Solar System Survey – Saturn (Part V)

By Dr. Gary L. Deel, Ph.D., J.D.
Faculty Director, School of Business, American Military University

This is the fifth article in a seven-part series reviewing the extraterrestrial planets and other bodies of the solar system, as well as exploratory missions to study them.

Aside from being the second-largest planet after Jupiter, Saturn is also the least dense. In fact, the planet’s density is so low that, if one could find a pool of water large enough, Saturn would actually float in it.

Saturn also rotates so quickly on its axis that it flattens the planet at the poles into what is called an oblate spheroid. Essentially, this means that Saturn is fatter at the equator than it is at the poles — a deformity dramatic enough to be noticeable in images and telescope perspectives.

Saturn also comes in a close second to Jupiter in another category: the number of moons. To date, 62 moons have been documented orbiting around Saturn; Jupiter has 67 moons. Researchers are investigating the potential that some form of life might exist on some of these moons.

Only a few spacecraft have visited the Saturnian system, and we’ve learned a great deal from them.

NASA Missions

In 1979, after a gravitational assist from Jupiter, Pioneer 11 flew by Saturn on its way out of the solar system. It flew to within 20,000 km (12,427 miles) of the ringed planet and took detailed pictures. Instruments onboard Pioneer 11 discovered two previously undetected moons and one ring layer. The probe also mapped the magnetic field of Saturn. This data would later be used to measure Saturn’s rotational speed, since this was not determinable from surveilling the planet itself due to the thick atmosphere. Finally, Pioneer 11 confirmed that temperatures on Saturn’s moon Titan were too cold to support Earth life.

In 1980, Voyager 1 arrived in the Saturnian system on its way out of the solar system. Voyager 1 did not come quite as close to Saturn as did Pioneer 11 — its closest approach was 64,000 km (39, 768 miles). But it did take about 16,000 pictures of the giant planet, its moons, and its famous rings.

In 1981, less than a year later, Voyager 2 followed its sister spacecraft into the region. It flew closer to the planet’s atmosphere — within 41,000 km (25,476 miIes) — and it also took about 16,000 pictures of the system. While Voyager 1’s flight path was more or less in line with the ecliptic plane, Voyager 2 passed through the system with more of a polar trajectory, so the two spacecraft were able to capture very different photographic angles and data.

Together, the two Voyager probes discovered an additional three moons, provided useful data about the spoke-like structures of the planetary rings, and took detailed measurements of the atmosphere and magnetic field. From there, the Voyagers headed out toward the edges of the solar system. NASA is still able to communicate with the probes. They recently sent data indicating that they are finally exiting the heliosphere and entering deep space.

In 1997, NASA launched the Cassini-Huygens space probe, and it would take almost seven years to make it to its destination, with gravitational assists from three different planets — Venus, Earth, and Jupiter. The probe successfully achieved orbit around Saturn in 2004.

The Cassini-Huygens mission was so successful that it was extended twice. It made a total of 283 orbits around the Saturnian system before its deliberate destruction in 2017. During that time, the spacecraft collected a plethora of data on the ringed planet and its moons. It also deployed an atmospheric probe on Titan, which revealed in extremely vivid detail the topographical characteristics of the icy moon, including the fact that there are seas of liquid methane on the surface.

Unfortunately, NASA has no definite plans to return to Saturn on its mission schedule at this time. However, five ideas have been proposed to pick up where Cassini-Huygens left off. These mission profiles include:

1. The SPRITE (acronym for Saturn Probe Interior and Atmosphere Explorer) mission which would focus on Saturn’s atmospheric dynamics;
2. The Oceanus mission, which would use an orbiter around Titan to study organic materials in the atmosphere and surface composition;
3. Titan Dragonfly, which would send a drone aircraft to Titan to study it from the surface and air;
4. The Enceladus Life Finder (ELF) mission, which would send an orbiter to fly through the geyser plumes erupting from Enceladus’s subsurface ocean to look for organic compounds or life;
5. The Enceladus Life Signatures and Habitability mission, which has not been discussed in great detail yet, but which would presumably be similar in nature to ELF.

Saturn and its moons are some of the most beautiful and interesting celestial bodies in our solar system. The few missions that we’ve sent in their direction since the 1970s have revealed mysterious worlds that call to us for further exploration. There is still much more to learn, so we can only hope that future missions will be planned and funded to continue this exploration and discovery.

Read the next article in this series: Uranus, Neptune and the Kuiper Belt.

About the Author

Dr. Gary Deel is a Faculty Director with the School of Business at American Military University. He holds a J.D. in Law and a Ph.D. in Hospitality/Business Management. Gary teaches human resources and employment law classes for American Military University, the University of Central Florida, Colorado State University and others.