Context

NASA is ending its Spitzer Space Telescope mission, which observed the universe in infrared for 16 years.

About

• The Spitzer Space Telescope (SST), formerly known as ‘Space Infrared Telescope Facility’ (SIRTF), is an infrared space telescope.
• • It was launched in 2003.
  • It retired on 30 January 2020.
• Naming of the telescope: Unlike most telescopes that are named after famous deceased astronomers, the new name for SIRTF was obtained from a contest open to the general public.
  • Keeping with NASA tradition, the telescope was renamed after its successful demonstration of operation.
• Mission plan: The planned mission period was to be 2.5 years, with an extendable period depending upon exhaustion of on-board liquid helium supply.
  • Spitzer was launched from Cape Canaveral SLC-17B aboard a Delta II 7920H rocket.
• Shut down: NASA is shutting down SIRTF; which was its long-lasting space observatories.
  • The telescope had been wandering through space for nearly two decades.
  • NASA has run out of money to fund the spacecraft.
  • In 2018 it had cost roughly $12 million to operate the telescope.
  • In 2017, NASA made an unsuccessful attempt to search for private organizations to take over Spitzer.
• Infrared Science Archive (IRSA): All Spitzer data, from both the primary and warm phases, are archived at the Infrared Science Archive (IRSA).

Lyman Spitzer

• Earlier, the telescope was named in honour of astronomer Lyman Spitzer, who had promoted the concept of space telescopes in the 1940s.
  • He has been cited for his pioneering contributions to rocketry and astronomy.
• Extra-terrestrial observatory: In 1946 Spitzer described the advantages of an extra-terrestrial observatory, and how it could be realized with available or upcoming technology.

Functioning

• Helium supply: Liquid helium is needed to cool the telescope to very low temperatures.
  • Low temperatures are needed in order to operate; otherwise most of the instruments will not be usable.
• Orbit path: It follows a heliocentric instead of geocentric orbit, trailing and drifting away from Earth's orbit at approximately 0.1 astronomical units per year (a so-called "earth-trailing" orbit).
• Earth-trailing orbit: The spacecraft is in more or less the same orbit as Earth, lagging behind the planet as it travels around the Sun.
  • Spitzer gets farther and farther from Earth each year and doesn’t warm up from the heat coming off our planet.
  • That way it stays nice and cool.
  • For an extra layer of coolness, Spitzer is launched to space with a special liquid helium coolant, which helped to keep the spacecraft and its instruments at a frigid temperature of -459 degrees Fahrenheit (or -273 degrees Celsius).
• Low temperatures: Anything that emits a lot of heat also emits a lot of infrared light, which means there are plenty of sources that can come up in observations.
  • Earth’s atmosphere is a source of infrared light, which makes it difficult to observe the Universe in infrared from the ground.
  • If the telescope gets too warm, the infrared light it emits can also be a source of confusion.
  • Hence, cold telescopes like Spitzer in space.
• Primary mirror: The primary mirror is 85 centimetres (33 in) in diameter, f/12, made of beryllium and was cooled to 5.5 K (−268 °C; −450 °F).
• Three instruments: The satellite contains three instruments that allow it to perform astronomical imaging.
  • Photometry from 3.6 to 160 micrometers.
  • Spectroscopy from 5.2 to 38 micrometers.
  • Spectrophotometry from 5 to 100 micrometers.
• Infrared visibility: Spitzer’s charge has been to observe infrared light, a type of light that humans can’t see, but can sense as heat.
  • Objects that are faint and super cold can still be seen by the infrared light that they produce, so Spitzer can show us things that might otherwise seem invisible.

Achievements of SIRTF

• Spitzer took images of some of the coldest and most ancient objects in the Universe.
• It proven to be a remarkable tool for learning more about the cosmos.
• Helped discover newly forming stars, new rings of Saturn, and even an entire solar system around 40 light-years away.
• The telescope revealed a new ring around the planet Saturn.
• Old stars and galaxies were Spitzer’s specialty, as well as extra cold objects that may be cold by human standards, but are actually warmer than the backdrop of our extra cold Universe.
• Spitzer could spot baby stars in the middle of forming, which are too faint to see but observable in infrared.
• The North America Nebula seen in visible and infrared light was taken from Spitzer Image.
• Despite being offline, Spitzer could still help scientists make more discoveries in the future.
• The entire archive of observations made by the telescope will be available to anyone who wants to use it.
• It’s possible that even more great finds are hiding in these records.

Spitzer Warm Mission

• Spitzer operated in its “cold mission” for 5.5 years, well beyond the 2.5 years that NASA had hoped.
• But eventually, the spacecraft ran out of the liquid helium coolant, which prompted Spitzer’s warm mission.
• The telescope warmed up, but it didn’t warm up very much.
• It wasn’t able to observe as much as it could before.
• Its biggest find during its warm phase: the discovery of an entire solar system of seven Earth-sized planets, orbiting a star called TRAPPIST-1.

TRAPPIST-1 star TRAPPIST-1 is a planetary system, located 12 parsecs away from the Solar system (39 light years), and is 12 times less massive than the Sun and only slightly larger than the planet Jupiter. There are at least seven rocky planets orbiting the star.

NASA observatories

• Spitzer is one of four space telescopes operated by NASA known as the Great Observatories.
  • Compton Gamma Ray Observatory
  • Chandra X-ray Observatory
  • Hubble Space Telescope.
  • Spitzer Space Telescope
• Combined, the four telescopes were meant to observe the Universe in as many wavelengths of light as possible — ranging from the visible light that we can see, to the kinds of light our eyes cannot register.
• James Webb Space Telescope: NASA’s next great space observatory, the James Webb Space Telescope is in making.
  • Designed to study the Universe in infrared, the James Webb will be the most powerful space telescope ever made.
  • It will be able see back in time to the beginning of the Universe.