* Astronomy

Scientists are set to explore the world's deepest undersea volcanoes, which lie 6km down in the Caribbean.
Delving into uncharted waters to hunt for volcanic vents will be Autosub6000, Britain's new autonomously controlled, robot submarine.
Once found, the life, gas and sediment around the vents - the world's hottest - will be sampled and catalogued.

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U.S. marine biologists have discovered thousands of new kinds of microbes at two deep-sea hydrothermal vents in the Pacific Ocean off the Oregon coast.
The discovery was made by scientists from the Marine Biological Laboratory in Woods Hole, Maine, and the University of Washington's Joint Institute for the Study of Atmosphere and Ocean.
Using a new analytical technique called 454 tag sequencing, the scientists surveyed 1 million DNA sequences of bacteria and archaea. The DNA was taken from samples collected from two hydrothermal vents on the Pacific deep-sea volcano, Axial Seamount.
The researchers discovered that while there might be as few as 3,000 different kinds of archaea at those sites, the bacteria exceed 37,000 different kinds.
Most of these bacteria had never been reported before, and hundreds were so different from known microbes that we could only identify them to the level of phylum, said lead author Julie Huber of the MBL. Clearly, additional sampling of these communities will be necessary to determine the true diversity.
The research is reported in journal Science.

Source UPI

Hot vents deep in the ocean harbour thousands of previously unknown microorganisms, scientists report. By examining the DNA of microbes taken from two hydrothermal vents off the coast of Oregon, researchers identified as many as 37,000 different kinds of bacteria and 3,000 archaea, a type of microorganism distinct from bacteria, according to researchers from the Marine Biological Laboratory at Woods Hole, Mass. and the University of Washington.
Their findings are reported in Friday's edition of the journal Science.

"Most of these bacteria had never been reported before. Clearly, additional sampling of these communities will be necessary to determine the true diversity" - lead author Julie Huber, MBL

The researchers also reported that the populations living at the two vents differed because of different chemical environments.
The research was funded by the NASA Astrobiology Institute, National Research Council, L'Oreal USA, the Alfred P. Sloan Foundation and the W.M. Keck Foundation.

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Title: Prolonged Exposure of Basement Edifices caused by Dissolution of Biogenic Ooze by Hydrothermal Venting
Authors: Bekins, B. A.; Spivack, A. J.; Davis, E. E.; Mayer, L. A.

Seafloor hydrothermal convection may continue for millions of years, but if the sediment cover is sufficiently thick, recharge of seawater diminishes, effectively reducing the water/rock ratio and causing changes in fluid composition that reflect more extensive reaction with host rocks. Outcrops formed by basement edifices provide sites for recharge and discharge, enhancing off-axis ventilation of the crust by relatively unaltered seawater; but their life-time as a conduit is thought to end once the seafloor sediment thickness exceeds their maximum height. A recent and exciting discovery is the widespread occurrence of closed depressions in biogenic oozes in the Equatorial Pacific. The position of these features overlying basement edifices, suggests that they are formed by sediment dissolution due to venting fluids. We computed the calcium carbonate precipitated by a fluid of bottom water composition at a range of basement temperatures; and assume this fluid has an equivalent carbonate dissolution potential during subsequent cooling and discharge. For a basement temperature of ~25° C dissolution can outpace moderate Equatorial Pacific carbonate mass accumulation rates of 1-5 g cm2/ky if fluid fluxes exceed 2- 10 m/yr respectively. This range of fluid fluxes is consistent with the regional heat flow deficit and basement permeability. Lower basement temperatures require either higher fluid flux or lower sedimentation rates to produce the dissolution features. By maintaining sediment-free basement outcrops, this process is self- sustaining and promotes wide-spread circulation of relatively unaltered seawater in the basement in an area where the average sediment thicknesses of 300-500 meters would otherwise create an impermeable cap. This dynamic relationship between enhanced ventilation, dissolution and permeability explains several previous observations in this region, including the existence of the closed sediment depressions, the long-standing puzzle of very low heat flow in this region, the presence of relatively unaltered seawater in the basement, and the existence of aerobic and nitrate-reducing microbial activity in the deepest section of the sediment where it would not otherwise exist.

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