We know that there are giant planets, like Jupiter, around some of
the nearby stars. We do not yet know if there planets like the
Earth. If there are any, and if they are at a reasonable distance
from the star they are orbiting, their temperature could be such as
to permit an atmosphere and surface water like the Earth's. What
could we learn from studying their atmospheres? The surprising
answer is that we could tell if there is oxygen-producing life on the
planet, as no natural process can sustain large amounts of oxygen.
Much work will be done from the ground over the coming years in
detecting more large planets, and understanding how planets form. But
the detection of small planets like the Earth and especially the
study of their atmospheres will demand a special type of telescope in
space - an infrared interferometer some 50 - 10 metres across.
Technology has progressed so that it is now feasible to build such a
telescope, and ESA has decided to study the possibility of including
one in its Horizons 2000 plan. This talk will describe a possible
design and the science that could be done with it.