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SPACE & SCIENCE NEWS: December 2002
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New-formed crater found on the Moon Dec 20, 2002
Possible biological precursors found in Tagish Lake meteorite Dec 5, 2002
SETI@home to revisit 100 most promising signals Dec 5, 2002

Flash recorded by Leon Stuart
New-formed crater found on the Moon
(Dec. 20, 2002)

Two researchers believe they have identified a lunar crater made just four decades ago. In 1953, American amateur astronomer Leon Stuart photographed a flash on the Moon (right, see bright spot) that was taken to be the impact of a small asteroid, but ground-based telescopes weren't powerful enough to see any crater. The crater found by Buratti and JohnsonNow, however, a small, fresh, crater in the same position as the flash has been found in images taken by the Clementine probe in 1994 (left). Bonnie Buratti of NASA/JPL and Lane Johnson of Pomona College, California, looked at Leon Stuart's photo and estimated that the object that struck the Moon was about 300 meters across and that its impact would have resulted in a crater 1-2 km wide. They estimate the energy released in the impact was about 35 times more powerful than the Hiroshima bomb. A search of images from the Clementine mission revealed a 2-km-wide crater with a bright, blue, fresh-appearing ejecta blanket at the exact location of the 1953 flash. Finding the new crater is important because it will enable scientists to study samples of unaltered subsurface lunar soil. The research is to be published in a forthcoming issue of Icarus.

map of Tagish Lake region
Possible biological precursors found in Tagish Lake meteorite
(Dec. 5, 2002)

A team of researchers has identified organic globules inside the Tagish Lake carbonaceous chondrite that fell over the Yukon Territory of Canada (see map) in 2000. In a study in the Dec. 11 issue of International Journal of Astrobiology, the Japanese and American scientists claim that the globules contain a previously unseen type of primitive carbon-rich material that predates the Solar System. The microscopic hydrocarbon bubbles closely resemble those produced in laboratory experiements intended to simulate organic synthesis on the surface of ice-coated dust grains in interstellar space. One of the authors of the paper, Michael Zolensky, suggests that these hollow capsules such as these, arriving from space, may have served to protect and incubate primitive organisms on Earth. "They would have been ready-made homes for early life forms," he said. "If, as we suspect, this type of meteorite has been falling onto Earth throughout its entire history, then the Earth was provided with these hydrocarbon globules at the same time life was first forming here." Last year, researchers at NASA's Ames Research Center in Moffett Field, Calif., announced that they had made basically identical hydrocarbon globules in the laboratory from materials present in the early solar system and interstellar space. "What we have now shown is that that these globules were in fact made naturally in the early solar system, and have been falling to Earth throughout time," Zolensky said. The researchers believe the Tagish Lake meteorite came from the outer asteroid belt, toward Jupiter, and that similar organic materials may have been falling onto the moons of Jupiter, including Europa. "It is interesting to speculate about the presence of these organics in the ocean we believe may be present under the ice cap of this moon," Zolensky said.

Arecibo radio telescope
SETI@home to revisit 100 most promising signals
(Dec. 5, 2002)

In early 2003, the giant Arecibo telescope will be devoted for a full 24-hour period to checking out the 100 most promising signals collected over the past few years by the SETI@home project. In preparation for this, SETI@home scientists are sifting through the several billion signals (mostly natural radio sources in the Galaxy and beyond) that have been picked up by the project so far in order to identify their target list. This will involve not only singling out interesting spikes that might possibly be artificial but taking into account whether any of these also coincide with fairly nearby Sunlike stars. For more on the selection process, read the Planetary Society's article here. You may also want to see my encyclopedia entry on the Wow! signal – easily the most intriguing signal detected by SETI searches over the past four decades.


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