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SPACE & SCIENCE NEWS: November 2000
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First land life pushed back over a billion years Nov 30, 2000
Science teams selected for Space Interferometry Mission Nov 29, 2000
High-flying balloon captures mystery bacterium Nov 24, 2000
Further signs of liquid water on Mars Nov 21, 2000
New phylum of animal discovered Nov 20, 2000
TNA one? Nov 15, 2000
Organic matter in Leonid meteors Nov 15, 2000
Bacteria found thriving in snow at South Pole Nov 9, 2000
Evidence of recent volcanity activity on Mars Nov 3, 2000
Are there planets in globular clusters? Nov 2, 2000

Earliest appearance of life on land pushed back over a billion years
(Nov. 30, 2000)

Scientists with NASA's Astrobiology Institute (NAI) have discovered fossilized remnants of microbial mats that developed on land between 2.6 billion and 2.7 billion years ago in the Eastern Transvaal district of South Africa. This pushes back the earliest evidence of life on land some 1.4 billion years. It also suggests that an ozone shield and an oxygen-rich atmosphere existed on Earth 2.6 billion years ago, both necessary conditions for life on land to emerge. The results are reported in the November 30 issue of Nature.

For more, go here.

The Space Interferometry Mission
Science teams selected for Space Interferometry Mission
(Nov. 29, 2000)

NASA has chosen 10 science teams to spearhead research to be carried out with the Space Interferometry Mission (SIM), scheduled for launch in 2009. A major space-based observatory in NASA's Origins Program, SIM will be the first mission to carry an optical interferometer as its main instrument. It will combine the light from two sets of four 30-cm- (1-ft.-) diameter telescopes arrayed across a 10-m (33-ft.) boom to achieve a resolution approaching that of a 10-m-diameter mirror. This will allow it to perform extremely sensitive astrometry enabling it to detect very small wobbles in the movement of a star due to undeen companions. Among other things, SIM will search for Earth-sized extrasolar planets. One of the principal investigators will be Geoffrey Marcy, of the University of California, Berkeley. Other planetary investigators will include JPL's Michael Shao (Extrasolar Planets Interferometric Survey) and Charles A. Beichman (The Search for Young Planetary Systems and the Evolution of Young Stars).

For more, go here.

High-flying balloon captures mystery bacterium
(Nov. 24, 2000)

Researchers from the Indian Space Research Organization (ISRO), Cardiff University and the University of Wales College of Medicine claim that a previously unidentified bacterium caught in the filter of an ISRO balloon may have come from a passing comet. The microbe was captured at a height of 16 kilometers. But the astrobiology community will need to see a lot more evidence before it seriously entertains the claim, particularly as its chief advocate is Chandra Wickramasinghe who, along with Fred Hoyle, has long championed the highly controversial idea of microbes arriving on Earth from space. Commented Wickramasinghe: "[the bacterium] is so different from anything we've seen before that there are only two possible explanations." The first, he explained, is that "organisms have been lifted from the Earth to great heights in the skies and have somehow multiplied there and changed over time." The second is "that this is an example of primitive alien life."

Gullies on the slopes of Hale crater
Further signs of liquid water on Mars
(Nov. 21, 2000)

New images from Mars Global Surveyor, obtained on November 10, show more gullies on the Martian surface that may have been carved by water. The latest pictures reveal channels on the slopes of some large sand dunes inside the 136-kilometre-wide Hale crater in the planet's southern hemisphere. They add to a growing body of evidence gleaned by MGS which suggests that water could exist in a porous layer of rock buried just below the Martian surface. Winter in the Martian southern hemisphere begins in mid-December. Over the next few months, NASA scientists will examine closely new pictures of the planet in an attempt to bolster their evidence.

L. maerski
New phylum of animal discovered
(Nov. 20, 2000)

Researchers from the universities of Copenhagen and Aarhus, in Denmark, claim (in Journal of Morphology) to have found a completely new kind of animal living on algae in a well in Greenland. The 0.1-millimeter long freshwater organism does not fit into any previously known family of animals. Named Limnognathia maerski, it shares some characteristics with certain seawater creatures. However, its discoverers have tentatively assigned it to a new phylum called Micrognathozoa. Its most remarkable feature is a set of very complicated jaws that it uses to scrape the bacteria and algae that it feeds on from underwater moss which freeze over during the long Arctic winter. L. maerski reproduces through parthenogenesis. The animal was discovered in 1994 in samples taken from Isunngua on Disco Island in northwestern Greenland. Now, an entire colony of females lives in a refrigerator at Copenhagen University.

For more, go here.

TNA and RNA nucletides
TNA one?
(Nov. 15, 2000)

Scientists have long puzzled how the first replicating molecule came about on Earth. A popular theory is that there was a time, before DNA and proteins existed, when primitive life was based on RNA – a molecule that can serve both as a genetic material and a catalyst for its own formation. However, RNA itself is so complex that it's hard to see how it could have been the first replicator. Now, an international team of biochemists has produced new nucleotides that can be joined to form a double helix and can be cross-paired with RNA or DNA strands. The new units, alpha-threofuranosyl nucleotides, are simpler than those of RNA or DNA, and so, in theory, could have been manufactured more easily in the prebiological regime. This leads the team to speculate that there may have been an era before the RNA World when TNA - threofuranosyl nucleic acid – formed the basis of life.

Reference: K.-U. Schöning, P. Scholz, S. Guntha, X. Wu, R. Krishnamurthy, A. Eschenmoser, "Chemical Etiology of Nucleic Acid Structure: The [alpha]-Threofuranosyl-(3'->2') Oligonucleotide System," Science, 290: 1347-1351 (2000).

Organic matter in Leonid meteors
(Nov. 15, 2000)

Researchers of the NASA and U.S. Air Force-sponsored Leonid Multi-Instrument Aircraft Campaign report the astrobiological significance of their observations of last year' s Leonid meteor storm in this weeks's special issue of Earth, Moon and Planets. Their findings have implications for the existence and survival of life's precursors in comet material that reaches Earth. Said Peter Jenniskens of Ames Research Center and principal investigator for the airborne research mission: "Findings to date indicate that the chemical precursors to life – found in comet dust — may well have survived a plunge into early Earth's atmosphere." Jenniskens and his colleagues think that much of the organic matter in comet dust may survive entry into Earth' s atmospheric entry. "Organic molecules in the meteoroid didn' t seem to burn up," he explained. Another way in which organic matter can survive the plunge into Earth's atmosphere was discovered by a team from the Aerospace Corporation, Los Angeles, who detected the fingerprint of complex organic matter, identical to space-borne cometary dust, in the path of a bright Leonid fireball. This "fingerprint" is still under investigation to ensure that trace-air compounds are not contributing to the detection. Another finding with potentially important implications for astrobiology is that meteors are not as hot as researchers had previously believed. "We discovered that most of the visible light of meteors comes from a warm wake just behind the meteor, not from the hot meteoroid's head," said Jenniskens. This wake has just the right temperature for the creation of life' s chemical precursors, he said. Utah State University researchers found that, during the meteors' demise in the atmosphere, their rapid spinning caused small fragments to be ejected in all directions, quite far from the meteoroid's head. This is an important finding for astrobiology, because it means that meteors may be able to chemically alter large amounts of atmosphere.

For more, go here.

Psychrophilic bacteria in South Pole snow
Bacteria found thriving in snow at the South Pole
(Nov. 9, 2000)

Microbiologist Ed Carpenter of the State University of New York in Stony Brook and his colleagues have found up to 5,000 bacteria per millilitre of melted snow from the South Pole. Tests have shown that the microbes can grow and divide even at -17°C – the coldest condition the team tested. "Probably they could live at even lower temperatures," says Carpenter. Bacteria have been found in snow near the Pole before, but they were thought to have blown in accidentally. It wasn't believed they could grow in the harsh conditions there, where temperatures range between -85° and -13°C. DNA tests have shown that all the organisms belong to previously unknown species. Their closest relatives are the Deinococcus, well known for their extremely efficient DNA repair mechanisms. It was not known why the Deinococcus evolved such high protection, since nowhere on Earth is ultraviolet radiation strong enough to damage DNA so badly. However, severe dehydration can harm DNA as much as UV radiation does – and the Antarctic is a very dry place. This new discovery adds to the suspicion that life could exist in other environments previously thought too harsh, such as the polar ice caps on Mars, the researchers say. The research is described in Applied and Environmental Microbiology, 66(10): 4514-4517, 2000.

For more, go here (pre-publication BBC report) and here (New Scientist report).

Olympus Mons
Evidence of recent volcanic activity on Mars
(Nov. 3, 2000)

Observations by the Mars Global Surveyor have been interpreted by astronomers as evidence of vulcanism on the Red Planet within the past 10 million years or so. Mars has a number of giant volcanoes, including Olympus Mons (pictured here) – the largest volcano in the solar system. Planetary astronomers believe that images sent back by MGS show molten lavas to the south of Elysium Mons in the fairly recent past, suggesting that Mars may still be volcanically active. This has important climatological, and possibly biological, implications. If some of the Martian volcanoes are still capable of erupting it's possible that Mars may periodically go through cycles of warming due to the increased greenhouse effect of released gases, including carbon dioxide. Such periods could provide a more clement environment for any vestigial life that remains dormant on the planet today.

For more, go here and here.

47 Tuc
Are there planets in globular clusters?
(Nov. 2, 2000)

A survey of 35,000 stars in the globular cluster 47 Tucanae has failed to find traces of planets. The work, to be reported in Astrophysical Letters in December, involved using the Hubble Space Telescope to look for tell-tale dips in brightness due to transits by planets orbiting around them. However, the null result is not surprising and certainly doesn't mean that globular clusters are devoid of planets. The survey was only capable of detecting "hot Jupiters" – large gas giants in tiny, circular orbits – like those discovered around some Sun-like stars in the solar neighborhood (and even then the orbit of the planet would have to be virtually edge-on to our line of sight to enable a transit). These are not the kind of planets you would expect to find in a globular cluster where there is a deficiency of heavy elements needed for building planetary cores. Where the metal content of a star (and by implication the material available for planet-building) is low, the planets that form around it are likely to be smaller than those we see in the solar system. We are only likely to find globular cluster planets – assuming any exist – when we have the capability to search them for small gas giants or terrestrial-type worlds. There's the further complication that we're not even sure of the status of many of the known extrasolar "planets".

For more, go here. For earlier coverage of this story, go here.


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