**6. Concluding remarks**

Saturn and its moon have always been fascinating. Ever since Galileo Galilei noted in his early telescopic observations that "Saturn has ears," the excitement

**47**

*Solar System Exploration Augmented by In Situ Resource Utilization: System Analyses, Vehicles…*

Detailed exploration of the major moons can be completed with a set of small chemical propulsion moon landers and nuclear electric orbital transfer vehicles. A series of such OTV and landers showed several optimal locations for conducting a moon survey. Dione was an optimal location for the minimization of the OTV and lander fleet mass. A central moon location allowed a large ISRU factory to fuel

Far future human exploration of the Saturn system may employ very highenergy nuclear propulsion systems. Nuclear pulse propulsion vehicles may allow fast transfers to Saturn and the delivery of robotic exploration vehicles and human explorers. Using ISRU for refueling a fast Saturn mission was analyzed. Saturn's atmosphere was considered a likely source of nuclear fuels: helium 3 and deuterium. After analyses of the ISRU transportation systems, it was found that Uranus was a more likely atmospheric fuel source. There are numerous benefits of ISRU in Saturn and Uranus systems. With ISRU, our exploration options are nearly endless, and the abilities to uncover the secrets of Saturn moons are awaiting our scientific

for Saturn exploration has been strong. Both Saturn and its moons are rich with resources: hydrogen and helium in the planet's atmosphere and ices on the moons. Using the resources of the outer planet moons, new options for exploration are possible. Multiple moons can be visited and explored. High-power OTV with nuclear power can reveal the nature of the ices and regolith of the

*DOI: http://dx.doi.org/10.5772/intechopen.88067*

many OTV and exploration lander flights.

moons.

investments.

**Nomenclature**

3He helium 3

4He helium (or helium 4)

delta-V change in velocity (km/s)

ISRU in situ resource utilization Isp specific impulse (s)

kWe kilowatts of electric power

MWe megawatt electric (power level) NEP nuclear electric propulsion NPP nuclear pulse propulsion NTP nuclear thermal propulsion NTR nuclear thermal rocket

PSC permanently shadowed craters PSR permanently shadowed regions

ASC aerospacecraft CC closed cycle

GCR gas core rocket GTOW gross takeoff weight

LEO low Earth orbit MT metric tons

OC open cycle O2 oxygen

PPB parts per billion

H2 hydrogen He helium 4

K kelvin

AMOSS atmospheric mining in the outer solar system

*Solar System Exploration Augmented by In Situ Resource Utilization: System Analyses, Vehicles… DOI: http://dx.doi.org/10.5772/intechopen.88067*

for Saturn exploration has been strong. Both Saturn and its moons are rich with resources: hydrogen and helium in the planet's atmosphere and ices on the moons. Using the resources of the outer planet moons, new options for exploration are possible. Multiple moons can be visited and explored. High-power OTV with nuclear power can reveal the nature of the ices and regolith of the moons.

Detailed exploration of the major moons can be completed with a set of small chemical propulsion moon landers and nuclear electric orbital transfer vehicles. A series of such OTV and landers showed several optimal locations for conducting a moon survey. Dione was an optimal location for the minimization of the OTV and lander fleet mass. A central moon location allowed a large ISRU factory to fuel many OTV and exploration lander flights.

Far future human exploration of the Saturn system may employ very highenergy nuclear propulsion systems. Nuclear pulse propulsion vehicles may allow fast transfers to Saturn and the delivery of robotic exploration vehicles and human explorers. Using ISRU for refueling a fast Saturn mission was analyzed. Saturn's atmosphere was considered a likely source of nuclear fuels: helium 3 and deuterium. After analyses of the ISRU transportation systems, it was found that Uranus was a more likely atmospheric fuel source. There are numerous benefits of ISRU in Saturn and Uranus systems. With ISRU, our exploration options are nearly endless, and the abilities to uncover the secrets of Saturn moons are awaiting our scientific investments.

### **Nomenclature**

*Planetology - Future Explorations*

orbit may be cumbersome.

**Figure 7.**

60 km/s mission requires less than 6000 MT.

*Saturn NPP sizing and mission data, B = 0.01 Mp [23].*

moon landers as consistent as possible. If a lander were to be used for many flights, repacking parachutes or reoutfitting a robotic lander with additional parachutes on

In Ref. [23], using ISRU for refueling a fast Saturn mission was analyzed. Saturn's atmosphere was considered a likely source of the nuclear fuels: helium 3 and deuterium. After analyses of the ISRU transportation systems, it was found that Uranus was a more likely atmospheric fuel source. The complexity of moving OTVs from low Saturn orbit to an assembly point (such a Titan) and the trip time for the low-thrust transfers (for a round-trip delta-V of over 94 km/s) were very prohibitive. With the Uranus option, the nuclear fuels were mining and sent to Titan. The round-trip OTV delta-V for lifting the mined fuels to a moon of Uranus was approximately 32 km/s. While the delta-V for mining transportation is lower, the need for an interplanetary transfer vehicle (ITV) is apparent. A relatively low-energy Uranus to Saturn transfer is possible with an NEP ITV. While the ISRU option for the fast Saturn mission is attractive, the time for gathering the nuclear fuels may require 10 years of mining

Saturn and its moon have always been fascinating. Ever since Galileo Galilei noted in his early telescopic observations that "Saturn has ears," the excitement

**Figure 7** shows the mass of the Saturn missions for a range of delta-V of 60–120 km/s. While the 60 km/s missions represent a fast mission to Saturn (approximately 250–500 days), a fast mission in both directions may require 120 km/s. The vehicle mass for the 120 km/s missions is over 47,000 MT, while the

**46**

operations.

**6. Concluding remarks**

