Voyage to Unveil the Hazy: Spitzer Space Telescope

Spitzer space telescope

To unravel the cornucopia of hidden mysteries and to gather information on remote planets, galaxies, and other astronomical entities, NASA initiated the concept of a multi-wavelength set of Great Observatories by giving birth to four legendary observatories; to study the universe at the entire electromagnetic spectrum. Its fourth and last element is the Spitzer Space Telescope; considered to be the most sensitive infrared telescope in history so far. It satisfies and observes the cosmos at infrared wavelengths. Spitzer launched into operation in 2003 and concluded its illustrious service in 2020, revealing oodles of splendor in the universe.

Detecting the Undetectable

Dedicated to infrared astronomy, Spitzer penetrates the universe unfolding the cosmic objects concealed and enshrouded in dense clouds of gas and dust which cannot be grasped by optical telescopes. To gain a sound knowledge of the universe, it is necessary to understand the composition, history, and evolution of celestial objects. It is only by observing and gathering information about the universe through the entire electromagnetic spectrum, we can see and understand the whole picture.

Even if human eyes encounter infrared light, we cannot see it though we can sense some of it as heat. All hot objects emit radiation including infrared radiation. The sun emits radiation mostly as visible light and infrared radiation as well. Cooler objects like planets, cool stars, nebulae, etc. emit the most radiation in the infrared. To unlock these pieces of the cosmic puzzle, infrared astronomy is crucial as that kind of telescope detects celestial objects that are too cool and dim to be detected by optical telescopes.

Spitzer space telescope
Figure 01: The difference between visible and infrared astronomy

Infrared wavelengths are longer than visible light wavelengths. Therefore, infrared waves are capable of penetrating the hazy regions of gas and dust in space enabling us to see through the regions of star formation, newly forming planetary systems, centers of galaxies, extrasolar planets, giant molecular clouds, etc. Many molecules in the universe absorb infrared radiation and therefore, infrared telescopes aid to determine the composition of astrophysical bodies.

Spitzer space telescope
Figure 02: An infrared image captured by NASA’s Spitzer showing countless stars and galaxies obscured in visible light by cosmic dust. Credit: NASA/JPL – Caltech

Spitzer Space Telescope: Most Sensitive Infrared Telescope in History

Spitzer Space Telescope
Figure 03: The main components of Spitzer

The Spitzer was comprised of many technological features never used on a space mission before. It was 4 meters tall and weighed approximately 865 kilograms. The Spitzer telescope had to be kept cool as it detected infrared wavelengths, but the other components on board of Spitzer were kept at room temperature as it was the suitable temperature to function properly. Therefore, the observatory was compartmentalized into two parts to satisfy the needs.

  • The cryogenic telescope assembly (CTA)

Facilitated the cold components including the 0.85 telescope and three scientific instruments.

  • The spacecraft

Kept the warm components including solar panels, telescope controls, and communication tools that were used to transmit information to the Earth and receive information from the Earth.

Three Scientific Instruments on Board

The Spitzer carried three cryogenically cooled scientific instruments to fulfil its objectives by performing astronomical imaging and photometry. They were stowed inside the Spitzer’s Multiple Instrument Chamber.

  • Infrared Array Camera (IRAC)
  • Infrared Spectrograph (IRS)
  • Multiband Imaging Photometer for Spitzer (MIPS)
Spitzer Space Telescope
Figure 04: Multiple Instrument Chamber
Spitzer Space Telescope
Figure 05: The telescope

A Noteworthy Career of 16 Years

Figure 06: More than 16 years of Space exploration through the Spitzer Space Telescope

On 25th August in 2003, Spitzer Space Telescope was launched from Cape Canaveral, Florida, promising the scientists a fine opportunity to unlock more about the universe as NASA’s premier infrared observatory. Even though NASA initially scheduled for a 2.5-year primary mission, Spitzer outlived far beyond its expected runtime.

Peering into the early universe, Spitzer was able to observe light from the earliest galaxies to form in the universe. Light from the most distant galaxies detected by Spitzer traveled for 13.4 billion years to reach the Earth. Among these discoveries, scientists identified “big baby” galaxies that were larger and more mature than early forming galaxies were supposed to be.

Spitzer unfolded a comprehensive image that shows us our home galaxy, Milky Way in infrared light. It is known as the GLIMPSE360º project, short for Galactic Legacy Infrared Mid-Plane Survey Extraordinaire. Our galaxy is warped and twisted and to the naked eye, we observe it as a hazy band of light. With Spitzer’s GLIMPSE, we were able to view the galaxy with infrared eyes stretching into the far corners of the galaxy where optical telescopes could not.

Figure 07: Panorama image from Spitzer’s Telescope shows our galaxy’s plane all the way around in infrared light. Credits: NASA/JPL – Caltech/University of Wisconsin

Spitzer paved the way for a number of discoveries in history including an unknown ring around Saturn called the Phoebe ring which was visible to infrared, unique, roughly spherical carbon molecules in space called the ‘buckyballs’, a chain of exoplanets known as the TRAPPIST-1 system among others.

Figure 08: Spitzer’s journey from beginning to end

In May 2009, Spitzer’s ‘Cold Mission’ concluded as its coolant/cryogen which was essential to keep its instruments at suitable temperature ran out. Spitzer’s prime mission came to an end which lasted about 5 months longer than the expected time duration. Two of Spitzer’s instruments, the Infrared Spectrograph (IRS) and Multiband Imaging Photometer for Spitzer (MIPS) stopped operating due to this. Then on, Spitzer’s ‘warm mission’ took reins. In October 2018, Spitzer although supposed to conclude its operation, NASA extended its lifetime to 2020. The name “Spitzer Beyond” then replaced the name “Warm Mission” in August 2016. In May 2019, NASA declared the decommission of the Spitzer mission to be on January 30, 2020, naming the rest of the mission the ‘Spitzer Final Voyage’. On 30 January 2020, Spitzer shut down all the systems on board and went into ‘safe mode’ successfully wrapping up its legendary expedition.

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