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kottke.org posts about Cassini

The intricate wave structure of Saturn’s rings

posted by Jason Kottke   Sep 07, 2017

Saturn Waves by Cassini

On one of its final passes of Saturn, the Cassini probe captured this image of a wave structure in Saturn’s rings known as the Janus 2:1 spiral density wave. The waves are generated by the motion of Janus, one of Saturn’s smaller moons.

This wave is remarkable because Janus, the moon that generates it, is in a strange orbital configuration. Janus and Epimetheus (see “Cruising Past Janus”) share practically the same orbit and trade places every four years. Every time one of those orbit swaps takes place, the ring at this location responds, spawning a new crest in the wave. The distance between any pair of crests corresponds to four years’ worth of the wave propagating downstream from the resonance, which means the wave seen here encodes many decades’ worth of the orbital history of Janus and Epimetheus. According to this interpretation, the part of the wave at the very upper-left of this image corresponds to the positions of Janus and Epimetheus around the time of the Voyager flybys in 1980 and 1981, which is the time at which Janus and Epimetheus were first proven to be two distinct objects (they were first observed in 1966).

The photograph is also an optical illusion of sorts. The rings appear to be getting farther away in the upper lefthand corner but the plane of the photograph is actually parallel to the plane of the rings…it’s just that the wavelength of the density wave gets shorter from right to left.

Update: Here are those density waves converted into sound waves. The first set sounds like an accelerating F1 car.

Two Saturnian moons, lined up

posted by Jason Kottke   Jan 06, 2016

Saturn Two Moons

The Cassini spacecraft took a photo of two moons of Saturn, Tethys and Enceladus, beautifully aligned with each other. The cosmic ballet goes on. (via slate)

11 years of Saturn photos from the Cassini probe

posted by Jason Kottke   Nov 20, 2015

The Cassini probe, launched from Earth in 1997 (six months before I started publishing kottke.org), has been taking photos of Saturn and its moons for 11 years now. The Wall Street Journal has a great feature that shows exactly what the probe has been looking at all that time. (Note: the video above features flashing images, so beware if that sort of thing is harmful to you.)

Cassini sippin’ on Enceladus

posted by Jason Kottke   Oct 28, 2015

Whoa, how have I not heard about this before today: the Cassini spacecraft is going to dive through a jet of water erupting from Enceladus, a Saturnian moon.

Discovering life was not on the agenda when Cassini was designed and launched two decades ago. Its instruments can’t capture microbes or detect life, but in a couple of dozen passes through the plumes of Enceladus, it has detected various molecules associated with life: water vapor, carbon dioxide, methane, molecular nitrogen, propane, acetylene, formaldehyde and traces of ammonia.

Wednesday’s dive will be the deepest Cassini will make through the plumes, only 30 miles above the icy surface. Scientists are especially interested in measuring the amount of hydrogen gas in the plume, which would tell them how much energy and heat are being generated by chemical reactions in hydrothermal vents at the bottom of the moon’s ocean.

That’s pretty crazy…it sounds like science fiction. NASA is doing a wonderful job producing great science with the lean budgets they are given.

Saturn without its rings

posted by Jason Kottke   Oct 17, 2013

Over at The Planetary Society, Emily Lakdawalla highlighted an image taken by the Cassini spacecraft of Saturn separate from its rings.

This enormous mosaic showing the flattened globe of Saturn floating amongst the complete disk of its rings must surely be counted among the great images of the Cassini mission. From Earth, we never see Saturn separate from its rings. Here, we can see the whole thing, a gas giant like Jupiter, separated at last from the rings that encircle it.

Taking this idea one step further, I removed the rings completely, along with the “ringlight” lighting up the night hemisphere, creating a more-or-less pure look of what Saturn would look like without its rings.

Saturn Without Rings

Larger version is available on Mlkshk.

Waltz Around Saturn

posted by Jason Kottke   Jul 25, 2013

Fabio Di Donato made this fantastic short film about Saturn using hundreds of thousands of images taken by the Cassini-Huygens spacecraft.

I love the editing technique employed here…the film feels like a silent short from the 1920s but also very contemporary. (via ★interesting)

Saturn fly-by video

posted by Jason Kottke   Mar 15, 2011

There is no 3-D CGI involved in this amazing Saturn fly-by video…it’s made from thousands of hi-res photographs taken by the Cassini orbiter.

Wait for the full-frame full-color video starting at around 1:00. (thx, sam)

Evidence of liquid water has been found

posted by Jason Kottke   Mar 09, 2006

Evidence of liquid water has been found by Cassini on Enceladus, one of Saturn’s moons and “the shiniest object in the solar system”.

Cassini spacecraft finds complex hydrocarbons in the atmosphere of Titan

posted by Jason Kottke   Apr 26, 2005

Cassini spacecraft finds complex hydrocarbons in the atmosphere of Titan.