Shine On, Cassini

Titan Layers (detail)

“Each flyby gives us a little more knowledge of Titan and its striking similarities to our world. Even with its cold surface temperatures of minus 290 degrees Fahrenheit (94 kelvins), Titan is like early Earth in a deep freeze.”


It’s a cosmic diamond jubilee, of sorts. The clock is running, with Cassini set to undertake it’s T-99 flyby of Titan tomorrow (March 6, 2014; 0725 PST). An additional flyby undertaken after the original schedule was settled makes this officially the spacecraft’s one-hundredth survey of Saturn’s largest moon.

According to NASA:

During this flyby the Radio Science Subsystem instrument (RSS) team carries out a Titan Gravity science observation, one of only three in the entire Solstice Mission. The main science objectives of gravity measurements at Titan are: 1) assess the presence of a global subsurface ocean by measuring the short-period changes of the gravity field caused by Saturn’s tidal field; 2) determine the exact shape of the satellite and the presence of large scale gravity anomalies; and 3) determine the rheology of how the icy crust changes shape (or flows) via altimetric data.

Additionally, Titan is one of the prime candidates for the presence of extraterrestrial life. As Gay Hill explains for JPL:

Since its 2004 arrival at Saturn, Cassini’s radar instrument has identified remarkable surface features on Titan. The features include lakes and seas made of liquid methane and ethane, which are larger than North America’s Great Lakes, and an extensive layer of liquid water deep beneath the surface. Organic molecules abound in Titan’s atmosphere, formed from the breakup of methane by solar radiation ….

…. As spring turns to summer in Titan’s northern hemisphere for the first time since Cassini arrived at Saturn, scientists are looking forward to entering potentially the most exciting time for Titan weather – with waves and winds picking up. With increasing sunlight, the north polar lakes and seas can now be seen in near-infrared images, enabling scientists to learn more about their composition and giving them clues about the surrounding terrain.

“Methane is not only in the atmosphere, but probably in the crust,” said Jonathan Lunine, a scientist on the Cassini mission at Cornell University, Ithaca, N.Y. “It’s a hint there are organics not only in Titan’s air and on the surface, but even in the deep interior, where liquid water exists as well. Organics are the building blocks of life, and if they are in contact with liquid water, there could be a chance of finding some form of life.”

It is an achievement for Cassini, which will hurtle past Titan at 13,000 miles an hour—just over 3.6 miles per second—at an altitude of 932 miles.

The Solstice Mission will run through September, 2017, almost twenty years after the probe launched. And throughout, Cassini will continue to provide a “daily stream of data”, as it has since its arrival in 2004.

Cassini catapulted our knowledge of giant, haze-enshrouded Titan into a whole new realm. During the primary and extended missions Cassini investigated the structure and complex organic chemistry of Titan’s thick, smog-filled atmosphere. On the frigid, alien surface, the spacecraft and its Huygens probe revealed vast methane lakes and widespread stretches of wind-sculpted hydrocarbon sand dunes. Cassini researchers also deduced the presence of an internal, liquid water-ammonia ocean.

Titan remains a top priority as scientists hope to catch the moon’s surface features in the act of changing. The spacecraft will look for signs of seasonal climate change such as storms, flooding, or changes in lake levels, as well as evidence of volcanic activity.

There is a lot going on out there. Showtime is all of fifteen hours away.

Hill, Gay. “Cassini Nears 100th Titan Flyby with a Look Back”. Jet Propulsion Laboratory. March 5, 2014.

NASA. “Titan Flyby (T-99): The 100th Flyby”. Jet Propulsion Laboratory. March 6, 2014.

NASA. “Mission Overview”. Cassini Solstice Mission. (n.d.)

Image credit: Detail of image by A. D. Fortes.

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