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As Hubble's
"heat sensor," the Near Infrared Camera and Multi-Object Spectrometer
(NICMOS) can see objects in deepest space — objects whose light
takes billions of years to reach us here on Earth. NICMOS allows astronomers
to use Hubble's exquisite detail to open an important window of the
electromagnetic spectrum.
Making the Invisible
Visible
The instrument's three "cameras" — each with different fields of
view — are specially designed to see objects in the near-infrared
wavelengths, which are slightly longer
than the wavelengths of visible light (human eyes cannot see infrared
light).
Many secrets about the birth of stars, solar systems, and galaxies are
revealed in infrared light, which can penetrate the interstellar gas
and dust that block visible light. In addition, light from the most
distant objects in the universe "shifts" into the infrared
wavelengths. By studying objects and phenomena in this spectral region,
astronomers probe our universe's past, present, and future, learn how
galaxies, stars, and planetary systems form, and reveal a great deal
about our universe's basic nature.
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NICMOS's infrared detectors sit inside this chilled "thermos"
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A Cool Customer
As a camera
for recording visible light must be dark inside to avoid exposure to
unwanted light, a camera for recording infrared light must be cold inside
to avoid exposure to unwanted light in the form of heat. To make sure
that NICMOS is recording infrared light from space (as opposed to heat
created by its own electronics), the sensitive infrared detectors in
NICMOS must operate at very cold temperatures — below –321
degrees Fahrenheit, or 77 degrees Kelvin.
The instrument's detectors used to be cooled inside a cryogenic dewar
(a thermally insulated container much like a thermos bottle). When NICMOS
was installed in 1997, the dewar contained a 230-pound block of nitrogen
ice. The dewar, which successfully cooled the detectors for about two
years, ran out of coolant prematurely. NICMOS was rechilled during Servicing
Mission 3B with a "cryocooler," a machine that operates much
like a household refrigerator.
NICMOS, which was built by Ball Aerospace, was installed in the Hubble
Space Telescope during the 1997 Second
Servicing Mission.
Cool Views from NICMOS
•
Faraway galaxies
• Objects obscured by dust and gas
• Newly forming stars and clusters
• Planetary atmospheric changes over time
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