This artist’s concept shows Spitzer surrounded by examples of exoplanets the telescope has examined.
Image: NASA/JPL-Caltech
How engineers revamped
Spitzer to probe exoplanets
Passing its 10th anniversary, NASA’s
Spitzer Space Telescope has evolved into
a premier observatory for an endeavor
not envisioned in its original design: the
study of worlds around other stars, called
exoplanets.
While the engineers and scientists
who built Spitzer did not have this goal
in mind, their visionary work made this
unexpected capability possible. Thanks
to the extraordinary stability of its design
and a series of subsequent engineering
reworks, the space telescope now has
observational powers far beyond its
original limits and expectations.
“When Spitzer launched back in 2003,
the idea that we would use it to study
exoplanets was so crazy that no one
considered it,” said Sean Carey of NASA’s
Spitzer Science Center at the California
Institute of Technology in Pasadena. “But
now the exoplanet science work has
become a cornerstone of what we do
with the telescope.”
Spitzer views the universe in the infrared
light that is a bit less energetic than the
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light our eyes can see. Infrared light can
easily pass through stray cosmic gas
and dust, allowing researchers to peer
into dusty stellar nurseries, the centers of
galaxies, and newly forming planetary
systems.
This infrared vision of Spitzer’s also
translates into exoplanet snooping. When
an exoplanet crosses or “transits” in front
of its star, it blocks out a tiny fraction
of the starlight. These mini-eclipses as
glimpsed by Spitzer reveal the size of an
alien world.
Exoplanets emit infrared light as well,
which Spitzer can capture to learn about
their atmospheric compositions. As an
exoplanet orbits its sun, showing different
regions of its surface to Spitzer’s cameras,
changes in overall infrared brightness
can speak to the planet’s climate. A
decrease in brightness as the exoplanet
then goes behind its star can also
provide a measurement of the world’s
temperature.
While the study of the formation of
stars and the dusty environments from
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