Saturn, its rings and moons small to large in this Cassini image. Credit: NASA/JPL/Space Science Institute
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This latest offering from the Cassini spacecraft shows a wide-angle view of Saturn, its rings, and a sampling of the planet’s moons in varying sizes. Saturn’s largest moon, Titan, is in the center of the image, with the smaller moon Enceladus on the far right, while appearing just below the rings on the far left beyond the thin F ring is teeny-tiny Pandora. Oh, to have this view out your spacecraft window as you approach the ringed-world for a flyby!
How do the moons shown here vary in size? Titan is 5,150 kilometers, or 3,200 miles, across. Enceladus is 504 kilometers, or 313 miles across, while Pandora is 81 kilometers, or 50 miles across. This view looks toward anti-Saturn side of Titan and toward the northern, sunlit side of the rings from just above the ringplane.
The image was taken with the Cassini spacecraft wide-angle camera on Jan. 15, 2011, from a distance of about 844,000 kilometers (524,000 miles) from Titan. Image scale is 50 kilometers (31 miles) per pixel.
Saturn's moon Helene. Credit: NASA//JPL/SSI, image enhanced by Stu Atkinson
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The Cassini spacecraft recently had a mini ‘grand tour’ of several of Saturn’s moons and just sent back some great images of Helene, Mimas, Enceladus and Dione. Above is an amazing view of the Trojan moon Helene, which is only 32 kilometers (20 miles across) and shares an orbit with Dione. Cassini came withing 28,000 km (17,398 miles) of Helene. Thanks to Stu Atkinson for an enhanced version of this raw Cassini image. See one of the original raw images of Helene here.
This image of Saturn's moon Enceladus was obtained by NASA's Cassini spacecraft on Jan. 31, 2011. It shows the famous jets erupting from the south polar terrain of Enceladus. Image credit: NASA/JPL/SSI
Cassini captured several images of the plumes spewing from Enceladus, and other closeup views of the moon’s terrain.
Closeup of Enceladus from approximately 78,015 kilometers away. Credit: NASA/JPL/SSIThis view shows the bright, icy Mimas in front of Saturn's delicate rings. Image credit: NASA/JPL/SSI
A close look at Enceladus, with Saturn's rings in the background. Credit: NASA/JPL/Space Science Institute
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The Cassini spacecraft has taken a some recent images of two of Saturn’s most notorious moons, where in both images the planet’s rings serve as a backdrop. Above, Enceladus stands out with its cratered surface, but Cassini’s camera also catches a glimpse of the planet’s rings in the background. Geologically young terrain in the middle latitudes of the moon shifts to older, cratered terrain in the northern latitudes.
The image was taken during the spacecraft’s flyby of Enceladus on Nov. 30, 2010, in visible with Cassini’s spacecraft narrow-angle camera, from a distance of approximately 46,000 kilometers (29,000 miles) from Enceladus. Image scale is 276 meters (906 feet) per pixel.
Below is a ‘raw’ view of Titan, and the rings.
A closeup of Titan rings, in front of Saturn's rings. Credit: NASA/JPL/Space Science Institute.
This close-up view of Titan was taken on January 15, 2011, shows the cloudy atmosphere of the moon, with the rings in the background. Cassini was about 839,213 kilometers away from Titan.
Enceladus and Dione, as seen by Cassini. Credit: NASA/JPL/Space Science Institute
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We’ve all experienced the Moon Illusion, where our own full Moon looks bigger when seen on the Earth’s horizon. But how about this illusion where you can’t really tell which of these two moons of Saturn is actually bigger, or which is closer, as seen by the Cassini spacecraft? Here, Dione, top right, appears closer to the spacecraft because it is larger than the moon Enceladus, lower left. However, Enceladus was actually closer to Cassini when its visible light, narrow-angle camera took this image.
Dione (1,123 kilometers, or 698 miles, across) is more than twice the size of Enceladus (504 kilometers, or 313 miles, across). The two moons are contrasted with Enceladus’ bright, reflective trailing hemisphere, and Dione’s darker, micrometeor-dusted side, decorated with wispy lighter materials.
Cassini took this image on Dec. 1, 2010 from about 510,000 kilometers (317,000 miles) from Enceladus and approximately 830,000 kilometers (516,000 miles) from Dione. Image scale is 3 kilometers (2 miles) per pixel on Enceladus and 5 kilometers (3 miles) per pixel on Dione.
Enceladus and Dione line up for the Cassini camera. Credit: NASA/JPL/Space Science Institute
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Here are a few raw images from the Cassini spacecraft’s most recent flyby of Enceladus. The probe seems to be in good health following several weeks in safe mode, after a bit flipped in the command and data subsystem computer. This prevented the spacecraft from registering and following instructions. But she appears to be humming along just fine now, and snapped this great picture of Enceladus and Dione yesterday (have to quote @lukedones on Twitter: “Dione going in the corner pocket!”) Cassini focused on the Enceladus during a close flyby on November 30, so see more below, including a wonderful shot of a veritable curtain of geyser “spray.”
A good look at the spray from the fissures on Enceladus. NASA/JPL/Space Science Institute Enceladus, backdropped by Saturn's rings. Credit: NASA/JPL/ Space Science Institute. Closeup of Enceladus. Credit: NASA/JPL/Space Science Institute. An even closer closeup of Enceladus. Credit: NASA/JPL/Space Science Institute.
Small water ice particles fly from fissures in the south polar region of Saturn's moon Enceladus in this image taken during the Aug. 13, 2010, flyby of the moon by NASA's Cassini spacecraft. Image credit: NASA/JPL/SSI
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As Cassini scientists await the data from today’s flyby of Enceladus, images and data from August of this year have provided more insight into the active fissures on the icy moon’s south polar region. These geyser-spewing fractures are warmer and more complicated than previously thought.
“The exquisite resolution obtained on one segment of the Damascus fracture — one of the most active regions within the south polar terrain — has revealed a surface temperature reaching a staggering 190 Kelvin, or 120 degrees below zero Fahrenheit,” said Cassini imaging team lead Carolyn Porco, in an email announcing the new images. “Far from the fractures, the temperature of the south polar terrain dips as low as 52 Kelvin, or 365 degrees below zero Fahrenheit.”
Porco said that what this means is that a phenomenal amount of heat is emerging from the fractures which are “undoubtedly the result of the tidal flexing of Enceladus brought about by its orbital resonance with Dione. However, details of this heating process are still unclear and are being studied at this very moment.”
This image shows a high-resolution heat intensity map of part of the south polar region of Saturn's moon Enceladus, made from data obtained by NASA's Cassini spacecraft. Image credit: NASA/JPL/GSFC/SWRI/SSI
The flyby on August 13, 2010 provided infrared spectroscopy along with high resolution images which have enabled scientists to construct the highest-resolution heat intensity maps yet of the hottest part of a region of long fissures spraying water vapor and icy particles from Enceladus. These fissures — known as “tiger stripes,” appear to be laid on in a complex web, and could be connected underground.
Additional high-resolution spectrometer maps of one end of the tiger stripes Alexandria Sulcus and Cairo Sulcus reveal never-before-seen warm fractures that branch off like split ends from the main tiger stripe trenches. They also show an intriguing warm spot isolated from other active surface fissures.
“The ends of the tiger stripes may be the places where the activity is just getting started, or is winding down, so the complex patterns of heat we see there may give us clues to the life cycle of tiger stripes,” said John Spencer, a Cassini team scientist based at Southwest Research Institute in Boulder, Colo.
The temperature measured in this flyby appears slightly higher than previously measured temperatures at Damascus, which were around 170 Kelvin (minus 150 degrees Fahrenheit).
Spencer said he isn’t sure if this tiger stripe is just more active than it was the last time Cassini’s spectrometer scanned it, in 2008, or if the hottest part of the tiger stripe is so narrow that previous scans averaged its temperature out over a larger area. In any case, the new scan had such good resolution, showing details as small as 800 meters (2,600 feet), that scientists could see for the first time warm material flanking the central trench of Damascus, cooling off quickly away from the trench. The Damascus thermal scan also shows large variations in heat output within a few kilometers along the length of the fracture. This unprecedented resolution will help scientists understand how the tiger stripes deliver heat to the surface of Enceladus.
Cassini acquired the thermal map of Damascus simultaneously with a visible-light image where the tiger stripe is lit by sunlight reflecting off Saturn. The visible-light and thermal data were merged to help scientists understand the relationships between physical heat processes and surface geology.
“Our high-resolution images show that this section of Damascus Sulcus is among the most structurally complex and tectonically dynamic of the tiger stripes,” said imaging science team associate Paul Helfenstein of Cornell University, Ithaca, N.Y. Some details in the appearance of the landforms, such as a peculiar pattern of curving striations along the flanks of Damascus, had not previously been noticed in ordinary sunlit images.
ets of water ice particles spew from Saturn's moon Enceladus in this image obtained by NASA's Cassini spacecraft on Aug. 13, 2010. Image credit: NASA/JPL/SSI
The Aug. 13 flyby of Enceladus is the last one dedicated to thermal mapping until 2015 and also gave Cassini its last look at any part of the active south polar region in sunlight.
The flyby today will aid in understanding the interior of the moon through gravity measurements.
NASA’s Cassini Spacecraft is doing some awesome stuff. Stay tuned to NASA’s twitter feed Space Cadets, today should be interesting. I’m Benjamin Higginbotham and this is your SpacePod for November 30th, 2010. Continue reading “Cassini visits Enceladus – SpacePod 2010.11.30”
At least four distinct plumes of water ice spew out from the south polar region of Saturn's moon Enceladus. Credit: NASA/JPL/Space Science Institute
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What is going on inside Saturn’s moon Enceladus and what powers the icy geysers and jets? A pair of upcoming flybys by the Cassini spacecraft could help answer those questions. Radio instruments on board will measure the gravity field of Enceladus and focus particularly on the very intriguing south polar hot spot.
Of course, the success of these flybys hinges on the Cassini mission controllers being able to wake up the dormant spacecraft which has been in safe mode since November 2. Teams will attempt to get Cassini up and running again tomorrow, November 24, and they don’t anticipate any problems.
Cassini went into the protective standby mode and the likely cause of the problem was a faulty program code line, or a flipped bit in the spacecraft’s command and data system computer.
The upcoming flybys of Enceladus will put Cassini very close – about 48 kilometers (30 miles) above the surface. The first will take place on November 30. Pairing this flyby with one on April 28, should provide scientists enough information to determine the nature of the interior right under the hot spot. The next flyby on December 21, Cassini will make 50-kilometer pass over the north pole of Enceladus. The fields and particles instruments will be trying to “sniff” anything coming from the moon.
There will be two three-hour “wing” observations before and after closest-approach (from five to eight hours from closest approach on either side), and then three more hours centered directly around closest approach. The Cassini team is throwing almost the entire gamut of instruments into the flyby program, between radio science (RSS) observations, the imaging science system (ISS) and composite infrared spectrometer (CIRS) which will observe this moon on the inbound leg, and CIRS and the visible and infrared mapping spectrometer (VIMS) which will take data on the outbound leg, with other optical remote sensing and fields, particles and waves instruments also taking data.
An artist illustration of the Cassini spacecraft. Credit: NASA/JPL
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NASA announced that the Cassini spacecraft in orbit around Saturn will have its suite of scientific cameras offline until at least Nov. 24. Cassini is currently in safe mode due to a malfunction in the spacecraft’s computer. This shut down all non-essential systems to prevent any further damage happening to the spacecraft. This means that all scientific efforts on the mission have been suspended until the problem can be resolved.
Although these seem like severe issues, mission managers are relatively sure that they will have no serious long-term effects on the overall mission. Cassini entered safe mode around 4 p.m. PDT (7 p.m. EDT) on Tuesday, Nov. 2. Managers want to review what took place onboard Cassini, correct what they can and ensure that this doesn’t happen again. Programmers have already ascertained that the likely cause of the problem was a faulty program code line that made its way back to Cassini.
Cassini captured this startling image of Saturn's moon Hyperion. Photo Credit: NASA/JPL
Ordinarily when faulty code is sent from Earth to Saturn, Cassini would reject any coding that is deemed ‘bad.’ However, this did not happen in this case, causing the problem. Controllers are not totally convinced that a solar fare didn’t corrupt the code on its way out to the gas giant.
“The spacecraft responded exactly as it should have, and I fully expect that we will get Cassini back up and running with no problems,” said Bob Mitchell, Cassini’s program manager at JPL. “Over the more than six years we have been at Saturn, this is only the second safing event. So considering the complexity of demands we have made on Cassini, the spacecraft has performed exceptionally well for us.”
Cassini launched from Cape Canaveral Air Force Station back in 1997 atop a Titan rocket. In the thirteen years since that time it has entered ‘safe’ mode a total of six times.
Cassini discovered that Saturn's moon Enceladus is 'jet-powered' in the form of geysers erupting from the moon's surface into space. Photo Credit: NASA/JPL
The largest loss for Cassini’s planners is this will cost them a flyby of Titan, one of Saturn’s moons and the only moon in the solar system with an appreciable atmosphere. All is not lost however, as there are still some 53 possible flybys of the moon currently scheduled. The mission is currently planned to last until 2017.
The Cassini-Huygens mission is a cooperative program managed between NASA, the European Space Agency (ESA) and the Italian Space Agency. JPL, a division of the California Institute of Technology (Caltech) manages the Cassini program for NASA’s Science Mission Directorate located in Washington, D.C.
