The Urban Astronomer hosts the latest Carnival of Space.
Carnival of Space #534 – Urban Astronomer
Category Archives: Gas giants Saturn, Jupiter, et al
More views of Saturn’s rings from the Cassini Finale
A wonderful view of Saturn as seen by Cassini about a month before the probe’s mission ended by entering the planet’s atmosphere:
Saturn’s graceful lanes of orbiting ice — its iconic rings — wind their way around the planet to pass beyond the horizon in this view from NASA’s Cassini spacecraft. And diminutive Pandora, scarcely larger than a pixel here, can be seen orbiting just beyond the F ring in this image.
Also in this image is the gap between Saturn’s cloud tops and its innermost D ring through which Cassini would pass 22 times before ending its mission in spectacular fashion in Sept. 15, 2017. Scientists scoured images of this region, particularly those taken at the high phase (spacecraft-ring-Sun) angles, looking for material that might pose a hazard to the spacecraft.
This view looks toward the sunlit side of the rings from about 19 degrees above the ringplane. The image was taken in green light with the Cassini spacecraft wide-angle camera on Aug. 12, 2017. Pandora was brightened by a factor of 2 to increase its visibility.
The view was obtained at a distance to Saturn of approximately 581,000 miles (935,000 kilometers) from Saturn. Image scale is 35 miles (56 kilometers) per pixel. The distance to Pandora was 691,000 miles (1.1 million kilometers) for a scale of 41 miles (66 kilometers) per pixel.
The Cassini spacecraft ended its mission on Sept. 15, 2017.
The Cassini mission is a cooperative project of NASA, ESA (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. 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, Colorado.
For more information about the Cassini-Huygens mission visit https://saturn.jpl.nasa.gov and https://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.
Credit: NASA/JPL-Caltech/Space Science Institute
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See also Cassini: The Grand Finale: Fresh Findings From Cassini – NASA JPL
Cassini obtained the images in this mosaic on May 28, 2017, looking over the horizon just after its sixth pass through the gap between Saturn and its rings as part of the mission’s Grand Finale.
In this view, Saturn looms in the foreground on the left, adorned by ring shadows. To the right, the rings emerge from behind the planet’s hazy limb, stretching outward from Cassini’s perspective. The view is of the rings’ unilluminated face, where sunlight filters through from the other side. The part of the planet seen here is in the southern hemisphere.
A wider, uncropped version of the mosaic (Fig. B), which shows more of the rings, is also available.
For another mosaic showing the view from between Saturn and the rings, see Inside-Out Rings: View From Beneath. A previously released movie sequence showed Cassini’s changing view, gazing out upon the rings as the spacecraft passed through the ring plane from north to south (see Cassini’s ‘Inside-Out’ Rings Movie).
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Video: Marvelous imagery from Juno’s latest low pass over Jupiter
The Mission Juno spacecraft recently completed its 8th low pass over the clouds of Jupiter. Images from Perijove 08 can be found on the JunoCam site, including images that have been enhanced by amateur astro-imaging whizzes.
This video of enhanced imagery from the 8th pass displayed with a musical soundtrack is quite spectacular:
Here is a more interpretive approach to Juno’s data:
A multimedia project based on an image of Jupiter I processed that was captured by Juno spacecraft. Illustration, animation and special effects by Rachel Richards. Music composed and performed by Rachel Richards.
A Perijove 08 image “Heavily processed via Photoshop” by RichDaMann:
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Video: Cassini mission to Saturn comes to an end
The Cassini spacecraft made its final orbit of Saturn this morning:
NASA’s Cassini Spacecraft Ends Its Historic Exploration of Saturn
A thrilling epoch in the exploration of our solar system came to a close today, as NASA’s Cassini spacecraft made a fateful plunge into the atmosphere of Saturn, ending its 13-year tour of the ringed planet.
“This is the final chapter of an amazing mission, but it’s also a new beginning,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate at NASA Headquarters in Washington. “Cassini’s discovery of ocean worlds at Titan and Enceladus changed everything, shaking our views to the core about surprising places to search for potential life beyond Earth.”
Telemetry received during the plunge indicates that, as expected, Cassini entered Saturn’s atmosphere with its thrusters firing to maintain stability, as it sent back a unique final set of science observations. Loss of contact with the Cassini spacecraft occurred at 4:55 a.m. PDT (7:55 a.m. EDT), with the signal received by NASA’s Deep Space Network antenna complex in Canberra, Australia.
“It’s a bittersweet, but fond, farewell to a mission that leaves behind an incredible wealth of discoveries that have changed our view of Saturn and our solar system, and will continue to shape future missions and research,”
said Michael Watkins, director of NASA’s Jet Propulsion Laboratory in Pasadena, California, which manages the Cassini mission for the agency. JPL also designed, developed and assembled the spacecraft.
Cassini’s plunge brings to a close a series of 22 weekly “Grand Finale” dives between Saturn and its rings, a feat never before attempted by any spacecraft.
“The Cassini operations team did an absolutely stellar job guiding the spacecraft to its noble end,” said Earl Maize, Cassini project manager at JPL. “From designing the trajectory seven years ago, to navigating through the 22 nail-biting plunges between Saturn and its rings, this is a crack shot group of scientists and engineers that scripted a fitting end to a great mission. What a way to go. Truly a blaze of glory.”
As planned, data from eight of Cassini’s science instruments was beamed back to Earth. Mission scientists will examine the spacecraft’s final observations in the coming weeks for new insights about Saturn, including hints about the planet’s formation and evolution, and processes occurring in its atmosphere.
“Things never will be quite the same for those of us on the Cassini team now that the spacecraft is no longer flying,” said Linda Spilker, Cassini project scientist at JPL. “But, we take comfort knowing that every time we look up at Saturn in the night sky, part of Cassini will be there, too.”
Cassini launched in 1997 from Cape Canaveral Air Force Station in Florida and arrived at Saturn in 2004. NASA extended its mission twice – first for two years, and then for seven more. The second mission extension provided dozens of flybys of the planet’s icy moons, using the spacecraft’s remaining rocket propellant along the way. Cassini finished its tour of the Saturn system with its Grand Finale, capped by Friday’s intentional plunge into the planet to ensure Saturn’s moons – particularly Enceladus, with its subsurface ocean and signs of hydrothermal activity – remain pristine for future exploration.
While the Cassini spacecraft is gone, its enormous collection of data about Saturn – the giant planet, its magnetosphere, rings and moons – will continue to yield new discoveries for decades to come.
“Cassini may be gone, but its scientific bounty will keep us occupied for many years,” Spilker said. “We’ve only scratched the surface of what we can learn from the mountain of data it has sent back over its lifetime.”
An online toolkit with information and resources for Cassini’s Grand Finale is available at: https://saturn.jpl.nasa.gov/grandfinale
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. JPL, a division of Caltech in Pasadena, manages the mission for NASA’s Science Mission Directorate in Washington.
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Videos: Cassini nears its final orbit around Saturn
On Friday, the Cassini probe will end its 13 year mission at the ringed planet when its final orbit takes the spacecraft into Saturn’s atmosphere: Cassini Spacecraft Makes Its Final Approach to Saturn | NASA
NASA’s Cassini spacecraft is on final approach to Saturn, following confirmation by mission navigators that it is on course to dive into the planet’s atmosphere on Friday, Sept. 15.
Cassini is ending its 13-year tour of the Saturn system with an intentional plunge into the planet to ensure Saturn’s moons – in particular Enceladus, with its subsurface ocean and signs of hydrothermal activity – remain pristine for future exploration. The spacecraft’s fateful dive is the final beat in the mission’s Grand Finale, 22 weekly dives, which began in late April, through the gap between Saturn and its rings. No spacecraft has ever ventured so close to the planet before.
The mission’s final calculations predict loss of contact with the Cassini spacecraft will take place on Sept. 15 at 7:55 a.m. EDT (4:55 a.m. PDT). Cassini will enter Saturn’s atmosphere approximately one minute earlier, at an altitude of about 1,190 miles (1,915 kilometers) above the planet’s estimated cloud tops (the altitude where the air pressure is 1-bar, equivalent to sea level on Earth). During its dive into the atmosphere, the spacecraft’s speed will be approximately 70,000 miles (113,000 kilometers) per hour. The final plunge will take place on the day side of Saturn, near local noon, with the spacecraft entering the atmosphere around 10 degrees north latitude.
When Cassini first begins to encounter Saturn’s atmosphere, the spacecraft’s attitude control thrusters will begin firing in short bursts to work against the thin gas and keep Cassini’s saucer-shaped high-gain antenna pointed at Earth to relay the mission’s precious final data. As the atmosphere thickens, the thrusters will be forced to ramp up their activity, going from 10 percent of their capacity to 100 percent in the span of about a minute. Once they are firing at full capacity, the thrusters can do no more to keep Cassini stably pointed, and the spacecraft will begin to tumble.
When the antenna points just a few fractions of a degree away from Earth, communications will be severed permanently. The predicted altitude for loss of signal is approximately 930 miles (1,500 kilometers) above Saturn’s cloud tops. From that point, the spacecraft will begin to burn up like a meteor. Within about 30 seconds following loss of signal, the spacecraft will begin to come apart; within a couple of minutes, all remnants of the spacecraft are expected to be completely consumed in the atmosphere of Saturn.
Due to the travel time for radio signals from Saturn, which changes as both Earth and the ringed planet travel around the Sun, events currently take place there 83 minutes before they are observed on Earth. This means that, although the spacecraft will begin to tumble and go out of communication at 6:31 a.m. EDT (3:31 a.m. PDT) at Saturn, the signal from that event will not be received at Earth until 83 minutes later.
“The spacecraft’s final signal will be like an echo. It will radiate across the solar system for nearly an hour and a half after Cassini itself has gone,” said Earl Maize, Cassini project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “Even though we’ll know that, at Saturn, Cassini has already met its fate, its mission isn’t truly over for us on Earth as long as we’re still receiving its signal.”
Cassini’s last transmissions will be received by antennas at NASA’s Deep Space Network complex in Canberra, Australia.
Cassini is set to make groundbreaking scientific observations of Saturn, using eight of its 12 science instruments. All of the mission’s magnetosphere and plasma science instruments, plus the spacecraft’s radio science system, and its infrared and ultraviolet spectrometers will collect data during the final plunge.
Credits: NASA/JPL-Caltech
Chief among the observations being made as Cassini dives into Saturn are those of the Ion and Neutral Mass Spectrometer (INMS). The instrument will directly sample the composition and structure of the atmosphere, which cannot be done from orbit. The spacecraft will be oriented so that INMS is pointed in the direction of motion, to allow it the best possible access to oncoming atmospheric gases.
For the next couple of days, as Saturn looms ever larger, Cassini expects to take a last look around the Saturn system, snapping a few final images of the planet, features in its rings, and the moons Enceladus and Titan. The final set of views from Cassini’s imaging cameras is scheduled to be taken and transmitted to Earth on Thursday, Sept. 14. If all goes as planned, images will be posted to the Cassini mission website beginning around 11 p.m. EDT (8 p.m. PDT). The unprocessed images will be available at: https://saturn.jpl.nasa.gov/galleries/raw-images
Live mission commentary and video from JPL Mission Control will air on NASA Television and the agency’s website from 7 to 8:30 a.m. EDT (4 a.m. to 5:30 a.m. PDT) on Sept. 15. A post-mission news briefing from JPL is currently scheduled for 9:30 a.m. EDT (6:30 a.m. PDT), also on NASA TV.
A new NASA e-book, The Saturn System Through the Eyes of Cassini, showcasing compelling images and key science discoveries from the mission, is available for free download in multiple formats at: https://www.nasa.gov/ebooks
An online toolkit of information and resources about Cassini’s Grand Finale and final plunge into Saturn is available at: https://saturn.jpl.nasa.gov/grandfinale
Follow the Cassini spacecraft’s plunge on social media using #GrandFinale, or visit:
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. JPL, a division of Caltech in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.
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More about the Cassini mission and its ending: