New analysis suggests robots discovered microbes in 1976.
A fresh look at NASA data suggests that a robotic
mission uncovered microbial life on Mars—more than 35 years ago.
In 1976 NASA sent two space probes, Vikings 1 and 2, to
Mars to determine whether life exists on the red planet. The probes carried
three experiments specially designed for the task, one of which was called the
Labeled Release (LR) apparatus.
The LR experiment worked by scooping up a bit of Martian
soil and mixing it with a drop of water that contained nutrients and
radioactive carbon atoms.
The idea was that if the soil contained microbes, the
life-forms would metabolize the nutrients and release either radioactive carbon
dioxide or methane gas, which could be measured by a radiation detector on the
probe.
A number of control experiments were also performed,
including heating some Mars soil samples to different temperatures and
isolating other samples in the dark for months—conditions that would kill
microbes that are photosynthetic or that rely on photosynthetic organisms for
survival. These control samples were also mixed with the nutrient solution.
To the delight of many biologists at the time, the LR
experiment came out positive for life, and the control experiments came out
negative.
"The minute the nutrients were mixed with the soil
sample, you got something like 10,000 counts" of radioactive molecules—a
huge spike from the 50 or 60 counts that constituted the natural background
radiation on Mars, said study team member Joseph Miller, a neurobiologist at
the University of Southern California and a former NASA space shuttle project
director.
Unfortunately, the Labeled Release experiment results were
not backed up by the probes' other two experiments, both of which came out
negative for life, so the space agency dismissed the possibility.
Now, after running Viking's LR data through a mathematical
test designed to separate biological signals from nonbiological signals,
Miller's team believes that the LR experiments did indeed find signs of
microbial life in Martian soil.
"It's very possible that if you have microbes, they're
living a couple of inches beneath the soil, close to water ice," he said.
Clustering Viking's Mars Data
For the study, Miller and mathematician Giorgio Bianciardi,
of Italy's University of Siena, used a technique called cluster analysis, which
groups together similar-looking data sets.
"We just plugged all the [Viking experimental and
control] data in and said, Let the cluster analysis sort it," Miller said.
"What happened was, we found two clusters: One cluster constituted the two
active experiments on Viking and the other cluster was the five control
experiments."
To bolster their case, the team also compared the Viking
data to measurements collected from confirmed biological sources on Earth—for
example, temperature readings from a rat—and from purely physical,
nonbiological sources.
"It turned out that all the biological experiments from
Earth sorted with the active experiments from Viking, and all the nonbiological
data series sorted with the control experiments," Miller said. "It
was an extremely clear-cut phenomenon."
The team concedes, however, that this finding by itself
isn't enough to prove that there's life on Mars.
"It just says there's a big difference between the
active experiments and the controls, and that Viking's active experiments
sorted with terrestrial biology and the controls sorted with nonbiological
phenomena," Miller said.
Evidence for Martian Rhythm
Still, the new findings are consistent with a previous study
published by Miller, in which his team found signs of a Martian circadian
rhythm in the Viking LR experiment results.
Circadian rhythms are internal clocks found in every known
life-form—including microbes—that help control biological processes, such as
waking, sleeping, and temperature regulation.
On Earth this clock is set to a 24-hour cycle, but on Mars
it would be about 24.7 hours—the length of a Martian day.
In his previous work, Miller noticed that the LR
experiment's radiation measurements varied with the time of day on Mars.
"If you look closely, you could see that the RGM [radioactive-gas
measurement] was going up during the day and coming down at night. ... The
oscillations had a period of 24.66 hours just about on the nose," Miller
said.
"That is basically a circadian rhythm, and we think
circadian rhythms are a good signal for life."
Despite his own conviction that the Viking mission detected
life on Mars, Miller said he doesn't expect most people will be convinced until
they can look at a video of Martian bacteria sitting in a petri dish.
"But for some reason, NASA has never flown a microscope
that would let you do something like that," he said. "If they can fly
a microscope for the geologists, they should be able to fly one for the
biologists."
NASA's following Martian missions—the Mars Science Laboratories,
aka Curiosity and Opportunity—arrived on the red planet and still did not carry
such a microscope neither undertook a life detaction experiment, as in Viking 2
and 3.
"It did not test the hypothesis [for life on Mars]
directly" Miller said. "And if they see a circadian rhythm in the
methane release into the atmosphere, it would be very consistent with what we
saw."
No experiments were conducted to test that possibility.
For some reason, the people who made decisions on NASA did
not want to find life, they probably found it and try very hard to deny the
obvious interpretation of the life detection experiments in Viking 1 and 2.
Adapted from:
Kar Than, National Geographic News, 2012
Recommending to watch this video on the subject
Recommending to watch this video on the subject
"Why We May Have Already Found Life On Mars with
Dr. Patricia Ann Straat"
https://www.youtube.com/watch?v=ykTxJCkJYwI
No comments:
Post a Comment