tony baldwin / blog

dailygalaxy.com wrote the following post 8 hours ago:

Could Titan's Hydrocarbon Chemistry Have Crossed the Chasm to Life? (Today's Most Popular)



Saturn’s giant moon Titan has water frozen as hard as granite and Great Lakes-sized bodies of fed by a complete liquid cycle, much like the hydrological cycle on Earth, but made up of methane and ethane rather than water. Methane and ethane, the simplest hydrocarbon molecules, can assemble themselves into fantastically complex structures. Since complex hydrocarbons form the basis of life on Earth, scientists are wondering if hydrocarbon chemistry on Titan could have crossed the chasm from inanimate matter to some form of life?

Titan has been considered a “unique world in the solar system” since 1908 when, the Spanish astronomer, José Comas y Solá, discovered that it had an atmosphere, something non-existent on other moons.
It seems perfectly appropriate that one of the prime candidates for life in our solar system, Saturn's largest moon, should have surface lakes, lightning, shorelines, relatively thick nitrogen atmosphere -- and seasons. Titan can be viewed as an early-model Earth. And 100% of all known Earths have awesome life on them. The significantly lower temperature is a bit of a stumbling block (it's ten times as far from the sun as us), but there's a strong possibility of subterranean microbial life -- or even a prebiotic "Life could happen!" environment.

If a space traveler ever visits Titan, they will find a world where temperatures plunge to minus 274 degrees Fahrenheit, methane rains from the sky and dunes of ice or tar cover the planet's most arid regions -- a cold mirror image of Earth's tropical climate, according to scientists at the University of Chicago.

Titan's ice is stronger than most bedrock found on earth, yet it is more brittle, causing it to erode more easily, according to new research by San Francisco State University Assistant Professor Leonard Sklar. Sklar and his team developed new measurements from tests on ice as cold as minus 170 degrees Celcius which demonstrate that ice gets stronger as temperature decreases. Understanding ice and its resistance to erosion is critical to answering how Titan's earth-like landscape formed. Titan has lakes, rivers and dunes, but its bedrock is made of ice as cold as minus 180 degrees Celcius, eroded by rivers of liquid methane.

"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.

The-lagoons-of-titan-oily-liquid-confirmed-on-saturn-moon1 Titan, one of Saturn's 60 moons, is the only moon in the solar system large enough to support an atmosphere. Pierrehumbert and colleague Jonathan Mitchell, have been comparing observations of Titan collected by the Cassini space probe and the Hubble Space Telescope with their own computer simulations of the moon's atmosphere.

"One of the things that attracts me about Titan is that it has a lot of the same circulation features as Earth, but done with completely different substances that work at different temperatures," Pierrehumbert said. On Earth, for example, water forms liquid and is relatively active as a vapor in the atmosphere. But on Titan, water is a rock. "It's not more volatile on Titan than sand is on Earth."

Methane-natural gas-assumes an Earth-like role of water on Titan. It exists in enough abundance to condense into rain and form puddles on the surface within the range of temperatures that occur on Titan.

"The ironic thing on Titan is that although it's much colder than Earth, it actually acts like a super-hot Earth rather than a snowball Earth, because at Titan temperatures, methane is more volatile than water vapor is at Earth temperatures," Pierrehumbert said.

Pierrehumbert and Mitchell even go so far as to call Titan's climate tropical, even though it sounds odd for a moon that orbits Saturn more than nine times farther from the sun than Earth. Along with the behavior of methane, Titan's slow rotation rate also contributes to its tropical nature. Earth's tropical weather systems extend only to plus or minus 30 degrees of latitude from the equator. But on Titan, which rotates only once every 16 days, "the tropical weather system extends to the entire planet," Pierrehumbert said.

Titan's dense, nitrogen-methane atmosphere responds much more slowly than Earth's atmosphere, as it receives about 100 times less sunlight than Earth. Seasons on Titan last more than seven Earth years. Its clouds form and move much like those on Earth, but in a much slower, more lingering fashion.

Physicists from the University of Granada and University of Valencia, analyzing data sent by the Cassini-Huygens probe from Titan, have “unequivocally” proved that there is natural electrical activity on Titan. The world scientist community believes that the probability of organic molecules, precursors of life, being formed is higher on planets or moons which have an atmosphere with electrical storms.

Scientists with NASA's Cassini mission have monitored Titan's atmosphere for three-and-a-half years, between July 2004 and December 2007, and observed more than 200 clouds. They found that the way these clouds are distributed around Titan matches scientists' global circulation models. The only exception is timing -- clouds are still noticeable in the southern hemisphere while fall is approaching.

"Titan's clouds don't move with the seasons exactly as we expected," said Sebastien Rodriguez of the University of Paris Diderot, in collaboration with Cassini visual and infrared mapping spectrometer team members at the University of Nantes, France. "We see lots of clouds during the summer in the southern hemisphere, and this summer weather seems to last into the early fall. It looks like Indian summer on Earth, even if the mechanisms are radically different on Titan from those on Earth. Titan may then experience a warmer and wetter early autumn than forecasted by the models."

On Earth, abnormally warm, dry weather periods in late autumn occur when low-pressure systems are blocked in the winter hemisphere. By contrast, scientists think the sluggishness of temperature changes at the surface and low atmosphere on Titan may be responsible for its unexpected warm and wet, hence cloudy, late summer.

Scientists will continue to observe the long-term changes during Cassini's extended mission, which runs until the fall of 2010, which will offer plenty of opportunities to monitor climate change on Titan -- the spacecraft makes its next flyby of the moon on June 6. We'll learn if the sluggish weather is the result of a slow rate of temperature change at the surface.

Cassini results so far don't show if Titan has an ocean beneath the surface, but scientists say this hypothesis is very plausible and they intend to keep investigating. Detecting tides induced by Saturn, a goal of the radio science team, would provide the clearest evidence for such a hidden water layer.

"Additional flybys may tell us whether the crust is thick or thin today," says Jonathan Lunine, a Cassini interdisciplinary investigator with the University of Rome, Tor Vergata, Italy, and the University of Arizona, Tucson. "With that information we may have a better understanding of how methane, the ephemeral working fluid of Titan's rivers, lakes and clouds, has been resupplied over geologic time. Like the history of water on Earth, this is fundamental to a deep picture of the nature of Titan through time."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.

The image at the top of the page is a NASA/JPL artist's concept of lake on Titan.

The Daily Galaxy via the University of Chicago and nasa.gov

Related articles
Saturn's 'Spring Sun' Lights Up Bizarre Polar Hexagon
Last Close Cassini Flyby of Saturn's Moon Rhea
Extraterrestrial Smog --Saturn's Titan rivals Beijing

hewiak wrote the following post 1 hour ago:

A nonprofit foundation wants to recruit a man and a woman - possibly a married couple - for a bare-bones, 501-day journey to Mars and back that would start in less than five years, project organizers said on Wednesday.

The mission, expected to cost upwards of $1 billion, would be privately financed by donations and sponsorships.

Project founder Dennis Tito, a multimillionaire who in 2001 paid $20 million for a trip to the International Space Station, said he will pay start-up costs for two years to begin development of life-support systems and other critical technologies.
more

SCIENTISTS HAVE DISCOVERED THE two biggest black holes ever observed, each with a mass billions of times greater than the Sun's, according to a new study published.

The two giants are located in the heart of a pair of galaxies several hundred million light years from Earth, said the study in scientific journal Nature.

Each black hole is estimated to have a mass about 10 billion times greater than the Sun, dwarfing the previously largest-known black hole, which has a mass of 6.3 billion suns.

The University of California, Berkeley, team led by Nicholas McConnell and Chung-Pei Ma said one black hole is located in NGC 3842, the brightest of a cluster of galaxies about 320 million light years from Earth.

The second hole is of "comparable or greater mass" and is located in NGC 4889, the brightest galaxy in the Coma cluster, about 335 million light years away.

A new paper by scientists on NASA's Cassini mission finds that blocks of hydrocarbon ice might decorate the surface of existing lakes and seas of liquid hydrocarbon on Saturn's moon Titan. The presence of ice floes might explain some of the mixed readings Cassini has seen in the reflectivity of the surfaces of lakes on Titan.
"One of the most intriguing questions about these lakes and seas is whether they might host an exotic form of life," said Jonathan Lunine, a paper co-author and Cassini interdisciplinary Titan scientist at Cornell University, Ithaca, N.Y. "And the formation of floating hydrocarbon ice will provide an opportunity for interesting chemistry along the boundary between liquid and solid, a boundary that may have been important in the origin of terrestrial life."

Titan is the only other body besides Earth in our solar system with stable bodies of liquid on its surface. But while our planet's cycle of precipitation and evaporation involves water, Titan's cycle involves hydrocarbons like ethane and methane. Ethane and methane are organic molecules, which scientists think can be building blocks for the more complex chemistry from which life arose. Cassini has seen a vast network of these hydrocarbon seas cover Titan's northern hemisphere, while a more sporadic set of lakes bejewels the southern hemisphere.

Scientists think the variations in reflectivity, or brightness, have to do with the smoothness or texture of the surface. If a lake is fully liquid, it looks dark, but if it is only partially liquid, it looks brighter.

Up to this point, Cassini scientists assumed that Titan lakes would not have floating ice, because solid methane is denser than liquid methane and would sink. But the new model considers the interaction between the lakes and the atmosphere, resulting in different mixtures of compositions, pockets of nitrogen gas, and changes in temperature. The result, scientists found, is that winter ice will float in Titan's methane-and-ethane-rich lakes and seas if the temperature is below the freezing point of methane—minus 297 degrees Fahrenheit (90.4 kelvins).

The scientists realized all the varieties of ice they considered would float if they were composed of at least 5 percent "air," which is an average composition for young sea ice on Earth. ("Air" on Titan has significantly more nitrogen than Earth air and almost no oxygen.)

If the temperature drops by just a few degrees, the ice will sink because of the relative proportions of nitrogen gas in the liquid versus the solid. Temperatures close to the freezing point of methane could lead to both floating and sinking ice - that is, a hydrocarbon ice crust above the liquid and blocks of hydrocarbon ice on the bottom of the lake bed. Scientists haven't entirely figured out what color the ice would be, though they suspect it would be colorless, as it is on Earth, perhaps tinted reddish-brown from Titan's atmosphere.

"We now know it's possible to get methane-and-ethane-rich ice freezing over on Titan in thin blocks that congeal together as it gets colder—similar to what we see with Arctic sea ice at the onset of winter," said Jason Hofgartner, first author on the paper and a Natural Sciences and Engineering Research Council of Canada scholar at Cornell. "We'll want to take these conditions into consideration if we ever decide to explore the Titan surface some day."

Cassini's radar instrument will be able to test this model by watching what happens to the reflectivity of the surface of these lakes and seas. A hydrocarbon lake warming in the early spring thaw, as the northern lakes of Titan have begun to do, may become more reflective as ice rises to the surface. This would provide a rougher surface quality that reflects more radio energy back to Cassini, making it look brighter. As the weather turns warmer and the ice melts, the lake surface will be pure liquid, and will appear to the Cassini radar to darken.

"Cassini's extended stay in the Saturn system gives us an unprecedented opportunity to watch the effects of seasonal change at Titan," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We'll have an opportunity to see if the theories are right."

A team was looking through data from the Galaxy Evolution Explorer (Galex) satellite for star-forming regions around a galaxy called NGC 6872.

But they were shocked to see a vast swathe of ultraviolet light from young stars, indicating that the galaxy is actually big enough to accommodate five of our Milky Way galaxies within it.

The find was reported at the American Astronomical Society meeting in the US.

NGC 6872, a galaxy about 212 million light-years away in the constellation Pavo, was already known to be among the largest spiral galaxies.

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope have seen a key stage in the birth of giant planets for the first time. Vast streams of gas are flowing across a gap in the disc of material around a young star. These are the first direct observations of such streams, which are expected to be created by giant planets guzzling gas as they grow. The result is published on 2 January 2013 in the journal Nature.

European astronomers have discovered a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system — the nearest to Earth. It is also the lightest exoplanet ever discovered around a star like the Sun. The planet was detected using the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile. The results will appear online in the journal Nature on 17 October 2012.

Despite claims in the 1890s that Mars with filled with canals teeming with water, research over the past several decades has suggest that in fact, Mars has only a tiny amount of water, mostly near its surface.Then, during the 1970s, as part of NASA’s Mariner space orbiter program, dry river beds and canyons on Mars were discovered—the first indications that surface water may have once existed there. The Viking program subsequently found enormous river valleys on the planet, and in 2003 it was announced that the Mars Odyssey spacecraft had actually detected minute quantities of liquid water on and just below the surface, which was later confirmed by the Phoenix lander.



Now, according to an article published yesterday in the journal Geology, there is evidence that Mars is home to vast reservoirs of water in its interior as well. The finding has weighty implications for our understanding of the geology of Mars, for hopes that the planet may have at some point in the past was home to extraterrestrial life, and for the long-term prospects of human colonization there.



“There has been substantial evidence for the presence of liquid water at the Martian surface for some time,” said Erik Hauri, one of the study’s authors. “So it’s been puzzling why previous estimates for the planet’s interior have been so dry. This new research makes sense.”



Future trips of spacecraft such as the Phoenix lander (above) to Mars could reveal more about the nature of water on the red planet



The research team, led by led by University of New Mexico scientist Francis McCubbin, didn’t even have to go all the way to Mars to find the water—they just closely looked at a pair of meteorites we’ve already had for some time. The Shergotty meteorite, which crashed in Bihar, India in 1865, and the Queen Alexandria Range 94201 meteorite, which landed in Antarctica and was discovered in 1994, were both ejected from Mars roughly 2.5 million years ago. Because they formed due to volcanic activity, when molten Martian mantle was brought to the surface and crystallized, they can tell us a great deal about the planet’s insides.



“We analyzed two meteorites that had very different processing histories,” Hauri said. “One had undergone considerable mixing with other elements during its formation, while the other had not.” For both of the meteorites, the team looked specifically at the amount of water molecules locked inside crystals of the mineral apatite, and used this as a proxy for how much water was contained in the original rock on Mars that produced the meteorites. To determine the precise amount of water, they used a technology called secondary ion mass spectrometry, which shoots a focused beam of ions at the sample and measures the amount of ions that bounce off of the surface.



The amount of water in the meteorites suggested that the Martian mantle contains somewhere between 70 and 300 parts per million of water—an amount strikingly similar to Earth’s own mantle. Because both the samples contained roughly the same water content despite their different geological histories on Mars, the researchers believe that the planet incorporated this water long ago, during the early stages of its formation. The paper also provides us with an answer for how underground water may have made its way to the Martian surface: volcanic activity.



Earlier this week, we discussed how solar radiation is among the many problems that face potential human colonization of Mars, but finding a huge underground store of water inside the planet would still go a long way towards making settlement a legitimate possibility. In the long-term, drilling for underground water may be cheaper and easier than, say, trying to melt surface ice, or subsisting off the tiny amount of surface water that we know is present.



Additionally, the finding is getting an entire separate crowd excited: those who are hoping to find fossil or other evidence that Mars once supported life. The fact that water has apparently existed on the planet for such a long time makes the odds of life originating there just a little less scarce scant.



All this from a pair of meteorites that crashed on our planet over a century ago. Just imagine what we might learn during future missions to Mars, such as NASA’s unmanned space laboratory, Curiosity, which will land on Mars on August 5th.



Still, it won’t be easy. Watch this NASA video to learn about the riskiest part of the whole mission—the seven minutes between when the rover hits the top of the Martian atmosphere and when it touches down.

Remember that image from a few weeks back that showed Earth with all its water gathered up in a sphere beside it? Well here's that image again, only this time, it also features Jupiter's moon Europa, along with all of its water. Notice anything interesting?



Based on data acquired by NASA's Galileo satellite, astronomers think the global oceans sloshing around beneath Europa's icy exterior are likely 2—3 times more voluminous than the oceans here on Earth. Not 2—3 times more proportionally, 2—3 times more in total volume.