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SPACE & SCIENCE NEWS: February 2002
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Evolved space civilizations will be eyeing Earth Feb 26, 2002
Under pressure: life at the bottom Feb 21, 2002
Life's likelihood elsewhere Feb 20, 2002
Ring around the Sun suggests new way to seek extrasolar worlds Feb 17, 2002
Europan tides might foster life Feb 8, 2002
New NASA budget: implications for astrobiology Feb 5, 2002


Earth
Evolved space civilisations will be eyeing Earth
(Feb. 26, 2002)


This article by Helen Pearson from the American Association for the Advancement of Science, Boston.

Alien cultures more advanced than our own will have spotted us by now, say astronomers. Tell-tale rainbows from any inhabited planets will soon show us where to gaze back. Within 15 years, next-generation telescopes will be scouring the skies for light from other Earth-like planets. A slight technological edge would mean that any life-forms on those planets could already be peering at us. "Our own Earth has been putting out a signal for a billion years," says astronomer Roger Angel of the University of Arizona in Tucson. "Any civilization slightly more advanced than our own would know there was life on this planet," he told the meeting of the American Association for the Advancement of Science in Boston.

For lack of anything else to go on, astronomers expect planets harbouring life to resemble Earth. "We have to look for what we understand," says molecular biologist Norman Pace of the University of Colorado in Boulder.

Within a blob of light sent from a distant planet, the spectrum of wavelengths should reveal signs of life. Bright blue suggests an Earth-like atmosphere of gases, and green plants strongly reflect infrared. Life-supporting gases such as oxygen and nitrogen also absorb characteristic infrared wavelengths. The overall hue might be purplish, suggests Wesley Traub of the Harvard Smithsonian Center for Astrophysics in Cambridge, Massachusetts. With these indicators, "we'd feel fairly convinced there's something going on there", says Traub.

No telescopes are currently able to pick up the giveaway beams, as faint light reflected by the planet is blasted out by its bright parent star. But powerful future devices that can scan stars within 100 light years are already being planned. Huge arrays of telescopes called interferometers, for example, act as points on a giant mirror. By focusing faint light, they should have the resolution to distinguish planet light from its adjacent parent star. Both NASA and the European Space Agency (ESA) are planning planet-hunting interferometers. NASA's four-telescope Terrestrial Planet Finder is scheduled for launch by 2013, ESA's six-telescope Darwin interferometer should follow in 2015.

Even if it were found, such a planet could never be reached: we'll just have to watch and wait. But fluctuations in the spot's brightness might tell us about its oceans, land and weather, says Traub.

Nature News Service / Macmillan Magazines Ltd 2002

Another reminder of the forthcoming marriage of SETI and astrobiology. It's an interesting realization that we are giving ourselves away not only (and perhaps not mainly) by our radio leakage and limited attempts at signaling, but also by the biogenic signatures in our planet's atmosphere and surface. As we refine our abilities to detect these life-markers on extrasolar worlds in the coming years, we may also learn how to search for the tell-tale signs of industrial populations, including atmospheric pollutants, ozone holes, and the like. Then SETI would have some real targets for its efforts at communication.

Thanks to Al Harrison at the University of California, Davis, for notification of this.

Read more. Source: BBC

E. coli
Under pressure: life at the bottom
(Feb. 21, 2002)


Tom Gold will be delighted. The author of The Deep Hot Biosphere has long argued that the bulk of terrestrial – and extraterrestrial – life dwells far underground, in the instices of rock, under almost unimaginably high pressure. But what kind of things could dwell in such a place? The humble E. coli bacterium for one, it would seem. James Scott and Anurag Sharma of the Carnegie Institution have shown that this best-loved but most mundane of laboratory guinea-pigs can survive and even multiply under the kind of pressures that exist 50 km below the Earth's surface. And if something as ordinary as this denizen of human stomachs can eke a living as a deep endolith, how much better will organisms cope that have actually evolved far underground? Of course, it does lead to an interesting question: How did E. coli acquire this amazing survival trick?

For more on the work at the Carnegie Institution, go here.

Trapezium in Orion
Life's likelihood elsewhere
(Feb. 20, 2002)


University of Colorado biochemist Norman Pace offered his thoughts about the prospects for life beyond Earth at this year's AAAS meeting in Boston (Feb. 14-19) in his talk "Molecular Perspectives of Extreme Life." Signs of life elsewhere in the galaxy or universe may be "co-occurring, non-equilibrium gases like oxygen and methane-an indication the gases are being replenished," said Pace. He also pointed out that an intelligent species looking back at our own planet would have little difficulty diagnosing the presence of an abundant biology here. Interferometers and other instruments due to be placed in orbit over the next 10-20 years will likewise enable us to detect signs of biological activity on extrasolar worlds.

For more on Pace's talk, go here.

COBE image showing solar disk
Ring around the Sun suggests new way to seek extrasolar worlds
(Feb. 17, 2002)


European Space Agency scientists have found direct evidence that a bright disk of dust surrounds the Solar System, beyond the orbit of Saturn. This strengthens the idea that such features around mature stars are signposts to planetary systems and will allow mission planners to draw up a short-list of target stars to be observed by ESA's future planet-search missions, Eddington and Darwin. The fact that the Solar System has a disk means its dust supply must be continually replenished (at an estimated rate of 50 tons/second) otherwise it would have been lost a long time ago-swallowed up by the outer planets and moons or ejected into interstellar space. The finger of suspicion points at collisions between objects in the Kuiper Belt as the source of the dusty ring. If the same process is happening in other planetary systems, then those stars should be encircled by dust too; in fact, such features have already been detected around Vega, Epsilon Eridani, and a number of other relatively nearby systems. Astronomers will now been studying these and other candidate stars much more closely in an effort to learn more about the possible sizes and distribution of any planets that may be associated with them.

For more, go here (ESA).

Europa
Europan tides might foster life
(Feb. 8, 2002)


Jupiter's moon Europa might not only sustain life but encourage its evolution, according Richard Greenberg at the University of Arizona, a member of the Galileo Imaging Team. He reports in the February issue of American Scientist that a combination of factors, including tidal processes, warm waters, and periodic surface exposure might drive evolution by forcing organisms to adapt to changing conditions. Tides, in particular, could play a pivotal role. Ocean tides on Europa are larger than Earth's with heights reaching 500 meters; even the shape of the moon is stretched along the equator due to Jupiter's pull on the waters below the icy surface. Because Europa's orbit is in sync with its rotation, it keeps the same face towards the giant planet for thousands of years. But over longer periods, any given niche freezes, Greenberg points out. "That would require an organism to adapt in some way." The surface of Europa was previously thought to be tens of km thick, never exposing the oceans. But recent studies of surface features suggest that exposure may occur quite commonly. "The ocean is interacting with the surface," Greenberg said. "There is a possible biosphere that extends from way below the surface to just above the crust." Tides have created two types of Europan surface features: cracks/ridges and chaotic areas. The ridges are thought to be built over thousands of years by water seeping up the edges of cracks and refreezing to form higher and higher edges until the cracks close to form a new ridge. The chaotic areas are thought to be evidence of the melt-through necessary for exposure to the oceans. The tidal heat, created by internal friction, could be enough to melt the ice, he said. Undersea volcanoes are also a possible explanation for large melt-throughs. Greenberg said this combination of factors would give organisms a stable but changing environment-exactly the type that would encourage evolution.

For more, go here.

Europa Orbiter
New NASA budget: Implications for astrobiology
(Feb. 5, 2002)


The Bush administration proposes to give NASA $15 billion next fiscal year, a 1.4% increase over 2002. Surprisingly, given the hawkish mood of the White House, the budget request allows for a modest expansion of the planetary exploration program. The Mars robotic program is fully supported, which is excellent news for astrobiologists. However, cost overruns have led to the cancellation of the Europa Orbiter-a major blow to researchers hoping to learn more about the nature of this moon's subsurface-and no further funding to study a possible mission to Pluto. The latter is disappointing because Pluto's atmosphere is freezing out as the planet moves further from the Sun, lowering hopes that there will be any gases left for a visiting spacecraft to detect. The Outer Planets program is being reformulated into what NASA is calling the New Frontiers program. New Frontiers missions will be capped at $650 million and have development cycle times of 48 months. Each New Frontiers mission will be selected through an open, peer-reviewed competition modeled after NASA's Discovery series of planetary missions. The Bush administration held up the Discovery program (which has included the Lunar Prospector, Mars Pathfinder, Stardust, and Genesis missions) as one of the few effective ones at the space agency. NASA space science chief Ed Weiler said the agency will issue its first New Frontiers announcement of opportunity this spring, with selection targeted for 2003. For the Planetary Society's reaction to the budget proposal, go here.

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