Tag Archives: cassini probe

Titan Ligeia Mare.

Never before seen “magic island” pops up on Saturn’s Moon Titan

Titan Ligeia Mare.

Titan’s Ligeia Mare. Image via NASA.

Astronomers have discovered a previously unspotted geological feature on Saturn’s moon, Titan. Pictures taken by the Cassini probe revealed a transient geological feature – a “magic island”.

Now you see it, now you don’t

The bright, mysterious object was seen in Ligeia Mare, the second-largest sea on Saturn’s moon Titan. But Cassini took pictures of that area before, and the island wasn’t spotted – which can only mean that this is a transient geological feature, something which comes and goes. It’s not exactly clear what’s the cause, but astronomers have a few ideas.

Reporting in Nature Geoscience, scientists note that this is the first time an active geological feature was observed on Titan’s surface.

“This discovery tells us that the liquids in Titan’s northern hemisphere are not simply stagnant and unchanging, but rather that changes do occur,” said Jason Hofgartner, a Cornell University graduate student in the field of planetary sciences, and the paper’s lead author. “We don’t know precisely what caused this ‘magic island’ to appear, but we’d like to study it further.”

To discover the feature, astronomers relied on an old fashioned technique – flipping. The Cassini spacecraft sent forth a lot of data, which was received in July 2013. Hofgartner and his colleagues flipped between older Titan images and newer ones, relying on their own eyes to detect any changes. Despite being quite non-technological, this technique is often used to detect asteroids, comets and other small celestial objects.

“With flipping, the human eye is pretty good at detecting change,” said Hofgartner.

With previous observations, that area of the Ligeia Mare was completely devoid of any features – including waves. But in these newer pictures, they detected something else: an island, apparently popping up out of nowhere. It’s not clear exactly why it appeared, but the theory is that it showed up as a result of season changing, which on Titan takes much longer and is much stronger than on Earth.

Titan's Ligeia Mare.

Titan’s Ligeia Mare.

There are 4 proposed mechanisms:

– The nothern winds are causing waves, and what they are seeing is in fact a “ghost island” – a continuum of waves. This is the simplest theory, and the least spectacular (very likely though).

– Gases are pushing out from the sea floor, causing bubbles to burst towards the surface.

– As the water becomes warmer, sunken objects become buoyant and float towards the surface

– Ligeia Mare has suspended solids, which are neither sunken nor floating, but act like silt in a terrestrial delta.

It’s not clear which one of these is happening (or if we are in fact dealing with something else, completely different).

“Likely, several different processes — such as wind, rain and tides — might affect the methane and ethane lakes on Titan. We want to see the similarities and differences from geological processes that occur here on Earth,” Hofgartner said. “Ultimately, it will help us to understand better our own liquid environments here on the Earth.”

Surprising Titan

Titan is one of the most interesting places in the solar system. It’s been theoretized for quite a while that the moon harbors a liquid ocean beneath its frozen surface, and recent studies seem to back that idea up. Titan also has mountains made from ice, and it sometimes gets foggy. Along with Europa and Enceladus it is one of the likeliest places in the solar system to have alien life.

Source: Cornell University.

‘Waves’ detected on Titan moon’s lakes – Scientists detect waves on another world for the first time

We are detecting waves on a world 1,272,000,000 km away from Earth.

An interesting world

The signature of isolated ripples was observed in a sea called Punga Mare on the surface of Saturn’s moon Titan; but before you get overly excited, you should know that these seas are not filled with water, but with hydrocarbons like methane and ethane.

Titan is one strange place; it’s a satellite, but it’s bigger than Mercury. It’s also the only place in our solar system where evidence of liquid has been found on the surface, but wait, it gets even better – researchers believe that there is also an underground ocean, which might harbor life.

If you look at it a little, Titan has a lot in common with Earth. It has an atmosphere and seasonal cycles, river channels modeled by wind and rain, seas, dunes and even shorelines. But if you look at it even closer, you’ll also see just how different it is from our planet. The surface temperature on Titan is about -180degrees Celsius (-292 Fahrenheit). Its landforms are made of ice, rather than rock or sand, and liquid hydrocarbons take up many of the roles played by water on Earth. Just so you can get a sense of scale, one of these seas, Ligeia Mare, is estimated to contain about 9,000 cubic km of mostly liquid methane – about 40 times the proven reserves of oil and gas on Earth.

Titanic waves

An image of Titan’s north pole taken by the Cassini probe during a flyby in July 2012 shows sunlight being reflected from surface liquid in much the same way as a mirror re-directs light. The phenomenon is called specular reflection, and interestingly enough, has been described 2.000 years ago. Analyzing this reflection, scientists believe they can identify waves on the surface of Titan. Specifically, Dr Barnes, from the University of Idaho in Moscow, US, used a mathematical model to analyze the reflections, and showed that they are compatible with waves.

“We think we’ve found the first waves outside the Earth,” he told the meeting. What we’re seeing seems to be consistent with waves at just a few locations in Punga Mare [with a slope] of six degrees.”

This is not an absolute certainty, as he says that other causes such as a wet mudflat, could not be ruled out. But if they are indeed waves (as it seems more likely), the wind speed is estimated at about 0.75 m/s – a mere breeze. The waves are also estimated to be just 2cm high.

“Don’t make your surfing vacation reservations for Titan just yet,” Dr Barnes jokes.

However, as I said above, Titan also has seasonal changes – and pretty soon, it will undergo one. The winds are expected to intensify as this mysterious world will change season.

“The expectation is that any day now, the winds will start getting strong enough as we move into northern summer, and the waves will start picking up,” Ralph Lorenz, from the Johns Hopkins Applied Physics Laboratory (JHUAPL) in Maryland, told ZME Science. “You can also get a phenomenon known as wind set-up, where wind over a body of water will cause the liquid to pile up, potentially causing a storm surge.”

Weather on Titan

Artistic vision of weather on Titan.

Computer models of Titan’s weather suggest that in the norther hemisphere, the dry season is drawing closer to an end, and it’s almost rainy season. What happens during the rainy season? Hydrocarbons are “pumped” from the south pole to the north by the climate cycle, and, well, it will start raining hydrocarbons.

“We have a long-term picture of liquid levels rising in the north and declining in the south. But that’s against the backdrop of seeing what we think are evaporite deposits around the northern seas and lakes,” Dr Lorenz explained.

Astrophysicists and geophysicists are starting to put together more and more pieces of the puzzle… but it’s a really complicated puzzle. But one thing’s for sure – the liquids play a key role.

“Everything is really starting to come together, and the seas and lakes are very much becoming the central topic in Titan science.”

(c) NASA/JPL-CALTECH/SPACE SCIENCE INSTITUTE

Breathtaking photo captured by Cassini shows Earth as seen from Saturn

(c) NASA/JPL-CALTECH/SPACE SCIENCE INSTITUTE

(c) NASA/JPL-CALTECH/SPACE SCIENCE INSTITUTE

That faint blue dot at the center of this beautiful composition is none other than our very own blue marble – planet Earth. The opaque giant surrounded by the countless colored rings in the foreground is, as most of you have already guessed, Saturn.

Step back, take a moment to reflect over this picture and consider this was taken 560 million miles away by a space probe, named Cassini, designed, built and launched here on Earth. Yeah, WOOOOOW!

To catch this beautiful still, Cassini had to wait a while. As you can see from the photo, Saturn was in the dark and the sun was just about rising. These weren’t some lighting conditions that astronomers were hoping to catch for a nice picture, they’re they only kind of conditions you can see the Earth in from Saturn, and this does not happen very often. To get an idea, this is the first time Cassini, which has been orbiting Saturn since 2004, has taken a snapshot of our pale blue planet. This is because during much of the rest of the time, like is the case of observing Mercury from Earth, there is too much like coming in from the sun. You need to shoot right before or after the sun rises or sets.  A very rare occasion indeed, and today we’re ready to celebrate!

 

Saturnian storm caught choking on its own tail

The Uroburos is a mythological symbol representing a serpent or dragon eating its own tail – a symbol of cyclicality and eternal return. The Cassini spacecraft watching Saturn recently caught a glimpse of a storm that looks remarkably like the mythological creature – only it choked on its own tail.

saturn

This mosaic of false-color images from NASA’s Cassini spacecraft shows what a giant storm in Saturn’s northern hemisphere looked like about a month after it began. The bright head of the storm is on the left. Via NASA.

The storm came out incredibly violent, churned around the planet until it made it to the other side and back again, choking on its own tail.

“This Saturn storm behaved like a terrestrial hurricane – but with a twist unique to Saturn,” said Andrew Ingersoll, a Cassini imaging team member based at the California Institute of Technology, Pasadena, who is a co-author on the new paper in the journal Icarus. “Even the giant storms at Jupiter don’t consume themselves like this, which goes to show that nature can play many awe-inspiring variations on a theme and surprise us again and again.”

Earth’s hurricanes typically feed off energy from warmer waters, leaving behind a cold-water wake – this storm in Saturn’s northern hemisphere also feasted off warm “air” in the gas giant’s atmosphere in a similar fashion. From what we know of however, terrestrial storms have never encountered their own wakes – they stumble upon topographic features such as mountains and are blocked by them. The bright, turbulent storm head was able to stomp a path all the way across the planet, and it was only when it ran into itself again that it stopped.

saturn2

This is also a mosaic of false color.

“This thunder-and-lightning storm on Saturn was a beast,” said Kunio Sayanagi, the paper’s lead author and a Cassini imaging team associate at Hampton University in Virginia. “The storm maintained its intensity for an unusually long time. The storm head itself thrashed for 201 days, and its updraft erupted with an intensity that would have sucked out the entire volume of Earth’s atmosphere in 150 days. And it also created the largest vortex ever observed in the troposphere of Saturn, expanding up to 7,500 miles [12,000 kilometers] across.”

Every Saturn year (~30 Earth years), massive storms occur – but this one was definitely the largest in that period.

“Cassini’s stay in the Saturn system has enabled us to marvel at the power of this storm,” said Scott Edgington, Cassini‘s deputy project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “We had front-row seats to a wonderful adventure movie and got to watch the whole plot from start to finish. These kinds of data help scientists compare weather patterns around our solar system and learn what sustains and extinguishes them.”

Via NASA

Brightly reflective Enceladus (504 kilometers, 313 miles across) appears above the center of the image. Saturn's second largest moon, Rhea (1528 kilometers, 949 miles across), is bisected by the right edge of the image. The smaller moon Mimas (396 kilometers, 246 miles across) can be seen beyond Rhea also on the right side of the image. (c) NASA

Five of Saturn’s moons aligned [amazing photo]

Brightly reflective Enceladus (504 kilometers, 313 miles across) appears above the center of the image. Saturn's second largest moon, Rhea (1528 kilometers, 949 miles across), is bisected by the right edge of the image. The smaller moon Mimas (396 kilometers, 246 miles across) can be seen beyond Rhea also on the right side of the image. (c) NASA

Brightly reflective Enceladus (504 kilometers, 313 miles across) appears above the center of the image. Saturn's second largest moon, Rhea (1528 kilometers, 949 miles across), is bisected by the right edge of the image. The smaller moon Mimas (396 kilometers, 246 miles across) can be seen beyond Rhea also on the right side of the image. (c) NASA

On July 29th the Cassini orbiter probe captured a stunning glimpse of five of Saturn’s satellites beautifully aligned. Cassini has been sending incredible photos of Saturn and its surroundings since 2004, as well as remarkable insights like the discovery of a salty ocean under one of its moon’s surface. Click the photo for a larger view.

It’s the methane rainy season on Titan

On Saturn’s largest moon, Titan, precipitations under the form of methane has scientists staggered. NASA’s Cassini spacecraft, through the use of its infrared camera, detected signs of heavy spring rain of the highly flammable liquefied natural gas sprinkling across vast fields of dunes near Titan’s equator.

“They see for the very first time evidence of rainfall at the equator of Titan,” said planetary meteorologist Tetsuya Tokano at the University of Koln in Germany, who studies the moon but wasn’t involved in the project.

As opposed to Earth, Titan’s cycles of precipitation, evaporation and cloud formation involve hydrocarbons such as methane and ethane. At its two poles, the moon features thousands of such hydrocarbon filled lakes, many as big as the ones you can find at the Great Lakes.

Using the Cassini probe, the scientists led by planetary geologist Elizabeth Turtle at Johns Hopkins University in Maryland compared images of Titan’s dunes between August 2009 and this past January. They realized there was a  sudden decreases in the brightness of the moon’s surface after clouds had swept over the region, and after a swift analysis they concluded that the ground there had darkened because it was wet.

“It may be a case of surface wetting,” Dr. Turtle said. “It wouldn’t take much. A millimeter of rain over this area would have done it.” Their research was published in Science.

Titan is one of the most fascinating space bodies in our solar system, mostly because it’s the only moon known to have a dense atmosphere capable of forming precipitation and because it has weather patterns resembling Earth. This latest study offers important insights regarding Titan’s climate.

The researchers’ observations may help explain the presence of dry river beds in Titan’s equatorial region. Scientists have been unsure if these channels formed during wetter climates in the past or from occasional methane storms that then dried out.

“Equatorial precipitation is likely to occur near equinoxes,” Tokano said. “The rain belt, while being intermittent, swings between the south and north pole, so every area on Titan could experience rainfall in the course of a Titan year.”

For the upcoming months up ahead, Turtle and his colleagues will be busy watching Titan for more climate change insights, particularly looking to see if the precipitation travels into Titan’s northern hemisphere, as predicted by atmospheric models.

More posts involving the extraordinary Cassini space-craft covered by ZME Science can be found here.

Saturn may be surrounded by undiscovered partial rings

saturnThere are still so many things we don’t know about our solar system, and if by some way we manage to acquire information about it, probably many mysteries would be solved. Still, it’s always nice to see that scientists are not wasting time and almost every week they find something incredible.

For example, gaps in the soup of high energy particles near the orbits of two of Saturn’s tiny moons indicate that Saturn may be surrounded by undiscovered, near-invisible partial rings. aturn’s interior is hot (12000 K at the core) and Saturn radiates more energy into space than it receives from the Sun. Until 1980, the structure of the rings of Saturn was explained exclusively as the action of gravitational forces.

“These observations tell us that even Saturn’s smallest moons could be a source of dust in the Saturnian system,” said Elias Roussos, the paper’s lead author from the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany.

“What’s odd is that these inferred ring arcs still remain undetected in Cassini images, while the rings at Janus, Epimetheus and Pallene orbits, thought to form under the same process, are visible,” said Roussos. “This means the dust grains making up these two different classes of rings have different characteristics and sizes. However the reason behind this difference is a mystery.”