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Artist's
illustration of a possible design for the TPF.
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Probably
the most ambitious of the projects recommended by the Astronomy
and Astrophysics Survey Committee, the Terrestrial Planet Finder
(TPF) will offer humanity the means to discover Earth-like planets
orbiting other stars. Still in a conceptual stage, one version of
the TPF would consist of four infrared-observing telescopes, each
with a 3.5-meter mirror and spaced as much as a kilometer apart.
So that they will be shielded from radiation that would interfere
with their observations, the telescopes will orbit the Sun far from
Earth's interfering infrared radiation. The telescopes will deploy
panels to keep
the Sun's rays from warming them, so that they can maintain temperatures
close to 400 degrees below zero Fahrenheit and thus largely avoid
emitting their own infrared radiation. The infrared domain offers
better prospects than visible light for revealing an Earth-like
planet. In this spectral region, a typical star outshines an Earth-like
planet by a factor of only one million, rather than by a factor
of one billion at visible wavelengths. By using a technique called
nulling interferometry, the TPF could overcome this ratio of one
million, which threatens to drown a planet's firefly light in the
glare of the nearby stellar searchlight. Nulling interferometry
effectively darkens the brilliant, pointlike starlight by diverting
it along two paths that cancel each other, leaving a nearby planet
visible.When not studying nearby stars for signs of extrasolar planets
like our own, the TPF will observe other cosmic objects with an
angular resolution a hundred times better than that of any previous
instrument. This resolution will allow the TPF to study planetary
systems in formation and star-forming regions in distant galaxies
with a stunning clarity. Among other achievements, the TPF's high-resolution
capability could allow it to verify the current hypothesis that
the phenomena of quasi-stellar radio sources (quasars) and active
galactic nuclei arise from matter swirling into black holes at the
centers of galaxies.
Visit
the Official TPF Site
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