Cassini probe at Saturn... (warning -- large images!)

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Titan's haze and clouds are well-known but there's fog now too

Astronomers say the presence of fog provides the first direct evidence for the exchange of material between the surface and the atmosphere, and thus of an active hydrological cycle, which previously had only been known to exist on Earth.

The discovery was made using data from the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft, which has been observing Saturn's system for the past five years. The VIMS instrument provides "hyperspectral" imaging, covering a large swath of the visible and infrared spectrum.

Researchers investigated all Cassini data collected over the moon's south pole from October 2006 through March 2007, and filtered the data to separate out features occurring at different depths in the atmosphere, ranging from 20 kilometers (12.4 miles) to .25 kilometers (820 feet) above the surface. Using other filters, they homed in on "bright" features caused by the scattering of light off small particles—such as the methane droplets present in clouds.

In this way, they isolated clouds located about 750 meters (less than a half-mile) above the ground. These clouds did not extend into the higher altitudes—into the moon's troposphere, where regular clouds form. In other words, says Brown, they had found fog.

"Fog—or clouds, or dew, or condensation in general—can form whenever air reaches about 100 percent humidity," Brown says. "There are two ways to get there. The first is obvious: add water (on Earth) or methane (on Titan) to the surrounding air. The second is much more common: make the air colder so it can hold less water (or liquid methane), and all of that excess needs to condense."

On Earth, this is the most common method of making fog, Brown says. "That fog you often see at sunrise hugging the ground is caused by ground-level air cooling overnight, to the point where it cannot hang onto its water. As the sun rises and the air heats, the fog goes away."

Similarly, fog can form when wet air passes over cold ground; as the air cools, the water condenses. And mountain fog occurs when air gets pushed up the side of a mountain and cools, causing the water to condense.

However, none of these mechanisms work on Titan.

The reason is that Titan's muggy atmosphere takes a notoriously long time to cool (or warm). "If you were to turn the sun totally off, Titan's atmosphere would still take something like 100 years to cool down," Brown says. "Even the coldest parts of the surface are much too warm to ever cause fog to condense."

Mountain fog is also out of the question, he adds. "A Titanian mountain would have to be about 15,000 feet high before the air would get cold enough to condense," he says. And yet the tallest mountains the moon could possibly carry (because of its fragile, icy crust) would be no more than 3000 feet high.

The only possible way to make Titanian fog, then, is to add humidity to the air. And the only way to do that, Brown says, is by evaporating liquid—in this case, methane, the most common hydrocarbon on the moon, which exists in solid, liquid, and gaseous forms.

Brown notes that evaporating methane on Titan "means it must have rained, and rain means streams and pools and erosion and geology. The presence of fog on Titan proves, for the first time, that the moon has a currently active methane hydrological cycle."

The presence of fog also proves that the moon must be dotted with methane pools, Brown says. That's because any ground-level air, after becoming 100 percent humid and turning into fog, would instantly rise up into the atmosphere like a giant cumulus cloud. "The only way to make the fog stick around on the ground is to both add humidity and cool the air just a little," he explains. "The way to cool the air just a little is to have it in contact with something cold, like a pool of evaporating liquid methane."

Elvis Telecom, Tuesday, 22 December 2009 03:36 (4 years ago) Permalink

Meet Prometheus the space yam

Elvis Telecom, Monday, 28 December 2009 05:41 (4 years ago) Permalink

1 month passes...

So remember those spokes in the B-ring of Saturn? They're 100% water ice

Elvis Telecom, Monday, 1 February 2010 00:24 (4 years ago) Permalink

A nicely banal answer (not everything needs to be mysterious!)

Ned Raggett, Monday, 1 February 2010 01:42 (4 years ago) Permalink

And Cassini is go to keep on going (potentially through 2017)

Elvis Telecom, Wednesday, 3 February 2010 19:57 (4 years ago) Permalink

Visiting the Death Star

Elvis Telecom, Tuesday, 16 February 2010 23:16 (4 years ago) Permalink

No trench no credibility

Ned Raggett, Tuesday, 16 February 2010 23:19 (4 years ago) Permalink

1 month passes...

Lightning spotted visually in Saturn's atmosphere

(there's a movie at the NASA link)

Elvis Telecom, Wednesday, 14 April 2010 20:02 (4 years ago) Permalink

1 month passes...

The Big Picture goes to Saturn: http://www.boston.com/bigpicture/2010/05/checking_in_on_saturn.html

Elvis Telecom, Saturday, 22 May 2010 01:33 (4 years ago) Permalink

does anybody know when NASA's gonna probe uranus?

Face Book (dyao), Saturday, 22 May 2010 01:44 (4 years ago) Permalink

seriously, though

Saturn's tiny moon Helene, seen here by Cassini on March 03, 2010. Discovered in 1980, Helene is only 35 km (28 mi) wide. (NASA/JPL) #

the fact that we can discover something so small floating in space is mind boggling.

Face Book (dyao), Saturday, 22 May 2010 01:51 (4 years ago) Permalink

I also love this:

Cassini scientists were able to correlate the reflection to the southern shoreline of a Titan lake called Kraken Mare. The sprawling Kraken Mare covers about 400,000 sq km (150,000 sq mi).

kraken mare!

Face Book (dyao), Saturday, 22 May 2010 01:56 (4 years ago) Permalink

2 weeks pass...

Not from Cassini, but related: Image of the Day: Saturn's Newly Discovered Immense Outer Ring

NASA's Spitzer Space Telescope discovered an enormous ring around Saturn -- by far the largest of the giant planet's many rings. The belt lies at the far reaches of the Saturnian system, with an orbit tilted 27 degrees from the main ring plane. The bulk of its material starts about six million kilometers (3.7 million miles) away from the planet and extends outward roughly another 12 million kilometers (7.4 million miles). One of Saturn's farthest moons, Phoebe, circles within the newfound ring, and is likely the source of its material.

Saturn's newest halo is thick, too -- its vertical height is about 20 times the diameter of the planet. It would take about one billion Earths stacked together to fill the ring.

"This is one supersized ring," said Anne Verbiscer, an astronomer at the University of Virginia, Charlottesville. "If you could see the ring, it would span the width of two full moons' worth of sky, one on either side of Saturn."

The ring itself is tenuous, made up of a thin array of ice and dust particles. Spitzer's infrared eyes were able to spot the glow of the band's cool dust. The telescope, launched in 2003, is currently 107 million kilometers (66 million miles) from Earth in orbit around the sun.

The discovery may help solve an age-old riddle of one of Saturn's moons. Iapetus has a strange appearance -- one side is bright and the other is really dark, in a pattern that resembles the yin-yang symbol. The astronomer Giovanni Cassini first spotted the moon in 1671, and years later figured out it has a dark side, now named Cassini Regio in his honor. A stunning picture of Iapetus taken by NASA's Cassini spacecraft is online http://photojournal.jpl.nasa.gov/catalog/PIA08384 .

Saturn's newest addition could explain how Cassini Regio came to be. The ring is circling in the same direction as Phoebe, while Iapetus, the other rings and most of Saturn's moons are all going the opposite way. According to the scientists, some of the dark and dusty material from the outer ring moves inward toward Iapetus, slamming the icy moon like bugs on a windshield.

"Astronomers have long suspected that there is a connection between Saturn's outer moon Phoebe and the dark material on Iapetus," said Hamilton. "This new ring provides convincing evidence of that relationship."

The ring would be difficult to see with visible-light telescopes. Its particles are diffuse and may even extend beyond the bulk of the ring material all the way in to Saturn and all the way out to interplanetary space. The relatively small numbers of particles in the ring wouldn't reflect much visible light, especially out at Saturn where sunlight is weak.

"The particles are so far apart that if you were to stand in the ring, you wouldn't even know it," said Verbiscer.

Spitzer was able to sense the glow of the cool dust, which is only about 80 Kelvin (minus 316 degrees Fahrenheit). Cool objects shine with infrared, or thermal radiation; for example, even a cup of ice cream is blazing with infrared light. "By focusing on the glow of the ring's cool dust, Spitzer made it easy to find," said Verbiscer.

Elvis Telecom, Wednesday, 9 June 2010 23:33 (4 years ago) Permalink

yup 80 kelvin

Jarlrmai, Thursday, 10 June 2010 11:46 (4 years ago) Permalink

3 months pass...

Springtime on Titan

Elvis Telecom, Thursday, 23 September 2010 01:59 (4 years ago) Permalink

1 month passes...

Stockhausen's Helicopter Quartet (Elvis Telecom), Wednesday, 3 November 2010 00:13 (3 years ago) Permalink

4 weeks pass...

Enceladus Fissures Keep Getting Warmer and More Complex

As Cassini scientists await the data from today’s flyby of Enceladus, images and data from August of this year have provided more insight into the active fissures on the icy moon’s south polar region. These geyser-spewing fractures are warmer and more complicated than previously thought.

“The exquisite resolution obtained on one segment of the Damascus fracture — one of the most active regions within the south polar terrain — has revealed a surface temperature reaching a staggering 190 Kelvin, or 120 degrees below zero Fahrenheit,” said Cassini imaging team lead Carolyn Porco, in an email announcing the new images. “Far from the fractures, the temperature of the south polar terrain dips as low as 52 Kelvin, or 365 degrees below zero Fahrenheit.”

Porco said that what this means is that a phenomenal amount of heat is emerging from the fractures which are “undoubtedly the result of the tidal flexing of Enceladus brought about by its orbital resonance with Dione. However, details of this heating process are still unclear and are being studied at this very moment.”

By way of comparison, Antarctica at it's coldest is about -120F. However, these kinds of surface temperatures at the distance of Saturn is pretty special.

Stockhausen's Ekranoplan Quartet (Elvis Telecom), Wednesday, 1 December 2010 00:50 (3 years ago) Permalink

3 months pass...

No CGI used in this fly-by video of Saturn - it's made up entirely of images

Stockhausen's Ekranoplan Quartet (Elvis Telecom), Wednesday, 16 March 2011 03:55 (3 years ago) Permalink

this is The Thread That Keeps On Giving. Great work again, ET.

Bill A, Wednesday, 16 March 2011 10:46 (3 years ago) Permalink

wow!!

Morty Maxwell (crüt), Wednesday, 16 March 2011 11:00 (3 years ago) Permalink

There's a nice interview with the guy who did it here.
http://www.outsideinthemovie.com/filmmaker/

I'm sorry, I did not create the cosmos, I merely explain it. (Ned Trifle II), Wednesday, 16 March 2011 11:02 (3 years ago) Permalink

Also additional vid on how he did some of it.

I'm sorry, I did not create the cosmos, I merely explain it. (Ned Trifle II), Wednesday, 16 March 2011 11:07 (3 years ago) Permalink

Holy fuck, that's just beautiful.

the most cuddlesome bug that ever was borned (James Morrison), Wednesday, 16 March 2011 22:54 (3 years ago) Permalink

2 months pass...

Cassiniqatsi

(sorry about the name... couldn't help myself. anyway, go watch it!)

Stockhausen's Ekranoplan Quartet (Elvis Telecom), Saturday, 11 June 2011 00:45 (3 years ago) Permalink

http://www.jpl.nasa.gov/news/news.cfm?release=2011-190

PASADENA, Calif. -- NASA's Cassini spacecraft has discovered the best evidence yet for a large-scale saltwater reservoir beneath the icy crust of Saturn's moon Enceladus. The data came from the spacecraft's direct analysis of salt-rich ice grains close to the jets ejected from the moon.

Data from Cassini's cosmic dust analyzer show the grains expelled from fissures, known as tiger stripes, are relatively small and predominantly low in salt far away from the moon. But closer to the moon's surface, Cassini found that relatively large grains rich with sodium and potassium dominate the plumes. The salt-rich particles have an "ocean-like" composition and indicate that most, if not all, of the expelled ice and water vapor comes from the evaporation of liquid salt water. The findings appear in this week's issue of the journal Nature.

"There currently is no plausible way to produce a steady outflow of salt-rich grains from solid ice across all the tiger stripes other than salt water under Enceladus's icy surface," said Frank Postberg, a Cassini team scientist at the University of Heidelberg, Germany, and the lead author on the paper. When water freezes, the salt is squeezed out, leaving pure water ice behind. If the plumes emanated from ice, they should have very little salt in them.

Stockhausen's Ekranoplan Quartet (Elvis Telecom), Thursday, 23 June 2011 01:15 (3 years ago) Permalink

I love me that probe.

Ned Raggett, Thursday, 23 June 2011 01:16 (3 years ago) Permalink

are they investigating the whole enceladus?

StanM, Thursday, 23 June 2011 02:26 (3 years ago) Permalink

3 months pass...

This recent picture of Enceladus is knocking me out.

The geyser jets are backlit by the sun and Enceladus here is lit by Saturn-shine.

Stockhausen's Ekranoplan Quartet (Elvis Telecom), Wednesday, 5 October 2011 01:34 (2 years ago) Permalink

wow

corey, Wednesday, 5 October 2011 01:45 (2 years ago) Permalink

Crazy great.

Ned Raggett, Wednesday, 5 October 2011 01:58 (2 years ago) Permalink

cool. but is that, like, a shit load of trucks coming towards us over the horizon?

Summer Slam! (Ste), Wednesday, 5 October 2011 08:24 (2 years ago) Permalink

Read the end of Elvis T's comment again...

Ned Raggett, Wednesday, 5 October 2011 12:36 (2 years ago) Permalink

Too late, I can only think of Sam Rockwell mining Enceladus...

willem, Wednesday, 5 October 2011 13:23 (2 years ago) Permalink

cool. but is that, like, a shit load of trucks coming towards us over the horizon?

― Summer Slam! (Ste), Wednesday, 5 October 2011 09:24 (5 hours ago) Bookmark Suggest Ban Permalink

otm looks like burning man

caek, Wednesday, 5 October 2011 13:28 (2 years ago) Permalink

5 months pass...

Time to migrate.

Ned Raggett, Wednesday, 7 March 2012 05:37 (2 years ago) Permalink

Subject line says it all: Massive Ice Avalanches on Iapetus

Reality Check Cashing Services (Elvis Telecom), Friday, 23 March 2012 23:56 (2 years ago) Permalink

2 weeks pass...

What things might sound like on Titan (the waterfall and splashdown sounds are great!)

Reality Check Cashing Services (Elvis Telecom), Tuesday, 10 April 2012 09:54 (2 years ago) Permalink

Reality Check Cashing Services (Elvis Telecom), Tuesday, 24 April 2012 00:22 (2 years ago) Permalink

the people i work with are v upset because this thing got selected by a science panel instead of an x-ray telescope, but tbh i think it looks awesome

http://sci.esa.int/science-e/www/area/index.cfm?fareaid=107

caek, Tuesday, 24 April 2012 00:29 (2 years ago) Permalink

some more links

http://www.bbc.co.uk/news/science-environment-17773383
andyxl.wordpress.com/2012/04/19/x-ray-astronomy-crunch/
andyxl.wordpress.com/2012/04/23/turbulence-in-the-gravy-waves/

caek, Tuesday, 24 April 2012 00:33 (2 years ago) Permalink

That's no moon, that's a Kuiper Belt Object

Saturn’s curious moon Phoebe features a heavily-cratered shape and orbits the ringed planet backwards at a considerable distance of over 8 million miles (12.8 million km). According to recent news from the Cassini mission Phoebe may actually be a Kuiper Belt object, having more in common with planets than it does with any of Saturn’s other satellites.

132 miles (212 km) in diameter, Phoebe is the largest of Saturn’s irregular moons — a cloud of small, rocky worlds held in distant orbits at highly inclined paths. Its backwards (retrograde) motion around Saturn and dense composition are dead giveaways that it didn’t form in situ within the Saturnian system, but rather was captured at some point when it strayed too close to the gas giant.

In fact it’s now thought that Phoebe may be a remnant from the formation of the Solar System — a planetesimal — with its own unique history predating its adoption into Saturn’s extended family of moons.

Reality Check Cashing Services (Elvis Telecom), Monday, 30 April 2012 02:57 (2 years ago) Permalink

juice confirmed: http://physicsworld.com/cws/article/news/2012/may/02/juice-picked-for-launch. launch in 2022, reaches jupiters moons in 2030, so perhaps a bit early to change the thread title, but it's going to be rad.

caek, Thursday, 3 May 2012 10:11 (2 years ago) Permalink

2 weeks pass...

it was a dark and stormy genitals. (Phil D.), Wednesday, 23 May 2012 13:19 (2 years ago) Permalink

4 months pass...

Looking at landslides on Iapetus: http://www.planetary.org/blogs/guest-blogs/20121001-iapetus-sturzstroms.html

Elvis Telecom, Wednesday, 3 October 2012 08:11 (1 year ago) Permalink

1 month passes...

Saturn's North Polar Vortex

Elvis Telecom, Wednesday, 28 November 2012 21:53 (1 year ago) Permalink

The vortex itself is just a small feature at the center of the northern hexagon

Elvis Telecom, Wednesday, 28 November 2012 21:54 (1 year ago) Permalink


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