“August 12, 2014. Although solid-looking in many images, Saturn’s rings are actually translucent. In this picture, we can glimpse the shadow of the rings on the planet through (and below) the A and C rings themselves, towards the lower right hand corner.
For centuries people have studied Saturn’s rings, but questions about the structure and composition of the rings lingered. It was only in 1857 when the physicist James Clerk Maxwell demonstrated that the rings must be composed of many small particles and not solid rings around the planet, and not until the 1970s that spectroscopic evidence definitively showed that the rings are composed mostly of water ice.
This view looks toward the sunlit side of the rings from about 17 degrees above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera in near-infrared light centered at 752 nanometers. The view was obtained at a distance of approximately 1.4 million miles (2.3 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 24 degrees. Image scale is 85 miles (136 kilometers) per pixel.”
Image credit: NASA/JPL-Caltech/Space Science Institute
“Voyager 1 is a space probe launched by NASA on September 5, 1977. Part of the Voyager program to study the outer Solar System, Voyager 1 launched 16 days after its twin, Voyager 2. Having operated for 40 years and 13 days as of September 18, 2017, the spacecraft still communicates with the Deep Space Network to receive routine commands and return data. At a distance of 139 AU (2.08×1010 km) from the Sun as of July 1, 2017, it is the farthest spacecraft from Earth as well as the farthest man-made object. It is also the most distant object in the solar system whose location is known, even farther than Eris (96 AU) and V774104 (~103 AU).
The probe’s objectives included flybys of Jupiter, Saturn and Saturn’s large moon, Titan. While the spacecraft’s course could have been altered to include a Pluto encounter by forgoing the Titan flyby, exploration of the moon, which was known to have a substantial atmosphere, took priority. It studied the weather, magnetic fields and rings of the two planets and was the first probe to provide detailed images of their moons.
After completing its primary mission with the flyby of Saturn on November 20, 1980, Voyager 1 became the third of five artificial objects to achieve the escape velocity that will allow them to leave the Solar System. It is pursuing an extended mission to explore the regions and boundaries of the outer heliosphere. On August 25, 2012, Voyager 1 crossed the heliopause to become the first spacecraft to enter interstellar space and study the interstellar medium.
Voyager 1’s extended mission is expected to continue until around 2025 when its radioisotope thermoelectric generators will no longer supply enough electric power to operate its scientific instruments.”
“January 23, 2014. The Cassini spacecraft captures a glimpse of the moon Atlas shortly after emerging from Saturn’s shadow. Although the sunlight at Saturn’s distance is feeble compared to that at the Earth, objects cut off from the Sun within Saturn’s shadow cool off considerably. Scientists study how the moons around Saturn cool and warm as they enter and leave Saturn’s shadow to better understand the physical properties of Saturn’s moons.
This view looks toward the sunlit side of the rings from about 44 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 1.6 million miles (2.6 million kilometers) from Atlas and at a Sun-Atlas-spacecraft, or phase, angle of 93 degrees. Image scale is 10 miles (16 kilometers) per pixel.”
Image credit: NASA/JPL-Caltech/Space Science Institute
“October 10, 2013. This portrait looking down on Saturn and its rings was created from images obtained by NASA’s Cassini spacecraft. It was made by amateur image processor and Cassini fan Gordan Ugarkovic. This image has not been geometrically corrected for shifts in the spacecraft perspective and still has some camera artifacts. The mosaic was created from 12 image footprints with red, blue and green filters from Cassini’s imaging science subsystem. Ugarkovic used full color sets for 11 of the footprints and red and blue images for one footprint.”
“The Cassini–Huygens (commonly called Cassini) mission was a collaboration between NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a probe to study the planet Saturn and its system, including its rings and natural satellites. The Flagship-class unmanned robotic spacecraft comprised both NASA’s Cassini probe, and ESA’s Huygens lander which would be landed on Saturn’s largest moon, Titan. Cassini was the fourth space probe to visit Saturn and the first to enter its orbit. The craft were named after astronomers Giovanni Cassini and Christiaan Huygens.
Launched aboard a Titan IVB/Centaur on October 15, 1997, Cassini was active in space for more than 19 years, with 13 years spent orbiting Saturn, studying the planet and its system after entering orbit on July 1, 2004. The voyage to Saturn included flybys of Venus (April 1998 and July 1999), Earth (August 1999), the asteroid 2685 Masursky, and Jupiter (December 2000). Its mission ended on September 15, 2017, when Cassini was commanded to fly into Saturn’s upper atmosphere and burn up in order to prevent any risk of contaminating Saturn’s moons, which may offer habitable environments to stowaway terrestrial microbes on the spacecraft. (At that point Cassini lacked sufficient impulse to leave the Saturn system, so it could only be left in orbit, where it might collide with a moon, or be destroyed.) The mission is widely perceived to have been successful beyond expectation. Cassini-Huygens has been described by NASA’s Planetary Science Division Director as a “mission of firsts”, that has revolutionized human understanding of the Saturn system, including its moons and rings, and our understanding of where life might be found in the Solar System.
Cassini’s original mission was planned to last for four years, from June 2004 to May 2008. The mission was extended for another two years until September 2010, branded the Cassini Equinox Mission. The mission was extended a second and final time with the Cassini Solstice Mission, lasting another seven years until September 15, 2017, on which date Cassini was de-orbited to burn up in Saturn’s upper atmosphere.
The Huygens module traveled with Cassini until its separation from the probe on December 25, 2004; it was successfully landed by parachute on Titan on January 14, 2005. It successfully returned data to Earth for around 90 minutes, using the orbiter as a relay. This was the first landing ever accomplished in the outer Solar System and the first landing on a moon other than our own. Cassini continued to study the Saturn system in the following years.
At the end of its mission, the Cassini spacecraft executed the “Grand Finale” of its mission: a number of risky passes through the gaps between Saturn and Saturn’s inner rings. The purpose of this phase was to maximize Cassini’s scientific outcome before the spacecraft was destroyed. The atmospheric entry of Cassini effectively ended the mission.”
“August 24, 2013. Saturn’s moon Prometheus orbits near some of its handiwork in the F ring. Prometheus (53 miles, or 86 kilometers across) and its partner Pandora gravitationally sculpt and maintain the narrow F ring.
This view looks toward the unilluminated side of the rings from about 53 degrees below the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 1.1 million miles (1.8 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 104 degrees. Image scale is 7 miles (11 kilometers) per pixel.”
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