ROOM
77
Space Science
The Tatel Telescope was
the first major radio
telescope at the National
Radio Astronomy
Observatory in Green
Bank, West Virginia, USA.
The 85-foot antenna was
used by Frank Drake in
1960 for the first modern
SETI experiment.
level our cities - there seems to be a widespread
presumption that many of the trillion or so planets
that populate the Milky Way are carpeted with life.
And surveys routinely show that the majority of
the public believes that we share the cosmos with
other life – even intelligent life.
Looking for life
Today, the search for life on other worlds drives
much of our exploration of space. Among the
several worlds of the inner solar system, Mars
receives the bulk of our interest and hardware. A
lot of the red planet’s attraction is due to the fact
that it has (and perhaps more importantly, had in
the past) environments that could nourish biology.
Planned missions to the outer solar system moons
Europa and Enceladus are also motivated by the
hope of finding life beyond Earth.
But while we might discover living things in our
own backyard, they would almost certainly be
simple and small. Bacteria could conceivably find
adequate sustenance in the relentless darkness
of a subsurface ocean, but it’s hard to imagine
that complex life could. Intelligence on a par
with Homo sapiens, which requires an elaborate
nervous system or its functional equivalent, is
unlikely to arise on any of the places we can reach
with our rockets. Rather, if we wish to find clever
aliens, we must turn to worlds orbiting other stars.
Investigations using NASA’s Kepler space
telescope suggest that perhaps as many as one in
five stars host a planet that could support some
sort of biology. This is still a tentative result and
the fraction of stars with a planet or moon that
could evolve intelligent life is surely less. But
even if that fraction is but one in a thousand,
the number of worlds suitable for creatures as
mentally agile as ourselves would still tally in the
hundreds of millions And, this is only looking at
real estate in our own galaxy.
Tuning-in to the cosmos
Such arguments fuel the interest in SETI (Search
for Extraterrestrial Intelligence). It doesn’t look
for life directly but for signals that would indicate
life possessing a degree of technical sophistication
at least as great as our own. Most of the SETI
experiments of the last five decades have tried to
tune in radio signals that are either deliberately or
inadvertently beamed our way.
This search, like the public’s interest in aliens,
grew out of technical developments during
the Second World War. When the high-power
microwave transmitters that are essential to radar
became commonplace, scientists made a simple
calculation that surprised them: such signals could
be easily received at distances comparable to the
typical separation of stars.
Unlike some Victorian physicists who thought
that gas lamps and mirrors might be useful for
sending messages to the putative inhabitants of
Mars, the post-war world finally had a technology
that would be adequate for communicating across
astronomical distances. Perhaps the skies were
filled with signals from aliens, merely awaiting
efforts to detect them.
That doesn’t seem to be the case. Despite more
than 50 years of experiments, no confirmed,
artificially produced signal from the cosmos has
ever been found.
While that is an obvious disappointment to those
who would like to believe in the Hollywood portrayal
of a cosmos littered with clever inhabitants, it is
certainly premature to conclude that we’re alone. For
one thing, the SETI effort has been poorly funded.
This might be ascribed to the fact that its hypothesis
– namely that there is intelligence elsewhere – is
impossible to falsify. This circumstance separates it
frommuch conventional research. Second, success
cannot be guaranteed no matter how much time or
money is expended.
In addition, SETI must deal with a perception
that looking for our extraterrestrial doppelgangers
is somehow a silly enterprise. Space aliens, to
many, are like ghosts. Sure, ghosts are fun, but
for a variety of reasons, they aren’t plausible. But
given the staggering plentitude of planets, one can
hardly say the same for aliens.
The largest SETI effort to date began in the
1970s by NASA. The plan was to build specialised
radio receivers - spectrometers with resolutions
SETI must
deal with a
bothersome
perception that
looking for our
extraterrestrial
doppelgangers
is somehow a
silly enterprise
