
ALT Photo of a Hall thruster identical to those on NASA’s Psyche operating in a vacuum chamber at JPL during tests. A ring of blue light emits a hazy stream of glowing material. The blue light is generated by xenon ions being accelerated through an electromagnetic field, which gives the spacecraft a gentle but steady acceleration. NASA/JPL-Caltech

ALT Saturn's largest and second largest moons, Titan and Rhea, appear to be stacked on top of each other in this true-color scene from NASA's Cassini spacecraft. The north polar hood can be seen on Titan appearing as a detached layer at the top of the moon on the top right. This view looks toward the Saturn-facing side of Rhea (949 miles or 1528 kilometers across). North on Rhea is up and rotated 35 degrees to the right. Images taken using red, green and blue spectral filters were combined to create this natural-color view. The images were acquired with the Cassini spacecraft narrow-angle camera on June 16, 2011, at a distance of approximately 1.1 million miles (1.8 million kilometers) from Rhea and 1.5 million miles (2.5 million kilometers) from Titan. Image scale is 7 miles (11 kilometers) per pixel on Rhea and 9 miles (15 kilometers) on Titan. Credit: NASA/JPL-Caltech/Space Science Institute

ALT A blue hue, present in the northern hemisphere of Saturn is seen here by NASA's Cassini spacecraft. The changing blue hue marks winter at Saturn and is likely due to reduction of ultraviolet sunlight and the haze it produces, making the atmosphere clearer and increasing the opportunity for Rayleigh scattering (scattering by molecules and smaller particles) and methane absorption. This view looks toward the unilluminated side of the rings from about 44 degrees below the ring plane. Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were taken with the Cassini spacecraft wide-angle camera on July 29, 2013. Credit: NASA/JPL-Caltech/Space Science Institute























