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Each of the four telescopes will
have a diameter of around 3.5m in diameter based
on the design used for the Herschel mission. The
small flotila will be launched on 2 Soyuz-Fregat
rockets.
Because the telescopes will be used to detect infrared
light, they must be shielded from the Sun's rays. If
not, sunlight would heat the telescope, causing it to
emit its own infrared radiation, blinding its view of
the distant planets. To prevent this, each telescope
is equipped with a large sunshield.
During launch, the sunshields are wrapped around their
telescopes to save space. Once Darwin is in orbit, the
shields are deployed like unfurling an umbrella. Although,
Darwin will face away from the Sun, it must also tilt
up and down by an angle of 45 degrees, to see all of
its target stars, whilst keeping the telescope's tube
in the shade, requiring a large sunshield with a diameter
of 7.4 metres.
A platform will sit behind the sunshield, consisting
of a communications antenna, various receivers to detect
the motion of the spacecraft and a small propulsion system.
Below this, constantly facing the Sun, will be a solar
array to generate power. |
