Cassini to Confirm if 'Caspian Sea' is Liquid-Filled
For Cassini's next flyby of Titan on May 12, 2007, the radar instrument was originally pointing north of where it is now pointed. Due to the discovery of probable large seas on Titan, Cassini's quick-thinking team repointed the radar instrument south, so it could fly over a large, expansive dark area dubbed the "Caspian Sea." This flyby will confirm whether it is liquid-filled. This area on Titan's north pole stretches 1,000 kilometers (620 miles) and is only slightly smaller than Earth's Caspian Sea.
The presence of seas on Titan reinforces the idea that Titan's surface must be re-supplying methane to its atmosphere.
Instruments on NASA's Cassini spacecraft have found evidence for seas, likely filled with liquid methane or ethane, in the high northern latitudes of Saturn's moon Titan. One such feature is larger than any of the Great Lakes of North America and is about the same size as several seas on Earth. Cassini's radar instrument imaged several very dark features near Titan's north pole. Much larger than similar features seen before on Titan, the largest dark feature measures at least 100,000 square kilometers (39,000 square miles). Since the radar has caught only a portion of each of these features, only their minimum size is known. Titan is the second largest moon in the solar system and is about 50 percent larger than Earth's moon.
Two years ago, planetary scientists across the world watched as Europe and the US did something amazing. The Huygens descent module drifted down through the hazy atmosphere of Saturn's moon Titan, beaming its data back to Earth via the Cassini mothership. Today, Huygens's data are still continuing to surprise researchers. Titan holds a unique place in the Solar System. It is the only moon covered in a significant atmosphere. The atmosphere has long intrigued scientists as it may be similar to that of the early Earth but the deeper mystery was: what lies beneath the haze?
Huygens parachuted to the surface of Titan on 14 January 2005. While Cassini keeps flying by this moon of Saturn collecting new amazing data, one can say that the data collected by Huygens’s six instruments during its 2.5-hour descent and touch-down have provided the most spectacular view of this world yet and first dramatic change in the way we now think about it.
The existence of oceans or lakes of liquid methane on Saturn's moon Titan was predicted more than 20 years ago. But with a dense haze preventing a closer look it has not been possible to confirm their presence. Until the Cassini flyby of July 22, 2006, that is.
Radar imaging data from the flyby, published this week in the journal Nature, provide convincing evidence for large bodies of liquid. This image, used on the journal's cover, gives a taste of what Cassini saw. Intensity in this colorized image is proportional to how much radar brightness is returned, or more specifically, the logarithm of the radar backscatter cross-section. The colors are not a representation of what the human eye would see.
The lakes, darker than the surrounding terrain, are emphasized here by tinting regions of low backscatter in blue. Radar-brighter regions are shown in tan. The strip of radar imagery is foreshortened to simulate an oblique view of the highest latitude region, seen from a point to its west.
This radar image was acquired by the Cassini radar instrument in synthetic aperture mode on July 22, 2006. The image is centered near 80 degrees north, 35 degrees west and is about 140 kilometers (84 miles) across. Smallest details in this image are about 500 meters (1,640 feet) across.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries.
For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov/home/index.cfm .
N00065334.jpg was received on Earth, Sept. 8, 2006. The camera was pointing toward TITAN at approximately 137,854 kilometers away, using the CL1 and CB3 filters. The image reportedly has not been validated or calibrated. A validated/calibrated image is expected to be archived with the NASA Planetary Data System in 2007.
Access to the Huygens archive is available via the ESA Planetary Science Archive (PSA). NASA’s Cassini spacecraft orbited Saturn for four years, surveying the ringed planet and its moons. The ESA Huygens probe was first to land on the surface of Titan, Saturn’s largest moon. Data from Cassini and Huygens was intended to offer clues about how life began on Earth.
The data sets include calibration information and documentation necessary to understand and process the products, and to carry out scientific analyses. It is available to scientist as well as the public for download and is also available in the NASA Planetary Data System (PDS).
"This achievement is the result of a major effort performed during the last three years by all the Huygens teams, scientists and engineers, from Europe and the United States," outlines Olivier Witasse, ESA planetary scientist.
Saturn's moon Enceladus - an active, icy world with an unusually warm south pole - may have performed an unusual trick for a planetary body. New research shows Enceladus rolled over, literally, explaining why the moon's hottest spot is at the south pole.
Enceladus recently grabbed scientists' attention when the Cassini spacecraft observed icy jets and plumes indicating active geysers spewing from the tiny moon's south polar region.
"The mystery we set out to explain was how the hot spot could end up at the pole if it didn't start there," said Francis Nimmo, assistant professor of Earth sciences, University of California, Santa Cruz.
The researchers propose the reorientation of the moon was driven by warm, low-density material rising to the surface from within Enceladus. A similar process may have happened on Uranus' moon Miranda, they said. Their findings are in this week's journal Nature.
More on Enceladus. Credit: NASA
"We realize that this is a radical conclusion --that we may have evidence for liquid water within a body so small and so cold," said Dr. Carolyn Porco, Cassini imaging team leader at Space Science Institute, Boulder, Colo. "However, if we are right, we have significantly broadened the diversity of solar system environments where we might possibly have conditions suitable for living organisms."
High-resolution Cassini images show icy jets and towering plumes ejecting large quantities of particles at high speed. Scientists examined several models to explain the process. They ruled out the idea that the particles are produced by or blown off the moon's surface by vapor created when warm water ice converts to a gas. Instead, scientists have found evidence for a much more exciting possibility -- the jets might be erupting from near-surface pockets of liquid water above 0 degrees Celsius (32 degrees Fahrenheit), like cold versions of the Old Faithful geyser in Yellowstone.
In the spring of 2008, scientists will get another chance to look at Enceladus when Cassini flies within 350 kilometers approximately 220 miles), but much work remains after Cassini's four-year prime mission is over.
Mission scientists report these and other Enceladus findings in this week's issue of Science.
More: NASA - Potential Liquid Water on Enceladus
Using recent Cassini, Huygens and Earth-based observations, scientists have been able to create a computer model which explains the formation of several types of ethane and methane clouds on Titan.
Clouds have been observed recently on Titan, Saturn’s largest moon, through the thick haze, using near-infrared spectroscopy and images of the south pole and temperate regions near 40° South. Recent observations from Earth-based telescopes and the NASA/ESA/ASI Cassini spacecraft are now providing an insight into cloud climatology.
More:ESA Science-Predicting the weather on Titan
More: NASA - It Takes Two to Tango
Link: NASA - Cassini-Huygens Mission to Saturn and Titan
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In a spectacular kick-off to its first season of prime ring viewing, which began last month, the Cassini spacecraft has confirmed earlier suspicions of an unseen moon hidden in a gap in Saturn's outer A ring. A new image and movie show the new moon and the waves it raises in the surrounding ring material.
The moon, provisionally named S/2005 S1, was first seen in a time- lapse sequence of images taken on May 1, 2005, as Cassini began its climb to higher inclinations in orbit around Saturn. A day later, an even closer view was obtained, which has allowed a measure of the moon's size and brightness.
The images show the tiny object in the center of the Keeler gap and the wavy patterns in the gap edges that are generated by the moon's gravitational influence. The Keeler gap is located about 250 kilometers (155 miles) inside the outer edge of the A ring, which is also the outer edge of the bright main rings. The new object is about 7 kilometers (4 miles) across and reflects about half the light falling on it -- a brightness that is typical of the particles in the nearby rings.
Links to More Information about the Cassini Mission
More: JPL - NASA's Cassini Spacecraft Continues Making New Saturn Discoveries
Link: USGS - Cassini Mission
USGS Astrogeology maintains the official list of planetary feature names for the IAU, called the Gazetteer of Planetary Nomenclature. Additionally, we are active on several IAU working and task groups.
More: USGS Astro - Phoebe's Craters on the Official Gazeteer of Planetary Nomenclature view the complete list of craters and the origin of each name
Image: NASA/JPL - Phoebian Explorers 1 (PIA06117)
Image: NASA/JPL - Phoebian Explorers 2 (PIA06118)
Link: Wikipedia - Jason and the Argonauts