Rick Robinson

May 8th 2018

Cassini Photography: A Full Color Roadmap of Saturn


Last year, the Cassini space probe made its final swan dive into Saturn, bringing its 20-year exploration voyage to an end. The spaceship plunged into Saturn’s atmosphere and burned up, ensuring that no earthly microbes would contaminate ecosystems of life that may exist on one or more of the planet’s many moons.

Gone, But Not Forgotten

Cassini may be gone, but it left behind important memories, such as the documentary record of its photography: images that have transformed our understanding of Saturn, its rings and its moons. While some mysteries have been resolved, the full, detailed study of the images has scarcely begun. More answers will be found as researchers continue to study the Cassini photography record in years to come.

The Cassini probe was more than a camera platform, though. According to NASA, the ship carried a payload of 12 scientific instruments, often with impressive names, such as the Ion and Neutral Mass Spectrometer (INMS) or Radio and Plasma Wave Science (RPWS) instrument.

One of the 12 Cassini instrument sets was known simply as the Imaging Science Subsystem — a pair of digital cameras capable of a wide-angle view and a zoomed-in detailed view. Each had multiple filters to allow for color and other image processing, and both were able to image not only in visible light but also in some ultraviolet and infrared wavelengths. All of those gorgeous images were sent back by the Imaging Science Subsystem for researchers to study.

Additionally, Cassini carried a robotic passenger — the Huygens probe. It detached from Cassini and landed on Saturn’s moon Titan back in 2005, carrying its own set of instruments, including a camera.

More Than Just Eye Candy

NASA has explored space for nearly 60 years. It might be tempting to think that the mass spectrometers, plasma wave instruments, cosmic dust analyzer and the rest of the instruments were doing the real work, while the camera was sent along merely to snap the pretty pictures.

Not so. Cassini photography was and is integral to the scientific investigation and exploration of Saturn, alongside the data sent back by the other instruments. Often, images and other instrument readings combined reveal surprises that neither could have detected by itself.

A good example of this was the discovery of geysers on Saturn’s moon Enceladus. Camera imagery showed us the spectacular and unexpected geysers. Then, other instruments were needed to determine that the erupting material was water — showing that Enceladus harbors an underground ocean and could potentially be a habitat for life.

Cassini photography played the lead role in other discoveries as well, such as revealing the striking hexagonal cloud pattern, larger than Earth’s diameter, that surrounds Saturn’s north pole. As yet, we only have tentative guesses about the atmospheric forces that create and sustain this striking pattern. Whatever the cause, storms on Saturn have plenty of lessons to teach us about planetary atmospheres and their behavior, including our own.

Photography is a uniquely powerful scientific tool because the human eye can register an enormous amount of data in a single image. A picture can be worth a thousand words — or a thousand individual data readings. Plus, they can be gorgeous to look at, to boot.