It 'lifted the cosmic veil on the universe:' NASA's Spitzer Space Telescope to be 'retired' on Thursday

One of NASA's most successful missions will be coming to an end on Thursday.

After more than 16 "extraordinary years of exploration," NASA said that its Spitzer Space Telescope will be turned off on Thursday.

The telescope, which is in orbit around the sun, has made many discoveries far beyond the imaginations of its designers, NASA said. Among them: planets outside our solar system, called exoplanets, and galaxies that formed close to the beginning of the universe.

Altogether, Spitzer observed 800,000 celestial targets and churned out more than 36 million raw images as part of its $1.4 billion mission.

“Although it would be great to be able to operate all of our telescopes forever, this is not possible,” NASA’s astrophysics director Paul Hertz said.

Over the 16 years it operated, Spitzer's science work let astronomers stretch across time and space alike, thanks to its unique talent of observing the universe in infrared light, according to Space.com.

Infrared light is one type of light that our eyes can't see. Thanks to infrared light, astronomers can study clouds of dust and gas, and can even peer into the hearts of galaxies wrapped in dusty clouds, Astronomy magazine said.

With its infrared instruments, it was able to sense heat coming off celestial objects like night vision goggles, said Suzanne Dodd, a former project manager who now oversees NASA’s Deep Space Network at the Jet Propulsion Laboratory in Pasadena, California.

By seeing through dust, “we’re lifting the cosmic veil on the universe,” Dodd said.

With more than 8,700 scientific papers published based on Spitzer's discoveries, the telescope has been a "tremendous asset to astronomers," NASA said.

Although Spitzer's time is at an end, a new telescope is slated to take its place next year: The James Webb Space Telescope is expected to launch in 2021.

Webb is about 1,000 times more powerful than the Spitzer telescope, and it will be able to push Spitzer's science findings to new frontiers, from identifying chemicals in the atmospheres of planets beyond our solar system, to locating some of the first galaxies to form after the Big Bang.

However, this week, the Government Accountability Office warned of possible further delays to the Webb Telescope because of technical challenges.

Contributing: The Associated Press

This article originally appeared on USA TODAY: Spitzer Space Telescope to be 'retired' on Thursday by NASA