by Rob Waugh
13 April 2012
Soil samples from Viking 1
which visited Mars in 1976
Mathematical analysis shows strong sign of organics
Samples had been dismissed as contaminated
'99% probability of life' claims one scientist
In July 1976, the
Viking 1 probe touched down on Mars
and failed to find traces of life - but now, three decades later,
scientists think the experiment was flawed.
VIking 1 did find evidence of extraterrestrial microbes in soil
the Red Planet.
Mathematical analysis of the samples concluded that salts in the
soil on Mars 'threw off' initial estimates - and that the soil
samples show strong evidence of microbial life.
The new analysis looked for 'complexity' in the samples - an
indication of life.
To the surprise of the scientists, they
The Viking 1 lander
which arrived on Mars in July 1976.
believe there is strong evidence of microbial life
in the soil samples
analyzed by Viking 1
Viking 1 launched by a Titan Centaur rocket
from Complex 41 at
Cape Canaveral Air Force Station
'This suggests a robust biological
response,' say the researchers, from the University of Siena and
California's Keck Institute.
'These analyses support the interpretation that the Viking LR
experiment did detect extant microbial life on Mars.'
The reassessment was prompted by the
discovery of 'perchlorates'
in the soil at the landing site of another Mars lander, Phoenix, in
The presence of the chemicals in Viking's samples had led scientists
to conclude the samples were contaminated. The scientists behind the
experiment remain divided over how conclusive the evidence for life
on Mars is.
Christopher McKay of Nasa's Ames Research Centre said, in an
interview with Discovery News,
'Finding organics is not evidence of
life or evidence of past life. It's just evidence for organics.'
'The ultimate proof is to take a video of a Martian bacteria.
They should send a microscope - watch the bacteria move,' said
Josheph Miller of USC's Keck School of Medicine.
'On the basis of what we've done so far, I'd say I'm 99 percent
sure there's life there.'
Future Mars missions may be able to settle the question.
The Viking 1 lander
on display at the National Air and Space museum:
Did the craft
discover evidence of life on Mars?
Mars skyline at sunset, pictured from the Viking lander
Nasa's Mars Science Laboratory nicknamed Curiosity,
a nuclear powered
One forthcoming unmanned mission is the
new Mars Science Laboratory rover, called
Curiosity, scheduled for launch in
The $2.5 billion nuclear-powered machine will land on Mars' surface
with a suite of 10 science instruments to try to determine if
conditions are favorable for life.
Another key Mars mission is scheduled for 2016. Called the
ExoMars Trace Gas Orbiter, it will
carry five science instruments and will study gases in Mars'
atmosphere, including methane, for evidence of biological or
‘The instruments on that atmospheric
mission have a factor of 100 to 1,000 increase in sensitivity
over what is currently available from Mars orbiters or from
ground observations,’ said Mark Allen, Ph.D., who is the U.S.
project scientist for the 2016 Mars mission.