Titan Appears Earth-Like in New Image
The new image was created by combining multiple near-infrared images taken during a high-altitude flyby on November 13.
NASA has released a composite image of Saturn's largest moon Titan, constructed from photos taken by the Cassini spacecraft, that shows the moon's surface instead of its hazy atmosphere.
The image shows terrain mostly on the Saturn-facing hemisphere of Titan, including the dark, dune-filled regions of Fensal to the north and Aztlan to the south, which together form the shape of a sideways letter H.
Titan is tidal locked, meaning the same side always faces towards Saturn, just as the moon is tidal locked to Earth.
Cassini flew as close as 10,000 kilometers to the "rich and complex" world of Titan during the November 13 flyby, which was considerably higher than typical flybys at 1,200 kilometers but allowed the spacecraft to capture moderate-resolution views over wide areas, with a resolution of a few kilometers per pixel.
The image, which shows different levels of detail due to the different altitudes the individual pictures were taken from, was taken at near-infrared wavelengths that penetrated the thick orange haze of Titan's atmosphere.
The colors in the image are false and represent the wavelengths of light collected by Cassini's visual and infrared mapping spectrometer (VIMS) instrument, from blue at 1.3 microns, through green at 2.0 microns, to red at 5.0 microns.
Visible light is centered around 0.5 microns.
‘Remarkably Earth-like processes'
NASA says images taken by the Cassini orbiter show "remarkably Earth-like processes" shaping the surface of Titan.
The moon is covered with tall dunes, river channels and great lakes, and is the only moon in our solar system to have a thick atmosphere.
There are relatively few meteorite craters on Titan, meaning that its surface must be relatively young, being reshaped by wind, liquid and tectonic movement similar to processes on Earth.
However, because the surface of Titan is at -179 degrees Celsius, the sand is composed of dark hydrocarbon grains, solid surfaces are water ice as hard as rock, and the liquid present on Titan's surface, in its atmosphere and falling as rain, is methane, which is gaseous on Earth.
Although the atmosphere of Titan is mostly nitrogen (about 95 per cent), most of the remainder is methane, not oxygen.
Methane, a compound of carbon and hydrogen, is broken down by cosmic radiation in Titan's upper atmosphere, contributing to the orange haze that obscures the surface from visible light.
The carbon, hydrogen and nitrogen in Titan's atmosphere result in a range of organic molecules, making it similar to Earth's early atmosphere before life developed.
The Cassini mission is a cooperative project between NASA, the European Space Agency (ESA) and the Italian Space Agency, and is managed through NASA's Jet Propulsion Laboratory (JPL), which designed, developed and assembled the Cassini orbiter and its two onboard cameras This originally appeared on ABC Science Online.
Ten years ago,
and became the first ever robotic mission to touch down on a world in the outer solar system. During its daring 2 hour, 27 minute descent through the murky atmosphere of Saturn's largest moon, the probe revealed an unprecedented view of of the alien environment. On landing, Huygens survived on the hydrocarbon-rich surface for only 72 minutes before its batteries drained, but the data it transmitted via NASA's Cassini spacecraft was nothing short of revolutionary -- data that continues to be analyzed 10 years after that fateful day on Jan. 14, 2005.
Here are just a few mind-blowing images from Huygens as it gave us our first intimate look at the solar system's only moon known to possess a thick atmosphere and vast liquid methane-ethane lakes -- a world that, like Jupiter's moon Europa, invokes exciting hypotheses of extraterrestrial biology.
After traveling with the Cassini mission for seven years during its interplanetary transit from Earth to Saturn orbit, the command was given for Huygens to detach from its mothership. For 21 days, the small disk-like probe was by itself, cruising toward Titan. As Huygens ripped through Titan's atmosphere, eventually slowing down enough for its heatshield to drop away and parachutes deploy, the probe got to work, rapidly photographing its descent and collecting atmospheric data. On Wednesday, The European Space Agency released the full series of
, showing how the moon's dune-covered surface slowly came to view as Huygens slowly drifted to the surface below.
Looking down, Huygens also captured a slowly evolving view of its eventual landing spot. Shown here, a fish-eye view of the landscape below starts to detail some of the surface features the probe would be soon analyzing up-close. In the run-up to landing day, mission scientists were unsure whether Huygens would land on a solid surface or splash down in a methane/ethane puddle or lake. As it turned out, the probe "splatted down" in Titan's alien mud -- a mix of small grains of ice.
Photographs during descent gradually showed an alien, yet familiar, landscape. Titan is covered in dunes, valleys and lakes -- all shaped by erosion processes we'd find on Earth. The valleys are cut by liquid action and the thick atmosphere produces winds and weather systems that form dune fields of fine hydrocarbon sand. But these Titan weather systems are not driven by an Earth-like water cycle. As the atmosphere is too cold to support water in a liquid state, other chemicals, such as methane and ethane exist as a liquid, forming their own cycle. Methane rain is now known to fall onto the landscape, creating rivers that erode valleys and form deltas in vast liquid methane-ethane lakes.
By landing a probe onto Titan's surface, the joint NASA/ESA Cassini-Huygens mission was able to get "ground proof" of flyby imaging and radar. Last year, Cassini completed its 100th Titan flyby, so in the 10 years since Huygens landed, planetary scientists have been getting a front row seat of the moon. But in 2005, Titan science was as foggy as the moon's atmosphere, so by overlaying ground-based observations with Cassini images, a better interpretation of landscape features spotted by Cassini could be made.
Although low-resolution and grainy, the first images of the landscape surrounding Huygens after it landed at 13:34 CET (12:34 GMT) on Jan. 14, 2005, stunned the world. Rounded stones appeared to litter the grains of hydrocarbon sand and ice. The eroded rocks immediately reminded us of eroded pebbles -- rocks that have undergone liquid action for long periods of time. The landing zone resembled a dried-up lake bed and surrounding that area, evidence for rapid, transient flows of liquid could be seen.
The Huygens lander, in its short solo mission, punched well above its weight, opening our eyes to an alien world within our solar system that is littered with prebiotic chemicals, a world that resembles a young Earth, beckoning our inquiring minds to return some day.