Cassini's Swan Song

In a few days the Cassini-Huygens probe, the long running Saturn investigator, will take its final bow by plunging into the planet itself. Talk about an exit. For 20 years, the probe has returned amazing images of the ringed beauty, but all good things must come to an end. Although other spacecraft have flown by the ringed planet, no probe has conducted such a detailed exploration of the Saturn system. Before Cassini transmits the final bits of data, let’s look at the mission and its impact on all of us.

Cassini-Huygens is a joint project of the European Space Agency (ESA), NASA, and the Italian space agency Agenzia Spaziale Italiana (ASI) that was designed to peer into the scientific mysteries of Saturn and its moons. The project was the combination of two spacecraft—Cassini (the orbiter) and Huygens (the landing probe). Cassini carried a variety of experiments to study the Saturn system while Huygens was released to study Saturn’s moon Titan.  

Artist Illustration of Cassini (Image Credit: NASA)

On October 15, 1997, the Cassini-Huygens mission officially began by launching from Cape Canaveral using the Titan IVB Centaur rocket. Because the spacecraft was too heavy for a launch directly to the sixth planet, the spacecraft used several gravity assist maneuvers (flying around an object, typically the Sun or another planet to pick up speed) to reach its destination. It flew around or by the Sun, Venus, Earth, and Jupiter during these maneuvers. Finally, on June 30, 2004 the spacecraft reached Saturn, which was followed by a flyby of two moons, Titan and Dione, the same year.  

Huygens was also released in 2004, and the small probe began its journey to Titan. By January of the following year, the small lander descended through Titan’s atmosphere to learn more about the unexplored moon’s surface and chemical composition. After landing, the tiny lander spent 72 minutes on the surface before running out of battery power. Huygens sent back hundreds of photos, and remains the only landing of a human made object in the outer solar system. 

Huygens View of Titan (Photo Credit: NASA)

Cassini continued its mission and gave scientists a wealth of information about the Saturn system. Saturn’s moons were revealed to humanity not as cold desolate worlds, but as active and interesting environments that paralleled Earth in several ways. Titan, for example, has lakes, rivers, clouds, rain, and active geologic systems. Another moon, Enceladus, sprays icy particles from surface jets, and may contain a subsurface ocean capable of handling life. The probe didn't simply study these plumes from a distance, but actually flew through the plume to collect data. Observing Saturn’s rings has been another important scientific inquiry, and the exploration has yielded amazing information to scientists. Due to Cassini’s long stay around Saturn, much more science was accomplished than the relatively quick flybys of Pioneer 11 and the Voyager probes, thus leaving Uranus and Neptune as the only remaining planets without a long-term scientific investigation.

Cassini's Grand Finale Graphic (Image Credit: NASA)

Unfortunately, the Cassini-Huygens mission must come to an end. Although scientists would love to keep the mission going, fuel used for course correction and adjustment is running low. NASA is describing the final bit of the mission as the grand finale, which accurately sums up the end of the famous spacecraft. Beginning this April, the probe began a series of orbits designed to eventually end the mission. During these orbits, the spacecraft dove closer to the planet—including close encounters with the rings and dips into the upper atmosphere. Finally, on September 15, 2017, Cassini will dive into Saturn’s atmosphere to end the historic exploration. 

I remember one summer afternoon my parents took me to a planetarium to see a show—something I was undoubtedly begging for. That show happened to be about Cassini-Huygens, which was about to begin its encounter with Saturn. Walking away that day amazed wouldn’t describe my feelings completely. Cassini-Huygens grabbed my heart and never let go. So, in a few days, I’ll wake up a bit early just to watch a dear friend of mine send its last signal on NASA TV. My feelings will be bittersweet—grateful for the inspiration and knowledge Cassini-Huygens gave, but sad to say goodbye.            

Watch coverage of Cassini's final signals coming through on September 15 beginning 6:00 AM CST on NASA TV.  

Cassini's View of the Ringed Beauty (Photo Credit: NASA)

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To see more excellent photos from Cassini-Huygens, visit this link: https://saturn.jpl.nasa.gov/galleries/images/

Sources:

https://saturn.jpl.nasa.gov/

https://www.jpl.nasa.gov/missions/cassini-huygens/

http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

https://www.space.com/38010-cassini-spacecraft-saturn-grand-finale.html