The tiny Saturn moon Atlas. Image Credit:NASA/JPL-Caltech/Space Science Institute
Nice! The Saturn moon Atlas, not one we often get to see. Atlas was discovered in 1980 thanks to the Voyager spacecraft and JPL employee Richard Terrile. As moons go Atlas is tiny being only around 30 km (18 miles) in diameter.
From the Cassini site:
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 on Jan. 23, 2014.
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.
The little moon Pan is minding the (Enke) gap. Image: NASA/JPL-Caltech/Space Science Institute
If you’ve ever wondered how the Enke gap in the rings of Saturn can be, it is thanks to the tiny moon Pan who minds the gap, keeping it nice and orderly using its gravity. Pan is so small it barely shows up in the image above.
BTW: If you are out and about just after sunset and in the twilight AND have decent skies, look to the south, on your left or East about 15 degrees you will see the planet Mars, nice and red then on the right or West about 15 degrees you will see the bright blue star Sirius. I saw the two last evening and quite enjoyed it, the colors were really good against the twilight sky.
Here’s the Cassini caption from JPL:
Saturn’s moon Pan, named for the Greek god of shepherds, rules over quite a different domain: the Encke gap in Saturn’s rings.
Pan (17 miles, or 28 kilometers across) keeps the Encke gap open through its gravitational influence on the ring particles nearby.
The final journey of Cassini. Image: NASA
As hard as it seems, the Cassini spacecraft soon enough enter the final phase of its mission.
The new and final mission will begin in 2016 and promises to be incredible.
During this final phase the spacecrafts orbit will take it well above the north pole of Saturn, it will then plunge between the inner ring and the planet itself.
You can get the details of the final months of Cassini here.
In the mean time the Cassini team is looking for a name to call the mission and YOU can help.
Pick a name from a list.
Submit a name of your own.
A possible internal structure of Enceladus. Artist concept: NASA/JPL-Caltech
I love this! I know, it’s not “for sure positively” but close enough for me. I was in the “global ocean” camp, then I thought “why not” this seems perfectly reasonable.
I do have to take issue with the very last line of the ESA press release (included / linked below): “This experiment provides a crucial new piece of information towards understanding the formation of plumes on this intriguing moon,” says Nicolas Altobelli, ESA’s Cassini project scientist. Yeah it does provide a piece, but seems like it brings up more questions than it answered. That’s awesome is what it is!
Here is the Enceladus image gallery from NASA.
The press release from ESA is excellent:
Saturn’s icy moon Enceladus has an underground sea of liquid water, according to the international Cassini spacecraft.
Understanding the interior structure of 500 km-diameter Enceladus has been a top priority of the Cassini mission since plumes of ice and water vapour were discovered jetting from ‘tiger stripe’ fractures at the moon’s south pole in 2005.
Subsequent observations of the jets showed them to be relatively warm compared with other regions of the moon and to be salty – strong arguments for there being liquid water below the surface.
Four moons of Saturn at once! Click for larger. Credit: NASA/JPL-Caltech/Space Science Institute
We get to see four of Saturn;s moons in this Cassini image. NASA describes them below. They do not comment on one of more spectacular shots of the rings Cassini has taken; they show up better in the larger versions at the NASA website.
Two pairs of moons make a rare joint appearance. The F ring’s shepherd moons, Prometheus and Pandora, appear just inside and outside of the F ring (the thin faint ring furthest from Saturn). Meanwhile, farther from Saturn the co-orbital moons Janus (near the bottom) and Epimetheus (about a third of the way down from the top) also are captured.
Prometheus (53 miles, or 86 kilometers across) and Pandora (50 miles, or 81 kilometers across) sculpt the F ring through their gravitational influences. Janus (111 miles, or 179 kilometers across) and Epimetheus (70 miles, or 113 kilometers across) are famous for their orbital dance, swapping places about every four years. They are also responsible for gravitationally shaping the outer edge of the A ring into seven scallops.
This view looks toward the sunlit side of the rings from about 47 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on Oct. 11, 2013.
The view was acquired at a distance of approximately 810,000 miles (1.3 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 47 degrees. Image scale is 47 miles (76 kilometers) per pixel.
Continuing on this weekend’s theme:
13 years of Cassini for a Day! This is a great opportunity for both teachers and students, espeically students. Looking for a project? You could enter this and (or) use the essay at school. Surely an entry would earn some extra credit.
Students must be in grades 5 to 12 and the entry deadline is 17 April 2014. Note: that is a US deadline, other counties may have different deadlines which are not yet listed, typically they indeed different. The International link on the site is not yet current but it will be shortly.
Check out the Cassini Scientist for a Day website.
The contest meets U.S. National English and Science Education Standards.
Cassini Scientist for a Day is an essay contest designed to give students a taste of life as a scientist.
Students study three possible targets that the Cassini spacecraft can image during a given time set aside for education. They are to choose the one image they think will yield the best science results and explain their reasons in an essay.
The three targets are:
- Target 1 is Saturn’s F ring. Cassini will be taking 70 images of the F ring using the spacecraft’s Narrow Angle Camera to make a movie showing how the F ring changes as it orbits Saturn.
- Target 2 is Saturn’s largest moon, Titan. Cassini will be taking nine images of Titan’s north polar region using its Narrow Angle Camera. These images will be stitched together to form a mosaic.
- Target 3 is the planet Saturn. The Cassini spacecraft will use its Wide Angle Camera and its Narrow Angle Camera to image Saturn’s north pole, studying the hurricane at the north pole and the hexagon-shaped polar vortex.