Infrared Images of Saturn’s Poles

NASA’s Cassini spacecraft has taken new pictures showing a giant cyclone at Saturn’s north pole and its south pole, the latter apparently powered by Earth-type storm patterns.

The characteristics of these cyclones differs from Earth-based cyclones in interesting ways.

The north pole cyclone is only visible in the near-infrared wavelengths due to winter in that region of Saturn. At these wavelengths, seven times greater than that of visible light, the clouds deep inside Saturn’s atmosphere are only seen in silhouette against the background radiation of Saturn’s internally generated heat.

Saturn's South Polar Region Revealed

An infrared map of the north pole of Saturn has been created showing features as small as 120 km (75 mi) visible. The whirlpool-like cyclone there is rotating at 530 km/hr (325 mph), more than twice as fast as the highest winds measured in cyclones on Earth.

This cyclone is surrounded by a honeycombed-shaped hexagon, which itself does not seem to move while the clouds within it whip around at high speeds, also greater than 500 km/hr (300 mph). Neither the fast-moving clouds inside the hexagon nor this new cyclone seem to disrupt the six-sided hexagon.

Hurricanes on Earth are fueled by the ocean’s heat and water while Saturn’s cyclones have no body of water at their bases as Saturn’s hurricanes are locked to the planet’s poles, whereas terrestrial hurricanes drift across the ocean.

Just as condensing water in clouds on Earth powers hurricane vortices, the heat released from the condensing water in Saturn’s thunderstorms deep down in the atmosphere may be the primary power source energizing the vortex.

At the southern pole, the new infrared images of the pole, under the daylight conditions of southern summer, show the entire region is marked by hundreds of dark cloud spots. The Yet Yawning Gulf

The clouds, like those at the north pole, are likely composed of ammonium hydro-sulfide with possibly a mixture of other materials from below. Conversely, most of the hazes and clouds seen on Saturn are believed to be composed of ammonia, which condenses at higher and more visible altitudes.

NASA says that at least one of the large lakes on Titan, a moon of Saturn, consists of liquid hydrocarbons. The hydrocarbon ethane has been positively spotted, making Titan the only other object besides Earth known to hold liquid on its surface.

Thanks to the Cassini mission and the data provided by numerous flybys of Titan, analysis of light absorption and reflectivity in infrared light helped confirm the existence of the liquid lake. Scientists have seen hundreds of dark, lake-like features on Titan but did not know whether these features were liquid or merely dark rock or other dark material.

The hydrocarbon lake is called Ontario Lacus in the south polar region of Titan, and slightly largely that Lake Ontario between Canada and the United States. Titan’s surface temperatures approximate 300 degrees Fahrenheit below zero, yet shows evidence of evaporation, rain and fluid eroded and fluid carved channels draining into the hydrocarbon lake bed.

Earth has a hydrological cycle based on water but Titan has a cycle based on methane. Scientists have ruled out the presence of water ice, ammonia, ammonia hydrate and carbon dioxide in Ontario Lacus while observations also suggest the lake is evaporating as mentioned above. The lake is ringed by a dark beach. A black lake merges with the bright shoreline. Cassini observed a shelf and beach being exposed as the liquid in the lake evaporates.

NASA is extending the international Cassini-Huygens mission by two years. Originally scheduled to end in July of this year, planned projects are: twenty-six flybys of Titan, seven of Enceladus, one each of Dione, Helene, and Rhea, and further studies of Saturn’s rings, magnetosphere and planetary environment.

Saturn Moon Collage

This is really good news. It seems the spacecraft is operating well and is in good shape. There are three instruments that have ‘hiccups,’ not bad for having been launched ten years ago. There is still propellant available to carry out the maneuvers needed in the next two years. The discoveries and pictures just add to the mountain of questions and lists of items we would like to know more about.

Cassini has been providing data daily for the past four years. While operating costs are involved, chiefly in labor, all the equipment, a not insignificant cost, is working and paid for long ago. It actually saves money keep a mission going that yields scientific value. A second spacecraft can be delayed for some years that would entail much additional cost, a cost that can be avoided for a while by keeping Cassini “on the payroll.”. Plus Cassini is a proved success. This also helps ensure more focused and specific missions to Titan and Enceladus at some distant point in the future.

See NASA’s news release here: http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=833

Using radar measurements of the moon’s rotation, scientists believe the Cassini spacecraft has found evidence of an underground ocean on Titan, consisting of water and ammonia.

Titan cutaway

Artist’s impression of a cutaway view of Titan

Fifty unique landmarks on Titan were tracked over a period of 19 separate flybys by Cassini between October 2005 and May 2007. These prominent surface features were found to have shifted from their expected locations by up to 30 km (19 mi). If Titans’ icy crust is decoupled from its core by an internal ocean, then the shift makes sense. The ocean is believed to be 100 km (62 mi) below the crust of Titan.

A paper detailing these findings will be published March 21 in the journal Science.

Titan is of great interest because it has an organic-rich environment with the possibility of liquid water and an atmosphere 1.5 times denser than Earth’s. This may correlate to conditions on Earth which preceded the formation of living organisms.

Another flyby of Titan will occur on March 25 that will analyze Titan’s upper atmosphere and take pictures of the moon’s southeast quadrant.

Dione 031908 This image of Dione, released March 19, is the Saturn-facing side taken on February 8 at a distance of 211,000 km (131,000 mi) by the Cassini spacecraft.

Enormous canyons can be seen crossing from mid-latitude at right down to the moon’s south polar region. It looks like someone took a saw and started to make cuts into the surface of the moon.

Cassini is performing several flybys of the moons and rings of Saturn bringing in valuable data and wonderful pictures of these objects.

Dione is 1,126 km (700 mi) wide and was discovered in 1684. It is composed mainly of water ice with possibly some silicate rock at its core, making it the third densest moon of Saturn behind Enceladus and Titan.

Photo: NASA/JPL/Space Science Institute

Titan’s CloudsClouds on one of Saturn’s moons, Titan, have been photographed by the spacecraft Cassini at 60 degrees north latitude.

Titan is 3,193 miles across (5,150 km), which is larger than the planet Mercury by 5.5% and its pole is rotated twenty-six degrees to the right.

Titan is of great interest to scientists due to its thick atmosphere, the only moon known to have one, and for the presence of stable bodies of surface liquid. This twelfth most distant moon of Saturn is described as a satellite with planet-like characteristics. A circular 275 mile (440m) wide impact crater can be seen near the center of the above image.

The image was taken with the Cassini spacecraft narrow-angle camera on Jan. 20, 2008 using a combination of spectral filters sensitive to wavelengths of polarized infrared light centered at 938 and 746 nanometers. The view was acquired at a distance of approximately 1.3 million kilometers (800,000 miles) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 58 degrees.

The Cassini-Huygens mission is a joint project among NASA, the European Space Agency and the Italian Space Agency. The spacecraft consists of two main elements: the NASA Cassini orbiter, named after the Italian-French astronomer Giovanni Domenico Cassini, and the ESA Huygens probe, named after the Dutch astronomer, mathematician and physicist Christiaan Huygens.