Our SpaceFlight Heritage: Spitzer telescope’s top 15 discoveries
To celebrate the 15th anniversary of the Spitzer Space Telescope‘s operations in space, NASA’s Jet Propulsion Laboratory (JPL), which manages the mission, issued a statement highlighting the infrared observatory’s top 15 discoveries.
Launched on August 25, 2003 and placed in a solar orbit, Spitzer is one of NASA’s four Great Observatories in space. The other three are the Hubble Space Telescope (HST), which observes in visible light; the Compton Gamma Ray Observatory (CGRO), and the Chandra X-ray Observatory.
Spitzer‘s primary mission was designed to last two-and-a-half years. When its supply of liquid helium, which kept it cold, ran out in May 2009, most of its instruments became unusable. Since then, the telescope has operated in a “Warm Mission,” using the shortest-wavelength modules of its Infrared Array Camera (IRAC), which are highly sensitive and remain operable.
The space telescope’s numerous successes in various fields of astronomy are the result of its ability to observe in the infrared, as many objects emit light in infrared wavelengths.
Although Spitzer was not designed to study exoplanets, several of its top 15 successes as listed by JPL involved planetary discoveries.
The observatory was the first to ever directly image light from exoplanets. Hot Jupiters, gas giants that orbit close to their parent stars, emit infrared light. In 2005, Spitzer detected this light from two such planets, HD 209458b and TrEs-1.
Two years later, the space observatory directly observed molecules in the atmospheres of hot Jupiters HD 209458b and HD 189733b. Neither planet is habitable, but the ability to identify the composition of exoplanet atmospheres is an important step in the search for life beyond Earth.
In May 2009, Spitzer created the first ever weather map of an exoplanet, showing temperature variations and high winds on the hot Jupiter HD189733b.
Most exoplanets detected are located within approximately 1,000 light years from Earth. Spitzer in 2010 discovered one of the most distant planets ever detected, using the technique of gravitational microlensing. When a foreground object, such as a star, passes in front of a more distant object, the foreground object’s gravity magnifies and bends light from the background object. The remote planet Spitzer found is about 13,000 light years away.
One of the infrared telescope’s most famous discoveries is the TRAPPIST-1 system, which is composed of seven roughly-Earth-sized planets, all in close orbits around their parent star. Three of the planets are located in the star’s habitable zone, where temperatures could allow liquid water to exist on their surfaces. To determine the number of planets in the system, Spitzer observed it for more than 500 hours, monitoring reductions in the star’s light as individual planets passed in front of it.
Spitzer also observed dust eruptions in the circumstellar disk surrounding a very young star, possibly produced by two impacting asteroids.
Closer to home, Spitzer made several major discoveries in our own solar system. It observed the deliberate crash of NASA’s Deep Impact probe into Comet Tempel 1 in 2005. Scientists used its data along with information collected by the probe to identify the composition of cometary materials thrown up in the impact and were surprised to find clay, carbonates, iron-bearing compounds, and aromatic hydrocarbons. These ingredients functioned as the building blocks of the solar system’s planets, comets, and asteroids.
Infrared observations of Near-Earth Asteroids (NEAs) with Spitzer has helped scientists categorize these asteroids and determine their actual sizes, a task not always possible through observation in visible light.
A famous Spitzer finding in our solar system is Saturn’s largest ring, about 170 times wider than the planet and 20 times thicker than its diameter. This discovery was made because Spitzer‘s infrared capability enabled it to detect the glow of cool dust in the huge ring.
Among Spitzer‘s more distant discoveries are buckyballs, spherical carbon molecules that resemble geodesic domes. They were found in the material surrounding the dying sun-like star Tc 1 and likely were created in carbon that was blown off the star.
Because infrared light is better for seeing through dust and gas, Spitzer was able to discover regions of star birth that had previously been hidden by clouds of gas and dust, such as Rho Ophiuchi, a star-forming region about 410 light years from Earth.
In 2011, Spitzer found a growing proto-cluster of galaxies 12 billion light years away designated COSMOS-AzTEC3, giving researchers new insight into the growth and evolution of galaxy clusters.
The infrared telescope also identified two of the most distant supermassive black holes known. Located at the centers of quasars or active galaxies surrounded by disks of gas and dust, these supermassive black holes are approximately 13 billion years old.
Spitzer has also imaged infant galaxies whose light took 13.4 billion light years to reach Earth. Scientists were surprised to find these galaxies to be bigger than expected, indicating they formed very early in the universe’s history.
By collecting over two million Spitzer images over 10 years, scientists successfully constructed one of the most detailed maps of the Milky Way. The telescope’s infrared capability allowed it to see through dusty regions that cannot be seen in visible light. Known as GLIMPSE360, this map has helped researchers find new regions of star formation and better understand the galaxy’s spiral arms and central bar.
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.