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Signs of Life: On the Lookout for Extraterrestrial

From: UFO UpDates - Toronto <ufoupdates@virtuallystrange.net>
Date: Fri, 04 Jan 2002 08:21:07 -0500
Fwd Date: Fri, 04 Jan 2002 08:21:07 -0500
Subject: Signs of Life: On the Lookout for Extraterrestrial


SETI: Search For Life

Signs of Life: On the Lookout for Extraterrestrial Sweet Spots

By Leonard David
Senior Space Writer
posted: 07:00 am ET
03 January 2002

BOULDER, COLORADO - Looking for life elsewhere is a tough task
for human or robot. The good news is that the scientific skill
and tools to search for, detect and inspect extraterrestrial
life are advancing rapidly.

A revolution in the field of microbiology is afoot, along with
extraordinary progress in understanding the "geobiological"
history of Earth. And then there's growing amazement about life
on this planet and how it can survive and thrive even in the
most extreme and bizarre of environments. For example, within
the last ten years alone, more than 1,500 new species of
microorganisms have been discovered and genetically sequenced.

In a just issued report, Signs of Life, a multidisciplinary
group of scientists grappled with techniques and technologies to
detect evidence for extraterrestrial life - either on the spot
on other worlds, or within prime pickings hauled back to Earth
by robotic spacecraft.

Spurred largely by an April 2000 workshop held in Washington,
D.C., report findings and conclusions were pulled together by
the National Research Council (NRC) Committee on the Origins and
Evolution of Life.

"The report is based on a workshop that brought together a
healthy spectrum of senior experts and young researchers," says
Jonathan Lunine, co-chair of the committee and professor of
planetary science and physics at the University of Arizona in
Tucson. Many of the workshop attendees are developing techniques
to detect life, and modeling the environments in which such
techniques might be used on other planets, he explains.

John Baross, associate professor of oceanography at the
University of Washington in Seattle, also co-chairs the

"The discussion was vigorous and exciting. This is a different
world of life detection than that in 1976, at the time of
Viking," Lunine told SPACE.com.

Lunine feels the key to success in life detection in the field
is to try a range of techniques that vary in their specificity
and need for prior assumptions about the nature of life. Doing
so will maximize the chances for success in searches at the
planet itself.

"With returned samples, of course, one should throw everything
possible at the effort," Lunine explains.

The Committee on the Origins and Evolution of Life, Lunine adds,
is continuing its efforts with a study on the potential nature
of life that might be very different from terrestrial=85and how
one would go about detecting such life.

Elusive answers

Since the 1976 landings of two Viking landers on Mars, the
technological ability to spot life on celestial bodies has made
impressive strides. Furthermore, understanding the nature of
life and the concomitant power of analytical tools in the
biological sciences are viewed together as "one of the most
dramatic changes since Viking," the NRC report states.

In coming to grips with the central question of what is life,
the committee assumed that if life exists on other planets or
moons, it will be carbon based and dependent on liquid water.
Also, it will be self-replicating and capable of evolving.

The quest to find life beyond Earth involves answers to several
tough questions. For instance, how does one determine if there
are living organisms in a returned sample? Secondly, can living
organisms leave tell tale traces from earlier times that can be
found in a returned sample? Lastly, how does one determine
whether there are living organisms or fossils in samples
examined robotically on another solar system body?

Lessons from the "Mars rock"

Firm answers to these questions are elusive, reports the study
group. There are great uncertainties regarding the possible
range of chemistry and morphology that could constitute life.

The committee found that "there is a disconnect between those
techniques that have been developed to an exquisite degree of
sensitivity to identify terrestrial organisms and those that
could provide the greatest probability of detecting exotic life
forms from another planet."

"Given the extreme difficulty (or impossibility) of inductively
describing all possible living processes based on terrestrial
biochemistry, no single approach, or even combination of
approaches, will guarantee success on a given sample."

That view has been brought home, quite literally, by the ongoing
research of the often called "Mars rock" - the infamous ALH84001
meteorite. The claim of evidence for biological processes in
that rock of ages from the red planet remains controversial and

ALH84001 offers an important lesson in the fundamental
complexity of identifying the faint traces of present biology or
Martian life that is long gone.

"Perhaps even more difficult, if life or its remains is detected
in a sample, will be the determination of whether it is a
terrestrial containment from Earth, and if so, whether it was
delivered by the spacecraft or in the natural process of
cross-contamination via asteroidal or cometary impact," the
committee report adds.

Sterile approach

Dispatching high-tech gear to scout for life -- and not drag
along hitchhiking terrestrial microorganisms in the process --
is a difficult challenge, the committee notes. Spacecraft must
be sterilized to avoid tainting other planetary bodies with
Earth biology - a situation tagged as "forward contamination."

There remains, however, "intense debate", the NRC report
observes, over the level to which spacecraft sterilization
should be achieved for missions to particular solar system

Firstly, sterilization must be done in such a way as to avoid
damaging spacecraft components.

One procedure -- sterilization via dry heating in an oven -- was
performed on the two Viking landers that searched for life on
the red planet. However, that approach puts harsh demands on
spacecraft components and leads to a substantial increase in
mission cost and, possibly, the chances of mission failure, the
report states.

Sterilization by particle irradiation of a space probe is an
alternative. Yet this technique may not reach all spacecraft
subsystems, particularly when the mission design dictates
shielding electronic components from ambient sources of
radiation. That type environment, for example, is found in the
Jupiter system.

Another worry is that radiation-tolerant bacteria may dictate
that irradiation levels exceed even the extraordinary levels to
be experienced during the prime mission phase of, say, a mission
to Jupiter's moon, Europa.

Titan: cold soak

Regaining access to all parts of a spacecraft before launch to
assure that sterilization has taken place is an unsolved
problem, the committee reports.

Flagged in the report is the very compact Huygens probe now en
route to Saturn. The lander is to be dropped off on that
planet's mysterious moon, Titan, by the Cassini interplanetary
spacecraft after arrival in 2004.

The European Space Agency-built probe was not sterilized to a
high standard on the grounds that the profoundly cold Titan
environment would sterilize the lander soon after landing. "Yet
Titan is itself a target for investigating advanced stages of
organic chemistry that on Earth might have led to life," the
report notes.

In the area of spacecraft cleanliness, the committee encourages
further work to refine sterilization approaches, with an eye
toward minimizing impacts on spacecraft cost and mission

Hauling back the goods

Another hotly debated topic is that of back contamination,
whereby extraterrestrial samples brought back might harm
biological processes here on Earth.

At issue is whether organisms "out there" might exist that are
sufficiently different from terrestrial organisms "down here" to
escape laboratory detection, yet similar enough to pose a threat
to the health of our biosphere.

"In the debates about life detection and back contamination,
this 'niche' has not been explored to the extent that it should
be - in part because of the difficulties in answering the
question," the committee report states.

The committee recommends that a focused study be done in the
near future to address the detection of microorganisms with
varying degrees of nonterrestrial biochemistry, and the possible
threat that such organisms might pose to terrestrial organisms.

Similar in view from past studies on back contamination, the
committee report states that there are practical and societal
reasons for ensuring planetary protection for all interplanetary

"Although the probability that an extraterrestrial life form
could be pathogenic to humans, or even viable at all in the
terrestrial environment, is very low, it cannot be shown to be
zero," the report says.

Back in the lab

Due to the myriad of technical woes to overcome in returning
samples back to Earth, much of the search for life elsewhere may
initially be done "in situ", that is, on the spot, by robots.

One problem.

Many of the powerful and sensitive techniques for detecting life
in laboratories here on Earth are not yet "space rated". That
is, they are far too big, complex, and not ready for prime time
flight. That condition may remain so, at least in the near

Because of the continuing rapid improvements in technology, the
committee reports, it is not appropriate to recommend a specific
set of techniques for in situ life detection at this time.
Pressing on with the design of innovative and "miniaturizable"
techniques for in situ life detection is encouraged.

It is an almost certainly that the most interesting locales from
the point of view of the search for life will not be the easiest
to get to. Finding those comfy niches that could be just right
for life today, or were in the past, suggests the committee, is
likely to mean landing in less-than-totally-safe sites.

"It remains unclear as to which environments in our solar system
should be searched for signs of life," the committee found,
beyond the general identification of planetary targets - such as
Mars, Europa, and Titan. "In large measure, we yet do not known
enough about these bodies to target searches in particular

Picking those extraterrestrial sweet spots will require a series
of missions, including orbital reconnaissance, followed by
up-close-and-personal perusals using landed vehicles.

[UFO UpDates thanks The Anomalist www.anomalist.com for the lead]

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