Space & Astronomy/Space and Astronomy (October 1993).iso/mac/TEXT_ZIP/jplnews/0573.ZIP/0573.PR

Text File | 1993-04-21 | 7KB | 121 lines

OFFICE OF PUBLIC INFORMATION
JET PROPULSION LABORATORY, CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA.  TELEPHONE  [phone]

FOR RELEASE:  AM's of TUESDAY, FEBRUARY 24, 1970

          PASADENA--If there is life on Mars, it may be a
microbial form no more complex than blue-green algae, according
to Dr. Roy E. Cameron, head of the Jet Propulsion Laboratory's
Soil Science group.
          "The best we can hope for on Mars, it now appears, is
that micro-organisms exist," Cameron told a Caltech Lecture
Series audience last night (Monday).  "Bacteria and blue-green
algae have been found on every Earth desert we have explored,
including the Antarctic ice desert."
          The 1969 photographs of Mars taken by JPL's Mariners VI
and VII revealed a bleak planet with an atmosphere apparently
hostile to life.  Close-up pictures from the 1971 Mars orbiter
spacecraft may provide more data, but the answer probably will
depend on unmanned landings later in the decade.
          While conceding the prospects for Martian life are "not
too encouraging," Cameron said that "the most likely spot for it
would be around the edge of the south polar cap or below the soil
surface."
          Cameron, who has made four exploratory trips to
Antarctica, has found microbes live in the frozen soil there, as
well as in the Atacama Desert in Chile, the Moroccan Sahara, and
the harshest areas of southwestern deserts in the United States.

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          "Antarctica affords an approach to a possible model of
Martian ecology," the speaker told the Beckman Auditorium
audience.  "Mars is an extreme kind of desert, and so is
Antarctica, with its barren, windswept valleys, mountains, and
extremely low temperatures and precipitation.
          Since 1961, Cameron and his aides have collected nearly
20 tons--five tons from Antarctica alone--of Earth's desert soils
for the JPL Soil Science laboratory.  This collection, believed
the largest of its kind in the world, has been sampled for testing
and culturing, with a view to developing life-detection techniques
on Mars.
          The soil science explorations have been sponsored mainly
by the National Aeronautics and Space Administration, for which
Caltech operates JPL.  Other sponsoring agencies include the
Office of Polar Programs of the National Science Foundation, the
Smithsonian Institution, and the International Biological Program.
          Cameron hopes to receive lunar samples this year from
Apollo astronaut diggings and inject Antarctic microbes into Moon
soil to see if they can grow in it.  This could provide further
insight into what might live on Mars, whichuced by
the JPL researchMartian conditions.
          These same organic compounds are also believed to have
been precursors to biological molecules on the primitive Earth.
          The three researchers published their findings in the
March issue of the Proceedings of the National Academy of
Sciences.  The experiments have been a continuing project of the
JPL Bioscience Section which Horowitz formerly headed.  He is a
professor and executive officer of the Caltech biology division
and continues to take an active interest in exobiology, life in
space.

                               -2-

          "This is the most favorable indication for a possible
Martian biological evolution that we have had in the last five
years," Horowitz adds.  "There are still many uncertainties,
however, which won't be resolved until we land on the planet."
          Hopes for Martian life had been reduced by a bleak
pictures of the planet taken by Mariners 4, 6, and 7.  The next
spacecraft to Mars will be the twin Mariner orbiters, which JPL
will launch in May for the National Aeronautics and Space
Administration.  They will orbit and study Mars at close range
for three months beginning in November.
          The first proposed lander on Mars is NASA's 1975 Viking
Project.  NASA sponsored the JPL Mars-simulation research.
          The tests were made with soil or pulverized glass in a
gas mixture of 97% carbon dioxide, with added carbon monoxide and
water vapor to simulate the Martian atmosphere indicated by
Mariner 6 and 7 scientific findings.  The ultraviolet radiation
approximated the amount striking the surface of Mars, as measured
by the two spacecraft in 1969.
          The JPL researchers reported that ultraviolet rays of
longer than 2000 angstroms in wavelength produced organic com-
pounds in the surface or just beneath the surface of the soil, or
crushed glass.  Previously it was believed that ultraviolet rays
of this wavelength would be incapable of producing such compounds.
          "It would appear that radiation over a broad range below
3,000 angstroms can cause organic formation," the authors said in
their paper.  The ultraviolet reaching the surface of Mars is

                               -3-

above 1,950 angstroms.  All shorter wavelengths are believed
absorbed by the heavy carbon dioxide content of the Martian
atmosphere.  (An angstrom is 1/10 millionth of one millimeter).
          "Our findings suggest that ultraviolet presently
reaching the Martian surface may be producing organic matter,"
their report continues.  "The rates of production would be
limited by the low partial pressures of carbon monoxide and water
in the Martian atmosphere, but the amount of product formed could
be considerable over geological time."
          The experimenters said formaledehyde and acetaldehyde
are "important starting materials for the synthesis of a variety
of organic compounds, including sugars."
          The fine soil and powdered vycor glass samples were
sterilized by baking at high temperatures before being used in
the tests.  The ultraviolet sources were a high-pressure xenon
lamp and a low-pressure mercury lamp.
          Longer irradiation produced a larger conversion of
carbon monoxide to carbon dioxide and organic products, the
investigators reported.  Reducing the amount of water vapor on
the surface material reduced the organic accumulation.  The
investigators propose that carbon monoxide and water vapor are
absorbed by soil particles, where they react under the influence
of ultraviolet light.

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