which planets form had always been a coating that reflects as much of the heat
cornerstone of Spitzer’s science program, from the sun and solar panels as possible.
its exoplanet work only became possible It is the first infrared telescope to use
by reaching an unprecedented level this innovative design and has set the
of sensitivity, beyond its original design standard for subsequent missions.
specifications.
Fully transitioning Spitzer into an
Researchers had actually finalized the exoplanet spy required some clever
telescope’s design in 1996 before any modifications in-flight as well, long after it
transiting exoplanets had even been flew beyond the reach of human hands
discovered. The high degree of precision into an Earth-trailing orbit. Despite the
in measuring brightness changes needed telescope’s excellent stability, a small
for observing transiting exoplanets was not “wobbling” remained as it pointed at
considered feasible in infrared because target stars. The cameras also exhibited
no previous infrared instrument
had offered anything close to
what was needed.
Nevertheless, Spitzer was
built to have excellent control
over unwanted temperature
variations and a better startargeting pointing system than
thought necessary to perform
its duties. Both of these
foresighted design elements
have since paid dividends
in obtaining the extreme
precision required for studying
transiting exoplanets.
The fact that Spitzer can
still do any science work at all
still can be credited to some
early-in-the-game, innovative
thinking. Spitzer was initially
loaded with enough coolant
to keep its three temperaturesensitive science instruments
running for at least two-and-ahalf years. This “cryo” mission
ended up lasting more than
five-and-a-half-years before
exhausting the coolant.
But Spitzer’s engineers had a
built-in backup plan. A passive Spitzer was able to detect a super Earth’s direct light for the first time using
cooling system has kept its sensitive heat-seeking infrared vision. Seen here in this artist’s concept, the
one set of infrared cameras planet is called 55 Cancri e. Data revealed that it is very dark and that its sunhumming along at a super-low facing side is blistering hot at 3,140 degrees Fahrenheit. Image: NASA/JPL-Caltech
operational temperature of
minus 407 degrees Fahrenheit (minus 244 small brightness fluctuations when a star
Celsius, or 29 degrees above absolute moved slightly across an individual pixel
zero). The infrared cameras have of the camera. The wobble, coupled
continued operating at full sensitivity, with the small variation in the cameras,
letting Spitzer persevere in a “warm” produced a periodic brightening