Tag Archives: Titan

Exploding nitrogen on Titan

A new theory proposes that some of the smaller high rimmed methane lakes on Titan were formed when underground nitrogen warmed and exploded, forming the basin in which the methane ponded.

Most existing models that lay out the origin of Titan’s lakes show liquid methane dissolving the moon’s bedrock of ice and solid organic compounds, carving reservoirs that fill with the liquid. This may be the origin of a type of lake on Titan that has sharp boundaries. On Earth, bodies of water that formed similarly, by dissolving surrounding limestone, are known as karstic lakes.

The new, alternative models for some of the smaller lakes (tens of miles across) turns that theory upside down: It proposes pockets of liquid nitrogen in Titan’s crust warmed, turning into explosive gas that blew out craters, which then filled with liquid methane. The new theory explains why some of the smaller lakes near Titan’s north pole, like Winnipeg Lacus, appear in radar imaging to have very steep rims that tower above sea level – rims difficult to explain with the karstic model.

This is a theory that has merit. It also must be treated with skepticism, as our knowledge of Titan remains at this time very superficial, even with the more detailed information garnered from Cassini.

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NASA announces mission to Titan

NASA today announced that it has approved a new mission to Titan, called Dragonfly, that will be a rotorcraft able to fly from place to place.

Dragonfly will launch in 2026 as part of NASA’s New Frontiers program, and is expected to arrive at Titan in 2034. ‘Dragonfly is a bold, game-changing way to explore the solar system,’ said APL Director Ralph Semmel. ‘This mission is a visionary combination of creativity and technical risk-taking that will help us unravel some of the most critical mysteries of the universe — including, possibly, the keys to our origins.’

Initially, Dragonfly will carry out a 2.7-year mission to explore different sites across Titan, including dunes and impact craters. Observations from the Cassini mission indicate these areas once held liquid water and complex organic materials. The dual quadcopter will sample these organic surface materials and measure their composition in effort to characterize the large moon’s habitability.

Dragonfly will first touchdown in an equatorial area known as the ‘Shangri-La’ dune fields, which have been compared to the Namibian dunes in southern Africa.

It will then complete ‘leapfrog’ flights of around 5 miles (8km) each to hop to other areas, stopping to take samples from each site.

I hate to throw cold water on this magnificent and ambitious mission, but I will not be at all surprised if it ends up costing more than expected and ends up getting delayed. NASA’s track record in the past decade with big projects on the cutting edge, as this appears to be, has been abysmal. Worse, I have seen little at NASA to make me thing any of this has changed enough to ease my mind for the next decade.

I hope I am wrong, because the concept is wonderful, and the target, Titan, is a critical solar system location that must be explored.

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Weird minerals discovered in simulated Titan environment

In recreating their best guess as to the conditions and environment of Saturn’s moon Titan, scientists have produced a number of weird never-before-seen minerals.

To create Titan-like conditions in the laboratory, the researchers started with a custom-built cryostat, an apparatus to keep things cold. They filled the cryostat with liquid nitrogen to bring the temperature down. They then warmed the chamber slightly, so the nitrogen turned to gas, which is mostly what Titan’s atmosphere contains. Next, they threw in what abounds on Titan, methane and ethane, as well as other carbon-containing molecules, and looked for what formed.

The first things to drop out of their Titan hydrocarbon soup were benzene crystals. Benzene is perhaps best known as a component of gasoline and is a snowflake-shaped molecule made out of a hexagonal ring of carbon atoms. But Titan benzene held a surprise: The molecules rearranged themselves and allowed ethane molecules inside, creating a co-crystal.

The researchers then discovered the acetylene and butane co-crystal, which is probably a lot more common on Titan than benzene crystals, based on what’s known about the moon’s composition, Cable said.

The scientists think that these crystals might be found on the edge of Titan’s methane lakes, encrusted there like a bathtub ring.

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Data from Cassini’s last fly-by of Titan

Based on data from Cassini’s last fly-by of Titan, scientists have been able to estimate the depth of some of that planet’s northern lakes while also finding that they were filled mostly with methane.

The depths measured were as much as 300 feet. The data also shows that the geology of one hemisphere in the north was different from the other hemisphere.

On the eastern side of Titan, there are big seas with low elevation, canyons and islands. On the western side: small lakes. And the new measurements show the lakes perched atop big hills and plateaus. The new radar measurements confirm earlier findings that the lakes are far above sea level, but they conjure a new image of landforms – like mesas or buttes – sticking hundreds of feet above the surrounding landscape, with deep liquid lakes on top.

The fact that these western lakes are small – just tens of miles across – but very deep also tells scientists something new about their geology: It’s the best evidence yet that they likely formed when the surrounding bedrock of ice and solid organics chemically dissolved and collapsed. On Earth, similar water lakes are known as karstic lakes. Occurring in in areas like Germany, Croatia and the United States, they form when water dissolves limestone bedrock.

This data also suggests, as has previous data, that Titan could very well have extensive underground cave systems. Unlike the Moon or Mars, however, these are not going to be very hospitable to colonization, considering the presence of methane and the cold temperatures.

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Summer has finally arrived on Titan’s northern hemisphere

The uncertainty of science: In a review of Cassini data from 2016, scientists have finally identified rain in the northern polar regions of Titan, signaling the onset of summer there.

The whole Titan community has been looking forward to seeing clouds and rains on Titan’s north pole, indicating the start of the northern summer, but despite what the climate models had predicted, we weren’t even seeing any clouds,” said Rajani Dhingra, a doctoral student in physics at the University of Idaho in Moscow, and lead author of the new study accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union. “People called it the curious case of missing clouds.”

Dhingra and her colleagues identified a reflective feature near Titan’s north pole on an image taken June 7, 2016, by Cassini’s near-infrared instrument, the Visual and Infrared Mapping Spectrometer. The reflective feature covered approximately 46,332 square miles, roughly half the size of the Great Lakes, and did not appear on images from previous and subsequent Cassini passes.

Analyses of the short-term reflective feature suggested it likely resulted from sunlight reflecting off a wet surface. The study attributes the reflection to a methane rainfall event, followed by a probable period of evaporation. “It’s like looking at a sunlit wet sidewalk,” Dhingra said.

Though the data somewhat matches their climate models, those models did not predict the rain’s late arrival, which means they need revision. I guarantee that this will not be the last revision, though without an orbiter at Saturn it will probably be decades before we have new data to make that possible.

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Dust storms spotted on Titan

Scientists reviewing Cassini data have identified dust storms for the first time of Saturn’s moon Titan.

When Rodriguez and his team first spotted three unusual equatorial brightenings in infrared images taken by Cassini around the moon’s 2009 northern equinox, they thought they might be the same kind of methane clouds; however, an investigation revealed they were something completely different. “From what we know about cloud formation on Titan, we can say that such methane clouds in this area and in this time of the year are not physically possible,” said Rodriguez. “The convective methane clouds that can develop in this area and during this period of time would contain huge droplets and must be at a very high altitude — much higher than the 6 miles (10 kilometers) that modeling tells us the new features are located.”

The researchers were also able to rule out that the features were actually on the surface of Titan in the form of frozen methane rain or icy lavas. Such surface spots would have a different chemical signature and would remain visible for much longer than the bright features in this study, which were visible for only 11 hours to five weeks.

In addition, modeling showed that the features must be atmospheric but still close to the surface — most likely forming a very thin layer of tiny solid organic particles. Since they were located right over the dune fields around Titan’s equator, the only remaining explanation was that the spots were actually clouds of dust raised from the dunes.

Obviously there are large uncertainties here. Nonetheless, the conclusion is a reasonable one, as it is expected that such dust storms would occur on Titan.

Posted just outside Zion National Park in the town of Springdale.

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Cassini’s last view of Titan

The Cassini science team today released a mosaic of the last images Cassini took of Titan before it crashed into Saturn’s atmosphere four days layer.

The mosaic shows Titan’s north polar region, and shows seas, lakes, and spotty clouds. The lack of clouds is a puzzle to scientists, as they had expected the north polar region to be cloud-covered at this time as summer arrived there, as had been seen at the south pole.

During Titan’s southern summer, Cassini observed cloud activity over the south pole.

However, typical of observations taken during northern spring and summer, the view here reveals only a few small clouds. They appear as bright features just below the center of the mosaic, including a few above Ligeia Mare. “We expected more symmetry between the southern and northern summer,” said Elizabeth (“Zibi”) Turtle of the Johns Hopkins Applied Physics Lab and the Cassini Imaging Science Subsystem (ISS) team that captured the image. “In fact, atmospheric models predicted summer clouds over the northern latitudes several years ago. So, the fact that they still hadn’t appeared before the end of the mission is telling us something interesting about Titan’s methane cycle and weather.”

The truth is we haven’t the slightest idea whether the clouds over the south pole during its previous summer were normal or an aberration. We have barely seen a full year of seasons at Saturn and Titan. To confidently extrapolate any pattern from this slim data is silly.

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Global mosiacs of Titan in infrared

Titan in infrared

The Cassini science team today released global infrared mosaics of Titan, created from images accumulated during the more than 100 fly-bys of the moon during the spacecraft’s thirteen years in orbit around Saturn.

The image on the right, cropped and reduced in resolution to post here, is only one such global mosaic. Go to the story to see them all.

Making mosaics of VIMS images of Titan has always been a challenge because the data were obtained over many different flybys with different observing geometries and atmospheric conditions. One result is that very prominent seams appear in the mosaics that are quite difficult for imaging scientists to remove. But, through laborious and detailed analyses of the data, along with time consuming hand processing of the mosaics, the seams have been mostly removed. This is an update to the work previously discussed in PIA20022.

Any full color image is comprised of three color channels: red, green and blue. Each of the three color channels combined to create these views was produced using a ratio between the brightness of Titan’s surface at two different wavelengths (1.59/1.27 microns [red], 2.03/1.27 microns [green] and 1.27/1.08 microns [blue]). This technique (called a “band-ratio” technique) reduces the prominence of seams, as well as emphasizing subtle spectral variations in the materials on Titan’s surface. For example, the moon’s equatorial dune fields appear a consistent brown color here. There are also bluish and purplish areas that may have different compositions from the other bright areas, and may be enriched in water ice.

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Titan’s liquid hydrocarbon seas have a global sea level

New research using Cassini data has revealed that the liquid hydrocarbon oceans of Saturn’s moon Titan have a global sea level, with some small lakes perched at higher elevations.

The new study suggests that elevation is important because Titan’s liquid bodies appear to be connected under the surface in something akin to an aquifer system at Earth. Hydrocarbons appear to be flowing underneath Titan’s surface similar to the way water flows through underground porous rock or gravel on Earth, so that nearby lakes communicate with each other and share a common liquid level.

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Two finalists for 2020 deep space planetary mission picked by NASA

NASA has narrowed its choice for a 2020s deep space planetary mission to two finalists, either a sample return mission to Comet 67P/C-G or a drone that would fly through Titan’s atmosphere.

The sample return mission sounds very doable with today’s technology. The Titan drone mission however is far more intriguing.

Dragonfly is a dual-quadcopter lander that would take advantage of the environment on Titan to fly to multiple locations, some hundreds of miles apart, to sample materials and determine surface composition to investigate Titan’s organic chemistry and habitability, monitor atmospheric and surface conditions, image landforms to investigate geological processes, and perform seismic studies.

If it was up to me and I had unlimited funds, I’d go with Dragonfly. We know far less about the outer solar system, and this mission would be an ideal way to increase that knowledge. It is also far more daring, which carries the risk that the costs to build and launch will rise uncontrollably.

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Storms on Titan dump a lot of liquid methane, quickly

A new climate model for Titan that suggests the planet’s methane rainstorms occur about once a Saturn year (29.5 years) and at about 60 degree latitude correlates with Cassini surface data that found a high concentration of alluvial fans at that latitude.

“The most intense methane storms in our climate model dump at least a foot of rain a day, which comes close to what we saw in Houston from Hurricane Harvey this summer,” said Mitchell, the principal investigator of UCLA’s Titan climate modeling research group.

Sean Faulk, a UCLA graduate student and the study’s lead author said the study also found that the extreme methane rainstorms may imprint the moon’s icy surface in much the same way that extreme rainstorms shape Earth’s rocky surface. On Earth, intense storms can trigger large flows of sediment that spread into low lands and form cone-shaped features called alluvial fans. In the new study, the UCLA scientists found that regional patterns of extreme rainfall on Titan are correlated with recent detections of alluvial fans, suggesting that they were formed by intense rainstorms.

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Cassini’s last close look at Titan

Titan's magic lake district

The Cassini science team has released the last radar swath that the spacecraft will take of Titan, imaged on April 22.

You can see the full swath up close here. The image above is my crop of the section on the swath’s right portion, showing the shoreline of the hydrocarbon lake Ligeia Mare, where periodically an island has been seen by radar to intermittently appear and disappear.

No “island” feature was observed during this pass. Scientists continue to work on what the transient feature might have been, with waves and bubbles being two possibilities.

The fly-by also took the first, and last, depth measurement of 8 other lakes, finding that they all had the same depth, suggesting they are connected by an underground “water” table. In this case, it ain’t water, but liquid hydrocarbons like methane.

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Titan’s clearing northern skies

Titan's clearing northern skies

The image of Titan on the right, reduced in resolution to show here, was taken by Cassini less than a week ago, on June 9, as it continues its last orbits of Saturn prior to crashing into the gas giant’s atmosphere in September.

NASA’s Cassini spacecraft sees bright methane clouds drifting in the summer skies of Saturn’s moon Titan, along with dark hydrocarbon lakes and seas clustered around the north pole. Compared to earlier in Cassini’s mission, most of the surface in the moon’s northern high latitudes is now illuminated by the sun. …Summer solstice in the Saturn system occurred on May 24, 2017.

When Cassini arrived more than a decade ago, it was winter on Titan’s northern hemisphere, and the atmosphere was thick with haze. Now the sky is clearing as the stormy weather shifts to the winter in the southern hemisphere.

As with yesterday’s global map of Mimas, this image is in many ways a farewell look at Titan. While Cassini will likely get a few more global images of the Saturn moon before the mission ends in September, this image essentially marks the end of our ability to observe this strange planet closely, for decades to come. When Cassini crashes into Saturn, our vision at Saturn will go blind. And no one knows when our sight there will return, as no mission is presently in the works, or is even being considered, to return to Saturn.

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Cassini makes last fly-by of Titan

Cassini on April 21 made its last fly-by of Titan as the spacecraft is prepared for its final 22 orbits of Saturn.

The flyby also put Cassini on course for its dramatic last act, known as the Grand Finale. As the spacecraft passed over Titan, the moon’s gravity bent its path, reshaping the robotic probe’s orbit slightly so that instead of passing just outside Saturn’s main rings, Cassini will begin a series of 22 dives between the rings and the planet on April 26. The mission will conclude with a science-rich plunge into Saturn’s atmosphere on Sept. 15. “With this flyby we’re committed to the Grand Finale,” said Earl Maize, Cassini project manager at JPL. “The spacecraft is now on a ballistic path, so that even if we were to forgo future small course adjustments using thrusters, we would still enter Saturn’s atmosphere on Sept. 15 no matter what.”

The flyby zipped past Titan only a little more than 600 miles above its surface.

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Titan’s fizzy oceans?

New research suggests that the hydrocarbon lakes of Titan might periodically fizz with nitrogen bubbles.

A recent NASA-funded study has shown how the hydrocarbon lakes and seas of Saturn’s moon Titan might occasionally erupt with dramatic patches of bubbles.

For the study, researchers at NASA’s Jet Propulsion Laboratory in Pasadena, California, simulated the frigid surface conditions on Titan, finding that significant amounts of nitrogen can be dissolved in the extremely cold liquid methane that rains from the skies and collects in rivers, lakes and seas. They demonstrated that slight changes in temperature, air pressure or composition can cause the nitrogen to rapidly separate out of solution, like the fizz that results when opening a bottle of carbonated soda.

These results might help explain the mysterious islands that seem to appear and disappear and then reappear in Titan’s lakes. Rather than islands, they might be patches of nitrogen bubbles.

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Changing seasons on Titan

Since entering Saturn orbit in 2004, Cassini has seen the seasons on Titan shift through half a Saturn year.

As Titan approaches its northern summer solstice, NASA’s Cassini spacecraft has revealed dramatic seasonal changes in the atmospheric temperature and composition of Saturn’s largest moon. Winter is taking a grip on the southern hemisphere and a strong vortex, enriched in trace gases, has developed in the upper atmosphere over the south pole. These observations show a polar reversal in Titan’s atmosphere since Cassini arrived at Saturn in 2004, when similar features were seen in the northern hemisphere.

Sadly, there will not be any spacecraft at Saturn during the second half of this Saturn year. After Cassini ends its mission in 2017 it will likely be many decades before another spacecraft arrives, since at this moment none has even been proposed.

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Rivers of liquid carved deep gorges on Titan

Cassini radar data of Via Flumina

Cool image time! New data from Cassini has now both confirmed that there is liquid inside some of the river-like formations on Titan, and that this liquid has carved these formations into very deep gorges.

The Cassini observations reveal that the channels — in particular, a network of them named Vid Flumina — are narrow canyons, generally less than half a mile (a bit less than a kilometer) wide, with slopes steeper than 40 degrees. The canyons also are quite deep — those measured are 790 to 1,870 feet (240 to 570 meters) from top to bottom.

The branching channels appear dark in radar images, much like Titan’s methane-rich seas. This suggested to scientists that the channels might also be filled with liquid, but a direct detection had not been made until now. Previously it wasn’t clear if the dark material was liquid or merely saturated sediment — which at Titan’s frigid temperatures would be made of ice, not rock.

The diagram on the above right is from the paper itself, and shows some of the radar data obtained by Cassini. It also illustrates the deep and narrow nature of Via Flumina. This is almost the equivalent of what we call slot canyons on Earth, formed by periodic flash floods that cut their way down as the surface is slowly uplifted by other processes.

The new radar data showed that the surface at the base of the gorge was smooth and flat, just as you’d find if that base was filled with liquid.The altimeter data showed that gorge’s elevation matched that of Titan’s lakes at its insurgence, but as you traveled upstream the elevation rose, just as it does on any river on Earth. Moreover, this data was reasonably trustworthy as they had already used Cassini to successfully do exactly the same thing — identify a known river — when it flew past Earth on its way to Saturn.

Be prepared for one piece of misinformation when the press reports on this story, almost certainly caused by the American Geological Union’s press release about this paper. That press release incorrectly claims that the paper confirmed that these are methane rivers. It does no such thing. It only shows that the gorges have a liquid in them, and that the liquid almost certainly formed the gorges. Though methane is a very likely candidate for this liquid based on what we know of Titan, the actual make-up of the river remains uncertain.

I therefore predict our incompetent modern mainstream press will only read this press release and not the paper itself, and thus they will tout these incorrectly as methane rivers.

Below is a cropped Cassini radar image of Via Flumina, showing its river-like appearance. Scientists always suspected these were formed by flowing liquid. Now they have strong evidence from within the gorge to justify that suspicion.

Via Flumina on Titan

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Titan over Saturn’s rings

Titan over Saturn's rings

Cool image time! The picture on the right, taken on January 26, 2016 by Cassini and reduced and cropped to show here, captures Titan above Saturn’s rings, which are themselves partly obscured by the shadow of Saturn (unseen on the right) that falls across them.

Make sure you go to look at the full image. This is the kind of vista that artists in the 1950s imagined we’d see once we began to explore the solar system.

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The methane seas of Titan

Scientists have used the data that Cassini has gathered in more than a hundred fly-bys of Titan to assemble a rough outline of the geology and make-up of Titan’s liquid lakes.

There are three large seas, all close to the north pole, surrounded by dozens of smaller lakes in the northern hemisphere. Just one lake has been found in the southern hemisphere. The exact make-up of these liquid reservoirs remained elusive until recently. A new study using scans from Cassini’s radar during flybys of Titan between 2007 and 2015 confirms that one of the largest seas on the moon, Ligeia Mare, is mostly liquid methane.

“We expected to find that Ligeia Mare would be mostly ethane, which is produced in abundance in the atmosphere when sunlight breaks methane molecules apart,” explains Alice Le Gall from the Laboratoire Atmosphères, Milieux, Observations Spatiales and Université Versailles Saint-Quentin, France, and lead author of the new study. “Instead, this sea is predominantly made of pure methane.”

The data is also giving them the first understanding of the weather and geology that forms the lakes, including why methane instead of ethane dominates.

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Titan’s changing shorelines

Shoreline changes on Titan

Cool image time! Using radar images taken during the past decade by Cassini scientists have discovered changes taking place along the shorelines of Titan’s hydrocarbon seas.

Analysis by Cassini scientists indicates that the bright features, informally known as the “magic island,” are a phenomenon that changes over time. They conclude that the brightening is due to either waves, solids at or beneath the surface or bubbles, with waves thought to be the most likely explanation. They think tides, sea level and seafloor changes are unlikely to be responsible for the brightening.

The images in the column at left show the same region of Ligeia Mare as seen by Cassini’s radar during flybys in (from top to bottom) 2007, 2013, 2014 and 2015.

These shoreline changes are not the only ones spotted by Cassini. However, because these are radar images, not visual, there are many uncertainties about what causes the changes, which is why they list several possibilities. For example, with radar, a simple roughness on the surface (such as waves) could cause a brightening.

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New global maps of Titan

Titan's North Pole

The Cassini science team has released new maps of Titan, including new maps of both poles, assembled from images taken during the 100 flybys that the spacecraft has made of the moon since it arrived in orbit around Saturn.

The scale is rough, just less than a mile at best, and there is no topographic information because the thick atmosphere allows for no strong sunlight or shadows. The images show differences in surface brightness, which does tell us where Titan’s dark methane lakes are.

This is likely the best we will get of Titan for decades, until another spacecraft is sent there.

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The seas of Titan

Thar’s black gold up thar! Data from Cassini has confirmed the presence of ocean waves on Titan’s seas, while also providing suggesting that they are made mostly of liquid methane, not ethane as had been predicted.

The maximum depth of Kraken Mare appears to be 160 meters, and Ligeia Mare could be as much as 200 meters deep, reported Marco Mastrogiuseppe of Sapienza University of Rome. The fact that the radar signals could bounce off the sea bottom suggests that the seas were more transparent than expected and thus must contain mostly methane, not ethane. Hayes says his best estimate is about 90% methane. Essam Marouf, a planetary scientist at San José State University in California, reported on the first results from a separate radar experiment that sent radar reflections to Earth instead of back to the spacecraft. Those tests provide independent evidence that the seas are dominated by methane, Marouf says, and it implies that the lakes are kept filled by precipitating methane.

As the article also notes, this methane is “55 times Earth’s oil reserves.”

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Titan’s atmosphere is unexpectedly unbalanced

The uncertainty of science: New data from the ground-based telescope ALMA suggest that certain organic molecules in Titan’s atmosphere are not evenly distributed through the atmosphere as expected.

At the highest altitudes, the pockets of organic molecules were shifted away from the poles. These off-pole concentrations are unexpected because the fast-moving, east-west winds in Titan’s middle atmosphere should thoroughly mix the molecules formed there. The researchers do not have an obvious explanation for these findings yet.

I would not take these results too seriously, as the data are very sketchy. With better data many of these questions will vanish, replaced by new questions that are better based on reality.

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