The Lagoons of Titan: Oily Liquid Confirmed on Saturn Moon August 18, 2008
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Earthlings might be scrambling to find liquid hydrocarbons buried in our planet, but Saturn’s moon Titan has plenty to spare.
Scientists say that a dark, smooth surface feature spotted on the moon last year is definitely a lake filled primarily with liquid ethane, a simple hydrocarbon.
“This is the first observation that really pins down that Titan has a surface lake filled with liquid,” said the paper’s lead author, University of Arizona professor Robert Brown.
The new observations affirm that Titan is one of the likeliest places to look for life in our solar system. Some astrobiologists have speculated that life could develop in the moon’s hydrocarbon lakes, although it would have to be substantially different from known life on Earth, which requires liquid water.
Mixed in solution with the ethane, the lake is also believed to contain nitrogen, methane, and a variety of other simple hydrocarbons.
The Cassini-Huygens probe determined the chemical composition of the liquid by the way it reflected light, a technique known as spectrometry that has provided most of our knowledge about other planets’ atmospheric compositions.
“It was hard for us to accept the fact that the feature was so black when we first saw it,” Brown said. “More than 99.9 percent of the light that reaches the lake never gets out again. For it to be that dark, the surface has to be extremely quiescent, mirror smooth. No naturally produced solid could be that smooth.”
Further, the scientists saw the specific absorption signature of ethane, which absorbs light at exactly 2-micron wavelengths.
These kinds of measurements are made more difficult by the hydrocarbon haze that engulfs the moon, making it hard to actually see the Titanic ground. Cassini scientists have to take advantage of narrow observation windows. One of these occurred in December 2007, which allowed them to catch this view of the lake, Ontario Lacus. At 7,800 square miles, it’s slightly larger than the Earthbound Lake Ontario
Ethane is the byproduct of a solar-energy-induced reaction that transforms atmospheric methane, aka natural gas. Scientists believe ultrafine particles of ethane fall from the atmosphere to the surface and fill the lake.
Here on earth, ethane is used to create ethylene, which is used as an all-purpose chemical precursor and is the world’s most-produced organic compound.
Brown and his team will publish their results in the July 31 issue of the journal Nature.
[SOURCE: Wired Science http://blog.wired.com/wiredscience/2008/07/lake-of-petrole.html ]
Phoenix lander confirms ice in Martian soil August 18, 2008
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The Phoenix spacecraft has tasted Martian water for the first time, scientists reported Thursday.
By melting icy soil in one of its lab instruments, the robot confirmed the presence of frozen water lurking below the Martian permafrost. Until now, evidence of ice in Mars’ north pole region has been largely circumstantial.
In 2002, the orbiting Odyssey spacecraft spied what looked like a reservoir of buried ice. After Phoenix arrived, it found what looked like ice in a hard patch underneath its landing site and changes in a trench indicated some ice had turned to gas when exposed to the sun.
Scientists popped open champagne when they received confirmation Wednesday that the soil contained ice.
“We’ve now finally touched it and tasted it,” William Boynton of the University of Arizona said during a news conference in Tucson on Thursday. “From my standpoint, it tastes very fine.”
Phoenix landed on Mars on May 25 on a three-month hunt to determine if it could support life. It is conducting experiments to learn whether the ice ever melted in the red planet’s history that could have led to a more hospitable environment. It is also searching for the elusive organic-based compounds essential for simple life forms to emerge.
The ice confirmation earlier this week was accidental. After two failed attempts to deliver ice-rich soil to one of Phoenix’s eight lab ovens, researchers decided to collect pure soil instead. Surprisingly, the sample was mixed with a little bit of ice, said Boynton, who heads the oven instrument.
Researchers were able to prove the soil had ice in it because it melted in the oven at 32 degrees — the melting point of ice — and released water molecules. Plans called for baking the soil at even higher temperatures next week to sniff for carbon-based compounds.
The latest scientific finding is the first piece of good news for a mission that has been dogged by difficulties in recent weeks.
An electrical short on one of Phoenix’s test ovens threatened the instrument, but scientists said the problem has not recurred. The lander, which spent the past several weeks drilling into the hard ice, also had trouble delivering ice shavings into an oven until the success this week.
NASA said Phoenix has achieved minimum success thus far. The space agency on Thursday announced that it would extend the mission for an extra five weeks until the end of September, adding $2 million more to the $420 million price tag, said Michael Meyer, Mars chief scientist at NASA headquarters.
Unlike the twin rovers roaming near the Martian equator, Phoenix’s lifetime cannot be extended much more because it likely won’t have enough power to survive the Martian winter
The science team also released a color panorama of Phoenix’s landing site using more than 400 images taken by Phoenix. The view “was painstakingly stitched together,” said Mark Lemmon of Texas A&M University, who headed the effort.
The portrait revealed a Martian surface that was coated with dust and dotted with rocks.
[SOURCE: http://news.yahoo.com/s/ap/20080731/ap_on_sc/phoenix_mars;_ylt=AhSwPqvNaQtymiudhg9f9f8iANEA ]
By ALICIA CHANG, AP Science Writer
