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New Recipe For Oxygen On Icy Moons
Richland WA (SPX) Mar 27, 2006 Researchers at Pacific Northwest National Laboratory said they have uncovered the most detailed picture to date of how oxygen could be manufactured on water-rich but frigid moons in the outer solar system. Since its confirmation on Europa and other satellites orbiting the gas-giant planets of the solar system, extraterrestrial ice has remained a possible source for oxygen and therefore of complex life on other planets. The problem is planetary scientists have not been able to explain how, in the absence of sufficient heat, oxygen could be produced from the permafrost surfaces. The previous assumption was high-energy particles from space - protons, ultraviolet photons and electrons - broke the molecular bonds that chain oxygen to hydrogen and released it into the local environment. Those previous oxygen-production models, however, did not jibe with what PNNL scientists have been seeing in experiments. "The previous model was a two-step process," research team leader Greg Kimmel. "First, an energetic particle produces a stable precursor" - say, two hydrogen atoms coupled with two oxygen atoms (hydrogen peroxide) or a hydrogen atom paired with two oxygen atoms. "In step two, another energetic particle produces O2, or molecular oxygen, from the stable precursor." As they reported at an American Chemical Society meeting in Atlanta, Kimmel and colleagues grew a microscopically thin ice film on a platinum surface in a vacuum, and bombarded the film with high-energy electrons. The electron bursts lasted 30 to 60 seconds at 30 to 130 degrees Kelvin, approximating the minus-hundreds-of-degrees-Fahrenheit temperatures on the icy moons. Afterward, they measured the amount and location of any resulting oxygen, determined by the element's isotopes used to construct layers of the ice film. They discovered that an intermediate species of hydrogen-oxygen permeated the films. "We found that a simpler two-step could not account for our results," Kimmel said. "Our model is a four-step process." First, the energetic particle produces what is known as a common "reactive oxygen species" called a hydroxyl radical, or OH. Next, two OH molecules react to produce hydrogen peroxide. Third, another OH reacts with the hydrogen peroxide to form HO2 (hydrogen coupled to two oxygen atoms), plus a water molecule. Last, an energetic particle splits an oxygen molecule from the HO2. "One might have expected O2 to be produced throughout the region where the electrons penetrate in the film," Kimmel noted, "but this is not the case. It appears that the OH's can be made deeper in the film, but that they subsequently diffuse to and collect at the ice surface with the rest of the reactions (steps 2-4 above) preferentially occurring there." Community Email This Article Comment On This Article Related Links Pacific Northwest National Laboratory Jupiter and its Moons Explore The Ring World of Saturn and her moons The million outer planets of a star called Sol News Flash at Mercury
New Red Spot Growing Fast On Jupiter
Washington DC (SPX) Mar 06, 2006Backyard astronomers, grab your telescopes. Jupiter is growing a new red spot. Christopher Go of the Philippines photographed it on February 27th using an 11-inch telescope and a CCD camera: The official name of this storm is "Oval BA," but "Red Jr." might be better. It's about half the size of the famous Great Red Spot and almost exactly the same color. |
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