A thousand days in the life of the infrared universe (photos)

The Spitzer Space Telescope, launched in 2003 with its Infrared Array Camera (IRAC), is the largest infrared telescope ever sent into space. Its instruments give scientists the ability to peer into regions of space invisible to optical telescopes, including dusty stellar incubators, the centers of galaxies, and growing planetary systems, NASA says.

The telescope was originally launched with a supply of liquid helium coolant for its camera because the heat it gave off could interfere with infrared light given off by the warm objects it was observing. As expected the coolant slowly depleted and ran out in 2009, or about 1,000 days ago, but the IRAC can still take images, although without all its infrared sensors.

In this slideshow, we've put together a sampling of photos from the past 1,000 days.

Nicknamed the "Tornado" nebula, light emitted from a shocked molecular hydrogen, visible here in green, is believed to be caused by an outflowing jet of material from a young star that has generated shock waves in surrounding gas and dust.

Inside the famous nebula in Orion, IRAC has revealed many other young stars and a long filament of star-forming activity containing thousands of young protostars still in the process of formation, NASA says.

The IRAC is a four-channel camera with four different detectors, each measuring light at one particular wavelength. Taking simultaneous images, the camera records at wavelengths of 3.6, 4.5, 5.8 and 8.0 microns.

To properly operate, a tank of liquid helium acts as a coolant which produces a freezing vapor, cooling the entire instrument array to about -268 degrees Celsius.

But now that the cooling power of that liquid helium cryogen has run out, the IRAC is the only one of Spitzer's four instruments that is still functioning. The 5.8- and 8.0-micron detectors will be too warm and thus inaccurate to be useful, but the 3.6- and 4.5-micron detectors will still work at peak performance for several more years.

The IRAC "warm" program began once Spitzer used up its liquid helium coolant, thus completing its "cold" mission.

Following a long life of of hydrogen-burning nuclear fusion, stars move into later life states whose details depend on their masses. This IRAC image of the Helix Nebula barely spots the star itself at the center, but clearly shows how the aging star has ejected material into space around it, creating a "planetary nebula."

Swirling dust clouds and bright newborn stars are seen here in the Lagoon Nebula, also known as Messier 8 and NGC 6523, with green carbon-based dust and the red glow of the hottest dust.

Visible light shows the pools of hot gas surrounding the massive, young stars, while over-layed infrared imaging looks past the gas to show the dusty basin that it fills.

IRAC can actually watch stars form, as gravity pulls massive clouds of gas and dust together, resulting in the formation of new stars.

Star formation helps shape a galaxy's structure through shock waves, stellar winds, and ultraviolet radiation. In this image of the nearby Sombrero Galaxy, IRAC clearly sees a dramatic disk of warm dust, visible in red, caused by star formation around the central bulge, seen in blue. The Sombrero is located 28 million light-years away in the constellation Virgo.

More than 100 times as massive and a million times as bright as our own sun, Eta Carinae, seen here at the top center, is one of the giants of the Milky Way. In this composite image spanning the visible and infrared parts of the spectrum, areas that appear blue are not obscured by dust, while areas that appear red are hidden behind dark clouds of dust in visible light.

Recent x-ray and infrared observations have revealed new massive stars in regions of the nebula obscured by dust, suggesting that the Carina Nebula will produce twice as many supernova explosions as previously supposed.

IRAC studies how stars mature. It can observe how the processes of stellar evolution affect the environment. The Trifid Nebula, seen here, hosts stars at all stages of life, surrounded by gas and dust that form a beautiful roseate nebula.

Violent bubbles of dust and gas, as seen here in an infrared image of Cygnus X, trigger both the death and birth of stars. The brightest, yellow-white regions are warm centers of star formation, the middle wavelength green shows tendrils of dust, and the long wavelength red indicates other cooler dusts.

The young star cluster seen here emits winds and harsh ultraviolet light that warp the remnant cloud into fantastic shapes. Astronomers are not sure when that activity suppresses future star formation by disruption, and when it facilitates star formation through compression. The cluster, known as DR22, is in the constellation Cygnus the Swan.

Since its launch in 2002, the IRAC has systematically imaged the entire Milky Way, assembling a composite photograph containing billions of pixels with infrared emission from everything in this relatively narrow plane. The image here shows five end-to-end strips spanning the center of our galaxy. This image covers only one-third of the whole galactic plane.

This combined data from Spitzer's camera traces the interplay of the bright, young stars with the cold and dusty surrounding clouds of Orion.

A red whisp of cool gas can be seen running through the Trapezium, the intensely bright region that is home to four giant blue-white stars, and up into the rich star field.

Collisions play an important role in galaxy evolution. These two galaxies -- the Whirlpool and its companion -- are relatively nearby at a distance of just 23 million light-years from Earth. IRAC sees the main galaxy as very red due to warm dust -- a sign of active star formation that probably was triggered by the collision.

Infrared imaging captured by the Spitzer Space Telescope and Wide-field Infrared Survey Explorer (WISE) are combined in this image of RCW 86, what is believed to be the dusty remains of the oldest documented example of a supernova, or an exploding star.

An astounding 2,400 massive stars in the center of 30 Doradus, seen here, are producing intense radiation and powerful winds as they jettison material. Multimillion-degree gas detected in x-rays (blue) by the Chandra X-ray Observatory comes from shock fronts formed by these stellar winds and by supernova explosions. This hot gas carves out gigantic bubbles in the surrounding cooler gas and dust shown here in infrared orange captured by the Spitzer Space Telescope.

The many points of light in this field aren't stars but entire galaxies. A few, like the mini-tadpole at upper right, are only hundreds of millions of light-years away so their shapes can be discerned. The most distant galaxies are too far away and appear as dots. Their light is seen as it was over 10 billion years ago, when the universe was young.

The bright yellow-red nebula at the center of this image is in the constellation of Scutum, and has no common name since it is hidden behind dust clouds. It takes an infrared telescope like Spitzer, which sees beyond the visible spectrum of light, to see through this dark veil and reveal this spectacular hidden nebula.