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Darwin to look for
alien life
Biplab
Das
IS earth the lonely outpost of existence? Is there no
life elsewhere in the universe? To find out, astrobiologists from
the European Space Agency have embarked on an ambitious plan to
launch Darwin, a craft that will eavesdrop on other planets for
signs of life. By 2014, an Ariane-5 rocket will despatch Darwin to a
remote orbit beyond the moon, 1.5 million km from earth, where it
will roam for five years.
Darwin’s eyes are actually six
telescopes with a master satellite and a hub. These telescopes will
observe in the mid-infrared region of light. Why look in infrared
light for signs of life? Life on earth has been around for thousands
of millions of years and we have used radio waves for less than a
century, but the detection of infrared light is better than trying
to look for emission of radio waves which would only locate
intelligent life like ours. By detecting infrared radiation, even
the presence of humble life forms like viruses or bacteria can be
found. Any warm objects, animate or inanimate, emit infrared
radiation. On earth, life leaves its imprint in the shape of
infrared radiation. On earth, biological activity produces various
gases. For instance, plants give out oxygen and animals expel carbon
dioxide and methane. These gases, and other substances such as
water, absorb certain wavelengths of infrared light. With this clue,
an alien eavesdropper armed with infrared light detection equipment
can know earth teems with life. In a similar way, Darwin will look
for alien life beyond.
In the 1970s, British scientist James
Lovelock pointed out that just by breathing life affects the
composition of the earth’s atmosphere. “It is better to look for
similar effects as a way to search with telescopes for life on other
planets,” he said. “Thus, you can study the composition of an
atmosphere by splitting a planet’s light into a rainbow of colours.”
Darwin will look for oxygen which we know to be closely
associated with life. Some life forms use it and some produce it as
waste. Without life, all free oxygen in a planet’s atmosphere would
vanish within just four million years, as it reacts so easily with
other chemicals. “The best estimates suggest that Darwin will be
able to detect the build-up of oxygen caused within a few hundred
million years of life’s origin,” says says Malcom Fridlund, project
scientist for ESA’s Darwin mission.
(The author is a
freelance writer.)
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