Tag Archives: titan

Titan’s largest methane sea is over 1000 feet deep, says a new paper

Titan’s seas should be deep enough for a robotic submarine to wade through, a new paper explains. This should help pave the way towards our exploration of Titan’s depths.

Radar map of the polar region of Saturn’s moon Titan. Image credits NASA / JPL-Caltech.

Fancy a dip? Who doesn’t. But if you ever find yourself on Titan, Saturn’s biggest moon, you should stay away from swimming areas. A new paper reports that the Kraken Mare, the largest body of liquid methane on the moon’s surface is at least 1,000 feet deep near its center, making it both very deep and very cold.

While that may not be very welcoming to humans, such findings help increase our confidence in plans of exploring the moon’s oceans using autonomous submarines. It was previously unknown if Titan’s methane seas were deep enough to allow such a craft to move through.

Faraway seas

“The depth and composition of each of Titan’s seas had already been measured, except for Titan’s largest sea, Kraken Mare—which not only has a great name, but also contains about 80% of the moon’s surface liquids,” said lead author Valerio Poggiali, a research associate at the Cornell Center for Astrophysics and Planetary Science (CCAPS).

Titan is a frozen moon that shines with a golden haze as sunlight glints on its nitrogen-rich atmosphere. Beyond that, however, it looks surprisingly Earth-like with liquid rivers, lakes, and seas sprawling along its surface. But these are not made of water — they’re filled with ultra-cold liquid methane.

The findings are based on data from one of the last Titan flybys made during the Cassini mission (on Aug. 21, 2014). During this flyby, the probe’s radar was aimed at Ligeia Mare, a smaller sea towards the moon’s northern pole. Its goal was to understand the mysterious “Magic Island” that keeps disappearing and then popping back up again.

Its radar altimeter measured the liquid depth at Kraken Mare and Moray Sinus (an estuary on the sea’s northern shore). The authors of the paper, made up of members from both NASA’s Jet Propulsion Laboratory and Cornell University, used this data to map the bathymetry (depth) of the sea. They did this by tracking the return time on the radar’s signal for the liquid’s surface and the sea bottom while taking into account the methane’s effect on the signal (it absorbs some of the energy from the radio wave as it passes through, in essence dampening it to an extent).

Colorized mosaic of Titan’s Kraken Mare. Liquids are blue and black, land areas appear yellow to white. The surface was mapped using radar data from NASA’s Cassini. Image credits NASA / JPL-Caltech / Agenzia Spaziale Italiana / USGS via Wikimedia.

According to them, the Moray Sinus is about 280 feet deep, and the Kraken Mare gets progressively deeper towards its center. Here, the sea is too deep for the radar signal to pierce through, so we don’t know its maximum depth. The data also allowed us some insight into the chemical composition of the sea: a mix of ethane and methane, dominated by the latter. This is similar to the chemical composition of Ligeia Mare, Titan’s second-largest sea, the team explains. It might seem inconsequential, but it’s actually a very important piece of information: it suggests that Titan has an Earth-like hydrologic system.

Kraken Mare (‘mare’ is Latin for ‘sea’) is our prime choice for a Titan-scouting submarine due to its size — it is around as large as all five of America’s Great Lakes put together. We also have no idea why this sea doesn’t just evaporate. Sunlight is about 100 times less intense on Titan than Earth, but it’s still enough to make the methane evaporate. According to our calculations, this process should have completely depleted the seas in around 10 million years, but evidently, that didn’t happen. This is yet another mystery our space-faring submarine will try to answer.

“Thanks to our measurements,” he said, “scientists can now infer the density of the liquid with higher precision, and consequently better calibrate the sonar aboard the vessel and understand the sea’s directional flows.”

The paper “The Bathymetry of Moray Sinus at Titan’s Kraken Mare” has been published in the journal Journal of Geophysical Research: Planets.

First geological map of Titan reveals varied, intriguing geology

Different infrared views of Titan. Image credits: NASA / JPL.

Titan’s atmosphere is dense and hazy, just like Earth’s. The satellite also features intricate, stable bodies of liquid on its surface. But that’s where the similarities with the Earth end. Titan’s liquid isn’t water, but hydrocarbon (mostly methane). It’s atmosphere — 97% nitrogen, the rest methane and hydrogen.

Titan’s remarkable features make it extremely interesting for astronomers and geologists alike. It may not have water or oxygen, but aside from Earth, Titan is still the only body in the solar system to have an atmosphere and hydrologic system, which has a significant impact on its surface and evolution. However, its hazy atmosphere hinders our view of the surface, and it has been difficult to obtain a global vision of Titan’s geology.

Even after Titan was examined by both Voyager 1 and 2 in 1980 and 1981, respectively, it remained a mysterious object — a large satellite shrouded in an atmosphere too thick to enable observation.

All that changed with the Cassini mission. Armed with state of the art technology and perfectly equipped to deal with the planet’s rough conditions, Cassini revealed Titan in unprecedented detail.

Rosaly Lopes from NASA’s Jet Propulsion Laboratory and colleagues used data gathered with infrared and radar instruments aboard Cassini to reconstruct and map Titan’s surface, including its poles. They identified six major geological forms, describing their approximate age and distribution around the globe. While Titan’s geology has been mapped before, this is the most comprehensive map of its kind.

Titan’s main geological features. Image credits: Lopes et al.

Titan’s geology depends strongly on latitude. Most of the satellite is covered by featured organic plains, which are widespread at mid-latitudes. But around the equator, young dune fields and hydrocarbon lakes dominate the landscape. These dunes, most of which measure 80-130 meters high, are the second-most extensive unit on Titan. Another important feature is the hummocky landscape — rocky mounds that are exposed as isolated peaks or ranges, gently undulating from mid to high latitudes, generally aligned east-west. These structures may have formed through tectonic activity, early in Titan’s history.

Titan also features lakes and seas, either dry or liquid-filled. The polar regions alone contain over 650 lakes, the majority being in the northern polar region.

Titan isn’t a static environment. Its surface has been changed by several geological processes, including impact cratering, precipitation, tectonism, as well as erosion. Given its hydrocarbon-rich surface, Titan is also riddled in organic material. This material is constantly eroded, shifted, deposited, and transported. All these interactions make Titan’s geology much more difficult to understand — which is why a geological map comes in handy.

These observations demonstrate the extent to which Titan is shaped by its methane cycle — just like the Earth is shaped by the water cycle. The polar areas are humid enough to keep liquid bodies of methane, whereas the arid equatorial climate keeps wind-shaped dunes intact.

Titan’s sand dunes could be caused by cosmic rays

Titan’s sand dunes cover over 10 million square kilometres of the moon’s surface, an area about the size of the US, including Alaska.

Saturn’s largest moon has long intrigued scientists as its chemical composition is believed to mirror that of our own primordial planet. Now, thanks to new data obtained by researchers by the University of Hawaii (UH) at Manoa, we might be able to provide some answers to key question’s about Titan’s surface.

The team, led by physical chemist Ralf I. Kaiser, examined remote sensing data from NASA’s Cassini-Huygens mission to Titan to study its huge swathes of desert which are covered in sand dunes. These dunes stretch across the moon’s equatorial region in a space over 10 million kilometers (6,213,712 miles) and reach heights of up to about 100 meters in some places — think Egyptian pyramids tall.

The UH Manoa team exposed acetylene ice — a chemical that is used on Earth in welding torches and exists at Titan’s equatorial regions — at low temperatures to proxies of high-energy galactic cosmic rays.

“Titan’s dunes represent the dominating surface sink of carbon in Titan’s organic chemistry,” said Matthew Abplanalp, former chemistry graduate student at UH’s W.M. Keck Research Laboratory in Astrochemistry, and current researcher at the Naval Air Warfare Center Weapons Division at China Lake. “Therefore, unraveling the origin and chemical pathways to form this organic dune material is vital not only to understand Titan’s chemical evolution, but also to grasp how alike the chemistries on Titan and on Earth might have been like before life emerged on Earth 3.5 million years ago.”

The UH researchers exposed a rapid cosmic-ray-driven chemistry which converts simple molecules like acetylene to more complex organic molecules like benzene and naphthalene, a compound which is found in mothballs, but hopefully without the scent.

These findings will have unprecedented implications for the next space mission to Titan. In 2034, the three‐meters‐long Dragonfly rotorcraft will land in the ‘Shangri‐La’ dune‐fields near the moon’s equator. From there, it will use 1its eight rotors to traverse dozens of sites across Titan’s surface, taking samples and performing analysis. The purposes of the mission is to search for alien life and its molecular precursors.

“Overall, this study advances our understanding of the complex organics and fundamental chemical processing of simple molecules in deep space and provides a scientifically sound and proven mechanism of formation of aromatic structures in extreme environments in low temperature ices,” Kaiser concluded. “Since Titan is nitrogen-rich, the incorporation of nitrogen in these PAHs may also lead to carbon-nitrogen moieties (parts of a molecule) prevailing in contemporary biochemistry such as in DNA and RNA-based nitrogen-bases.”

Discovered in 1655 by the Dutchman Christiaan Huygens, Titan is located approximately 760,000 miles (1,223,101 kilometers) from Saturn. Cassini showed us that Titan’s surface has lakes, rivers, and even seas of liquid ethane and methane (the main component of natural gas), as well as vast expanses of sand dunes. Its climate is such that the methane can form clouds and even rain, as water does here on Earth. The moon’s atmosphere is four times denser than ours and its gravity is approximately 1/7th of Earth’s. Because it is so far from the Sun, Titan’s surface temperature hovers around a chilly ‐290 degrees Fahrenheit (‐179 degrees Celsius).

Dragonfly.

NASA plans to send a helicopter drone to Titan in search of life

This Thursday, NASA announced a new mission to Saturn’s largest moon, Titan.

Dragonfly.

Image credits Johns Hopkins / APL.

NASA’s next mission will take it to Titan. The Agency plans to send a drone helicopter the moon to search for the building blocks of life. Christened ‘Dragonfly‘, the mission will launch in 2026 and land Titan-side in 2034. The copter will then fly to dozens of locations across the moon on the back of Titan’s relatively thick atmosphere. Titan is of interest because it is the only body in our solar system (besides Earth) that has liquid rivers, lakes, and seas on its surface.

Fly, dragonfly

“Visiting this mysterious ocean world could revolutionize what we know about life in the universe, ” said NASA administrator Jim Bridenstine. “This cutting-edge mission would have been unthinkable even just a few years ago, but we’re now ready for Dragonfly’s amazing flight.”

The drone will be propelled by eight rotors over a 2.7-year-long mission, during which it will explore environments ranging from “organic dunes to the floor of an impact crater where liquid water and complex organic materials key to life once existed together for possibly tens of thousands of years,” NASA said in a statement. The goal of Dragonfly is to study how far along Titan’s chemistry has progressed towards life. Another point of interest is the moon’s atmospheric and surface properties, as well as its subsurface ocean and liquid reservoirs.

“Additionally, instruments will search for chemical evidence of past or extant life,” the statement adds.

The craft will first land on Titan’s equator to explore the region, and will then move around the area in short trips. A series of flights 5 miles- (8 kilometer)-long are also planned after that, to get the drone to various points of interest around Titan. It will collect samples at these points, and then make its way to the Selk impact crater, where there is evidence of a possible ‘primordial stew’ of liquid water, organic materials, and energy. All in all, the lander will eventually fly more than 108 miles (175 kilometers).

Titan’s atmosphere is made mostly of nitrogen, like Earth’s, but is four times denser. Its clouds and rains are methane, which pool into hydrocarbon lakes on the surface. The moon’s underground ocean, however, could harbor life as we know it.

Saturn’s moon Titan has rainfall and seasons

Titan has seas, lakes, and rivers — and now, researchers have found, it also has rainfall and seasonal variation.

A false-color radar mosaic of Titan’s north polar region. Blue coloring depicts hydrocarbon seas, lakes and tributary networks filled with liquid ethane, methane and dissolved nitrogen. Image credits: NASA / JPL-Caltech / USGS.

If you’d picture a place that has an atmosphere and liquids on its surface, it probably wouldn’t be Titan. This frigid moon is only 50% larger than Earth’s moon and mostly consists of ice and rocky material. It features a young and smooth geological surface, with few volcanic or impact craters, and remarkably, it has not only an atmosphere, but also geological features dunes, rivers, lakes, seas, and even deltas. But there’s a key difference.

Unlike Earth’s seas, which consist of water, Titan’s seas consist of hydrocarbons such as methane and ethane.

Conversely, Titan features a nitrogen atmosphere and has a nitrogen cycle analogous to Earth’s carbon cycle, something which stunned astronomers when it was first discovered. The Cassini mission, which landed a probe on Titan in 2005, first revealed a surface which seemed to be shaped by fluids.

But Titan has far from shared all its secrets. Recently, astronomers have analyzed images suggesting that intense rainfall occurs on Titan, indicating the start of “summer” in the northern hemisphere. It’s something researchers were expecting for a long time, especially as rain had been previously observed in the southern hemisphere.

“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. “People called it the curious case of missing clouds.”

New research provides evidence of rainfall on the north pole of Titan, the largest of Saturn’s moons, shown here. The rainfall would be the first indication of the start of a summer season in the moon’s northern hemisphere, according to the researchers. Credit: NASA/JPL/University of Arizona.

The image was taken in 2016, by the near-infrared instrument on the Cassini probe, which offered the bulk of what we know about Titan. The instrument spotted a reflective feature covering approximately 46,332 square miles, which did not seem to appear on any other images of Cassini. The analyses suggest that this reflective feature represents a wet surface.

“It’s like looking at a sunlit wet sidewalk,” Dhingra said.

So we have a strong confirmation that seasons are happening on Titan, which confirms the predictions astronomers made. However, this poses a new question that researchers will have to answer.

“We want our model predictions to match our observations.” Dhingra said. “Summer is happening. It was delayed, but it’s happening. We will have to figure out what caused the delay, though.”

The study was published in Geophysical Research Letters.

Artist impression of a dust storm on Titan. Credit: IPGP/Labex UnivEarthS/University Paris Diderot – C. Epitalon & S. Rodriguez.

Scientists spot dust storms on Titan for the first time

Artist impression of a dust storm on Titan. Credit: IPGP/Labex UnivEarthS/University Paris Diderot – C. Epitalon & S. Rodriguez.

Artist impression of a dust storm on Titan. Credit: IPGP/Labex UnivEarthS/University Paris Diderot – C. Epitalon & S. Rodriguez.

Although Titan is a moon, it has an intriguing geology and, in many aspects, is very similar to Earth. Titan has a substantial atmosphere and is the only body in the solar system other than Earth to host stable liquid (in its case, methane) on its surface. Now, researchers have identified giant dust storms in equatorial regions of Saturn’s moon. This makes Titan the third object in the solar system, along with Earth and Mars, where such a meteorological phenomenon has been observed.

Dust storms on Titan

Titan has active weather that changes from season to season, particularly during the equinox — the time when the sun crosses Titan’s equator — when massive clouds of methane and ethane can cause powerful storms in the moon’s tropical regions.

[panel style=”panel-info” title=”Titan: a strange world” footer=””]Titan is the only known moon with a fully developed atmosphere that consists of more than just trace gases. Titan’s temperature is about 94 K (−179 °C, or −290.2 °F) at the surface. At this temperature, water ice does not sublimate from solid to gas, so the atmosphere is nearly free of water vapor. “You have all these things that are analogous to Earth. At the same time, it’s foreign and unfamiliar,” said Ray Pierrehumbert, the Louis Block Professor in Geophysical Sciences at Chicago.[/panel]

During its numerous flybys of Titan, NASA’s Cassini spacecraft recorded many such storms. However, on one occasion, it spotted three unusual equatorial brightenings with its infrared instruments. At the time, in 2009, scientists thought these were some kind of methane clouds — but a subsequent examination revealed that they were dealing with something totally different.

The features were not frozen methane rain or icy lavas, either, because they did not match the chemical signature and should have remained visible for much longer than the bright features observed in the study. These appeared for only 11 hours to five weeks.

Bright spots recorded in infraded by NASA’s Cassini mission between 2009 and 2010. Credit: NASA/JPL-Caltech/University of Arizona/University Paris Diderot/IPGP/S. Rodriguez et al. 2018.

Modeling of the bright features also showed that the features must be atmospheric but still close to the surface, forming a thin layer of solid organic particles. Finally, because the features were located right above dune fields on Titan’s equator, the authors of the new study concluded that the only viable explanation remaining was that the spots were actually clouds of dust.

“Titan is a very active moon,” said Sebastien Rodriguez, an astronomer at the Université Paris Diderot, France, and the paper’s lead author. “We already know that about its geology and exotic hydrocarbon cycle. Now we can add another analogy with Earth and Mars: the active dust cycle, in which organic dust can be raised from large dune fields around Titan’s equator.”

Nine Cassini flybys of Titan in 2009 and 2010 show three instances when clear bright spots suddenly appeared in images taken by the spacecraft’s Visual and Infrared Mapping Spectrometer. Credit: NASA/JPL-Caltech/University of Arizona/University Paris Diderot/IPGP/S. Rodriguez et al. 2018.

Titan’s dust probably forms when organic molecules, resulting from methane’s interaction with sunlight, grow large enough to fall to the surface. In fact, Rodriguez says that one of NASA’s probe that touched down on Titan raised dust upon its landing — a first hint that dust storms were occurring on Saturn’s moon.

“We believe that the Huygens Probe, which landed on the surface of Titan in January 2005, raised a small amount of organic dust upon arrival due to its powerful aerodynamic wake,” said Rodriguez. “But what we spotted here with Cassini is at a much larger scale. The near-surface wind speeds required to raise such an amount of dust as we see in these dust storms would have to be very strong—about five times as strong as the average wind speeds estimated by the Huygens measurements near the surface and with climate models.”

Dust storms on Titan imply that the moon’s giant dunes are still active and continually changing. Wind could be transporting dust from far-away regions, triggering a global cycle of organic dust on the moon.

Scientific reference: S. Rodriguez et al. Observational evidence for active dust storms on Titan at equinox, Nature Geoscience (2018). DOI: 10.1038/s41561-018-0233-2.

NASA reveals new, crystal-clear images of Saturn’s moon Titan

NASA is spoiling us once again — this time with some stunning photos of Titan.

Image credits: NASA / JPL.

The six images above represent some of the clearest and sharpest images we have ever captured of the icy moon. They were taken by the Visual and Infrared Mapping Spectrometer (VIMS) instrument on board NASA’s Cassini spacecraft, whose mission to explore Saturn and its moons ended on September 15, 2017. Although Cassini’s mission ended, scientists are still analyzing data and images the shuttle sent our way.

The new images are the result of a multitude of different observations made under a wide variety of lighting and viewing conditions. Making mosaics from VIMS images of Titan is particularly challenging because the viewing angle and atmospheric conditions varied so greatly. As a result, most images had visible seams which overlapped on the image, but that was removed here through painstaking data analysis and hand processing.

With the seams now gone, this is quite possibly the best collection of Titan photos available, and the images can be used to study Titan’s features in unprecedented detail. NASA has also released a bigger, black & white map of Titan with labeled features — you can check that out here.

This map of Titan shows the names of many (but not all) features on the Saturnian moon that have been approved by the International Astronomical Union. Image credits: NASA / JPL.

From these images, it becomes apparent that Titan’s surface is anything but uniform. Even an untrained eye can quickly distinguish myriad different geological features, although what those features are remains a much more difficult question. For example, you can notice some equatorial dune fields, which appear a consistent brown color here. The bluish and purplish areas have a clearly different composition and possibly contain water ice.

It’s important to note that the image is not in the visual spectrum — observing the surface of Titan in the visible region of the spectrum is difficult, due to the globe enshrouding haze that envelops the moon. The aerosols in Titan’s atmosphere strongly scatter visible light, but leave a few infrared “windows” open — parts of the infrared spectrum where scattering and absorption are much weaker. This is where VIMS excels, and that’s how it was able to snap the good photos NASA worked on to develop the mosaic.

Titan is the largest moon of Saturn. It is the only moon known to have a dense atmosphere and the only object other than Earth where clear evidence of surface liquid has been found. Titan is primarily composed of water ice and rocky material, but, unlike Earth, which is largely covered by bodies of water, Titan features hydrocarbon lakes and seas. Titan’s methane cycle is analogous to Earth’s water cycle but at a much lower temperature (−179.2 °C; −290.5 °F).

Pure Quartz.

Silicon-based life on Earth? Only artificially, so far — but maybe natural on other planets

Scientists have successfully nudged a strain of bacteria to create carbon-silicon bonds for the first time. Such research will help flesh out our understanding of silicon-based life — which doesn’t appear on Earth but could on other planets.

Pure Quartz.

Quartz, or rock crystal, the second most abundant mineral in the Earth’s crust, is a mixture of (mostly) silicon and oxygen. The first most abundant mineral, feldspar, also contains (mostly) silicon.
Image credits Stefan Schweihofer.

You may not think of it much, but silicon is actually really common here on good ole Earth — it’s the second most common element in our planet’s crust after oxygen. About nine-tenths of crustal rocks contain silicon in the form of silica or other silicates. The processor that’s allowing you to read ZME Science contains silicon — the glass panes on your windows, too. It’s so ubiquitous in our planet’s chemical makeup that a geologist can tell you which volcanoes will explode, and which would simply ‘flow’ on eruption, just by looking at how much silicon its magma contains. Sitting just one step away from carbon in the periodic table, silicon shares most of the properties that made carbon ideally suited for organic use.

Which makes the following point that much more curious: life as we know it simply isn’t that big on using silicon. It pops up here and there, in the tissues of certain plants or the shells of some marine organisms, but surprisingly little overall. Instead, Earthlings much prefer carbon.

Research from the California Institute of Technology, however, may put the element back on biology’s menu. The team successfully coaxed E.coli into producing a protein that can form carbon-silicon (C-Si) bonds. Their work sheds more light on why the latter element seems to be shunned by Earthly life, and where we might find organisms that don’t feel the same way.

Silly cons

The team started by engineering a strain of E. coli bacteria to produce a protein normally found in bacteria from Icelandic hot springs which can bind silicon to carbon. When the team first used their engineered strain to produce the protein in question, the compound proved to be very inefficient. Successive iterations and natural mutations, however, resulted in an enzyme that could forge organic silicon molecules some 15 times more efficiently than any chemical process the team could apply to the same goal. Using this molecule, the team produced twenty organic C-Si compounds, all of which proved to be stable.

So, by this step, they had proven that life can incorporate silicon — it’s just that it doesn’t particularly want to.

“You might argue, gosh, it’s so easy for a biological system to do it, how do you know it’s not being done out there?” says coauthor Frances Arnold. “We don’t really know, but it’s highly unlikely.”

Arnold was referring to other planets in this context, but the point he’s trying to make can also be applied to Earth. Do we know beyond a doubt that there isn’t silicon life on Earth? Well, no. But we have reasonable grounds to assume that there isn’t.

The issue here is a problem of availability. Silicon is much more common on Earth than carbon, but virtually all of it is extremely costly for life to access. Silicon is so prevalent in the crust because it’s a huge fan of oxygen, and it will bind with any available atom of the gas to form rocks. All of the silicon compounds that the team fed their bacteria to make these new compounds were manmade and life wouldn’t have any chance of finding them in the wild.

Carbon, on the other hand, is very stable chemically. Its relative lack of interest in hooking up with oxygen is especially useful for life, as it can use the atom to create huge molecules without much risk of them oxidizing and breaking apart. It also allows carbon to exist in a pure state (graphite for example) in nature, while silicon can’t — this is a very important distinction, as in molecular ‘economy’, this means carbon can be acquired at a much, much lower price (energy expenditure) than silicon. Finally, when you burn carbon you get a gas that can then be re-used by life; silicon lacks this perk.

Silicon optics.

But it can be quite shiny, as these silicon optic pieces showcase.
Image credits Crystaltechno / Wikimedia.

Finally, silicon-based life couldn’t use water as carbon-based life does; the two simply don’t have chemistry. Instead, it would have to substitute another liquid, such as methane, for the job — but that’s not stable under normal conditions on Earth, either.

In the end, the heart of the matter isn’t that silicon can’t be a foundation for life — it’s just that, on Earth, carbon can do the job much more easily, at greater efficiency, and at a lower cost. The ‘job’ here being life.

However, that’s not to say silicon-carbon bonds aren’t useful. We produce such compounds in the lab all the time and use them in products ranging from electronics to pharmaceuticals. The team hopes that their bacteria can help produce these substances much faster, much more cheaply, and with a lesser environmental footprint. It could also open the way to whole new materials.

“An enzyme can do what chemists thought only they could do,” Arnold says.“The chemical bond could appear in thousands and thousands of different molecules, some of which could be useful,”

“They’re all completely new chemical entities that are easily available now just by asking bacteria to make them.”

Silly life

Beyond the immediate practical considerations, the research also begs the question: is Earth-based silicon life feasible? The results showed, at the very least, that silicon isn’t harmful to life as we know it. Perhaps, if life had ready access to the element, it would incorporate it more in its structures and processes, despite its limitations.

And that invites the question of whether life can be made to incorporate elements that we’ve never seen it use before.

“What happens when you incorporate other elements?” Arnold asks. “Can nature even do that?”

“Presumably we could make components of life that incorporate silicon—maybe silicon fat or silicon-containing proteins—and ask, what does life do with that? Is the cell blind to whether carbon is there or silicon is there? Does the cell just spit it out? Does the cell eat it? Does it provide new functions that life didn’t have before?”

“I’d like to see what fraction of things that chemists have figured out we could actually teach nature to do. Then we really could replace chemical factories with bacteria.”

One particularly well-suited solution to the limitations of silicon on our Earth is to move the context to another planet. Any seasoned lover of sci-fi, and I proudly count myself among their number, has run into the idea of silicon-based aliens at least once. For now, the “alien life” part remains in the domain of fantasy, but the chemistry behind that idea is very firmly lodged in the domain of science. For example Titan, Saturn’s largest moon, sports a chilly average temperature of -179° Celsius (-290° Fahrenheit), very little oxygen (that’s locked in water ice), and an abundance of methane rivers and lakes.

[Read Further] Yes that’s weird, but the weather gets even weirder on other planets — even simple rain.

In this context, silicon would be much better suited as a biochemical base for life than carbon. In what is perhaps a sprinkling of cosmic irony, however, Titan sports a lot of carbon (even more than Earth), but precious little silicon — and most of it is buried deep, near the moon’s core. But it goes to show that there are worlds out there where silicon is the way to go, not carbon. Overall our chances of finding silicon-based life, or life that incorporates silicon, are pretty slim. And that, again, comes down to the fact that carbon is the more stable of the lot. In the grand scheme of things, there can be silicon life out there — but it will probably be pretty rare.

Still, for now, research into C-Si bonds could usher in a new method of cheaply producing what, today, are relatively pricey compounds. And organic silicon compounds could have very valuable uses in medicine and other applications. So, while we look and pine for silicon-based life out in the universe, we stand to gain a lot from studying it on Earth.

The paper “Directed evolution of cytochrome c for carbon–silicon bond formation: Bringing silicon to life” has been published in the journal Science.

Titan composite.

Looking to put a sub on Titan, NASA recreated its methane oceans in Washington

NASA is hard at work trying to get a robot on Titan. To find out exactly what it would be up against, the agency has built a tiny, freezing methane ocean at the Washington State University.

Titan composite.

Composite image of Titan seen in near-infrared.
Image credits NASA / JPL.

Titan is the second largest moon in our solar system, only more modest in size than Jupiter’s Ganymede. However, it’s a spot that NASA has been itching to visit for quite some time now, as it is the largest body after Earth to harbor stable, liquid oceans. But put the snorkel away, because this is by no means an ocean you’d want to take a dip in. Titan isn’t covered in water, it’s covered in methane — frigid, liquid methane.

To coldly go where nobody has gone before

NASA plans to send an autonomous submarine to poke around Titan’s seas and oceans some time in the next 20 years. So far, they’ve been designing the mission and the craft based on data beamed back by the Cassini mission. However, environmental conditions on the moon are so dramatically different and extreme compared to those we’re used to, that the agency believes we need more experimental data to check the bot against.

As such, they’ve teamed up with scientists at Washington State University to recreate the moon’s methane ocean in a laboratory.

The WSU researchers built a test chamber filled with a “liquid mixture at very cold temperatures to simulate the seas of Titan,” a press release from the University details. “They added a two-inch, cylinder-shaped cartridge heater that would approximate the heat that a submarine would create”. The project was led by Ian Richardson, a former WSU graduate who interned at NASA on an unrelated research project.

“My research just took a right turn, and I went with it. It’s a crazy experiment, and I never thought I would have had this opportunity. It’s been a very fun and challenging experimental design problem,” he said.

The make-believe ocean has revealed two hurdles that researchers will have to overcome when designing the sub-to-be: the formation of gas bubbles and recording video at the freezing temperatures.

titan-design

NASA released this design for the Titan sub back in 2016.
Image credits NASA.

If the submarine is powered by a heat-generating mechanism, it would cause nitrogen bubbles to form in the very cold liquid on Titan (which is mostly made up of a methane-ethane mix at roughly -185° Celsius (-300° Fahrenheit). These bubbles have shown that they can severely hinder the submarine’s mobility and make it difficult for onboard sensors to collect data.

Even if such bubbles fail to materialize, snapping images and videos of the sub’s surroundings will be a challenging task — mostly because it’s a really cold, pressurized environment (comparable to being under 30 meters/100 feet of water).

One piece of good news is that the nitrogen fraction in the mix lowers the freezing point of Titan’s oceans from about -185° to roughly -200° Celsius (-297° to -324° Fahrenheit).

“That’s a big deal. That means you don’t have to worry about icebergs,’’ Richardson explains.

The team says they worked around the temperature and pressure problems and developed a device that allowed them to shoot video footage in the liquid and snow methane-ethane mix inside the chamber. In the future, all measurements and data recorded in this experiment will be used to ” to aid in thermodynamic modeling of the Titan seas as well as the design of the Titan Submarine,” he added.

The paper “Experimental PρT-x measurements of liquid methane-ethane-nitrogen mixtures.” has been published in the journal Fluid Phase Equilibria.

First topographic map of Titan reveals surprisingly Earth-like features

Titan, one of the least Earth-like places in our solar system, turned out to have surprisingly Earth-like features.

Doom Mons (mountain) and Sotra Patera (depression), two remarkable features on the surface of Titan. Topography has been vertically exaggerated by a factor of 10 for visibility. The false color shows different surface material compositions as detected by Cassini’s visual and infrared mapping spectrometer. Image credits: NASA/JPL.

Until recently, not much was known about Saturn’s moon Titan. But the Cassini-Huygens mission changed all that. Titan, a Mercury-sized world with a surface shrouded in a thick, nitrogen-rich atmosphere, was found to be the only place other than Earth where clear evidence of stable bodies of surface liquid has been found.

Titan is also a prime candidate for finding extraterrestrial life, which is why researchers have been trying to better understand its structure. Now, in two published papers, astronomers present the first proper map of Titan, revealing its features in unprecedented detail.

It took doctoral student Paul Corlies a year to assemble the map from all existing data. It was no easy feat since only 9 percent of Titan’s topography has been observed in relatively high-resolution. Another 25-30 percent of the topography imaged in lower resolution. The rest was created using an interpolation algorithm — which means we don’t really know how the rest of Titan is like, but we know how it probably looks like.

Cassini’s radar mapper has obtained stereo views of Titan’s surface during 19 flybys over the last five years. Image credit: NASA/JPL/USGS.

For starters, the map reveals Titan to be a bit flatter (more oblate) than previously thought. This suggests that the thickness of Titan’s crust also varies more than expected. Corlies also reports that the surface of Titan is covered by mountains, though none of them are higher than 700 meters (2300 feet). The map also shows Titan’s lows, allowing scientists to confirm that two locations in the equatorial region are in fact depressions — and not dried seas, as another theory proposed.

Researchers also analyzed Titan’s impressive lakes, but don’t get your hopes up just yet. As opposed to Earth’s lakes, which are covered by water, Titan’s lakes are filled with liquid methane, a hydrocarbon.

Starting from sea level

Corlies found that Titan’s three most massive lakes (or seas) share a common equipotential surface — which is just a fancy way of saying that they have a common sea level. Titan’s lakes communicate with each other through the subsurface; the lakes that are dry are all at higher elevations than the filled lakes in their vicinity. Alex Hayes, assistant professor of astronomy and also an author, predicted this in his previous models of Titan.

“We don’t see any empty lakes that are below the local filled lakes because, if they did go below that level, they would be filled themselves. This suggests that there’s flow in the subsurface and that they are communicating with each other,” said Hayes. “It’s also telling us that there is liquid hydrocarbon stored on the subsurface of Titan.”

The fact that astronomers are understanding so much about a satellite so far away from Earth is truly astounding, yet this is only a stepping stone for other research. Study authors say that the map will help others working on Titan’s geology and morphology, as well as those trying to improve models for extraterrestrial bodies. Ultimately, it could even help scientists understand whether or not life exists on Titan.

“We’re measuring the elevation of a liquid surface on another body 10 astronomical units away from the sun to an accuracy of roughly 40 centimeters. Because we have such amazing accuracy we were able to see that between these two seas the elevation varied smoothly about 11 meters, relative to the center of mass of Titan, consistent with the expected change in the gravitational potential. We are measuring Titan’s geoid. This is the shape that the surface would take under the influence of gravity and rotation alone, which is the same shape that dominates Earth’s oceans,” said Hayes.

Journal References:

  1. P. Corlies, et al. Titan’s Topography and Shape at the End of the Cassini MissionGeophysical Research Letters, 2017; 44 (23): 11,754 DOI: 10.1002/2017GL075518
  2. A. G. Hayes, et al . Topographic Constraints on the Evolution and Connectivity of Titan’s Lacustrine BasinsGeophysical Research Letters, 2017; 44 (23): 11,745 DOI: 10.1002/2017GL075468
Drone Explorer.

Dragonfly dual-quadcopter drone proposed to explore Titan to understand how life appeared

A new explorer joins the ranks of proposals for NASA’s New Frontiers initiative. Christened Dragonfly, this nuclear-powered robotic dual-quadcopter will take advantage of Titan’s thick atmosphere and low gravity to hop about the moon and beam back data from potentially habitable sites.

Drone Explorer.

Image credits JHUAPL/Mike Carroll.

Saturn’s largest moon, Titan, is quite an exciting place for scientists trying to understand how life develops. It has enough water to be comfortably called an ocean world. To be fair it’s frozen solid on the surface, but the interior seems to be a relatively warm, liquid ocean. It also has a diverse chemistry rich in the building blocks biology (as we know it) needs. Put the two together, and what you get is a place with a lot of organic material undergoing the same reactions that we believe went down in Earth’s early days.

All in all, it’s a place that could offer us insight into how life appeared that lab work simply can’t provide. So what NASA wants to do, as part of its New Frontiers exploration program, is to send a pair of eyes to Titan and see what’s what. That pair of eyes, engineers at the Johns Hopkins Applied Physics Laboratory believe, should come in the shape of a dual-quadcopter they named Dragonfly.

“This is the kind of experiment we can’t do in the laboratory because of the time scales involved,” said APL’s Elizabeth Turtle, principal investigator for the Dragonfly mission.

“Mixing of rich, organic molecules and liquid water on the surface of Titan could have persisted over very long timescales. Dragonfly is designed to study the results of Titan’s experiments in prebiotic chemistry.”

The drone explorer will carry an array of instruments to any points of interest across the moon’s surface. For this mission, flying sticks out as an ideal method of transportation. Given Titan’s dense atmosphere and low gravity, flying is much easier to do here than on Earth. This means Dragonfly will be able to carry more instruments with the same effort, and flying will let it navigate rugged terrain much faster and with less risk of damage than wheeling about the place.

At every site, the drone will sample atmospheric and surface chemistry with a suite of instruments. This data will allow scientists to estimate the habitability of the moon, see how far Titan’s chemistry has progressed towards biotic chemistry, even pick up eventual traces of water- or hydrocarbon-based life. Mass spectrometry will reveal atmospheric and soil composition, gamma-ray spectrometry will be used to probe into the chemical composition of the shallow sub-surface. A suite of meteorology and geophysics sensors will record wind, pressure, temperature, seismic activity, as well as a host of other factors. Finally, a camera will let scientists peer at the nature of the moon’s surface.

“We could take a lander, put it on Titan, take these four measurements at one place, and significantly increase our understanding of Titan and similar moons,” said Dragonfly project manager Peter Bedini of APL.

“However, we can multiply the value of the mission if we add aerial mobility, which would enable us to access a variety of geologic settings, maximizing the science return and lowering mission risk by going over or around obstacles.”

Later this year, NASA will select a few of the proposals for New Frontiers for further study. Sometime in mid-2019, one will be selected to become the fourth mission in the planetary exploration program.

‘Impossible’ clouds spotted on Titan – for the second time

Astronomers have made a puzzling observation which could have big implications for our understanding of Titan.

Near-infrared radiation from the Sun reflecting off Titan's hydrocarbon seas. Photo by NASA/JPL.

Near-infrared radiation from the Sun reflecting off Titan’s hydrocarbon seas. Photo by NASA/JPL.

Surprisingly, Titan is a lot like Earth. Even though it’s a moon of Saturn and even though it’s much colder, it shares many similarities to our planet. It’s the only place in the solar system where stable liquid sits on the surface – although it’s not water but seas of liquid methane. The geology of the satellite, with its grand canyons and numerous valleys also seems to showcase an active planet which might even host life. Now, we can add another similarity to Earth: clouds.

According to a study in Geophysical Research Letters, a seemingly impossible cloud on Titan may be created by familiar weather processes. The cloud they witnessed is made of a compound of carbon and nitrogen known as dicyanoacetylene (C4N2). The process for cloud formation was thought to be pretty straightforward: it generally involves condensation.

Here on Earth, we’re familiar with the water cycle. Water evaporates, forms clouds, then falls down on the ground through precipitation. It seemed that the same thing is happening on Titan but again, with methane instead of water. But when it comes to the vapor form of this chemical, Titan’s stratosphere, where the cloud should form, is as dry as a desert. Needless to say, this came as a surprise.

“The appearance of this ice cloud goes against everything we know about the way clouds form on Titan,” said Carrie Anderson, a CIRS co-investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study.

It’s not the first time this phenomenon was spotted. Decades ago, the infrared instrument on NASA’s Voyager 1 spacecraft spotted an ice cloud just like this one on Titan. That one, just like this one, had too little dicyanoacetylene – just one percent of the gas needed for the cloud to condense. Now, we know from Earth that some clouds don’t need condensation to form – through a kind of “solid-state” chemistry based on the interactions of ice particles. These clouds are bad news, according to Rachel Feltman from the Washington Post.

“Chlorine-based chemicals enter the air by way of pollution on the ground, then meet up with icy water crystals in the dry stratosphere. The chemical reactions that occur in these wispy clouds release chlorine molecules, which eat away at the ozone layer.”

But Earth and Titan’s chemistries vary greatly, so that’s still really surprising.

“The compositions of the polar stratospheres of Titan and Earth could not differ more,” said Michael Flasar, CIRS principal investigator at Goddard. “It is amazing to see how well the underlying physics of both atmospheres has led to analogous cloud chemistry.”

NASA plans to send an autonomous submarine into space — for a very good reason

NASA plans to explore Saturn’s moon Tian with an unlikely type of vehicle: a submarine. The agency is working on the design of an autonomous submersible that will explore the liquid hydrocarbon oceans of the moon.

The current design of the craft.
Image credits NASA.

The vehicle will have to endure bone-shattering cold as it will peer through the liquid methane and ethane oceans that cover the moon’s surface, relaying valuable data back to Earth, announced Jason Hartwig at the NASA Innovative Advanced Concepts (NIAC) Symposium last week. Its blueprints include a huge communications “fin” on the back of the sub that will allow it to cover the 1,492 million kilometer (886 million miles) span of space to communicate directly with Earth.

The submarine will be 6 meters (20 feet) long and will use Titan’s liquid methane instead of water in its ballast system. Its array of instruments will include meteorological tools, a sonar and radar, and an array of other sensors including cameras to take snapshots of what’s going on on the frigid moon.

The vehicle will be optimized to be as fuel efficient as possible, as chances of re-fueling are slim on Titan.

Ten thousand leagues over the ocean

Titan’s hydrocarbon oceans may be incredibly cold and seem strange to us, but scientists are interested in learning all they can about it as it resembles the conditions we think shaped an early Earth. It’s the only other known body in the Solar System that has stable, liquid seas on its surface. Titan’s atmosphere also functions similarly to our own, having its own hydrological (hydrocarbon?) cycles that dictate how liquids move from fresh to salt or from a gas, to a liquid, or a solid.

Artist rendering of a possible submersible bot exploring one the floor of one of Titan’s methane lakes. Image: NASA JPL

Artist rendering of a possible submersible bot exploring one the floor of one of Titan’s methane lakes. Image: NASA JPL

NASA wants to send a sub there because of its versatility. It can be used to measure waves, atmospheric composition and wind speeds on the surface, but can also analyze the composition of its seas or take sea floor samples after it submerges.

“If you can get below the surface of the sea, and get all the way down to the bottom in certain areas, and actually touch the silt that’s at the bottom, and sample it and learn what that’s made of, it’ll tell you so much about the environment that you’re in,” said Michael Paul from Penn State University, one of the researchers working on the project.

The submersible will also look very any signs of extraterrestrial life, as some experts believe the hydrocarbon soup can act as a replacing solvent for water to foster life.

“Think about life on Earth—we’re all either in water or we’re fancy bags of water,” says astrobiologist Kevin Hand of the Jet Propulsion Laboratory. “On Titan, life in the lakes would be ‘bags’ of liquid methane and/or ethane. That 90[Kelvin] liquid would be the solvent and then whatever is dissolved into the lakes would be the material that’s used to build the other components needed for life, and to power metabolism.”

The design efforts for the craft are on hold for now, as the agency awaits for more information on the moon’s oceans from the Cassini probe. New information about the depths, pressures, and temperatures of Titan’s oceans will be used to better tailor the sub to the environment it will function in. NASA hopes to reassess the project by March 2017.

But after the design is finalized and the sub built, that’s when the real waiting begins — its first mission has been tentatively scheduled for 2038.

That’s quite a wait.To help us pass the time, the guys and gals from NASA put together this teaser for the submarine. Enjoy!

 

One of Titan's huge methane sea. In the upper left you can see a network of methane filled canyon-structures called the Vid Flumina. Credit: NASA

Cassini finds canyons flooded with liquid hydrocarbons on Titan

One of Titan's huge methane sea. In the upper left you can see a network of methane filled canyon-structures called the Vid Flumina. Credit: NASA

One of Titan’s huge methane sea. In the upper left you can see a network of methane filled canyon-structures called the Vid Flumina. Credit: NASA

NASA’s ever-resourceful Cassini probe found steep-sided canyons on Saturn’s moon Titan. These geological formations are filled with liquid hydrocarbons like methane — the first evidence of both liquid-filled channels and hundreds of meters deep canyons on Titan. Remarkably, these canyons must have formed very similarly to those on Earth, like the Grand Canyon in Arizona.

These channels form a network branching out of the large Ligeia Mare sea, located on the northern side of the moon. They’re less than half a mile wide, with some slopes steeper than 40 degrees. The canyons are quite deep though, measuring anywhere from 790 to 1,870 feet (240 to 570 meters) from top to bottom.

False-color near infrared view of Titan's northern hemisphere, showing its seas and lakes. Orange areas near some of them may be deposits of organic evaporite left behind by receding liquid hydrocarbon. Credit: Wikimedia Commons

False-color near infrared view of Titan’s northern hemisphere, showing its seas and lakes. Orange areas near some of them may be deposits of organic evaporite left behind by receding liquid hydrocarbon. Credit: Wikimedia Commons

To find these channels, geologists working at NASA had to combine altimetry and radio wave readings as direct observations are made impossible by the thick hazy atmosphere surrounding Titan. Pings of radio waves bounced back and forth between the surface of the moon and the Cassini probe to determine the height of features. Then, the way radio signals reflected off surfaces told researchers what they were made off.

Since the signal was very similar to that observed on Titan’s rich hydrocarbon seas, the researchers concluded that the matter which covers the channels must be made of the same stuff. Previously, some suggested these sort of channels could be filled with saturated sediment, but the dark material seems much likelier to be liquid at this stage.

[ALSO SEE] NASA wants to explore Titan’s methane oceans with a robot submarine

As to the formation of these geological features, the NASA geologists posit processes akin to those found on Earth: uplift of terrain, changes in sea level (methane sea instead of water) or both.

“It’s likely that a combination of these forces contributed to the formation of the deep canyons, but at present it’s not clear to what degree each was involved. What is clear is that any description of Titan’s geological evolution needs to be able to explain how the canyons got there,” said Valerio Poggiali of the University of Rome, a Cassini radar team associate and lead author of the study which was published in the Geophysical Research Letters journal.

On Earth, such examples of canyon-carving processes are abundant, such as the canyons found along the Colorado River in Arizona. Uplift power erosion is what drove the formation of the Grand Canyon, while for those formed by variations in water level we can give Lake Powell as an example.

“Earth is warm and rocky, with rivers of water, while Titan is cold and icy, with rivers of methane. And yet it’s remarkable that we find such similar features on both worlds,” said Alex Hayes, a Cassini radar team associate at Cornell University, Ithaca, New York, and a co-author of the study.

Though Cassini made its flyby around Titan in 2013, scientists are still making sense of the wealth of data it beamed back. They expect we’ll soon have a very comprehensive picture of Titan’s landscape, but also of the forces involved in its formation.

Flying Aerobot drone is being designed to soar in the skies of Titan

In preparation for the Cassini probe’s departure from Saturn, NASA is looking to sent a drone on the giant’s moon Titan. The agency has awarded a Small Business Innovation Research (SBIR) Phase 1 contract for the early-stage development of these vehicles.

Artist’s impression of a winged vehicle entering the atmosphere of Saturn’s moon Titan.
Credit: GAC/NGAS

Two private companies, Global Aerospace Corp. and Northrop Grumman Aerospace Systems, have been picked by NASA to design a vehicle which will explore the surface of Saturn largest moon, known as the Titan Winged Aerobot. The agency also requested that they prepare a prototype of the vehicle for testing on Earth. The two companies will share a Phase 1 SBIR contract — NASA said that such contracts last six months and are worth up to US$125,000.

Several design elements will be incorporated into the Titan bot to allow it to function in the moon’s extreme environment, said principal investigator of the Phase I effort Benjamin Goldman in a statement from Global. The drone will need to have excellent lift and maneuverability while being solid enough to withstand Titan’s atmospheric pressure.

“Titan is a cold, harsh environment that poses many technical challenges for any lighter-than-air exploration platform,” he added.

This won’t be the first time a human craft will land on the moon. In 2005, the Cassini mission sent the Huygens probe to Titan’s surface, where it remained operational for several hours, feeding us data on the moon’s atmosphere and surface. However, the new drones are designed to remain mobile, soaring high above the frozen surface. This would still allow them to map Titan in greater detail than Cassini can achieve during its flybys. They would also be invaluable in astrobiology and habitability studies on the moon, Global representative said.

Unlike Huygens’ single landing, a Titan drone could soar above many locations. Because it will fly closer to the surface, it could map Titan in greater detail than the higher-ranging Cassini flybys. This provides potential for studies in astrobiology and habitability, Global representatives said. One novel feature the company plans to install on the Titan Winged Aerobot is a buoyancy system what let it change altitude without the need for propulsion or traditional control surfaces such as flaps. The robot could fly over sites several times and even send targeted probes down to the surface, they added.

Titan is the only moon in the solar system known to have a significant atmosphere and a liquid cycle — though its lakes are made of hydrocarbons, not water. Despite its incredibly low surface temperatures (minus 300 Fahrenheit, or minus 184 Celsius degrees) and lack of water, it has been proposed that the moon could support methane-based life. So there is a lot of excitement for what the drones might find on the moon.

While the glider is being designed for Titan, it can be adapted for use on  “any solar system body with an atmosphere,” Global added. Other applications could include returning cargo to Earth from the ISS or surveying Mars from a drone built for its thin atmosphere.

 

Scientists find hydrocarbon dunes on Saturn’s moon Titan

Titan – one of Saturn’s moons – is one of the most mysterious and mindblowing places in the solar system. Aside from Earth, it’s the only place we know that has liquid on its surface. Sounds like a nice place, only it’s not water.  These are in the form of lakes and rivers composed of liquid hydrocarbons including Ontario Lacus, a lake 240 kilometres (150 miles) long in Titan’s southern hemisphere. Funny thing is that these hydrocarbons undergo a similar process like the water system does on Earth. The methane evaporates from the surface, forming extremely thick clouds in the skies, before eventually raining down and replenishing the lakes and rivers on the ground.

Credit: NASA/JPL-Caltech/Space Science Institute

In the center of the moon, you can distinguish the H-shaped dunes. Credit: NASA/JPL-Caltech/Space Science Institute

Do you know what else Titan has? Dune fields. Once again, the similarities with Earth diverge in the details. Titan’s dunes are indeed made of sand, but the hydrocarbon variety. This particular photo was taken by NASA’s Cassini probe from 450,000 miles away. The  H-shaped area is filled with these hydrocarbon dunes. These are somewhat distinct. The north side is called Fensal and the south side is called  Aztlan.

NASA wrote:

Once known only as “the H” because the region looks something like the letter on its side, features in this region now possess provisional names assigned by the International Astronomical Union (see: http://planetarynames.wr.usgs.gov/). The northern branch of the H is now called “Fensal,” while the southern branch is known as “Aztlan.”

 

Cassini regularly monitors changes on Titan, and researchers hope that through this, they can better understand the geological and environmental setting of the moon. Titan is the only natural satellite known to have a dense atmosphere, and the only object other than Earth where clear evidence of stable bodies of surface liquid has been found, so the motivation is there to study it. The surface of Titan has been described as “complex, fluid-processed, [and] geologically young” – it’s dynamic and difficult to study.

 

 

Lakes on Titan might have formed like sinkholes on Earth

Researchers from the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA) have been trying to figure out how Titan’s seas formed – more exactly, how the depressions in which the seas are formed.

Artist impression of Saturn seen from Titan. Image: NASA JPL

Titan is Saturn’s largest moon and the only known satellite with an atmosphere and the only object other than Earth where clear evidence of stable bodies of surface liquid has been found. But don’t start thinking about water – Titan’s climate involves hydrocarbons such as methane and ethane. At its two poles, the moon features thousands of hydrocarbon lakes, many as big as the Great Lakes.

This happens because of Titan’s extremely low temperature, which keeps methane and ethane liquid. But having liquids is not enough for having lakes and seas – you also need some place where those liquids can accumulate: a depression.

They concluded that Titan’s depressions were formed through a similar process which forms sinkholes here on Earth: dissolution. Sinkholes are natural depressions typically caused by karst processes. Karst processes occur when the bedrocks are soluble, like in carbonate rocks (such as limestone or dolomite) or evaporitic rocks (such as gypsum or anhydrite). But unlike sinkholes on Earth, depressions on Titan take much longer to form.

Polar clouds, made of methane, on Titan (left) compared with polar clouds on Earth (right), which are made of water or water ice. Image via Wikipedia.

“We found that the dissolution process occurs on Titan some 30 times slower than on Earth due to the longer length of Titan’s year and the fact it only rains during Titan summer. Nonetheless, we believe that dissolution is a major case of landscape evolution on Titan and could be the beginning of its lakes.”

Still, this is just a theory for now, because of course, there is no way to observe the geological processes on Titan from ground level… yet. NASA’s Glenn COMPASS Team discussed at large the possibility of exploring Titan, Saturn’s largest moon, with a robotic submarine that would dive deep inside the oceans of liquefied natural gas

 

saturn titan methane sea

NASA wants to explore Titan’s methane oceans with a robot submarine

At this years’  Innovative Advanced Concepts (NIAC) Symposium, NASA’s Glenn COMPASS Team discussed at large the possibility of exploring Titan, Saturn’s largest moon, with a robotic submarine that would dive deep inside the oceans of liquefied natural gas.  Such a mission, if ever funded, could help answer some important questions like what are the defining chemical building blocks required to birth and sustain life. Titan is very similar to Earth  in terms of cycling systems, elemental composition and terrestrial geography, so there’s much insight to be gained.

An offworld submarine

saturn titan methane sea

Artist impression of Saturn seen from Titan. Image: NASA JPL

 

This is how Titan’s surface really looks like, as snapped by the Huygens lander in 2005. NASA/ESA/JPL/University of Arizona

This is how Titan’s surface really looks like, as snapped by the Huygens lander in 2005. NASA/ESA/JPL/University of Arizona

Titan is one of the few places in our solar system with stable liquids on its surface. Huge river systems, ponds, lakes and even seas can be seen throughout its surface. It also rains on Titan. But these liquids aren’t water – methane and ethane, two hydrocarbons that are usually gassy here on Earth under atmospheric conditions, comprise the bulk of liquid matter. In this strange world, freezing temperature that hovers at  -179 Celsius (or -290 Fahrenheit) makes water turn to rock-hard ice and hydrocarbons into liquids. With this in mind, how could life possibly exist in this hell?

Astrobiologists believe Titan’s alien life, if it exists or ever has, needs not necessarily rely on water. Instead, the hydrocarbon soup can act as a replacing solvent.

“Think about life on Earth—we’re all either in water or we’re fancy bags of water,” says astrobiologist Kevin Hand of the Jet Propulsion Laboratory. “On Titan, life in the lakes would be ‘bags’ of liquid methane and/or ethane. That 90[Kelvin] liquid would be the solvent and then whatever is dissolved into the lakes would be the material that’s used to build the other components needed for life, and to power metabolism.”

Basically, we humans are biased in thinking life is universally and invariably based on water. The truth is, we might never know unless we start exploring other worlds. And that’s not to say that a mission to Titan’s methane deeps would only be about this – there are scores of other, let’s say more practical things we might learn from Saturn’s moon, like its tides, weather, shoreline or mysterious disappearing islands. Titan is thought to be an analog to early Earth, and studying what lies beneath the surface of Kraken Mare could well turn up some scientific surprises, like what it took for primitive life to surface on our home planet.

titan submarine explore methane

Artist rendering of a possible submersible bot exploring one the floor of one of Titan’s methane lakes. Image: NASA JPL

NASA’s Glenn COMPASS Team and researchers with the Applied Research Lab envision a submersible robot, much akin to a submarine, that would land on Titan, then start exploring its liquid methane depths. A prime target is  Kraken Mare, one of the methane seas on Titan, which has been studied extensively by overlooking space probes like Cassini. There’s only so much radar can penetrate and nothing beats an on-spot probe. Yet the engineering difficulties are numerous.

“The focus for us is trying to get a vehicle that will operate in a hydrocarbon sea,” Steven Oleson of NASA’s Glenn Research Center in Cleveland  said. “Think of it as liquid natural gas. How would you get a vehicle to operate in there?”

“Do you use a plutonium-powered system, or do you put a small reactor on it, or do you go non-nuclear and take some oxidizer with you? It’s a sea of natural gas, after all,” Oleson said. Some sort of gas-powered fuel cell might do the trick, he said.

The video below released by NASA seeks to explain how the robot should work and their motives. Engineers and astrologists seem to agree this challenge is worth the effort – it only remains to be seen if people in charge of the budget also think the same. It might be a while until then – the team is considering a mission launch in the 2040s, during Titan’s summer.

Read more about NASA’s plans in this PDF.

titan saturn dune

Saturn’s Moon Titan has Strong Winds and Hydrocarbon Dunes

New experimental research found that Saturn’s largest Moon, Titan, has much stronger winds than previously believed. These rogue winds actually shape the hydrocarbon dunes observed on its surface.

titan saturn dune

Cassini radar sees sand dunes on Saturn’s giant moon Titan (upper photo) that are sculpted like Namibian sand dunes on Earth (lower photo). The bright features in the upper radar photo are not clouds but topographic features among the dunes.
Credit: NASA

Titan is, along with Earth, one of the few places in the solar system known to have fields of wind-blown dunes on its surface. The only other ones are Mars and Venus. Now, researchers led by Devon Burr, an associate professor in Earth and Planetary Sciences Department at the University of Tennessee, Knoxvillehas haves hown that previous estimates regarding the strength of these winds are about 40% too low. In other words, Titan has much stronger winds than previously believed.

Titan is the only known moon with a significant atmosphere, and just like Earth’s atmosphere, it is rich in nitrogen. The geological surface of the moon is also very interesting, with active geological processes shaping it. The Cassini spacecraft captured spectacular images of seas on Titan, but before you get your hopes up, you should know that the seas are not made of water, but of liquid hydrocarbons. However, many astronomers believe that Titan actually harbors an ocean of liquid water, but below its frozen surface – the surface temperature is –290° F (–180° C). It’s actually so cold, that even the sand on Titan is not like the sand on Earth – the sand is also made from solid hydrocarbons. But the thing is, we don’t really know where those grains come from.

“It was surprising that Titan had particles the size of grains of sand — we still don’t understand their source — and that it had winds strong enough to move them,” said Burr. “Before seeing the images, we thought the winds were likely too light to accomplish this movement.”

But the biggest mystery was the shape of the dunes. The Cassini data showed that the predominant winds that shaped the dunes blew from east to west. However, the streamlined appearance of the dunes around obstacles like mountains and craters  suggested that the winds blow from the opposite direction.

In order to figure this out, Burr and his team spent six years refurbishing a defunct NASA high-pressure wind tunnel to recreate Titan’s surface conditions. After the restauration was complete, they used 23 different varieties of sand in the wind tunnel to compensate for the fact that we don’t know exactly what the sand on Titan is made from. The first thing they found is that for all the likely varieties of sand, the winds have to be much stronger than believed.

“Our models started with previous wind speed models but we had to keep tweaking them to match the wind tunnel data,” said Burr. “We discovered that movement of sand on Titan’s surface needed a wind speed that was higher than what previous models suggested.”

They also found an explanation for the shape of the dunes.

“If the predominant winds are light and blow east to west, then they are not strong enough to move sand,” said Burr. “But a rare event may cause the winds to reverse momentarily and strengthen.”

According to the models, this wind reversal takes place every Saturn year – which is 30 Earth years. This also explains why Cassini missed this reversal.

“The high wind speed might have gone undetected by Cassini because it happens so infrequently.”

Journal Reference:

  1. Devon M. Burr, Nathan T. Bridges, John R. Marshall, James K. Smith, Bruce R. White, Joshua P. Emery. Higher-than-predicted saltation threshold wind speeds on Titan. Nature, 2014; DOI: 10.1038/nature14088
Image credits: NASA/JPL

New ‘Mystery Islands’ found on Titan’s Methane Sea

The enduring Cassini spacecraft returns with new insight into the hydrocarbon seas from Saturn’s moon Titan. The latest findings were reported after the spacecraft’s most recent flyby above Titan’s northern hemisphere on August 21, where it performed observations of the largest liquid methane/ethane sea, the 400,000 square kilometre Kraken Mare. The Cassini astronomers were looking to probe the methane sea’s depths, but meanwhile they come across something more interesting: strange floating features reminiscent of the “Magic Island” found on Ligeia Mare, another large methane sea.

Bright features on a huge sea of liquid methane

In contrast to a previously reported bright, mystery feature called “Magic Island” in another of Titan’s large seas, Ligeia Mare, these new features were observed with both  radar data and images from Cassini’s Visible and Infrared Mapping Spectrometer (VIMS). Because the researchers have two different data sets at two different wavelengths this will help them better assess what these mysterious features represent. So far, the VIMS data suggests these features might be waves or floating debris.

Mystery island

Cassini’s radar instrument images show that a bright feature appeared in Kraken Mare, Titan’s largest sea.
Image Credit: NASA/JPL-Caltech/ASI/Cornell

Ligeia Mare’s Magic Island was first discovered in July 2013,  covering an area of some 260 square kilometres. During another flyby in August 2013, data from the Synthetic Aperture Radar (SAR) showed that Magic Island was still there yet the bright features had evolved. Clearly, Cassini shows that Titan’s polar seas are extremely dynamic and hold many mysteries. More observations are required, but our next shot won’t be until January 2015, when Cassini is scheduled to observe the original “magic island” feature in Ligeia Mare once more.

On another note, just last week the same Cassini team put a huge grin up all our faces when they release some stunning photos of light bouncing off Titan’s atmosphere. Here are two of the best shots:

Image credits: NASA/JPL

Image credits: NASA/JPL

Another image from Cassini’s Visual and Infrared Mapping Spectrometer on July 24, 2012, showing a sunlight reflection on a Titanian sea. Image credits: Barnes et al./NASA/JPL/University of Arizona

Another image from Cassini’s Visual and Infrared Mapping Spectrometer on July 24, 2012, showing a sunlight reflection on a Titanian sea. Image credits: Barnes et al./NASA/JPL/University of Arizona

A shallow extraterrestrial sea

During this most recent flyby, Cassini also probed the depths of Kraken Mare. The spacecraft collect altimetry (or height) data, using the spacecraft’s radar instrument along a 120-mile (200-kilometer) shore-to-shore track of Kraken Mare. Reflections were isolated for a shallow 40 km segment. The distinctive double-peaked returns from a region near the mouth of a flooded river valley that feeds the sea indicates liquid methane depths of 20-35 m. For the remainder of 160 km, no observations could be made. The signal most likely became skewed because the liquid was more absorbing than Ligeia Mare or the depths were too high (greater than 200m). For comparison, central Ligeia Mare was 160 m deep. It should be interesting to see how deep Kraken Mare is off-coast.

Cassini radar data reveal the depth of a liquid methane/ethane sea on Saturn's moon Titan near the mouth of a large, flooded river valley. Image Credit: NASA/JPL-Caltech/ASI/Cornell

Cassini radar data reveal the depth of a liquid methane/ethane sea on Saturn’s moon Titan near the mouth of a large, flooded river valley.
Image Credit: NASA/JPL-Caltech/ASI/Cornell

Learn more at NASA’s Cassini mission homepage.