& SCIENCE NEWS: February 2002
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& science news > space & science news: February 2002
Evolved space civilisations will be eyeing
(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
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.
more. Source: BBC
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.
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.
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
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.
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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