A far-flung NASA space probe flying around Saturn zipped past the ringed planet's biggest moon for the 100th time on Thursday (March 6).
The Cassini spacecraft made its closest approach to the hazy moon Titan at 12:45 p.m. EST on Earth (5:45 GMT), according to officials at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
During the historic flyby, Cassini got within 933 miles (1,500 kilometers) of Titan's mysterious surface. [Amazing Photos: Titan, Saturn's Largest Moon]
Larger than Mercury in size, Titan has some compelling similarities to Earth. It's only other body in our solar system with an atmosphere and liquid on its surface. (It's also thought to be one of the best possible places to search for extraterrestrial life.)
JPL officials say Titan, where temperatures can drop to minus 290 degrees Fahrenheit (94 kelvins), is like early Earth in a deep freeze. It may even harbor ice volcanoes that spew water ice and hydrocarbons.
For 10 years, Cassini's images have helped scientists peer beneath the moon's orange, nitrogen-rich smog to see amazing features on the face of Titan like vast lakes made of methane and ethane that are larger than North America's Great Lakes and continually replenished by hydrocarbon rain showers.
With Cassini data, scientists have detected an ocean composed of water and ammonia below Titan's icy crust. Using radar data from the spacecraft, researchers have also determined that Ligeia Mare, the second largest sea on Titan, is about 525 feet (160 meters) deep.
The flyby comes during a change in Titan's long seasons. Spring is finally giving way to summer in in Titan's northern hemisphere for the first time since Cassini arrived at Saturn in 2004. This means icy clouds are retreating and revealing and never-before-seen views of the lakes and seas at the moon's north pole. Near-infrared images of the region could give scientists clues about the surrounding terrain, JPL officials say.
Because Titan harbors water and organic materials, scientists think it could be a potential host of alien life forms.
"Methane is not only in the atmosphere, but probably in the crust," Jonathan Lunine, a scientist on the Cassini mission at Cornell University, Ithaca, N.Y., explained in a statement from JPL. "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."
Linda Spilker, Cassini project scientist at JPL, said the potential for like on Titan is twofold because of its two types of liquid bodies.
"Could a unique form of methane-based life exist in Titan's liquid lakes and seas?" Spilker asked in a statement. With a global ocean of liquid water beneath its icy crust, could life exist in Titan's subsurface ocean?"