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Correction -- June 4, 1999: The speed of the Leibniz computer was originally quoted as 12 Gflops. In fact the speed is much closer to 1.2 Gflops. We regret the error. May 28, 1999: During the May 18th press conference
announcing Nobel Laureate Dr. Baruch Blumberg as the new head
of NASA's Astrobiology Institute, Blumberg posed a challenge
to the scientific community. NASA Administrator Dan Goldin concurred, stating, "We're
looking for any form of biological life. Single-cell (organisms)
would be a grand slam." |
But before we can conduct a comprehensive search for unknown
extraterrestrial forms of life, there needs to be an extensive
classification of known life forms on Earth. The history of life
on Earth provides us with a good model for how life can evolve
in the universe. Fossils, even microbial fossils, can tell us
a great deal about all the different life forms that have at
one time or another shown their face on our planet. By becoming forensic scientists, researchers at the Space Sciences Laboratory at the Marshall Space Flight Center can develop an encyclopedia of microbial life forms that have developed on Earth. Because so many life forms need to be catalogued, the scientists are working to develop a "D'Arcy Machine" to help them create a comprehensive "Book of Life." |
This Book of Life project has three phases. Phase 1 - compiling
a beginning database of microbial life forms - has already been
completed. This image database is composed of 10,000 examples
and distinguishes the basic microbial shapes such as rods, spheres,
filaments, clusters that look like grapes ( Phase 2 of the project will expand the basic database by using
a more powerful neural network. Funds from the NASA Advanced
Concepts Office provided Marshall scientists with a Beowulf-class
parallel computer. NASA developed the Beowulf Project to address
scientific problems associated with large data sets. "Human judgement is still very much depended upon for
identifying microbial life forms," says Dr. David Noever
of NASA's Marshall Space Flight Center. "Automated filters
would be much like the filters commonly used to sort out useful
e-mails from useless ones. The user of the neural network would
get a morning menu of microbial candidates for further detective
work."
By Phase 3 of the project, the neural network will be so advanced in its learning that it will be able to acquire and classify new images with minimal human supervision. This network would then be equipped for future search scenarios, including the examination of meteorites found on Earth and samples retrieved from lunar or interplanetary space missions. This advanced neural network will be a fast and efficient classifier of the vast amount of microbial images that will need to catalogued. |
A Big Problem While Thompson and other biomathematicians used almost exclusively linear and quadratic distortions to study how life forms change over time, it is unlikely that complex life forms throughout the universe will be confined to these narrow statistical relationships. In a paper presented last September at the 50th anniversary D'Arcy Thompson conference in Dundee, Scotland, Noever asked, "What if D'Arcy had had a computer?" When D'Arcy Thompson introduced the idea of studying organisms
by their geometric shapes, he could only draw figures by hand.
The computers of today can take Thompson's research much further.
By repeatedly comparing and contrasting learnable imagery, a
D'Arcy machine would expand the chapters of the Book of Life
Project and give us an interplanetary version of D'Arcy Thompson's
classic "On Growth and Form." Computers with artificial intelligence using neural networks
provide more opportunities to answer complex astrobiology imaging
questions. The non-linear evolution of artificial intelligence
is customized to handle the learning of multiple patterns or
images. Computers with artificial intelligence could accommodate
various influencing variables (such as gravity) that change over
scales much larger than a linear variance can include. Changes
in the effects of gravity on a body can occur, for instance,
when humans go into outer space. Astronauts often experience
fluid retention, excessive bone loss and muscle wasting due to
the effects of microgravity. The neural network at Marshall will be able to rapidly process the complex computations necessary for mathematically analyzing the shapes of life (morphometrics). If someone continuously used a hand calculator to tabulate just linear connections, at a rate of one calculation per second it would take forty years to finish a billion calculations. The Linux-based computer at Marshall speeds up this process dramatically, processing over a billion connections per second. |
Writing the Interplanetary Book of Life The powerful capabilities of a D'Arcy classification machine could also be used to study and catalogue images from the 14 known Martian meteorites. The total mass to be scanned exceeds 20 kilograms (44 lbs.), so if micron scale images are included in future projects (1 micron is 1-millionth of a meter, or 1/25,000 of an inch) the combined image handling capabilities for biogenic classification will exceed several trillion frames. "Looking for life forms in Mars rocks means analyzing microfossils - like potential nanometer-size - so small that 50,000 could fit across the width of a single strand of human hair," says Noever. Based on past performance, the Antarctic meteorite (ANSMET)
field teams are likely |
By using a D'Arcy machine to begin a morphometric study of microbial life on Earth, someday remote and automated instruments may be able to identify life elsewhere in the universe - whatever form that life may take. |
There are many details that make up the answer to the question, "What is life?" The following is an abbreviated list of some of the basic properties of life on Earth: Symmetries: Bilateral, asymmetry, posterior/anterior, radial (jellyfish, starfish), internal/external (humans have external symmetry but internal organs are not all symmetrical)... Appendages: amoebic extendable, ciliated (with brush-like sweeping motions), attachment pods, flagella tail (for forward propulsion)... Behaviors: locomotion or propulsion (dependent on gravity, fluid/gas environment, pressure), metabolic (feeding and respiration), methods of communication, avoidance of death... ![]() Nervous systems: diffuse (invertebrates), central nerve ring (starfish), dorsal nerve cord (vertebrates)... Sensitivity to light (sight): infrared (snakes), ultraviolet (moths, bees), polarized light (octopus)... Sensory perception for motion, temperature, position, gases (such as oxygen or carbon dioxide), certain chemicals, vibrations and electricity vary widely among organisms. Some sense perceptions seem to operate in a collective or cooperative manner, as in the case of army ants, termites, or bees, where group intelligence is greater than the knowledge of the single organism. |
Related Stories Life on the Edge -- Jan. 13, 1999, an educational initiative to
teach students about life in extreme environments Callisto makes a big splash -- Oct. 22, 1998, Scientists may have discovered a salty ocean and some ingredients for life on Jupiter's moon. Great Bugs of Fire -- Sep. 16, 1998, NASA sends volcano-loving microbes into orbit for materials science research. Earth microbes on the Moon -- Sep. 1, 1998, Three decades after Apollo 12, a remarkable colony of lunar survivors revisited. Exotic-looking microbes turn up in ancient
Antarctic ice -- Mar.
12, 1998, microbes in the ice above Lake Vostok. NASA's Office of Space Science press releases and other news related to NASA and astrophysics |
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