The earliest seafloor hydrothermal vents – supposedly more than three billion years old – may be nothing more than deposits from underground springs active in the last few thousand years. That is the claim of two US geologists who carried out a new analysis of rocks from South Africa which were previously dated to the Archaean period – when life first began to diversify. The findings could have important implications for our understanding of the early Earth and the microbial life forms that lived there. But one authority on the geology of the Barberton greenstone belt – where the rocks are found – launched a vigorous defence of evidence that they contain ancient hydrothermal vents.
Astronomers have compiled the largest, most detailed map of the Universe so far and believe that it shows beyond doubt the presence of an all-pervading "dark energy" throughout the cosmos. The three-dimensional map contains 200,000 galaxies and covers six per cent of the sky. The furthest galaxies in the map are two billion light years away. Such maps are invaluable because the large-scale structure of the Universe reveals the interplay of cosmic forces during the last 13 billion years. The new map comes from the Sloan Digital Sky Survey (SDSS), an international collaboration of over 200 astronomers at 13 institutes around the world.
Methane lakes may await Huygens on Titan
(Oct. 5, 2003)
The Huygens probe, scheduled to parachute down through the thick atmosphere of Titan in 2005, may be heading for a splashdown not a hard landing. That's the conclusion of a series of 25 radar observations, made using by the giant Arecibo telescope when Saturn came relatively close to Earth in 2001 and 2002. A portion of the radar echoes received from Titan showed that some parts of the big satellite were only reflecting about 2 percent of the radio waves falling on them – a low reflectivity that is characteristic of liquid hydrocarbons. The most likely substance involved is methane– normally a gas on Earth, but likely to be found as a liquid under the extremely low temperatures on Titan. The reflecting surfaces detected in the study are anywhere from a few tens to a few hundreds of kilometers across, suggesting they are methane lakes lying within large impact craters. In the event that Huygens splashes down rather than lands on a frozen part of the Moon, it will still be able to function for a while and send back data from the surface: ESA mission designers thoughtfully equipped the probe to float. For the Cornell press release on which this story is based, go here.
