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Warm Fractures on Enceladus
Description Warm Fractures on Enceladus
Full Description This image shows the warmest places in the south polar region of Saturn's moon Enceladus. The unexpected temperatures were discovered by Cassini's composite infrared spectrometer during a close flyby on July 14, 2005. The image shows how these temperatures correspond to the prominent, bluish fractures dubbed "tiger stripes," first imaged by Cassini's imaging science subsystem cameras. Working together the two teams were able to pinpoint the exact location of the warmest regions on Enceladus. The composite infrared spectrometer instrument measured the infrared heat radiation from the surface at wavelengths between 9 and 16.5 microns within each of the 10 squares shown here. Each square is 6 kilometers (4 miles) across. The color of each square, and the number shown above it, describe the composite infrared spectrometer's measurement of the approximate average temperature of the surface within that square. The warmest temperature squares, at 91 and 89 degrees Kelvin (minus 296 and minus 299 degrees Fahrenheit), are located over one of the "tiger stripe" fractures. They contrast sharply with the surrounding temperatures, which are in the range 74 to 81 degrees Kelvin (minus 326 to minus 313 degrees Fahrenheit). The detailed composite infrared spectrometer data suggest that small areas near the fracture are at substantially higher temperatures, well over 100 degrees Kelvin (minus 279 degrees Fahrenheit). Such "warm" temperatures are unlikely to be due to heating of the surface by the feeble sunlight striking Enceladus' south pole. They are a strong indication that internal heat is leaking out of Enceladus and warming the surface along these fractures. Evaporation of this relatively warm ice probably generates the cloud of water vapor detected above Enceladus' south pole by several other Cassini instruments. Scientists are unsure how the internal heat reaches the surface. The process might involve liquid water, slushy brine, or soft but solid ice. The imaging science subsystem image is an enhanced color view with a pixel scale of 122 meters (400 feet) that was acquired at the same time as the composite infrared spectrometer data. It covers a region 125 kilometers (75 miles) across. The spacecraft's distance from Enceladus was 21,000 kilometers (13,000 miles). The broad bluer fractures that can be seen running from the upper left to the lower right of the image are 1 to 2 kilometers (0.6 to 1.2 miles) wide and more than 100 kilometers (60 miles) long. The fractures are thought to be bluer than the surrounding surface because coarser-grained ice (which has a blue color just as thick masses of ice, like glaciers and icebergs, do on Earth) has been exposed in the fractures. The color image was constructed using an ultraviolet filter (centered at 338 nanometers) in the blue channel, a clear filter in the green channel, and an infrared filter (centered at 930 nanometers) in the red channel. 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 composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. The imaging operations center is based at the Space Science Institute in Boulder, Colo. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The composite infrared spectrometer team homepage is http://cirs.gsfc.nasa.gov/ . The imaging team homepage is at http://ciclops.org . Credit: NASA/JPL/GSFC/Space Science Institute
Date July 29, 2005
Enceladus Temperature Map
Description Enceladus Temperature Map
Full Description This image shows the surprise that startled Cassini scientists on the composite infrared spectrometer team when they got their first look at the infrared (heat) radiation from the south pole of Saturn's moon Enceladus. There is a dramatic warm spot centered on the pole that is probably a sign of internal heat leaking out of the icy moon. The data were taken during the spacecraft's third flyby of this intriguing moon on July 14, 2005. Based on data from previous flybys, which did not show the south pole well, team members expected that the south pole would be very cold, as shown in the left panel. Enceladus is one of the coldest places in the Saturn system because its extremely bright surface reflects 80 percent of the sunlight that hits it, so only 20 percent is available to heat the surface. As on Earth, the poles should be even colder than the equator because the sun shines at such an oblique angle there. The right hand panel shows a global temperature image made from measurements of Enceladus' heat radiation at wavelengths between 9 and 16.5 microns. Cassini made the observation from a distance of 84,000 kilometers (52,000 miles) on the approach to Enceladus, and the image shows details as small as 25 kilometers (16 miles). Equatorial temperatures are much as expected, topping out at about 80 degrees Kelvin (-315 degrees Fahrenheit), but the south pole is occupied by a well-defined warm region reaching 85 Kelvin (-305 degrees Fahrenheit). That is 15 degrees Kelvin (27 degrees Fahrenheit) warmer than expected. The composite infrared spectrometer data further suggest that small areas of the pole are at even higher temperatures, well over 110 degrees Kelvin (-261 degrees Fahrenheit). Evaporation of this relatively warm ice probably generates the cloud of water vapor detected above Enceladus' south pole by several other Cassini instruments. The south polar temperatures are very difficult to explain if sunlight is the only energy source heating the surface, though exotic sunlight-trapping mechanisms have not yet been completely ruled out. It therefore seems likely that portions of the polar region are warmed by heat escaping from the interior of the moon. This would make Enceladus only the third solid body in the solar system, after Earth and Jupiter's volcanic moon Io, where hot spots powered by internal heat have been detected. 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 composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The composite infrared spectrometer team homepage is, http://cirs.gsfc.nasa.gov/ . Credit: NASA/JPL/GSFC
Date July 29, 2005
Home Reef Reborn
title Home Reef Reborn
description In the South Pacific, south of Late Island along the Tofua volcanic arc in Tonga, the volcanic island Home Reef is being re-born. The island is thought to have emerged after a volcanic eruption in mid-August that also spewed large amounts of floating pumice into Tongan waters and swept across to Fiji about 350 km (220 miles) to the west of where the new island formed. In 2004, a similar eruption created an ephemeral island about 0.5 by 1.5 km (0.3 by 0.9 miles) in size, it was no longer visible in an ASTER image acquired November 2005. This simulated natural color image shows the vegetation-covered stratovolcanic island of Late Island in the upper right. Home Reef is found in the lower left. The two bluish plumes are hot seawater that is laden with volcanic ash and chemicals, the larger one can be traced for more than 14 km (8.4 miles) to the east. The image was acquired Oct. 10, 2006 and covers an area of 24.3 by 30.2 km. It is located at 18.9 degrees south latitude, 174.7 degrees west longitude. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitors the changing surface of our planet. It is one of five Earth-observing instruments launched Dec. 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Image credit: NASA/GSFC/METI/ERSDAC/JAROS and U.S./Japan ASTER Science Team
NASA Space Observatories Gli …
Title NASA Space Observatories Glimpse Faint Afterglow of Nearby Stellar Explosion
General Information What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. Back to top [ #top ]
NASA's Hubble Looks for Poss …
Title NASA's Hubble Looks for Possible Moon Resources
Hubble Finds that Earth is S …
Title Hubble Finds that Earth is Safe from One Class of Gamma-ray Burst
Hubble Finds that Earth is S …
Title Hubble Finds that Earth is Safe from One Class of Gamma-ray Burst
Hubble Finds that Earth is S …
Title Hubble Finds that Earth is Safe from One Class of Gamma-ray Burst
Hubble Finds that Earth is S …
Title Hubble Finds that Earth is Safe from One Class of Gamma-ray Burst
Hubble Finds that Earth is S …
Title Hubble Finds that Earth is Safe from One Class of Gamma-ray Burst
Hubble Finds that Earth is S …
Title Hubble Finds that Earth is Safe from One Class of Gamma-ray Burst
Hubble Finds that Earth is S …
Title Hubble Finds that Earth is Safe from One Class of Gamma-ray Burst
Hubble Finds that Earth is S …
Title Hubble Finds that Earth is Safe from One Class of Gamma-ray Burst
The Carina Nebula: Star Birt …
Title The Carina Nebula: Star Birth in the Extreme
General Information What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. In celebration of the 17th anniversary of the launch and deployment of NASA's Hubble Space Telescope, a team of astronomers is releasing one of the largest panoramic images ever taken with Hubble's cameras. READ: Junior version of this article Amazing Space Learn about this story in the Star Witness, a science newspaper available on our sister site, Amazing Space. [ http://amazing-space.stsci.edu/news/archive/2007/02/ ] It is a 50-light-year-wide view of the central region of the Carina Nebula where a maelstrom of star birth &#151, and death &#151, is taking place. This image is a mosaic of the Carina Nebula assembled from 48 frames taken with Hubble's Advanced Camera for Surveys. The Hubble images were taken in the light of neutral hydrogen during March and July 2005. Color information was added with data taken in December 2001 and March 2003 at the Cerro Tololo Inter-American Observatory in Chile. Red corresponds to sulfur, green to hydrogen, and blue to oxygen emission.
The Carina Nebula: Star Birt …
Title The Carina Nebula: Star Birth in the Extreme
General Information What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. In celebration of the 17th anniversary of the launch and deployment of NASA's Hubble Space Telescope, a team of astronomers is releasing one of the largest panoramic images ever taken with Hubble's cameras. READ: Junior version of this article Amazing Space Learn about this story in the Star Witness, a science newspaper available on our sister site, Amazing Space. [ http://amazing-space.stsci.edu/news/archive/2007/02/ ] It is a 50-light-year-wide view of the central region of the Carina Nebula where a maelstrom of star birth &#151, and death &#151, is taking place. This image is a mosaic of the Carina Nebula assembled from 48 frames taken with Hubble's Advanced Camera for Surveys. The Hubble images were taken in the light of neutral hydrogen during March and July 2005. Color information was added with data taken in December 2001 and March 2003 at the Cerro Tololo Inter-American Observatory in Chile. Red corresponds to sulfur, green to hydrogen, and blue to oxygen emission.
The Carina Nebula: Star Birt …
Title The Carina Nebula: Star Birth in the Extreme
General Information What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. In celebration of the 17th anniversary of the launch and deployment of NASA's Hubble Space Telescope, a team of astronomers is releasing one of the largest panoramic images ever taken with Hubble's cameras. READ: Junior version of this article Amazing Space Learn about this story in the Star Witness, a science newspaper available on our sister site, Amazing Space. [ http://amazing-space.stsci.edu/news/archive/2007/02/ ] It is a 50-light-year-wide view of the central region of the Carina Nebula where a maelstrom of star birth &#151, and death &#151, is taking place. This image is a mosaic of the Carina Nebula assembled from 48 frames taken with Hubble's Advanced Camera for Surveys. The Hubble images were taken in the light of neutral hydrogen during March and July 2005. Color information was added with data taken in December 2001 and March 2003 at the Cerro Tololo Inter-American Observatory in Chile. Red corresponds to sulfur, green to hydrogen, and blue to oxygen emission.
The Carina Nebula: Star Birt …
Title The Carina Nebula: Star Birth in the Extreme
General Information What is Hubble Heritage? A monthly showcase of new and archival Hubble images. Go to the Heritage site. In celebration of the 17th anniversary of the launch and deployment of NASA's Hubble Space Telescope, a team of astronomers is releasing one of the largest panoramic images ever taken with Hubble's cameras. READ: Junior version of this article Amazing Space Learn about this story in the Star Witness, a science newspaper available on our sister site, Amazing Space. [ http://amazing-space.stsci.edu/news/archive/2007/02/ ] It is a 50-light-year-wide view of the central region of the Carina Nebula where a maelstrom of star birth &#151, and death &#151, is taking place. This image is a mosaic of the Carina Nebula assembled from 48 frames taken with Hubble's Advanced Camera for Surveys. The Hubble images were taken in the light of neutral hydrogen during March and July 2005. Color information was added with data taken in December 2001 and March 2003 at the Cerro Tololo Inter-American Observatory in Chile. Red corresponds to sulfur, green to hydrogen, and blue to oxygen emission.
Elusive Planet Reshapes a Ri …
Title Elusive Planet Reshapes a Ring Around Neighboring Star
Hubble Finds Mysterious Disk …
Title Hubble Finds Mysterious Disk of Blue Stars Around Black Hole
Hubble Finds that Earth is S …
Title Hubble Finds that Earth is Safe from One Class of Gamma-ray Burst
Hubble Finds that Earth is S …
Title Hubble Finds that Earth is Safe from One Class of Gamma-ray Burst
Sequence of Clouds, Snow Cov …
Title Sequence of Clouds, Snow Cover, Sea Ice, Sea Surface Temperature and Biosphere
Abstract This animation is part of an NSF-funded, international project, Exploring Time. The two-hour television special, broadcast on the Discovery Channel in the spring of 2007, explores how the world changes over different timescales ... from billionths of seconds to billions of years. This animation portrays a variety of remotely sensed data elements at different temporal resolutions. Initially, the animation shows cloud cover in motion over North America in half-hour increments from Nov. 26 to Dec. 7, 2005. The temporal pace quickens to show a 5-day moving average of daily MODIS snow cover along with daily AMSR-E sea ice from Dec. 7, 2005 to Mar. 15, 2006. As the view swings south over the Gulf of Mexico, the AMSR-E Sea Surface Temperature reveals warming ocean temperatures from March through August, 2006. As it passes over the Atlantic Ocean, the biosphere fades into view, showing both chlorophyll concentration in the ocean along with Normalized Difference Vegetation Index over the land areas. The biosphere animates over time while the view pans over northern Africa and Europe, showing data collected from September 2002 through February 2006. This program was also broadcast in Japan through a partnership with the NHK international broadcasting service and in France through a partnership with the ARTE television network.
Completed 2006-11-29
Sequence of Clouds, Snow Cov …
Title Sequence of Clouds, Snow Cover, Sea Ice, Sea Surface Temperature and Biosphere
Abstract This animation is part of an NSF-funded, international project, Exploring Time. The two-hour television special, broadcast on the Discovery Channel in the spring of 2007, explores how the world changes over different timescales ... from billionths of seconds to billions of years. This animation portrays a variety of remotely sensed data elements at different temporal resolutions. Initially, the animation shows cloud cover in motion over North America in half-hour increments from Nov. 26 to Dec. 7, 2005. The temporal pace quickens to show a 5-day moving average of daily MODIS snow cover along with daily AMSR-E sea ice from Dec. 7, 2005 to Mar. 15, 2006. As the view swings south over the Gulf of Mexico, the AMSR-E Sea Surface Temperature reveals warming ocean temperatures from March through August, 2006. As it passes over the Atlantic Ocean, the biosphere fades into view, showing both chlorophyll concentration in the ocean along with Normalized Difference Vegetation Index over the land areas. The biosphere animates over time while the view pans over northern Africa and Europe, showing data collected from September 2002 through February 2006. This program was also broadcast in Japan through a partnership with the NHK international broadcasting service and in France through a partnership with the ARTE television network.
Completed 2006-11-29
Hurricane Paul
Title Hurricane Paul
Description As October drew to a close, Hurricane Paul was approaching the southern tip of Mexico's Baja Peninsula. The sixteenth named Pacific storm of the 2006 season, Paul was whipping up sustained winds of 165 kilometers per hour (105 miles per hour) at the time of the National Hurricane Center's 11:00 a.m. Pacific Daylight Time briefing on October 23. The storm track and intensity forecasts for Paul were still uncertain at that time, but landfall along the southern tip of Baja Peninsula as a strong storm was still a possibility. In this image from the Moderate Resolution Imaging Spectroradiometer (MODIS) [ http://modis.gsfc.nasa.gov ] on NASA's Terra satellite on October 22, 2006, the eye of Hurricane Paul was several hundreds kilometers southwest of Baja. A bright disk of clouds spirals counter-clockwise into a cloudy eye at the heart of the storm. In places, this smooth-seeming cloud deck is rippled by puffy cloud tops—a sign of thunderstorms lofting heat and moisture high into the atmosphere. The southern tip of Baja Peninsula appears along the top edge of the image. In 2005, the record-breaking Atlantic hurricane season was the focus of attention, with the number of named storms exhausting the letters of the alphabet. But as of late October 2006, the hurricane activity in the eastern Pacific Ocean was outpacing the Atlantic: 16 named storms (9 of them hurricanes) versus 9 named storms (5 of them hurricanes). On average, the eastern Pacific Ocean experiences more tropical storms and hurricanes than the Atlantic Basin, 16.4 compared to 10.1. Powerful hurricanes in the eastern Pacific rarely make landfall in the western United States. Persistent easterly winds not only tend to steer storms away from the coast, but they also "shove" the ocean's surface water westward, away from the coast, allowing cool water to well up to replace it. The cool water weakens any storms that do approach the coast. NASA image created by Jesse Allen, Earth Observatory, using data provided courtesy of the MODIS Rapid Response [ http://rapidfire.sci.gsfc.nasa.gov/ ] team.
Flooding in Columbia and Ven …
Title Flooding in Columbia and Venezeula
Description Though water levels have subsided since mid-February, the Escalante River of southwestern Venezuela and northeastern Colombia was still flooded on February 26, 2005. The floods along this river and others were triggered by days of heavy rain early in February, and resulted in nearly 100 deaths and left thousands homeless throughout both countries. In this image, taken by the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Terra [ http://terra.nasa.gov/ ] satellite, the muddy flood water is light blue. The river covers a broader area than it did on January 27, 2005. In both images, clouds are white and turquoise, plant-covered land is bright green, and deep, clear water is black. Further evidence of flooding can be seen in Lake Maracaibo in the center of the image. Flood water carries dirt into the rivers that empty into the lake. The sediment entering the lake reflects light, which makes the water appear a lighter shade of blue in satellite imagery. While sediment is present in the southwest corner of the lake on January 27, the sediment plume is much brighter and larger on February 26. On both dates, green swirls of duck weed [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=12404 ] float on the surface of the lake. NASA image created by Jesse Allen, Earth Observatory, using data obtained from the MODIS Rapid Response team and the Goddard Land Processes DAAC.
Flooding in Columbia and Ven …
Title Flooding in Columbia and Venezeula
Description Though water levels have subsided since mid-February, the Escalante River of southwestern Venezuela and northeastern Colombia was still flooded on February 26, 2005. The floods along this river and others were triggered by days of heavy rain early in February, and resulted in nearly 100 deaths and left thousands homeless throughout both countries. In this image, taken by the Moderate Resolution Imaging Spectroradiometer (MODIS [ http://modis.gsfc.nasa.gov ]) on NASA's Terra [ http://terra.nasa.gov/ ] satellite, the muddy flood water is light blue. The river covers a broader area than it did on January 27, 2005. In both images, clouds are white and turquoise, plant-covered land is bright green, and deep, clear water is black. Further evidence of flooding can be seen in Lake Maracaibo in the center of the image. Flood water carries dirt into the rivers that empty into the lake. The sediment entering the lake reflects light, which makes the water appear a lighter shade of blue in satellite imagery. While sediment is present in the southwest corner of the lake on January 27, the sediment plume is much brighter and larger on February 26. On both dates, green swirls of duck weed [ http://earthobservatory.nasa.gov/NaturalHazards/natural_hazards_v2.php3?img_id=12404 ] float on the surface of the lake. NASA image created by Jesse Allen, Earth Observatory, using data obtained from the MODIS Rapid Response team and the Goddard Land Processes DAAC.
Tyrrhenian Sea and Solstice …
Title Tyrrhenian Sea and Solstice Sky
Explanation Today the Solstice [ http://aa.usno.navy.mil/data/docs/ EarthSeasons.php ] occurs at 0608 Universal Time [ http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/ TimeZone.html ], the Sun reaching its southernmost declination in planet Earth's sky [ http://www.astro.uiuc.edu/~kaler/celsph.html ]. Of course, the December [ http://aa.usno.navy.mil/faq/docs/dark_days ] Solstice marks the beginning of [ http://www.phy6.org/stargaze/Sseason.htm ] winter in the northern hemisphere and summer in the south. When viewed from northern latitudes, the Sun will make its lowest arc through the sky along the southern horizon. So in the north, the Solstice day has the shortest length of time between sunrise and sunset and fewest hours of daylight. This striking composite [ http://www.danilopivato.com/miscellany/sequences_and_sunsets/ winter_solstice.htm ] image follows the Sun's path through the December Solstice day of 2005 in a beautiful blue sky, looking down the Tyrrhenian Sea [ http://en.wikipedia.org/wiki/Tyrrhenian_Sea ] coast from Santa Severa toward Fiumicino, Italy. The view covers about 115 degrees in 43 separate, well-planned exposures from sunrise to sunset.
G21.5-0.9: A Supernova's Cos …
Title G21.5-0.9: A Supernova's Cosmic Shell
Explanation The picture is lovely, but this pretty cosmic shell [ http://chandra.harvard.edu/photo/2005/g21/ ] was produced by almost unbelievable violence - created when a star with nearly 20 times the mass of the sun blasted away its outer layers in a spectacular supernova explosion [ http://chandra.harvard.edu/photo/2005/g21/ animations.html ]. As the expanding debris cloud swept through surrounding interstellar material, shock waves heated the gas causing the supernova remnant to glow in x-rays [ http://heasarc.gsfc.nasa.gov/docs/xte/ learning_center/ASM/welcome.html ]. In fact, it is possible that all supernova explosions create similar shells [ http://arxiv.org/abs/astro-ph/0504369 ], some brighter than others. Cataloged as G21.5-0.9, this shell supernova remnant [ http://myuminfo.umanitoba.ca/ index.asp?sec=2&too=100&eve=8&dat=4/19/2005&npa=8264 ] is relatively faint, requiring about 150 hours of x-ray data from the orbiting Chandra Observatory [ http://chandra.harvard.edu/chronicle/index.html ] to create this false-color image. G21.5-0.9 is about 20,000 light-years distant in the constellation Scutum [ http://hawastsoc.org/deepsky/sct/index.html ] and measures about 30 light-years across. Based on the remnant's size, astronomers estimate that light from the original stellar explosion first reached [ http://chandra.harvard.edu/photo/cosmic_lookback.html ] Earth several thousand years ago.
Warm Fractures on Enceladus
PIA06433
Saturn
Composite Infrared Spectrome …
Title Warm Fractures on Enceladus
Original Caption Released with Image 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 composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. The imaging operations center is based at the Space Science Institute in Boulder, Colo. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov [ http://saturn.jpl.nasa.gov ]. The composite infrared spectrometer team homepage is http://cirs.gsfc.nasa.gov/ [ http://cirs.gsfc.nasa.gov/ ]. The imaging team homepage is at http://ciclops.org [ http://ciclops.org ], This image shows the warmest places in the south polar region of Saturn's moon Enceladus. The unexpected temperatures were discovered by Cassini's composite infrared spectrometer during a close flyby on July 14, 2005. The image shows how these temperatures correspond to the prominent, bluish fractures dubbed "tiger stripes," first imaged by Cassini's imaging science subsystem cameras. Working together the two teams were able to pinpoint the exact location of the warmest regions on Enceladus. The composite infrared spectrometer instrument measured the infrared heat radiation from the surface at wavelengths between 9 and 16.5 microns within each of the 10 squares shown here. Each square is 6 kilometers (4 miles) across. The color of each square, and the number shown above it, describe the composite infrared spectrometer's measurement of the approximate average temperature of the surface within that square. The warmest temperature squares, at 91 and 89 degrees Kelvin (minus 296 and minus 299 degrees Fahrenheit), are located over one of the "tiger stripe" fractures. They contrast sharply with the surrounding temperatures, which are in the range 74 to 81 degrees Kelvin (minus 326 to minus 313 degrees Fahrenheit). The detailed composite infrared spectrometer data suggest that small areas near the fracture are at substantially higher temperatures, well over 100 degrees Kelvin (minus 279 degrees Fahrenheit). Such "warm" temperatures are unlikely to be due to heating of the surface by the feeble sunlight striking Enceladus' south pole. They are a strong indication that internal heat is leaking out of Enceladus and warming the surface along these fractures. Evaporation of this relatively warm ice probably generates the cloud of water vapor detected above Enceladus' south pole by several other Cassini instruments. Scientists are unsure how the internal heat reaches the surface. The process might involve liquid water, slushy brine, or soft but solid ice. The imaging science subsystem image is an enhanced color view with a pixel scale of 122 meters (400 feet) that was acquired at the same time as the composite infrared spectrometer data. It covers a region 125 kilometers (75 miles) across. The spacecraft's distance from Enceladus was 21,000 kilometers (13,000 miles). The broad bluer fractures that can be seen running from the upper left to the lower right of the image are 1 to 2 kilometers (0.6 to 1.2 miles) wide and more than 100 kilometers (60 miles) long. The fractures are thought to be bluer than the surrounding surface because coarser-grained ice (which has a blue color just as thick masses of ice, like glaciers and icebergs, do on Earth) has been exposed in the fractures. The color image was constructed using an ultraviolet filter (centered at 338 nanometers) in the blue channel, a clear filter in the green channel, and an infrared filter (centered at 930 nanometers) in the red channel. The Cassini-Huygens mission is a cooperative project of
Enceladus Temperature Map
PIA06432
Saturn
Composite Infrared Spectrome …
Title Enceladus Temperature Map
Original Caption Released with Image . The composite infrared spectrometer team homepage is http://cirs.gsfc.nasa.gov/ [ http://cirs.gsfc.nasa.gov/ ]., This image shows the surprise that startled Cassini scientists on the composite infrared spectrometer team when they got their first look at the infrared (heat) radiation from the south pole of Saturn's moon Enceladus. There is a dramatic warm spot centered on the pole that is probably a sign of internal heat leaking out of the icy moon. The data were taken during the spacecraft's third flyby of this intriguing moon on July 14, 2005. Based on data from previous flybys, which did not show the south pole well, team members expected that the south pole would be very cold, as shown in the left panel. Enceladus is one of the coldest places in the Saturn system because its extremely bright surface reflects 80 percent of the sunlight that hits it, so only 20 percent is available to heat the surface. As on Earth, the poles should be even colder than the equator because the sun shines at such an oblique angle there. The right hand panel shows a global temperature image made from measurements of Enceladus' heat radiation at wavelengths between 9 and 16.5 microns. Cassini made the observation from a distance of 84,000 kilometers (52,000 miles) on the approach to Enceladus, and the image shows details as small as 25 kilometers (16 miles). Equatorial temperatures are much as expected, topping out at about 80 degrees Kelvin (-315 degrees Fahrenheit), but the south pole is occupied by a well-defined warm region reaching 85 Kelvin (-305 degrees Fahrenheit). That is 15 degrees Kelvin (27 degrees Fahrenheit) warmer than expected. The composite infrared spectrometer data further suggest that small areas of the pole are at even higher temperatures, well over 110 degrees Kelvin (-261 degrees Fahrenheit). Evaporation of this relatively warm ice probably generates the cloud of water vapor detected above Enceladus' south pole by several other Cassini instruments. The south polar temperatures are very difficult to explain if sunlight is the only energy source heating the surface, though exotic sunlight-trapping mechanisms have not yet been completely ruled out. It therefore seems likely that portions of the polar region are warmed by heat escaping from the interior of the moon. This would make Enceladus only the third solid body in the solar system, after Earth and Jupiter's volcanic moon Io, where hot spots powered by internal heat have been detected. 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 composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md. For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov [ http://saturn.jpl.nasa.gov ]
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