**7. Saturn science**

Many incredible discoveries were uncovered by the Cassini-Huygens mission during its 20 years of flight; a few of those fascinating encounters are mentioned here. **Figure 11** depicts six of the more than 60 of Saturn's known moons, which range in size from a few hundred meters to larger than planet Mercury. The top row of this figure, from the left (not to scale), shows the tiny odd looking moon Pan, Mimas (which looks like the "Death Star" space station from movie Star Wars), and Hyperion, which resembles a sponge. On the bottom row are Iapetus, Titan (the largest of Saturn's moons), and Enceladus, which contains "tiger stripe" fissures with erupting plumes, implying an underground reservoir of water that is suspected to be around 10 km deep (i.e., an underground ocean). **Figure 12** depicts an artist's impression of the hydrothermal activity taking place on this south polar

*SSR SBE counts from late 2015 through EOM (courtesy of S. Adamiak).*

region of Enceladus. Hot water traveling upward from the ocean comes into contact with cooler water, which is eventually expelled through the vents that connect the ocean to the surface of the moon.

**Figure 12.** *Enceladus moon hydrothermal activity (image credit: NASA/JPL-Caltech).*

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architecture.

**Figure 14.**

Administration.

**Acknowledgements**

*Robotic Autonomous Spacecraft Missions: Cassini Mission-To-Saturn Example*

**Figure 13** depicts how different organic compounds make their way to Titan's seas and lakes. Ligeia Mare is one of three of Titan's seas, consisting of pure methane and a seabed covered by sludge-like organic-rich material. Titan's atmosphere of nitrogen and methane react to produce organic molecules, the heaviest of which fall to the surface through air and rainfall, some of which make their way to the sludge on the sea floor. **Figure 14** depicts the giant hexagonal hurricane at Saturn's north pole (approximately 30,000 km across). An intense six-sided jet stream with winds at 320 km/h spirals around a massive storm which rotates anticlockwise at the heart

For robotic spacecraft to complete their goals successfully without significant risk or degradation to mission objectives, preventative measures for instruments and subsystems must be implemented by way of a robust FP strategy and onboard FSW flexibility. Prelaunch analyses and tests conducted to preclude problems do not always safeguard against human error, the flight environment, or design oversights, nor can they capture all fault cases. Mission planners must acknowledge that unknown problems can still surface after launch. During the Cassini-Huygens mission, this was proven true by the need for several new FP routines, FSW updates, and FSW patches required to resolved unexpected problems not anticipated by prelaunch designers. For interplanetary spacecraft like Cassini, these fixes were made more manageable given that significant time was available during the cruise phase to augment the FP and patch FSW in order to address these unforeseen problems, due to the flexibility that designers built into the FSW

This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space

*DOI: http://dx.doi.org/10.5772/intechopen.82161*

of this region (false color image).

**8. Conclusions and lessons learned**

*Saturn's polar hurricane (NASA/JPL-Caltech/SSI/Hampton University).*

**Figure 13.** *Titan's sea and lake organic compounds.*

*Robotic Autonomous Spacecraft Missions: Cassini Mission-To-Saturn Example DOI: http://dx.doi.org/10.5772/intechopen.82161*

**Figure 14.** *Saturn's polar hurricane (NASA/JPL-Caltech/SSI/Hampton University).*

**Figure 13** depicts how different organic compounds make their way to Titan's seas and lakes. Ligeia Mare is one of three of Titan's seas, consisting of pure methane and a seabed covered by sludge-like organic-rich material. Titan's atmosphere of nitrogen and methane react to produce organic molecules, the heaviest of which fall to the surface through air and rainfall, some of which make their way to the sludge on the sea floor. **Figure 14** depicts the giant hexagonal hurricane at Saturn's north pole (approximately 30,000 km across). An intense six-sided jet stream with winds at 320 km/h spirals around a massive storm which rotates anticlockwise at the heart of this region (false color image).
