Gobierno de la ciudad de Buenos Aires
Hospital Neuropsiquiátrico
"Dr. José Tiburcio Borda"
Laboratorio de Investigaciones Electroneurobiológicas
y
Revista
Electroneurobiología
ISSN: ONLINE 1850-1826 - PRINT 0328-0446
Modern Myths Concerning Life on Mars
by
Gilbert V. Levin*
BioSpherix Division, Spherix
Incorporated, Annapolis, MD 21401, USA
Contact: glevin@spherix.com;
phone 410-224-3319; fax 410-224-3010
Electroneurobiología 2006; 14 (5), pp. 3-25; URL <http://electroneubio.secyt.gov.ar/index2.htm>
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Table of Contents
1. Introduction
3. The Viking Labeled Release Experiment
4. The LR Pedigree
5. The LR on Mars
6. The Standard Model Specific Obstacles
Raised and Rebuttals
7. The Present Situation
8. Future Life Detection Experiments
9. Recommendations
ABSTRACT: July 30, 2006 was the 30th
anniversary of the Viking Mission’s first Labeled Release (LR) life detection
experiment on Mars. The strong response,
together with supporting results from eight additional LR tests of Martian
soil, established the presence of an active agent that was inhibited by
heating. The data satisfied the
pre-mission criteria for the detection of living microorganisms. However, the scientific community reacted
cautiously, generally concluding that the activity in the soil was caused by
chemistry or physics.
Over the last
three decades, investigation of Mars has greatly increased. Soil, rock, and atmospheric analyses have
been made. Multi-spectral observations
have been made from Mars and Earth orbits and from Earth-based telescopes. Knowledge of extreme habitats on Earth and
bizarre life forms that populate them has increased dramatically. However, this
vast amount of new astrobiological information has yet to be integrated into an
objective scientific evaluation of the LR results and the possibilities for
life on Mars. Indeed, in part upon
misinterpretations of the new findings, myths have been embedded into the scientific
literature of Mars.
Based on these
myths as key ingredients, a false “standard model” of Martian life potential
has been developed. It has been accepted
by much of the astrobiological community, and, through its endorsement, the
world at large. This paper attempts to
bring the supportable facts together in calling for a revision of the current
consensus regarding life on Mars. It
recommends actions to facilitate the paradigm change.
Key words: Life on Mars, astrobiology, extreme
habitats, Viking mission Labeled Release experiment, Martian environment, water
on Mars
œ
1. INTRODUCTION
July 30, 2006 marked the 30th anniversary of the
Viking Mission’s first Labeled Release (LR) life detection experiment on
Mars. Its strongly positive response
established the presence of an active agent(s) in the Martian soil. In subsequent runs, the response from the
soil was shown to be eliminated or substantially reduced by heating or by
months-long storage in the dark at about 10o C, within the Martian
ambient surface temperature.[1] Similar responses were obtained at the two
Viking landing sites some 4,000 miles apart.
The data satisfied and, through improvised additional LR sequences,
exceeded the pre-mission criteria set for the detection of living
microorganisms. However, the results
were treated very cautiously, and the general scientific community concluded
that the activity in the soil was chemical or physical, rather than biological.
Over the last three decades, the scientific investigation of
Mars has greatly increased. Soil, rock
and atmospheric analyses have been made on Mars. Multi-spectral observations have been made
from orbit, and telescopic observations made from Earth. Our knowledge concerning extreme habitats on
Earth and bizarre life forms that inhabit them has increased dramatically. However, this vast amount of new
astrobiological information has yet to be integrated into a scientific
evaluation of the possibilities and prospects for life on Mars. Indeed, despite these recent findings, and,
in part, based upon their misinterpretations, a demonstrably erroneous
“standard model” for Martian life has been developed. The model has been accepted by much of the
astrobiological community, and, through its endorsement, the world at
large. This paper attempts to bring
together the relevant discrete findings about life on Mars, and justify a
revision of the current consensus.
2.
THE STANDARD MODEL
The
generally accepted “standard model” for life on Mars postulates:
·
The surface of Mars is inimical to extant life because of the
absence of liquid water, the intense UV flux and an ubiquitous layer of highly
oxidizing chemical(s).
·
The absence of organic matter in the surface material is
proof of the oxidizing layer and/or the effect of the UV flux, and of the
absence of life.
·
Life may have existed on the surface in the geological past
when conditions were more hospitable.
·
Extant life may inhabit underground oases where there is
liquid water and environmental conditions provide a favorable habitat.
Any claim to the
detection of life on Mars must deal with each of the obstacles posed by this
model and relevant corollaries resulting there from. This paper will attempt to show that the
Standard Model and its corollaries, comprising the “Modern Myths of Mars,” are
not supported in fact.
3.
THE VIKING LABELED RELEASE EXPERIMENT
Because life is the most complex phenomenon, the detection of
any chemical on Mars is unlikely to be accepted as proof of life. Therefore, the demonstration of active metabolism was the basis of the LR life detection experiment. A simple diagram of the experiment is shown
in Figure 1.
FIGURE 1. Schematic of the Viking Labeled Release experiment
The nutrients were selected for the LR based on theory and
experiment. All the nutrients, or
substrates, were simple Miller-Urey molecular compounds believed to have formed
early on primitive Earth and, therefore, likely to have been incorporated into
the earliest life forms, and probably retained throughout their evolutionary
process. Each candidate nutrient was
uniformly tagged with 14C.
Those nutrients having optical isomers were included as racemic mixtures
to make either stereoisomer available to potential Martian life. The nutrients were used in minimal
concentrations in pure aqueous solution to preclude possible toxicity as
sometimes occurs when microorganisms are overly dosed with organic and/or
inorganic matter. Table 1 presents the
LR nutrients showing their concentrations and activities.
TABLE 1. Labeled
Release Nutrients
|
|
Structure
and |
|
|
Specific
Activity |
|
14C-glycine |
NH3·*CH2·*COOH |
2.5
× 10-4M |
4 |
16 |
*Total = 34 μCi, which yields 6.8 × 107 dpm ml-1
Thousands of tests were made on microbial species, covering
all types available: pure cultures, mixed cultures and soils; and many field
tests of soils were conducted over a wide range of environments during the twenty
years of development of the LR. Examples
of field tests made with the early “sticky string” version of the instrument,
which ejected and reeled in a silicone-covered string to collect its sample,
are shown in Figures 2 to 4. False
positives were never obtained from sterilized samples. Certainty of response from living organisms,
sensitivity[2]
(to as little as ~30 cells/g), and rapidity of response provided a high level
of confidence in the experiment.
FIGURE 2. LR Test at 12,000 Ft. (above timberline) on
White Mountain, CA
FIGURE 3 (left). LR test on Death Valley sand dune
FIGURE 4 (right). LR “Sticky String” test on
Salton Sea desert flats
4.
THE LR PEDIGREE
An unsolicited proposal to develop the LR (originally
“Gulliver”) experiment was submitted to NASA in 1958. After extensive review, the proposal was
funded in 1959. The experiment
immediately showed promise. This was
detailed in quarterly and annual reports submitted to NASA. A new proposal for continuation had to be
submitted to NASA annually for review for continuation. There was constant interaction with NASA
throughout the project. The Viking
Project was formed in 1969, and NASA invited competition for life detection
experiments. Many proposals were
submitted, including that for the LR, which again underwent the evaluation
process. The LR experiment was selected
by the four review committees established by NASA. Members included personnel from NASA, NSF,
NIH and academia. They all accepted LR’s
criteria for life: evolution of 14C-labeled
gas, followed by a heat-treated control producing little or no gas. Intensive reviews, scheduled and unscheduled,
of the LR were performed frequently by NASA and Viking Project committees and
“tiger teams” during the additional ten years of development, all of which
further increased the high level of confidence in which its many reviewers held
the LR experiment.
5.
THE LR ON MARS
After its flawless landing, Viking 1 performed the first LR experiment on July 30, 1976. The soil tested had been taken by the sampling arm from the surface to a depth of about four cm., placed in the distribution box and then dispensed to the LR. Immediately upon injection of nutrient, 14C-labeled gas began evolving. After about three days, the volume of the accumulating gas approached a plateau, but continued to show a very slight increase. At the end of the eight-sol Cycle 1 test, a second injection of nutrient was made. A sharp decrease in headspace gas occurred until about 20 % of it was re-adsorbed by the sample, after which a slow re-evolution of gas over the eight sols of Cycle 2 restored the full amplitude of Cycle 1. The protocol called for a control in the event of a positive response. Accordingly, a duplicate soil sample was inserted into a fresh cell, heated for three hours at 160o C to sterilize it (the control procedure established for all Viking biology experiments), allowed to cool and then was tested. It produced virtually no response, thus completing the pre-mission criteria for the detection of microbial life. Those criteria did not require a positive response to a second injection. Further, the LR tests showed that, isolated in the dark sample distribution box and held at ~ 10o C, the soil lost its activity over a period of two to three months. However, the positive responses had been obtained from soil samples that, prior to nutrient injection, had been