**2. In situ resource utilization (ISRU)**

In situ resource utilization (ISRU) is the use of materials on other bodies in the solar system. These in situ materials can be in the regolith, the atmosphere, or any other part of the natural environment. Using ISRU on or in the vicinity of many planetary bodies has been studied for decades. Numerous experiments have been conducted to define the methods of extracting resources from ices, gases, and regolith. Some of the earliest ISRU experiments were conducted in 1965 [1]. Based on spectroscopic measurements from Earth, simulated lunar rock and dust were created. The simulated rock and dust were then subjected to chemical processes that were designed to extract oxygen from the lunar materials [1]. Mars ISRU has been addressed in numerous references [2–6]. Reference [6] (JSC) discusses the six steps in ISRU development: identification, prospecting, resource capturing, utilization (propellants, etc.), power generation, and manufacturing. Additional extensive experiments and analyses are planned for the Mars 2020 rover, with an experiment called MOXIE that will separate oxygen from Mars' carbon dioxide atmosphere [7]. A concerted effort of many organizations, the commercial lunar propellant architecture, was focused on the efforts to capture lunar polar ice [8]. Using ISRU on outer planet moons was addressed in Refs. [9, 10] (HOPE, Ash, and BP). Outer planet analyses for capturing fusion fuels from Uranus and Neptune were conducted in Refs. [11–13].

### **3. Saturn and its moons**

Saturn is the second largest planet in the solar system. Its orbit has an average distance from the Sun of 1.433 million km. The ring system surrounding Saturn is very extensive and spectacular and has a rich set of resonances and dynamics. The Cassini mission spacecraft instruments gathered a rich set of data throughout its lifetime. Saturn also has powerful radiation belts both near the planet and far beyond the ring system. Due to the radiation environment, the moons are a more important location for any spaceflight operations.

Based on the observations of the Voyager and Cassini spacecraft, the moons of Saturn contain a rich set of ices. Spectroscopic data show the nature of these ices to be water ice with other frozen gases: nitrogen, methane, etc. The moons' temperatures are in the range on 75–130 K. **Table 1** provides the density of the major moons. The relatively low density also implies that the moons are primarily composed of frozen ices.

**Figure 1** shows the semimajor axes of the moon. Iapetus is the most distant at 3.56 million km from Saturn. The most proximate major moon is Mimas, which is only 185,000 km from Saturn [14–19]. Additional references on the moons of Saturn are provided at the end of this chapter [20–30].

#### **3.1 Enceladus**

Enceladus is a small icy moon near the outermost ring of Saturn; its radius is 248 km. Its semimajor axis is 238,020 km. Its gravity level is 2 × 10<sup>−</sup><sup>2</sup> of Earth's gravity. This moon is particularly exciting as it is sewing water into space, and its water

**37**

**3.2 Titan**

**Figure 1.**

**Table 1.**

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

is feeding mass to Saturn's rings. The water plume emanates from the so-called tiger stripes in the southern hemisphere. The temperature of the tiger stripes is 10–100°K warmer than the surrounding icy surface. The Cassini spacecraft had made multiple flybys of Enceladus and detected organic molecules in the water plume. Thus, this

Titan is the largest moon of Saturn with a radius of 2576 km. Its semimajor axis is 1.2218 million km. Titan has an appreciable atmosphere of 98.4% nitrogen, 1.4% methane, and other trace gases. Its gravity is 0.14 of Earth's gravity. Because of its dense clouds, radar must be used to gather data from space. The Cassini spacecraft observed lakes on Titan; these lakes are composed of liquid methane and ethane. These lakes are approximately that size of the Great Lakes of North America. The surface of Titan is approximately 94°K, and the surface is a complex crust of water ices and frozen hydrocarbons. Simulations and gravity data suggest an ocean of

moon may harbor the precursors of simple life forms.

*Semimajor axes of the seven major moons of Saturn.*

liquid water about 100 km below the frozen surface.

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

*Saturn moon density, modified from Ref. [14].*

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


#### **Table 1.**

*Planetology - Future Explorations*

**3. Saturn and its moons**

important location for any spaceflight operations.

Saturn are provided at the end of this chapter [20–30].

**2. In situ resource utilization (ISRU)**

moon landers. Far future human exploration, using nuclear propulsion is also addressed. A combination of these technologies may allow excellent surveys of the moons and then finally human exploration and perhaps moon base construction.

In situ resource utilization (ISRU) is the use of materials on other bodies in the solar system. These in situ materials can be in the regolith, the atmosphere, or any other part of the natural environment. Using ISRU on or in the vicinity of many planetary bodies has been studied for decades. Numerous experiments have been conducted to define the methods of extracting resources from ices, gases, and regolith. Some of the earliest ISRU experiments were conducted in 1965 [1]. Based on spectroscopic measurements from Earth, simulated lunar rock and dust were created. The simulated rock and dust were then subjected to chemical processes that were designed to extract oxygen from the lunar materials [1]. Mars ISRU has been addressed in numerous references [2–6]. Reference [6] (JSC) discusses the six steps in ISRU development: identification, prospecting, resource capturing, utilization (propellants, etc.), power generation, and manufacturing. Additional extensive experiments and analyses are planned for the Mars 2020 rover, with an experiment called MOXIE that will separate oxygen from Mars' carbon dioxide atmosphere [7]. A concerted effort of many organizations, the commercial lunar propellant architecture, was focused on the efforts to capture lunar polar ice [8]. Using ISRU on outer planet moons was addressed in Refs. [9, 10] (HOPE, Ash, and BP). Outer planet analyses for capturing

fusion fuels from Uranus and Neptune were conducted in Refs. [11–13].

Saturn is the second largest planet in the solar system. Its orbit has an average distance from the Sun of 1.433 million km. The ring system surrounding Saturn is very extensive and spectacular and has a rich set of resonances and dynamics. The Cassini mission spacecraft instruments gathered a rich set of data throughout its lifetime. Saturn also has powerful radiation belts both near the planet and far beyond the ring system. Due to the radiation environment, the moons are a more

Based on the observations of the Voyager and Cassini spacecraft, the moons of Saturn contain a rich set of ices. Spectroscopic data show the nature of these ices to be water ice with other frozen gases: nitrogen, methane, etc. The moons' temperatures are in the range on 75–130 K. **Table 1** provides the density of the major moons. The relatively low density also implies that the moons are primarily composed of

**Figure 1** shows the semimajor axes of the moon. Iapetus is the most distant at 3.56 million km from Saturn. The most proximate major moon is Mimas, which is only 185,000 km from Saturn [14–19]. Additional references on the moons of

Enceladus is a small icy moon near the outermost ring of Saturn; its radius is

ity. This moon is particularly exciting as it is sewing water into space, and its water

of Earth's grav-

248 km. Its semimajor axis is 238,020 km. Its gravity level is 2 × 10<sup>−</sup><sup>2</sup>

**36**

frozen ices.

**3.1 Enceladus**

*Saturn moon density, modified from Ref. [14].*

#### **Figure 1.**

*Semimajor axes of the seven major moons of Saturn.*

is feeding mass to Saturn's rings. The water plume emanates from the so-called tiger stripes in the southern hemisphere. The temperature of the tiger stripes is 10–100°K warmer than the surrounding icy surface. The Cassini spacecraft had made multiple flybys of Enceladus and detected organic molecules in the water plume. Thus, this moon may harbor the precursors of simple life forms.

#### **3.2 Titan**

Titan is the largest moon of Saturn with a radius of 2576 km. Its semimajor axis is 1.2218 million km. Titan has an appreciable atmosphere of 98.4% nitrogen, 1.4% methane, and other trace gases. Its gravity is 0.14 of Earth's gravity. Because of its dense clouds, radar must be used to gather data from space. The Cassini spacecraft observed lakes on Titan; these lakes are composed of liquid methane and ethane. These lakes are approximately that size of the Great Lakes of North America. The surface of Titan is approximately 94°K, and the surface is a complex crust of water ices and frozen hydrocarbons. Simulations and gravity data suggest an ocean of liquid water about 100 km below the frozen surface.


**Table 2.**

*Gravity levels of Saturn and its major moons.*
