Space Topics: Deep Impact
Science Instruments
The Deep Impact mission carries three science instruments, two on the Flyby
spacecraft and one on the Impactor.
The High Resolution Instrument (HRI), on the Flyby spacecraft, is
a 30-centimeter (12-inch) telescope that gathers light for a camera and
a spectrometer. The HRI was intended to help Deep Impact steer itself
onto a collision course with the comet. As the Flyby spacecraft approached
Tempel 1,
the HRI was then used to watch the impact take place and study the
aftermath. The HRI camera has nine different colored filters on a wheel,
allowing it to capture information on the color of the comet in visible
and near infrared wavelengths. The spectrometer gathers light in near-infrared
wavelengths. The HRI began to resolve the comet as more than a one-pixel
speck about a day before the impact.
The Medium Resolution Instrument (MRI), on the Flyby spacecraft,
is a 12-centimeter (5-inch) telescope with a field of view five times
wider than the HRI. The MRI provides context for the HRI images, and
aided navigation during the final approach to the comet. The MRI has
a filter wheel with nine filters, two of which are the same as those on
the HRI.
The Impactor Targeting Sensor (ITS), on the Impactor, was identical
to the MRI, except that it had no filter wheel. The ITS helped the
Impactor steer itself toward the best possible impact site on Tempel 1,
and captured images all the way down to the ground.
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