Bryan Palaszewski

Glenn Research Center, Cleveland, Ohio

Atmospheric Mining in the Outer Solar System:

Resource Capturing, Exploration, and Exploitation

NASA/TM—2015-218096

April 2015

AIAA–2013–3765
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Bryan Palaszewski

Glenn Research Center, Cleveland, Ohio

Atmospheric Mining in the Outer Solar System:

Resource Capturing, Exploration, and Exploitation

NASA/TM—2015-218096

April 2015

AIAA–2013–3765

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135

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NASA/TM—2015-218096 1

Atmospheric Mining in the Outer Solar System:

Resource Capturing, Exploration, and Exploitation

Bryan Palaszewski

National Aeronautics and Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Summary

Atmospheric mining in the outer solar system (AMOSS) has been investigated as a means of fuel 

production for high-energy propulsion and power. Fusion fuels such as helium 3 (3

He) and hydrogen can be 

wrested from the atmospheres of Uranus and Neptune and either returned to Earth or used in-situ for energy 

production. 3

He and hydrogen (deuterium, etc.) were the primary gases of interest, with hydrogen being the 

primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of 

analyses were undertaken to investigate resource capturing aspects of AMOSS. These analyses included the 

gas capturing rate, storage options, and different methods of direct use of the captured gases. Additional 

supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues. While 

capturing 3

He, large amounts of hydrogen and helium 4 (4He) are produced. With these two additional 

gases, the potential exists for fueling small and large fleets of additional exploration and exploitation 

vehicles. Additional aerospacecraft or other aerial vehicles (UAVs, balloons, rockets, etc.) could fly through 

the outer-planet atmosphere to investigate cloud formation dynamics, global weather, localized storms or 

other disturbances, wind speeds, the poles, and so forth. Deep-diving aircraft (built with the strength to 

withstand many atmospheres of pressure) powered by the excess hydrogen or 4

He may be designed to probe 

the higher density regions of the gas giants.

Nomenclature

3

He helium 3

4

He helium (or helium 4)

AMOSS atmospheric mining in the outer solar system

delta-V change in velocity (km/s)

GPS Global Positioning System

ISRU In-Situ Resource Utilization

Isp specific impulse (s)

Mp propellant mass

MT metric tons

NTP nuclear thermal propulsion

NTR nuclear thermal rocket

UAV unmanned aerial vehicle

Atmospheric Mining in the Outer Solar System

Atmospheric mining of the outer solar system (AMOSS) is one of the options for creating nuclear 

fuels, such as 3

He, for future fusion-powered exploration vehicles or powering reactors for Earth’s 

planetary energy. Uranus’s and Neptune’s atmospheres would be the primary mining sites, and robotic 

vehicles would wrest these gases from the hydrogen-helium gases of those planets. Preliminary estimates 
NASA/TM—2015-218096 2

of the masses of the mining vehicles have been created (Refs. 1 to 8), and additional supporting vehicles 

may enhance the mining scenarios (Refs. 9 to 20). Storing the mined gases at automated bases on outerplanet moons was conceived to ease the storage requirements on interplanetary transfer vehicles (that 

would return the cryogenic gases to Earth or deliver them to other destinations).

Resource Capturing Studies

Studies of the gas capture rate and its influence on mining time in the atmosphere were conducted. 

Aerospacecraft cruisers have been identified as a “best” solution for atmospheric mining (Refs. 1 to 8). To

power these vehicles, atmospheric hydrogen gas would be liquefied and used as a rocket propellant for 

the ascent to orbit. A nuclear gas-core rocket is a likely candidate for the cruiser (Figure 1, Refs. 17 to 

20). Gaseous or liquid hydrogen would be used to power the engines during atmospheric mining 

operations. Helium 3 (3

He) would be separated from the atmospheric hydrogen, and helium (helium 4, 

4

He) would be captured, liquefied, and stored as a payload that would be returned to orbit. Table I and 

Figure 2 provide the amount of 3

He in the outer-planet atmospheres (Ref. 1). Figure 3 and Figure 4 show 

the mining time versus the capture rate for Uranus and Neptune, respectively (Ref. 1). A 500-kg payload 

of 3

He is captured during the mining time.

Figure 5 and Figure 6 provide the sizing of the gas-core-powered vehicles and a comparison of the 

solid-core and gas-core vehicle options, respectively (Refs. 1 and 2). The relatively low thrust-to-weight 

ratio of the nuclear engines may necessitate the use of a more advanced gas-core nuclear engine over the 

solid-core nuclear thermal propulsion (NTP). Although the gas-core engine is likely more attractive for 

mining missions that require a return to orbit, other smaller nuclear thermal engines will be more 

applicable to atmospheric exploration missions that do not require orbital access.

AMOSS can be a powerful tool in extracting fuels from the outer planets and allow fast human and 

robotic exploration of the solar system. Preliminary designs of aerospacecraft with gas-core rocket nuclear 

engines for mining the outer planets have been developed (Refs. 1 and 2). The analyses showed that gascore engines can reduce the mass of such aerospacecraft mining vehicles very significantly: from 

72 to 80 percent reduction over NTP solid-core-powered aerospacecraft mining vehicles. Although this 

mass reduction is important in reducing the mass of the overall mining system, the complexity of a 

fissioning plasma gas-core rocket is much higher than the more traditional solid-core NTP engines. 

Additional analyses were conducted to calculate the capture rates of hydrogen and 4

He during the mining 

process. Very large masses of hydrogen and 4

He are produced every day during the often lengthy process of 

3

He capture and gas separation. Figure 7 shows the mass of hydrogen needed for the gas-core rocket and the 

potentially excess hydrogen captured every day (Ref. 1). Typically, these very large (excess) additional fuel 

masses can dwarf the requirements needed for hydrogen capture for ascent to orbit. Thus, the potential for 

fueling small and large fleets of additional exploration and exploitation vehicles exists. Aerial vehicle 

designs can take on many configurations. Additional aerospacecraft or other unmanned aerial vehicles 

(UAVs), balloons, rockets, and so forth, could fly through the outer-planet atmospheres for activities such as 

global weather observations, localized storm or other disturbance investigations, wind speed measurements, 

and polar observations. Deep-diving aircraft (built with the strength to withstand many atmospheres of 

pressure) powered by the excess hydrogen or 4

He may be designed to probe the higher density regions of the 

gas giants.

Based on these analyses, there will likely be several possible future ways to effectively use the gases 

of the outer planets for exciting and scientifically important atmospheric exploration missions. The 

analyses focused on Uranus and Neptune, as these planets offer vast reservoirs of fuels that are more 

readily accessible than those from Jupiter and Saturn (as Uranus and Neptune require lower energies 

needed to attain orbit and present less danger from powerful atmospheric lightning) and, with the advent 

of nuclear fusion propulsion, may offer us the best option for fast interplanetary travel and the first 

practical interstellar flight.
NASA/TM—2015-218096 3

Atmospheric Exploration Missions and Vehicles

This section will discuss the issues of future atmospheric exploration and the vehicles that may 

conduct that exploration.

Uranus and Neptune—Clouds and Dynamism

A series of exploration missions for the Uranus and Neptune clouds and overall atmosphere would 

yield many great discoveries of their dynamics. Appendix A provides a number of cloud images from 

Earth-based (Keck) and space-based (Hubble) telescopes and spacecraft (Voyager). Appendix B notes the 

cloud changes of many years of observations (Refs. 21 to 29). As an example, when the Voyager 

spacecraft flew by Neptune in 1989, it photographed the Great Dark Spot at 15° south latitude. Imaging 

conducted by the Hubble Space Telescope in 1991, 1996, and 1998 revealed that the Spot had completely 

disappeared, and no other clouds or disturbances were seen on or near that latitude (Refs. 25 to 29). At 

Uranus, the cloud structures were revealed with Earth-based telescopes and the Hubble Space Telescope 

in the 1990s and 2000s, whereas previous Voyager flyby images (from 1986) showed no clouds (Refs. 21

to 24). Gathering data on the clouds’ dynamics and the related atmospheric wind speeds can be 

accomplished with in situ UAV flights. Measuring wind velocities at varying altitudes can lead to 

improved understanding of the lifetime of the cloud features noted in the telescopic observations of the 

atmosphere. Also, atmospheric sampling may reveal the best places or safest places for 3

He or hydrogen 

mining, or both. Thus, with the right array of probes and UAVs, exploration and exploitation of the 

atmospheric phenomena and resources can be simultaneously conducted.

Atmospheric Exploration Vehicles

A series of UAV and probe concepts were identified for atmospheric exploration. Table II provides 

the classes of probes and UAVs that can significantly augment future atmospheric exploration. Probes 

that use free fall or parachutes as they take data in the atmosphere are the first and most mature option. 

The Galileo Probe shown in Figure 8 (Refs. 30 and 31) is the baseline for many future atmospheric probe 

missions. A more aggressive approach to probe- or UAV-based exploration is the rocket assisted probe. 

As it can take many hours to access the deeper parts of the atmosphere (Ref. 32), a rocket assist to 

accelerate the probe to deep depths was considered. In addition to this, a rocket return was also conceived.

Of course, high-pressure atmospheric flight operation of such vehicles will be a major challenge. Table III

shows the ranges of masses for the probes and UAVs. The mass of the vehicles may be high based on the 

structure and wall thicknesses to withstand many atmospheres of pressure. Unique designs using pulsed 

detonation engines have been conceived, and such high-pressure detonation engines may be crucial to any 

future designs. Alternatively, balloons may be inflated to allow rapid ascent of the probe to higher 

altitudes. Balloons for rising to higher attitude may be a lower mass option than the rocket return, but a 

high-speed option for gaining altitude may be essential (for escaping high winds, wind shear, etc.), 

favoring the rocket return option. Taking advantage of more traditional UAV designs will also provide 

many operational benefits. Remote-sensing instruments on subsonic winged UAVs can potentially 

provide extensive data sets on outer-planet winds, cloud dynamics, and cloud formation. References 33 to 

41 provide a range of applicable UAV designs and engine options.

Short-term observations (of several hours) can be accomplished with atmospheric entry probes that 

enter and then begin parachuting to lower altitudes. After a Galileo-class probe’s atmospheric entry, it 

would slow to Mach 1 and deploy a parachute, sending back data for approximately 60 min (Ref. 30). 

Alternatively, the probe can be cut free of the parachute, and the lower altitudes can be attained more

quickly in free fall. Figure 9 depicts the descent time for atmospheric probes exploring Uranus’s and 

Neptune’s atmosphere (Ref. 32).
NASA/TM—2015-218096 4

As noted in Reference 32,

“The times to descend to a given pressure level are shown in Figures 7(a) and 7, for 

Uranus and Neptune, respectively. The maximum time boundary is associated with a 

complete descent on the parachute as shown by the upper descent profile in the figures. 

Descent times to a pressure level of 200 bar on the parachute are about 5.5 hr in the 

Uranus atmosphere and 4.4 hr in the Neptune atmosphere. To descend to 400 bar will 

require 8 hr at Uranus and 7 hr at Neptune. These times are very large compared to with 

the actual descent time for the Galileo Probe at Jupiter (of 1 hr). The Galileo Descent 

Module was designed to reach a pressure level of about 10 to 20 bar before either the 

system fails or the communications are terminated.

The principal design problems associated with long descent times for Uranus and 

Neptune are: (1) maintaining the line of sight communications between the UAV or 

aerospacecraft and the probe for such a long period and (2) providing sufficient power 

during the long descent.”

A UAV for AMOSS can be used as a data relay for the deep probes to cover their descent, which can take 

many hours. With nuclear atmospheric gas-powered UAVs, the relay and exploration functions can be 

completed by two complementary vehicles. One UAV will fly near the top of the atmosphere while the 

other conducts the deeper atmospheric surveys. Figure 10 shows the line-of-sight data transmission 

visibility geometry (Ref. 32). As the complementary UAVs will both be in the atmosphere, the 

transmission visibility issues will be ameliorated.

Figure 11, Figure 12, and Figure 13 provide a series of UAV configuration options: supersonic and

subsonic (Refs. 36 and 37). Atmospheric gases are very attractive fuel for future UAV nuclear engines 

(Refs. 38 to 41). A ramjet UAV was investigated for operation on the Jovian atmosphere (Refs. 39 and

40). Figure 13 illustrates the nuclear ramjet (Refs. 39 to 42). The ramjet design is based on a small nuclear 

reactor called MITEE (Refs. 39 to 41). The engine inlet takes in the outer-planet atmospheric gases, feeds 

it to the reactor, and the reactor heats the gases and expands them through a nozzle for propulsion. Engine

masses for the reactors are noted in Table IV (Refs. 38 to 41). Final designs must be based on specific 

configurations and the pressure field during the deep atmospheric flight.

The mass of each of the rocket-assisted UAVs was predicted for a range of vehicle delta-V values. 

Total UAV delta-V values were selected at 1, 5, and 10 km/s. Figure 14 and Figure 15 are for the 1 km/s 

delta-V cases, Figure 16 and Figure 17 represent the cases for the 5-km/s delta-V values, and Figure 18

and Figure 19 show the results for UAVs with a 10-km/s delta-V capability. The vehicle dry mass (tank 

dry mass, without propellant) range was 0 to 10 000 kg. This mass range was selected to accommodate a 

range of dry mass values for a wide range of expected atmospheric pressures. More detailed analyses are 

needed to assess the specific masses for specific configurations. Tankage dry mass fractions were set at 

2 and 10 percent of the total propellant mass (or 0.02 and 0.10 Mp). The engine specific impulse (Isp) was 

selected to represent a nuclear engine at an Isp of 900 s. The UAV payload mass was 1000 kg. For a 

1-km/s delta-V UAV, a tankage mass of 0.10 Mp, and a 10 000-kg dry mass, the mass is approximately 

12 530 kg. For 10-km/s delta-V, a tankage mass of 0.10 Mp, and a 10 000-kg dry mass, the mass is 

approximately 44 450 kg. For example, the 10 km/s delta-V UAVs would have a capability of 1/2 orbital

speed and may allow simultaneous measurements with two of more UAVs on opposite sides of the planet. 

More detailed mission analyses can lead to specific mission selections for polar or more equatorial 

exploration flights or multivehicle campaigns. 

Supporting Analyses and Observations

In addition to the capturing studies, reviews of outer-planet spacecraft design issues were initiated.

A list of the issues to be addressed is noted below
NASA/TM—2015-218096 5

• Mission planning

• Cryogenic fuel storage issues

• Cryogenic dust (outer-planet moons, ice migration), mass concentrations (mascons) on the 

moons, and so forth

• Global Positioning System (GPS) vehicles in outer-planet orbits for navigation

• Observational satellite for outer-planet weather monitoring, diverting cruisers from harm

Also, Appendix B illuminates some of the issues to be analyzed. Appendix C contains gas and shock 

properties for a hydrogen-helium atmosphere (85 percent hydrogen and 15 percent helium by volume),

and Appendix D provides some data of detonation engines operating in extremely high-pressure 

environments.

Concluding Remarks

Atmospheric mining at Uranus and Neptune can allow for the production of fuels for significant 

exploration and exploitation missions. While capturing helium 3 (3

He), large amounts of hydrogen and 

helium 4 (

4

He) are produced. With these two additional gases, the potential for fueling small and large 

fleets of additional exploration and exploitation vehicles exists. Additional aerospacecraft or other aerial 

vehicles (unmanned aerial vehicles (UAVs), balloons, rockets, etc.) could fly through the outer-planet 

atmospheres, for global weather observations, localized storm or other disturbance investigations, wind 

speed measurements, polar observations, etc. Deep-diving UAV aircraft (built with the strength to 

withstand many atmospheres of pressure) powered by the excess hydrogen or 4

He may be designed to 

probe the higher density regions of the gas giants. Both nuclear ramjet and other rocket-powered probes 

were suggested. As there are powerful wind shear forces in the atmosphere, a compact ramjet UAV may 

be a best choice. The high aspect ratio and flexibility of a low-subsonic UAV may lead to serious damage 

during its flight due to wind shear.

The mass of the rocket-assisted UAVs was predicted for a range of vehicle delta-V values. For a

1 km/s delta-V UAV, the highest mass is approximately 12 530 kg. For 10 km/s, the largest mass was

approximately 44 450 kg. The 10 km/s delta-V UAVs would have a 1/2 orbital speed capability, and may 

allow simultaneous measurements with each on opposite sides of the planet. Issues of storing the large 

caches of propellants not needed for the orbital 3

He deliveries must be addressed. Small or large 

cryogenic hydrogen and helium tank farms in the atmosphere may be a solution. As the production rate 

and the amount of hydrogen and helium are high, the tank farms may have a similar configuration to the 

large aerospacecraft that carry the 3

He to orbit.
NASA/TM—2015-218096 6

TABLE I.—FRACTION OF 3He IN OUTER-PLANET ATMOSPHERES

Uranus Neptune

Amount of 3He in 4He 1.00×10–4 1.00×10–4

Amount of 4He in atmosphere 0.152 0.19

Amount of 3He in atmosphere 1.52×10–5 1.90×10–5

TABLE II.—PROBE AND UNMANNED AERIAL VEHICLE (UAV) CLASSES

Probes in free fall (no parachutes)

Probes (with parachutes)

Probes with rocket booster for accelerated attainment of low altitude (deep probe)

Probes with rocket (booster) return for return to high altitude

UAV (long persistence)

Mining aerospacecraft (long persistence)

TABLE III.—PROBE AND UNMANNED AERIAL 

VEHICLE (UAV) MASS REGIMES

Exploration UAV size ranges

Probe design Mass,

MT

Free fall 1 to 10

Parachute 1 to 10

Rocket boost 10 to 100

Rocket return 10 to 1000

Long duration, subsonic 10 to 1000

Aerospacecraft (mining) 100 to 10 000

TABLE IV.—UNMANNED AERIAL 

VEHICLE (UAV) NUCLEAR ENGINE 

MASSES AND THRUST LEVELS (REFS. 38 TO 41)

Engine Mass,

kg

Thrust,

lbf

MITEE 200.0 14 000

Nuclear thermal rocket (NTR) 2223.5 15 000
NASA/TM—2015-218096 7

Figure 1.—Gas-core propulsion for cruiser (from Refs. 1 and 9).

Figure 2.—Fractions of captured atmospheric gases for Neptune (from Ref. 1).
NASA/TM—2015-218096 8

Figure 3.—Mining time versus capture rate for Uranus (Ref. 1).

Figure 4.—Mining time versus capture rate for Neptune (Ref. 1).
NASA/TM—2015-218096 9

Figure 5.—Aerospacecraft mass, 1800-s Isp, Tankage mass = 10 percent Mp for H2, 

representative of gas core nuclear propulsion (Ref. 1).

Figure 6.—Nuclear thermal propulsion: solid-core and gas-core vehicle 

mass comparison, 100 000 kg dry mass, 2 percent Mp for H2 (Ref. 1).

1

10

100

1,000

10,000

100,000

1,000,000

10,000,000

100 1,000 10,000 100,000 1,000,000

Aerospacecraft mass, initial and final (kg)

Dry mass, without tankage (kg) 

Nuclear Aerospacecraft, 

Gas Core, 1,800-s Isp, 20-km/s delta-V capability, 

1,000-kg payload

Initial mass (Mo)

Final mass (Mf)

Tankage mass fraction = 10% Mp, for H2

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

900 s 1800 s 2500 s

Aerospacecraft initial mass (kg)

Engine specific impulse (s)

Nuclear Aerospacecraft:

Dry mass = 100,000 kg, Tankage mass = 2% Mp
NASA/TM—2015-218096 10

Figure 7.—3He mining time and hydrogen capture (mass per day) versus atmospheric 

gas capture rate for Neptune (Ref. 1).

Figure 8.—Galileo mission atmospheric probe mass summary (reprinted from Ref. 30 with permission).

0.01

0.10

1.00

10.00

100.00

1,000.00

10,000.00

100,000.00

1,000,000.00

10,000,000.00

0 10 20 30 40

Time for 3He capturing (days), hydrogen produced 

and required (kg) 

Atmospheric gas capture rate (kg/s)

AMOSS 3He mining time and hydrogen capturing requirements, 

3He = 1.9e^-5, Mdry = 1,000,000 kg 

Time needed for 

capturing 3He (days)

Mass of hydrogen 

produced per day

Gas core, 2500 s

Gas core Mp loads 

per day, 2500 s
NASA/TM—2015-218096 11

Figure 9.—Probe descent times for Uranus (upper) and Neptune (lower); 

descent time begins at Mach = 1.0 (Ref. 32). From Deep Atmospheric Probe 

Missions to Uranus and Neptune, Byron L. Swenson et al.; reprinted by 

permission of the American Institute of Aeronautics and Astronautics, Inc.
NASA/TM—2015-218096 12

Figure 10.—Probe and receiver (unmanned aerial vehicle (UAV) or 

aerospacecraft) data transmission visibility geometry (Ref. 32). 

From Deep Atmospheric Probe Missions to Uranus and Neptune, 

Byron L. Swenson et al; reprinted by permission of the American 

Institute of Aeronautics and Astronautics, Inc.

Figure 11.—UAV configuration options (reprinted from Ref. 36 with permission).
NASA/TM—2015-218096 13

Figure 12.—Low-subsonic-speed-class UAV (Ref. 36).

Figure 13.—Nuclear ramjet engine integrated into aircraft/UAV (Ref. 42). From Application of the 

MITEE Nuclear Ramjet for Ultra Long Range Flyer Missions in the Atmospheres of Jupiter and Other 

Giant Planets, George Maise et al.; reprinted by permission of the American Institute of Aeronautics 

and Astronautics, Inc.
NASA/TM—2015-218096 14

Figure 14.—Mass of UAV for atmospheric mining in the outer solar system (AMOSS) at 1 km/s 

delta-V capability and Mtank = 0.02 Mp.

Figure 15.—Mass of UAV for AMOSS at 1 km/s delta-V capability and Mtank = 0.1 Mp.
NASA/TM—2015-218096 15

Figure 16.—Mass of UAV for AMOSS at 1 km/s delta-V capability and Mtank = 0.02 Mp.

Figure 17.—Mass of UAV for AMOSS at 5 km/s delta-V capability and Mtank = 0.1 Mp.
NASA/TM—2015-218096 16

Figure 18.—Mass of UAV for AMOSS at 10 km/s delta-V capability and Mtank = 0.02 Mp.

Figure 19.—Mass of UAV for AMOSS at 10 km/s delta-V capability and Mtank = 0.1 Mp.
NASA/TM—2015-218096 17

Appendix A.—Planet Data—Uranus and Neptune

This appendix presents cloud images from Earth-based (Keck) and space-based (Hubble) telescopes 

and spacecraft (Voyager). Figure 20 to Figure 24 show the cloud changes over many years of 

observations. 

Figure 20.—Uranus cloud features (Keck II, Ref. 25).
NASA/TM—2015-218096 18

Figure 21.—Uranus cloud features and rings (Keck II, Ref. 25).
NASA/TM—2015-218096 19

Figure 22.—Neptune cloud features (Voyager, Hubble, Ref. 27).1

 1

Reprinted from Icarus, vol. 156, no. 1, L.A. Sromovsky, P.M. Fry, and K.H. Baines, The Unusual Dynamics of 

Northern Dark Spots on Neptune, pp.16–36, 2002, with permission from Elsevier. 
NASA/TM—2015-218096 20

Figure 23.—Neptune cloud features (Hubble, Ref. 26).2

 2

Reprinted from Icarus, vol. 163, L.A. Sromovsky et al., The Nature of Neptune’s Increasing Brightness: Evidence 

for a Seasonal Response, pp. 256–261, 2003, with permission from Elsevier.
NASA/TM—2015-218096 21

Figure 24.—Uranus winds velocities (from Ref. 43).

NASA/TM—2015-218096 23

Appendix B.—Issues for Cryogenic Operations

Cryogenic moons and operations on those bodies is important for outer-planet moon and planet 

exploration. Data for identifying the moons, their apparent densities, and the technological consideration 

in operations on those moons are presented in Figure 25 to Figure 28.

Figure 25.—Outer-planet moon densities (Ref. 44).3

Figure 26.—Issues for cryogenic outer-planet moon surface operations 

(Revolutionary Aerospace Concepts (RASC), Human Outer Planet Exploration 

(HOPE) study, Ref. 45).

 3

Reprinted from Icarus, vol. 185, no. 1, Hauke Hussmann, Frank Sohl, and Tilman Spohn, Subsurface Oceans and 

Deep Interiors of Medium-Sized Outer Planet Satellites and Large Trans-Neptunian Objects., pp. 258‒273, 2006, 

with permission from Elsevier

Moon Bases in Cryogenic 

Environments: Issues

• Power sources 

• Seals

• Rotating components

• Adhesives

• Flexible – inflatable surfaces

• Dust, ice characteristics

• Robots, for maintenance, etc.

• Warmth for, maintenance of astronauts
NASA/TM—2015-218096 24

Figure 27.—Uranus atmospheric structure, haze phenomena (Ref. 46).4

Figure 28.—Atmospheric mining issues.

 4

Reprinted from Icarus, vol. 172, K.A. Rages, H.B. Hammel, and A.J. Friedson, Evidence for Temporal Change at 

Uranus’ South Pole, pp. 548–554, 2004, with permission from Elsevier.
NASA/TM—2015-218096 25

Appendix C.—Gas and Shock Properties 

(85 Percent Hydrogen, 15 Percent Helium by Volume)

Figure 29 and Figure 30 (Ref. 47) present normal shock properties for hydrogen-helium mixtures with 

velocities to 70 km/s.

Figure 29.—Initial conditions ahead of incident normal shock in 0.85 H2-0.15 He (Ref. 47).
NASA/TM—2015-218096 26

Figure 30.—Thermodynamic properties and flow velocity behind an incident normal shock into a 

0.85 H2-0.15 He mixture (Ref. 47).
NASA/TM—2015-218096 27

Appendix D.—Detonation Engine Data

The appendix presents detonation rocket engine performance in Figure 31 and Figure 32. This type of 

engine was proposed for flight in high-pressure atmospheric environments. 

Figure 31.—Variation of specific impulse with ambient pressure for various ambient 

gases (carbon dioxide (CO2), nitrogen (N2), and helium (He)). with long-cone and 

firing-plug nozzles (Ref. 33). From Detonation Propulsion Experiments and Theory. 

Measurement of Detonation Propulsion in Helium and Performance Calculations, Lloyd 

H. Back, Warren L. Dowler, and Giulio Varsi; reprinted by permission of the American 

Institute of Aeronautics and Astronautics, Inc.
NASA/TM—2015-218096 28

Figure 32.—Engine specific impulse, including high angle nozzles (Ref. 34). From Detonation Propulsion for High 

Pressure Environments, Giulio Varsi and Lloyd H. Back; reprinted by permission of the American Institute of 

Aeronautics and Astronautics, Inc.
NASA/TM—2015-218096 29

References

1. Palaszewski, Bryan: Atmospheric Mining in the Outer Solar System: Resource Capturing, Storage, 

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Atmospheric Mining in the Outer Solar System: Resource Capturing, Exploration, and

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14. ABSTRACT

Atmospheric mining in the outer solar system (AMOSS) has been investigated as a means of fuel production for high-energy propulsion and

power. Fusion fuels such as helium 2 ( 3

He) and hydrogen can be wrested from the atmospheres of Uranus and Neptune and either returned

to Earth or used in-situ for energy production. 3

He and hydrogen (deuterium, etc.) were the primary gases of interest, with hydrogen being

the primary propellant for nuclear thermal solid core and gas core rocket-based atmospheric flight. A series of analyses were undertaken to

investigate resource capturing aspects of AMOSS. These analyses included the gas capturing rate, storage options, and different methods of

direct use of the captured gases. Additional supporting analyses were conducted to illuminate vehicle sizing and orbital transportation issues.

While capturing 3

He, large amounts of hydrogen and helium 4 (4He) are produced. With these two additional gases, the potential exists for

fueling small and large fleets of additional exploration and exploitation vehicles. Additional aerospacecraft or other aerial vehicles (UAVs,

balloons, rockets, etc.) could fly through the outer-planet atmosphere to investigate cloud formation dynamics, global weather, localized

storms or other disturbances, wind speeds, the poles, and so forth. Deep-diving aircraft (built with the strength to withstand many

atmospheres of pressure) powered by the excess hydrogen or 4

He may be designed to probe the higher density regions of the gas giants.

15. SUBJECT TERMS

In situ resource utilization; Propellants; Metallized gelled fuels; Cryogenics; Nuclear power; Electric propulsion; Planetary exploration;

Balloons; Atmospheric cruisers; Aerospacecraft; Uninhabited aerial vehicles; Probes; Clouds; Weather

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