A new movie sequence of images from Cassini shows the view as the orbiter swooped over Saturn during the first of its ‘Grand Finale’ dives between the gas giant and its rings on April 26, 2017.
The images in this sequence were captured in visible light using Cassini’s wide-angle camera.
“The images from the first pass were great, but we were conservative with the camera settings,” said Cassini imaging team member Dr. Andrew Ingersoll, a planetary scientist at the California Institute of Technology.
“We plan to make updates to our observations for a similar opportunity on June 28 that we think will result in even better views.”
The video comprises one hour of observations as Cassini moved southward over Saturn.
It begins with a view of the swirling vortex at the planet’s north pole, then heads past the outer boundary of the hexagon-shaped jet stream and beyond.
“I was surprised to see so many sharp edges along the hexagon’s outer boundary and the eye-wall of the polar vortex,” said Cassini imaging team member Dr. Kunio Sayanagi, from Hampton University.
“Something must be keeping different latitudes from mixing to maintain those edges.”
Toward the end of the movie, the camera frame rotates as Cassini reorients to point its 13-foot- (4 m) wide, dish-shaped high-gain antenna in the direction of the spacecraft’s motion. The antenna was used as a protective shield during the crossing of Saturn’s ring plane.
The speed at which the cloudscape below moves past also increases noticeably during the sequence, as Cassini moves with increasing speed the closer it comes to the gas giant.
As the movie frames were captured, Cassini’s altitude above the clouds dropped from 45,000 to 4,200 miles (72,400 to 6,700 km).
As this occurred, the smallest resolvable features in the atmosphere changed from 5.4 miles (8.7 km) per pixel to 0.5 mile (810 km) per pixel.
The original versions of these images, as sent by Cassini, have a size of 512 by 512 pixels. The small image size was chosen in order to allow the cameras to take images quickly as the orbiter passed over Saturn.
The images, which show Saturn’s curved surface, have been projected onto a flat plane here to enable assembly into a continuous movie sequence. Each image was mapped in polar stereo-graphic projection centered on the camera before being assembled into the movie.
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This article is based on a press-release from the National Aeronautics and Space Administration.