News: Enceladus Hints at the 'L' Word
- From: "Robert Karl Stonjek" <rstonjek@xxxxxxxxxxxxxx>
- Date: Mon, 31 Mar 2008 15:05:59 -0500 (EST)
Enceladus Hints at the 'L' Word
By Phil Berardelli
ScienceNOW Daily News
26 March 2008
The latest encounter between NASA's Cassini spacecraft and Saturn's moon
Enceladus has come tantalizingly close to revealing the second location in
the solar system that could support life.
Cassini first flew by the Arizona-sized moon 2 years ago and discovered it
was ejecting geysers of water vapor and ice crystals. Ever since, mission
scientists have been itching to take a closer look. They got their chance on
12 March, when the spacecraft skirted the moon at an altitude of only 50
kilometers before shooting through the vaporous jets. This time, the team
reported today at a news conference at NASA headquarters in Washington,
D.C., Cassini's instruments picked up the presence of organic molecules:
methane, ethane, formaldehyde, acetylene, cyanide, and propane. All are
precursors of the more complex chemicals that combined to give rise to life
on Earth.
"Enceladus's brew is like carbonated water with an essence of natural gas,"
said team member J. Hunter Waite Jr. of the Southwest Research Institute
(SwRI) in San Antonio, Texas. The spacecraft detected the organics after it
passed by Enceladus and trained its ultraviolet imaging spectrograph on the
light of a star called Zeta Orionis that was crossing behind the moon's icy
jets. The intervening molecules absorbed the starlight in well-defined
patterns to reveal their identity, explained team member Larry Esposito of
the University of Colorado, Boulder.
The organic materials represent "one of the three ingredients of biological
potential," Waite said. The other two ingredients--liquid water and a
sufficient source of heat--might also be present. Enceladus seems to be
pumping heat from its lower hemisphere. Cassini's infrared spectrometer
detected temperatures as high as -92°C. "I know that doesn't seem very
warm," team member John Spencer of SwRI's Boulder, Colorado, facility told
reporters, but it is more than 93° warmer than the surrounding surface. "A
great deal of energy is being delivered to the surface," he said.
The major unanswered question is whether Enceladus contains liquid water
beneath its surface. Finding out is the goal for future Cassini flybys, such
as the two scheduled for August and October of this year, Esposito said.
Astrophysicist Margaret Turnbull of the Global Science Institute in Antigo,
Wisconsin, says the new observations "highlight the fact that the basic
ingredients for carbon-based life can be found in many places in planetary
systems." The big question, she says, is whether Enceladus represents an
environment that can sustain living creatures. For that to happen, "the
presence of liquid water remains the number-one requirement," Turnbull says.
Source: Science
http://sciencenow.sciencemag.org/cgi/content/full/2008/326/1?etoc
Posted by
Robert Karl Stonjek
.
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