From: Stig Agermose <stig.agermose@get2net.dk>
Date: Sun, 07 Feb 1999 06:47:09 GMT
Fwd Date: Sun, 07 Feb 1999 13:28:06 -0500
Subject: E.T. in Quarantine


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Source: ABCNews

http://abcnews.go.com:80/sections/science/DailyNews/oberg990204.html

Stig

***

E.T. in Quarantine

By Jim Oberg

Special to ABCNEWS.com

Feb. 4 - Quarantines can help a society protect itself from
dangerous infections.

The word comes from the French, for the 40 days of isolation
once faced by new arrivals who may have been infected. After the
quarantine has passed, they were either certified to be
disease-free - or dead.

Quarantining an entire planet against potentially harmful
extraterrestrial diseases becomes more difficult.

Though the odds are minuscule, what's needed to prevent
something with global consequences? What protections are
reasonable?

The launch of Stardust to retrieve a milligram of dust from the
Wild-2 comet is the first human attempt to bring back
extraterrestrial samples in almost three decades.

NASA would like to bring back samples from Mars in less than 10
years. Other comet missions are also on tap, and the Russians
dream of retrieving samples from the Martian moons Phobos and
Deimos.


Space Spores


There's also the renewed debate over natural transport, via
meteorites and space dust.

A century ago, scientists used the term "panspermia" to describe
the possibility that spores could naturally pass from planet to
planet. Today, space experts have asked themselves if the
quarantine issue isn't already moot, since new evidence and
computer simulations suggest there never has been biological
isolation between planets.

Asteroid impacts on Earth, the moon and Mars have flung rocks
off each world, circling the sun until they slam into a nearby
world.

One extreme view is that life on Earth is the result of
contamination from Mars. That smaller planet cooled earlier than
Earth, and seems to have had oceans for hundreds of millions of
years while Earth's surface was still molten.

Martian rocks bearing spores could have rained upon Earth until
our oceans formed and provided a hospitable environment for a
few lucky survivors.


Rain From Mars


Even today, a hundred tons of meteorites and space dust fall on
Earth every day. About one-tenth of 1 percent of that - perhaps
100 kilograms per day - is from Mars. Four billion years ago,
during what planetary scientists call the Period of Heavy
Bombardment, there would have been much, much more.

But could microorganisms survive these interplanetary journeys?

During a conference on Mars exploration in Boulder, Colo., last
August, retired Swedish industrialist Curt Mileikowsky discussed
the work of a European team that evaluated exactly these
prospects. The group considered hazards such as shock and
heating during ejection off the planet's surface, cosmic rays
and heat-induced DNA decay while en route, and heating during
impact at the end of the journey.

For some meteorites, the Europeans were astonished to discover
that microbial survival rates could be very high even for trips
that lasted up to a million years.

While it's commonly thought that meteorites falling to Earth are
thoroughly seared by the heat of atmospheric entry, this is a
misconception. The outer skin may be burned off during the very
brief fireball phase, but most of the meteorite's interior
remains at the subfreezing temperature of deep space.

Freshly fallen meteorites, far from being red hot, often have
frost on them from condensation. Any microbial passengers would
have a gentle landing.


Hazards From Related Life


If ancient Mars life also left modern descendants at home, the
biohazard to its cousins on Earth is much higher than that from
two independent strands of life.

In a 1994 article entitled "Is It Dangerous To Return Samples
From Mars To Earth?," Carl Sagan wrote: "If putative Martian
organisms were originally transferred to Mars by collisions with
the Earth, they may be enough like us that they could be
pathogenic."

The same argument holds if the transfer was from Mars to Earth.

Whether Mars had - or has - life that's related to Earth life,
some sort of quarantine is called for. NASA has implemented some
protocols for its Mars samples, but the issue includes more than
just that planet.

Last year, the National Research Council in Washington, D.C.,
issued a report on the "biological potential" for samples from
other solar system bodies, and concluded that while some sources
could be judged entirely nonhazardous, others - including comets
- still require protective measures.


Space Sterilization


Stardust scientists insist that their collecting - high-speed
impact of cometary dust grains into the fine aerogel collectors
- will automatically sterilize the recovered material. Test
results back this up - at least for what we keep calling "life
as we know it."

Some scientists remain unconvinced that current protections are
good enough.

A new group called the International Committee Against Mars
Sample Return recently launched a Web site discussing its
concerns, with links to other documents on planetary quarantine.

Barry DiGregorio, co-founder of the group, says he's concerned
that NASA may relax its standards of Mars samples. One idea even
described a special-purpose space station designed to process
extraterrestrial samples in absolute isolation from Earth's
biosphere - a quarantine for the Space Age.         

James Oberg spent 22 years as a rocket scientist for NASA, and
has written eight books and numerous articles on space flight.


Life on the Moon, Maybe 

It's commonly thought that on at least one occasion, infectious
germs were brought back from the moon.

This occurred on the Apollo 12 mission in November 1969, when
the crew retrieved pieces of the Surveyor 3 robot that had been
on the moon for two years. Subsequent culturing of swabs from
various locations gave one positive result - viable
Streptococcus mitus spores were picked up from a swab rubbed
inside the Surveyor's camera case.

Microbiologists weren't all that startled by the finding, since
the temperatures inside the hardware on the lunar surface had
stayed well within the range that microbial spores were known to
tolerate, even if it had also been in a vacuum (and viable
spores have been retrieved from spacecraft brought back after
months or even years in Earth orbit).

Unfortunately, the technician collecting the lunar swabs back in
1969 was seen to violate isolation protocol by laying the new
swabs down on a non-sterilized table surface. So the positive
results could have been caused by somebody sneezing in the room
the previous day.

Even though it's intriguing that the one positive was the sample
taken from the most sheltered interior location of the hardware,
the finding must be chalked up as interesting if true, and left
to dangle in perpetual ambiguity. 


*Life on the Moon, Maybe                   


More on Stardust and E.T.:

*Comet Mission Launches Saturday
        
*Lee Dye: Life in the Extreme
        

Web Links:  

*The Mars Society
        
*National Research Council Report
        
*International Committee Against Mars Sample Return
        
*NASA's Stardust Site
        
*Cosmic Ancestry


Archive:

*Jim Oberg's past articles        


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