is in place, the cost of any activity in cis-lunar space will become drastically reduced. This is primarily due to the (presumed) availability of low cost propellant that does not have to be shipped out of the Earth’s gravity .

Lunar resource LH2 & LO2 propellant revenue stream (by ULA)

Tons of propellant delivered to LEO: 210

Price in LEO: $3M/ton

Tons of propellant produced on the moon: 1050

Price at the moon: $0.5M/ton

Tons of water mined: 1575

Total revenue at moon: $525M

Total revenue in LEO: $630M

ULA and Bigelow Aerospace are planning to launch the first B330 commercial space habitat in 2020 to start addressing the demands of commercial industry. Commercial activities fall into two broad categories: Development and production of goods and services to support terrestrial consumption and, Goods and services to support in space consumption.