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Propeller Motion
Description Propeller Motion
Full Description This magnified view illustrates the general orientation of the "propeller" features in Saturn's rings as they orbit the planet. The propellers are features detected in Cassini images that reveal the gravitational influence of moonlets approximately 100 meters (300 feet) in diameter. The view is from one of the two Saturn orbit insertion images, taken on July 1, 2004, in which the propellers were discovered. The two dashes of the propeller are oriented in the direction of orbital motion. The "leading" dash is also slightly closer to Saturn, this "radial offset" is about 300 meters (1000 feet). The unseen moonlet lies in the center of the structure. The grainy appearance of the image is due to magnification and the fact that the propellers are very faint--just visible above the level of background noise. Consequently, the image enhancement procedures used have also enhanced the noise. This propeller image is identified as "feature 1" in Four Propellers. The original Cassini spacecraft narrow-angle camera image has been magnified from its original scale for presentation. 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 and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo. 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 and its two onboard cameras were designed, developed and assembled at JPL. 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 Cassini imaging team homepage is at http://ciclops.org . Credit: NASA/JPL/Space Science Institute
Date March 29, 2006
Four Propellers
Description Four Propellers
Full Description These figures show four propeller-shaped structures discovered by the Cassini spacecraft in close-up images of Saturn's A ring. The propellers are about 5 kilometers (3 miles) long from tip to tip, and the radial offset (the "leading" dash is slightly closer to Saturn) is about 300 meters (1,000 feet). See Propeller Motion and Locating the Propellers for additional images and information about these features. The figures were cropped from two original Cassini spacecraft narrow-angle camera images and magnified for visibility. The images were then re-projected so that orbital motion is to the left and Saturn is up. The unseen moonlets lie in the center of each structure. The figures were cropped from two original Cassini spacecraft narrow-angle camera images, taken during Saturn orbit insertion on July 1, 2004, and magnified for visibility. 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 and its two onboard cameras were designed, developed and assembled at JPL. 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 Cassini imaging team homepage is at http://ciclops.org . *Credit:* NASA /JPL/Space Science Institute
Date March 29, 2006
Locating the Propellers
Description Locating the Propellers
Full Description This collection of Cassini images provides context for understanding the location and scale of propeller-shaped features observed within Saturn's A ring. Careful analysis of the highest resolution images taken by Cassini's cameras as the spacecraft slipped into Saturn orbit revealed the four faint, propeller-shaped double-streaks in an otherwise bland part of the mid-A ring. Imaging scientists believe the "propellers" provide the first direct observation of the dynamical effects of moonlets approximately 100 meters (300 feet) in diameter. The propeller moonlets represent a hitherto unseen size-class of particles orbiting within the rings. The left-hand panel provides broad context within the rings, and shows the B ring, Cassini Division, A ring and F ring. Image scale in the radial, or outward from Saturn, direction is about 45 kilometers (28 miles) per pixel, because the rings are viewed at an angle, the image scale in the longitudinal, or circumferential, direction is several times greater. The center image is a closer view of the A ring, showing the radial locations where propeller features were spotted. The view is approximately 1,800 kilometers (1,100 miles) across from top to bottom and includes a large density wave at bottom (caused by the moons Janus and Epimetheus), as well as two smaller density waves. The footprints of the propeller discovery images are between density waves, in bland, quiescent regions of the ring. The propellers appear as double dashes in the two close-up discovery images at the right and are circled. The unseen moonlets, each roughly the size of a football field, lie in the center of each structure. These two images were taken during Saturn orbit insertion on July 1, 2004, and are presented here at one-half scale. Resolution in the original images was 52 meters (171 feet) per pixel. The horizontal lines in the image represent electronic noise and do not correspond to ring features. The propellers are about 5 kilometers (3 miles) long from tip to tip, and the radial offset (the "leading" dash is slightly closer to Saturn) is about 300 meters (1,000 feet). The propeller structures are unchanged as they orbit the planet. In that way, they are much like the wave pattern that trails after a speedboat as it skims across a smooth lake. Such a pattern is hard to discern in a choppy sea. In much the same way, scientists think other effects may be preventing Cassini from seeing the propellers except in very bland parts of the rings. See Four Propellers and Propeller Motion for additional images showing these features. 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 and its two onboard cameras were designed, developed and assembled at JPL. 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 Cassini imaging team homepage is at http://ciclops.org . Credit: NASA/JPL/Space Science Institute
Date March 29, 2006
Locating the Propellers
title Locating the Propellers
date 07.01.2004
description This collection of Cassini images provides context for understanding the location and scale of propeller-shaped features observed within Saturn's A ring. Careful analysis of the highest resolution images taken by Cassini's cameras as the spacecraft slipped into Saturn orbit revealed the four faint, propeller-shaped double-streaks in an otherwise bland part of the mid-A ring. Imaging scientists believe the "propellers" provide the first direct observation of the dynamical effects of moonlets approximately 100 meters (300 feet) in diameter. The propeller moonlets represent a hitherto unseen size-class of particles orbiting within the rings. The left-hand panel provides broad context within the rings, and shows the B ring, Cassini Division, A ring and F ring. Image scale in the radial, or outward from Saturn, direction is about 45 kilometers (28 miles) per pixel, because the rings are viewed at an angle, the image scale in the longitudinal, or circumferential, direction is several times greater. The center image is a closer view of the A ring, showing the radial locations where propeller features were spotted. The view is approximately 1,800 kilometers (1,100 miles) across from top to bottom and includes a large density wave at bottom (caused by the moons Janus and Epimetheus), as well as two smaller density waves. The footprints of the propeller discovery images are between density waves, in bland, quiescent regions of the ring. The propellers appear as double dashes in the two close-up discovery images at the right and are circled. The unseen moonlets, each roughly the size of a football field, lie in the center of each structure. These two images were taken during Saturn orbit insertion on July 1, 2004, and are presented here at one-half scale. Resolution in the original images was 52 meters (171 feet) per pixel. The horizontal lines in the image represent electronic noise and do not correspond to ring features. The propellers are about 5 kilometers (3 miles) long from tip to tip, and the radial offset (the "leading" dash is slightly closer to Saturn) is about 300 meters (1,000 feet). The propeller structures are unchanged as they orbit the planet. In that way, they are much like the wave pattern that trails after a speedboat as it skims across a smooth lake. Such a pattern is hard to discern in a choppy sea. In much the same way, scientists think other effects may be preventing Cassini from seeing the propellers except in very bland parts of the rings. 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 and its two onboard cameras were designed, developed and assembled at JPL. 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 Cassini imaging team homepage is at http://ciclops.org [ http://ciclops.org ] . Credit: NASA/JPL/Space Science Institute
Image of Saturn's F-ring
PIA01387
Saturn
Imaging Science Subsystem - …
Title Image of Saturn's F-ring
Original Caption Released with Image Voyager 2 took this high-resolution image of Saturn's F-ring Aug. 26 from a distance of 51,500 kilometers (32,000 miles). This closeup view shows that the ring is made up of at least four distinct components. A higher-resolution scan through the F-ring, the result of the star occultation experiment conducted by the spacecraft's photopolarimeter, showed even finer structure in the ring. Voyager 1 showed a braiding effect not evident in this picture. The small black dots are reseau (reference) marks on the camera. The small bright dash in the middle right of the image is a star trail. The Voyager project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif.
Propeller Motion
PIA07791
Saturn
Imaging Science Subsystem - …
Title Propeller Motion
Original Caption Released with Image This magnified view illustrates the general orientation of the "propeller" features in Saturn's rings as they orbit the planet. The propellers are features detected in Cassini images that reveal the gravitational influence of moonlets approximately 100 meters (300 feet) in diameter. The view is from one of the two Saturn orbit insertion images, taken on July 1, 2004, in which the propellers were discovered. The two dashes of the propeller are oriented in the direction of orbital motion. The "leading" dash is also slightly closer to Saturn, this "radial offset" is about 300 meters (1000 feet). The unseen moonlet lies in the center of the structure. The grainy appearance of the image is due to magnification and the fact that the propellers are very faint--just visible above the level of background noise. Consequently, the image enhancement procedures used have also enhanced the noise. This propeller image is identified as "feature 1" in PIA07790 [ http://photojournal.jpl.nasa.gov/catalog/PIA07790 ]. The original Cassini spacecraft narrow-angle camera image has been magnified from its original scale for presentation. 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 and its two onboard cameras were designed, developed and assembled at JPL. 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/home/index.cfm [ http://saturn.jpl.nasa.gov ]. The Cassini imaging team homepage is at http://ciclops.org [ http://ciclops.org ].
Locating the Propellers
PIA07792
Saturn
Imaging Science Subsystem
Title Locating the Propellers
Original Caption Released with Image This collection of Cassini images provides context for understanding the location and scale of propeller-shaped features observed within Saturn's A ring. Careful analysis of the highest resolution images taken by Cassini's cameras as the spacecraft slipped into Saturn orbit revealed the four faint, propeller-shaped double-streaks in an otherwise bland part of the mid-A ring. Imaging scientists believe the "propellers" provide the first direct observation of the dynamical effects of moonlets approximately 100 meters (300 feet) in diameter. The propeller moonlets represent a hitherto unseen size-class of particles orbiting within the rings. The left-hand panel provides broad context within the rings, and shows the B ring, Cassini Division, A ring and F ring. Image scale in the radial, or outward from Saturn, direction is about 45 kilometers (28 miles) per pixel, because the rings are viewed at an angle, the image scale in the longitudinal, or circumferential, direction is several times greater. The center image is a closer view of the A ring, showing the radial locations where propeller features were spotted. The view is approximately 1,800 kilometers (1,100 miles) across from top to bottom and includes a large density wave at bottom (caused by the moons Janus and Epimetheus), as well as two smaller density waves. The footprints of the propeller discovery images are between density waves, in bland, quiescent regions of the ring. The propellers appear as double dashes in the two close-up discovery images at the right and are circled. The unseen moonlets, each roughly the size of a football field, lie in the center of each structure. These two images were taken during Saturn orbit insertion on July 1, 2004, and are presented here at one-half scale. Resolution in the original images was 52 meters (171 feet) per pixel. The horizontal lines in the image represent electronic noise and do not correspond to ring features. The propellers are about 5 kilometers (3 miles) long from tip to tip, and the radial offset (the "leading" dash is slightly closer to Saturn) is about 300 meters (1,000 feet). The propeller structures are unchanged as they orbit the planet. In that way, they are much like the wave pattern that trails after a speedboat as it skims across a smooth lake. Such a pattern is hard to discern in a choppy sea. In much the same way, scientists think other effects may be preventing Cassini from seeing the propellers except in very bland parts of the rings. See PIA07790 [ http://photojournal.jpl.nasa.gov/catalog/PIA07790 ] and PIA07791 [ http://photojournal.jpl.nasa.gov/catalog/PIA07791 ], for additional images showing these features. 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 and its two onboard cameras were designed, developed and assembled at JPL. 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/home/index.cfm [ http://saturn.jpl.nasa.gov ]. The Cassini imaging team homepage is at http://ciclops.org [ http://ciclops.org ].
Four Propellers
PIA07790
Saturn
Imaging Science Subsystem - …
Title Four Propellers
Original Caption Released with Image These figures show four propeller-shaped structures discovered by the Cassini spacecraft in close-up images of Saturn's A ring. The propellers are about 5 kilometers (3 miles) long from tip to tip, and the radial offset (the "leading" dash is slightly closer to Saturn) is about 300 meters (1,000 feet). See PIA07791 [ http://photojournal.jpl.nasa.gov/catalog/PIA07791 ] and PIA07792 [ http://photojournal.jpl.nasa.gov/catalog/PIA07792 ] for additional images and information about these features. The figures were cropped from two original Cassini spacecraft narrow-angle camera images and magnified for visibility. The images were then re-projected so that orbital motion is to the left and Saturn is up. The unseen moonlets lie in the center of each structure. The figures were cropped from two original Cassini spacecraft narrow-angle camera images, taken during Saturn orbit insertion on July 1, 2004, and magnified for visibility. 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 and its two onboard cameras were designed, developed and assembled at JPL. 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/home/index.cfm [ http://saturn.jpl.nasa.gov ]. The Cassini imaging team homepage is at http://ciclops.org [ http://ciclops.org ].
Meteor Search by Spirit, Sol …
PIA03613
Sol (our sun)
Panoramic Camera
Title Meteor Search by Spirit, Sol 643
Original Caption Released with Image , and Selsis et al. (2005) Nature, vol 435, p. 581). On Earth, some meteors come in "storms" or "showers" at predictable times of the year, like the famous Perseid meteor shower in August or the Leonid meteor shower in November. These "storms" happen when Earth passes through the same parts of space where comets sometimes pass. The meteors we see at these times are from leftover debris that was shed off of these comets. The same kind of thing is predicted for Mars, as well. Inspired by calculations about Martian meteor storms by meteor scientists from the University of Western Ontario in Canada and the Centre de Recherche en Astrophysique de Lyon in France, and also aided by other meteor research colleagues from NASA's Marshall Space Flight Center, scientists on the rover team planned some observations to try to detect predicted meteor storms in October and November, 2005. The views shown here are a composite of nine 60-second exposures taken with the panoramic camera on Spirit during night hours of sol 643 (Oct. 25, 2005), during a week when Mars was predicted to pass through a meteor stream associated with comet P/2001R1 LONEOS. Many stars can be seen in the images, appearing as curved "dash-dot" streaks. The star trails are curved because Mars is rotating while the camera takes the images. The dash-dot pattern is an artifact of taking an image for 60 seconds, then pausing about 10 seconds while the image is processed and stored by the rover's computer, then taking another image for 60 seconds, etc., for a total of about 10 minutes worth of "staring" at the night sky. Many stars from the southern constellations Octans and Pavonis can be seen in the images. The brightest ones in this view would be easily visible to the naked eye, but the faintest ones are slightly dimmer than the human eye can detect. In addition to the star trails, there are several smaller linear streaks, dots and splotches that are the trails left by cosmic rays hitting the camera detectors. Cosmic rays are high-energy particles that are created in the Sun and in other stars throughout our galaxy and travel through space in all directions. Some of them strike Earth or other planets, and ones that strike a digital camera detector can leave little tracks or splotches like those seen in these images. Because they come from all directions, some strike the detector face-on, and others strike at glancing angles. Some even skip across the detector like flat rocks skipped across a pond. These are very common phenomena to astronomers used to working with sensitive digital cameras like those in the Mars rovers, the Hubble Space Telescope, or other space probes, and while they can be a nuisance when taking pictures, they generally do not cause any lasting damage to the cameras. One streak in the image, crossing at an angle very different from the direction of the stars'"motion," might be a meteor trail or could be the mark of another cosmic ray. While hunting for meteors on Mars, Annotated Meteor Search by Spirit, Sol 643 The panoramic cameras on NASA's Mars Exploration Rovers are about as sensitive as the human eye at night. The cameras can see the same bright stars that we can see from Earth, and the same patterns of constellations dot the night sky. Scientists on the rover team have been taking images of some of these bright stars as part of several different projects. One project is designed to try to capture "shooting stars," or meteors, in the Martian night sky. "Meteoroids" are small pieces of comets and asteroids that travel through space and eventually run into a planet. On Earth, we can sometimes see meteoroids become brilliant, long "meteors" streaking across the night sky as they burn up from the friction in our atmosphere. Some of these meteors survive their fiery flight and land on the surface (or in the ocean) where, if found, they are called "meteorites." The same thing happens in the Martian atmosphere, and Spirit even accidentally discovered a meteor while attempting to obtain images of Earth in the pre-dawn sky back in March, 2004 (see http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040311a.html [ http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040311a.html ], is fun, ultimately the team wants to use the images and results for scientific purposes. These include helping to validate the models and predictions for interplanetary meteor storms, providing information on the rate of impacts of small meteoroids with Mars for comparison with rates for the Earth and Moon, assessing the rate and intensity of cosmic ray impact events in the Martian environment, and looking at whether some bright stars are being dimmed occasionally by water ice or dust clouds occurring at night during different Martian seasons.
Meteor Search by Spirit, Sol …
PIA03613
Sol (our sun)
Panoramic Camera
Title Meteor Search by Spirit, Sol 643
Original Caption Released with Image , and Selsis et al. (2005) Nature, vol 435, p. 581). On Earth, some meteors come in "storms" or "showers" at predictable times of the year, like the famous Perseid meteor shower in August or the Leonid meteor shower in November. These "storms" happen when Earth passes through the same parts of space where comets sometimes pass. The meteors we see at these times are from leftover debris that was shed off of these comets. The same kind of thing is predicted for Mars, as well. Inspired by calculations about Martian meteor storms by meteor scientists from the University of Western Ontario in Canada and the Centre de Recherche en Astrophysique de Lyon in France, and also aided by other meteor research colleagues from NASA's Marshall Space Flight Center, scientists on the rover team planned some observations to try to detect predicted meteor storms in October and November, 2005. The views shown here are a composite of nine 60-second exposures taken with the panoramic camera on Spirit during night hours of sol 643 (Oct. 25, 2005), during a week when Mars was predicted to pass through a meteor stream associated with comet P/2001R1 LONEOS. Many stars can be seen in the images, appearing as curved "dash-dot" streaks. The star trails are curved because Mars is rotating while the camera takes the images. The dash-dot pattern is an artifact of taking an image for 60 seconds, then pausing about 10 seconds while the image is processed and stored by the rover's computer, then taking another image for 60 seconds, etc., for a total of about 10 minutes worth of "staring" at the night sky. Many stars from the southern constellations Octans and Pavonis can be seen in the images. The brightest ones in this view would be easily visible to the naked eye, but the faintest ones are slightly dimmer than the human eye can detect. In addition to the star trails, there are several smaller linear streaks, dots and splotches that are the trails left by cosmic rays hitting the camera detectors. Cosmic rays are high-energy particles that are created in the Sun and in other stars throughout our galaxy and travel through space in all directions. Some of them strike Earth or other planets, and ones that strike a digital camera detector can leave little tracks or splotches like those seen in these images. Because they come from all directions, some strike the detector face-on, and others strike at glancing angles. Some even skip across the detector like flat rocks skipped across a pond. These are very common phenomena to astronomers used to working with sensitive digital cameras like those in the Mars rovers, the Hubble Space Telescope, or other space probes, and while they can be a nuisance when taking pictures, they generally do not cause any lasting damage to the cameras. One streak in the image, crossing at an angle very different from the direction of the stars'"motion," might be a meteor trail or could be the mark of another cosmic ray. While hunting for meteors on Mars, Annotated Meteor Search by Spirit, Sol 643 The panoramic cameras on NASA's Mars Exploration Rovers are about as sensitive as the human eye at night. The cameras can see the same bright stars that we can see from Earth, and the same patterns of constellations dot the night sky. Scientists on the rover team have been taking images of some of these bright stars as part of several different projects. One project is designed to try to capture "shooting stars," or meteors, in the Martian night sky. "Meteoroids" are small pieces of comets and asteroids that travel through space and eventually run into a planet. On Earth, we can sometimes see meteoroids become brilliant, long "meteors" streaking across the night sky as they burn up from the friction in our atmosphere. Some of these meteors survive their fiery flight and land on the surface (or in the ocean) where, if found, they are called "meteorites." The same thing happens in the Martian atmosphere, and Spirit even accidentally discovered a meteor while attempting to obtain images of Earth in the pre-dawn sky back in March, 2004 (see http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040311a.html [ http://marsrovers.jpl.nasa.gov/gallery/press/spirit/20040311a.html ], is fun, ultimately the team wants to use the images and results for scientific purposes. These include helping to validate the models and predictions for interplanetary meteor storms, providing information on the rate of impacts of small meteoroids with Mars for comparison with rates for the Earth and Moon, assessing the rate and intensity of cosmic ray impact events in the Martian environment, and looking at whether some bright stars are being dimmed occasionally by water ice or dust clouds occurring at night during different Martian seasons.
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