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Explained: How James Webb Space Telescope will search for the first formed galaxies

🔴 The James Webb Space Telescope is said to be the scientific successor to the Hubble and Spitzer space telescopes. Webb has a larger primary mirror — about 2.5 times larger in diameter than Hubble’s mirror.

Written by Aswathi Pacha , Edited by Explained Desk | Kochi |
Updated: November 30, 2021 11:50:14 am

The James Webb Space Telescope scheduled to be sent into orbit no earlier than December 22 is NASA’s largest and most powerful space science telescope ever constructed.

Carrying four scientific instruments – Near-Infrared Camera, Near-Infrared Spectrograph, Mid-Infrared Instrument, and Near-Infrared Imager and Slitless Spectrograph – the telescope will “hunt for the unobserved formation of the first galaxies, as well as to look inside dust clouds where stars and planetary systems are forming today,” according to NASA.

The collected data will help find answers to questions in four areas of modern astronomy:

  • First light
  • Assembly of galaxies
  • Birth of stars and protoplanetary systems
  • Planetary systems and the origin of life.

Why does it carry infrared cameras?

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About 13.8 billion years after the Big Bang, our universe was extremely hot and filled with dense particles. As it slowly cooled, it gave rise to the building blocks – helium and hydrogen. Studies have suggested that the first stars formed about 150–200 million years after the Big Bang. So what did the universe’s first light or stars look like? Webb is designed to help us to answer such questions using infrared cameras.

The light from the first stars and galaxies formed nearly 13.6 billion years ago will have to travel through space and time before reaching the telescope. By the time this light reaches the telescope, its colour changes, and this phenomenon is called redshift. The visible or UV light from the first stars and galaxies shift to redder wavelengths by the time the telescope sees it. For this reason, Webb is equipped with near- and mid-infrared instruments. By studying the earliest galaxies and comparing them to today’s galaxies we can understand the growth and evolution of galaxies.

How will Webb study the birth of stars and planetary systems?

Stars are born within clouds of warm gas and dust and young stars usually emit radiation in the near- and mid-infrared in the early stages, Webb’s near- and mid-infrared will help study these star-forming regions.

The Near-Infrared Imager and Slitless Spectrograph instrument will help Webb study the planetary systems. NIRISS can capture light from 0.6 microns (visible red) to 5 microns (mid-infrared) in wavelength.

Webb is also designed to study our Solar System’s planets – Mars, Jupiter, Saturn, Uranus, Neptune – and their satellites. It will also study comets, asteroids, and minor planets at or beyond the orbit of Mars.

Webb vs other space telescopes

The Webb telescope is said to be the scientific successor to the Hubble and Spitzer space telescopes. Webb has a larger primary mirror — about 2.5 times larger in diameter than Hubble’s mirror. Webb will operate much farther from Earth (1.5 million km away).

The Kepler telescope launched in 2009 and retired in 2018 helped identify planets that are located in or near the habitable zone of other stars. NASA says that Kepler was “designed to be a “wide and shallow” survey telescope, while Webb is designed for “narrow and deep” focused studies with near and mid-IR imaging and spectroscopy.”

Another large infrared telescope — the Herschel Space Observatory — built and operated by the European Space Agency was active from 2009 to 2013.

But Webb and Herschel are complementary. Webb will be sensitive to wavelengths from visible light to mid-infrared, while Herschel was sensitive in the far-infrared wavelength.

“By working at longer wavelengths, Herschel saw colder objects, such as the earliest stages of star formation in dark clouds and emission from molecules such as water. Webb will view more energetic phenomena including forming proto-stars and very distant galaxies,” says NASA.

How will Webb communicate with Earth?

The Webb telescope will send data to Earth via a high-frequency radio transmitter and large radio antennas part of the NASA Deep Space Network will receive these signals. It will be forwarded to the Webb Science and Operation Center at the Space Telescope Science Institute in Baltimore, Maryland, USA

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