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October 2017 - Discovering Gravitational Waves
Report #32 - Septemeber 2017
Cassini Goes Down Swinging
It all started on October 1997, when the $3.2 billion Cassini-Huygen mission was launched en route to Saturn, though it wouldn't make it there until June 30, 2004. In January 2005, after dropping off the Huygens lander on the surface of Saturn's largest moon, Titan, Cassini would embark on its long ten-year-plus mission of studying every nook and cranny of Saturn, from its rings to its moons to the planet itself.
Cassini's Legacy
What came from all those years of gathering data was a number of very important discoveries that helped to uncover many of Saturn's secrets, especially its moons. In fact, according to Space.com's Mike Wall, in his article, Cassini Battled Saturn Hard During Death Dive, "In 2005, Cassini spotted geysers of water ice and other material blasting from the south polar region of the Saturn satellite Enceladus," its source "from an ocean of salty water beneath the moon's icy crust," which may even be able to support life. Cassini also made the first discovery of another object to "harbor bodies of stable liquid on its surface" other than Earth, finding lakes and seas filled with liquid hydrocarbons on Titan.
Now it's time to say good-bye
An artist's interpretation of Cassini diving down into Saturn's atmosphere.
Credit: NASA/JPL-Caltech,
https://www.space.com/38453-cassini-battled-saturn-death-dive.html
After all its contributions to furthering our understanding of the second largest planet in our solar system, it was finally time for Cassini to retire. The spacecraft was already running out of fuel, so, in order to prevent it from crashing onto and contaminating Titan and Enceladus with Earthen microbes, scientists wanted to use the last of Cassini's fuel reserves to send it on a self-destructive path into Saturn's atmosphere.
Falling Towards Saturn
On September 15, 2017, Cassini was sent blasting toward Saturn. Even in its last moments, Cassini was still able to gather and send over some last-minute science and engineering data, keeping its antenna trained on Earth for as long as possible through a method known as "bang-bang control." When the spacecraft rotated too much and exceeded a specific range, a thruster was fired to "tip [it] back the other way." At the beginning of its dissent, Cassini was able to keep itself under control through "employing [only] subtle and discrete bang-bang thrusts." That is, until it reached Saturn's atmosphere and was "about 1,200 miles (1,900 kilometers) above the planet's cloud top."
A close-up image of Saturn.
Credit: https://nssdc.gsfc.nasa.gov/planetary/factsheet/saturnfact.html
Encountering Saturn's Atmosphere
Saturn's atmosphere is thin and wispy, but, diving into it at 77,000 mph (124,000 km/h), Cassini was met with major turbulence as it made its descent. Gas molecules pushed against the spacecraft, tipping it a little backward and forcing Cassini to fire its thrusters more frequently to remain level.
The End
The struggle intensified as Cassini dove deeper, its thrusters now firing continuously.
But Saturn's atmosphere is unforgiving, and Spacecraft Cassini was only able to last for about 91 seconds until Saturn destroyed the probe that had been studying the planet for over ten years.
Spacecraft Cassini may have finally met its end, but boy did it go down swinging.
SOURCES:
This report was a summary of the following article. Click the link for more information:
https://www.space.com/38453-cassini-battled-saturn-death-dive.html
Images:
https://www.space.com/38453-cassini-battled-saturn-death-dive.html
https://nssdc.gsfc.nasa.gov/planetary/factsheet/saturnfact.html
https://www.mdscc.nasa.gov/index.php?Section=Misiones&Id=8&ChangeLang=en