SPACE
& SCIENCE NEWS: December 2002
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& science news > space & science news: December 2002
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.  Now,
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. |
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. |
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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