“Are we alone in the universe?”
That is a question
that has long captivated
Dr. Jill Tarter, the current Bernard
M. Oliver Chair of the SETI (Search
for Extraterrestrial Intelligence) Institute.
She spoke about the efforts
of the SETI Institute to a packed Macleod
auditorium at the University
of Toronto on Saturday June 4th.

The search for extraterrestrial
life splits into two separate searches,
one for biosignatures that are
indicators of any sort of life form,
and the other for technosignatures
that are the product of sentient intelligence.
Dr. Tarter spent some
time discussing the remarkable
progress made by researchers
on the biosignature front. As Dr.
Tarter put it, “exoplanets and extremeophiles
are gamechangers.”

Extremeophiles are organisms that
thrive in physically extreme environments
that most life forms just
aren’t cut out for, while exoplanets
are planets that orbit stars other
than our sun.

Exoplanet hunting has become
much easier thanks to the 2009
launch of NASA’s Kepler spacecraft.
Kepler uses the ‘transit method’,
which looks for periodic changes
in the brightness of distant stars
to detect the presence of rotating
planets. Using the difference in
brightness to estimate the size of
the planet, and the time it takes for
one rotation we can work out the
planet’s distance from the star.

The most promising exoplanets
are those that lie within the habitable
zone of their star, where the
planet is neither too close nor far.
As of February, Kepler has found
exactly 1,235 candidates for exoplanets;
68 are earth-sized planets
and 171 are stars believed to have
multiple planets. In addition to the
transit method, astronomers also
look for slight wobbles in the star
that could be caused by the gravitational
distortion of an orbiting
planet.

When astrobiologists assess the
viability of life on a planet they look
at a few key requirements that are
crucial for life as we know it, including
temperature, pH levels, UV index,
and sunlight. It was originally
thought that if any of these indicators
were beyond a narrow range,
life would be near impossible. However,
the recent discoveries of ‘extremeophiles,’
or life in the nooks
and crannies of the most hostile
environments on our planet, have
dramatically widened the acceptable
range of the aforementioned
requirements of life.

The SETI Institute, however, is
more directly involved with detecting
technosignatures, signals from
other intelligent civilizations. Dr.
Tarter has gone through a variety
of imaginative yet debunked ideas
on possible signals of intelligence:
from traces of Dyson spheres, to fission
waste dumps. Detecting intelligible
radio signals remains the core
of SETI programs worldwide.

The idea for SETI first emerged
two years after Sputnik when two
physicists at Cornell University
mulled the possibility of using radio
telescopes to spot extraterrestrial
civilizations through the tell-tale
sign of intelligible radio messages.
Following this insight, there have
been more than 98 SETI-related initiatives
worldwide.

The SETI Institute, in tandem
with the University of California
Berkeley, had been operating the
Allen Telescope Array (ATA), a
dedicated array of telescopes operationally
equivalent to a 100-meter
radio telescope. Unfortunately,
because of budget cuts, the ATA
was just hibernated in April of this
year, with the equipment put into
a safe configuration waiting to be
put back to use once the SETI Institute
acquires other sources of
funding. Budgetary woes are nothing
new to the SETI Institute. The
SETI Institute managed to continue
part of the scientific research and
educational programs run under
NASA’s SETI program before the US
Congress abruptly cancelled funding
in 1994.

A project like SETI, by its very nature,
needs to be up and running for
the long haul. As Dr. Tarter and other
SETI researchers have shown,
the ramifications of even detecting
one intelligent signal from another
sentient civilization more than justifies
the cost of sustaining SETI.