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My compliments to SP Guide Publications for informative and credible reportage on contemporary aerospace issues over the past six decades.
NASA has launched its James Webb Telescope to explore previously hidden regions of the universe: early galaxies, forming planets, brown dwarfs, and much more
The Christmas of 2021 came in bearing an exclusive gift for the space industry; to peep into the far away universe with the launch of the largest telescope ever. However, the journey to receive the first image is still six months away. After a long process of putting this complex structure together and many delays, NASA (National Aeronautics and Space Administration) launched its much awaited James Webb Space Telescope (JWST) on an Ariane 5 rocket from Europe’s Spaceport in French Guiana, South America on December 24, 2021.
A joint effort with ESA (European Space Agency) and the Canadian Space Agency, the Webb observatory is NASA’s revolutionary flagship mission to seek the light from the first galaxies in the early universe and to explore our solar system as well as exoplanets (planets orbiting other stars).
The observatory was released at an altitude of approximately 870 miles (1,400 kilometers). Approximately 30 minutes after launch, Webb unfolded its solar array, and mission managers confirmed that the solar array was providing power to the observatory.
Established as the world’s largest and most complex space science observatory till now, the Webb Telescope has taken over half a decade to reach the launch date from the inception of its idea. Following the launch, it has started six months of commissioning in space. At the end of commissioning, Webb will deliver its first images. Webb carries four state-of-the-art science instruments with highly sensitive infrared detectors. Webb will study infrared light from celestial objects with much greater clarity than ever before.
“The launch of the Webb Space Telescope is a pivotal moment – this is just the beginning for the Webb mission. Once commissioning is complete, we will see awe-inspiring images that will capture our imagination,” informed Gregory L. Robinson, Webb’s programme director at NASA Headquarters.
|Primary Mirror Size
|21.3 feet (6.5 meters) across
|The mirror is comprised of 18 gold-plated hexagonal deployable segments
|Webb’s five-layer deployable sunshield is the size of a tennis court
|Webb has four science instruments: Near-Infrared Camera (NIRCam), Near-Infrared Spectrograph (NIRSpec), Mid-Infrared Instrument (MIRI), and Near-Infrared Imager and Slitless Spectrograph (NIRISS) with the Fine Guidance Sensor (FGS)
|Visible, Near Infrared, Mid Infrared (0.6-28.5 micrometers)
|1 million miles (1.5 million kilometers) from Earth
|Location in Space
|Orbiting the Sun around the second Lagrange point (L2)
After observing the telescope in space for about a week, the Webb mission operations team began the first steps in the process of tensioning the first layer of Webb’s sunshield. It will take the team two to three days to tension the five-layer sunshield. The tennis-court-sized sunshield helps keep the telescope cold enough to detect the infrared light it was built to observe. The first layer is the largest and the one closest to the Sun hence its tensioning was a critical step in the observatory’s complex sequence of deployments. By the fourth of January, the Webb team had completed tensioning for all the five layers of the observatory’s kite-shaped sunshield. The 47 feet across and 70 feet long sunshieldwill protect the telescope from the Sun’s radiation. It will reach a maximum of approximately 383K, approximately 230 degrees F, while keeping the instruments cold at a minimum of approximately 36K or around -394 degrees F.
WEBB’S CREATIVE DESIGN & ENGINEERING
JWST’s innovative design has been put together to tackle two main challenges for an infrared telescope:
Webb’s sunshields protect it from stray heat and light from the Sun, while its large segmented mirror—18 segments covering 6.5 meters (21.3 feet) at its widest point—enables it to effectively capture infrared light.
Launching such a large mirror into space was another huge challenge, for which the team designed an origami-inspired folding telescope. The sunshield as well as the mirrors were designed to unfold after the telescope separates from its launch vehicle and would unfold and deploy during the commissioning. Webb teams also successfully deployed the observatory’s secondary mirror support structure on January 5, 2021. When light from the distant universe hits Webb’s iconic 18 gold primary mirrors, it will reflect off and hit the smaller, 2.4-foot (.74-meter) secondary mirror, which will direct the light into its instruments. The secondary mirror is supported by three lightweight deployable struts that are each almost 25 feet long and are designed to withstand the space environment.
There are four instruments performing actual scientific observations, each specially designed to study different aspects of infrared light: the Near-Infrared Camera (NIRCam); Near-Infrared Spectrograph (NIRSpec); a Mid-Infrared Instrument (MIRI) with camera and spectrograph; and the Near-Infrared Image and Slitless Spectrograph (NIRISS).
Officials associated with the observatory state that these instruments include new technologies, like the microshutter array, that were developed for Webb to increase the telescope’s scientific capability and efficient operations throughout its mission. Both aspects are essential to Webb’s usefulness—efficiency allows more astronomers to make use of Webb while it is operational, and the best possible science capacity will help those astronomers investigate some of our most fundamental questions: How did we get here? How does the universe work?
WHAT IS WEBB SEEKING TO STUDY?
From within our solar system to the most distant observable galaxies in the early universe, to everything in between, the telescope’s “revolutionary technology” aims to explore every phase of cosmic history. Webb will reveal new and unexpected discoveries and help humanity understand the origins of the universe and our place in it.
JWST VS HUBBLE
The premier mission of JWST is the scientific successor to NASA’s iconic Hubble and Spitzer space telescopes, built to complement and further the scientific discoveries of these and other missions. What is important to note here is that JWST is not a replacement of Hubble, rather a successor that builds on what Hubble and Spitzer have already provided. The Hubble Telescope has been one of the most applauded structures that has provided us some of the best and most intriguing images of star nebulae. The JWST is way larger in diameter than hubble and hence has the capacity of capturing way fainter emissions hence allow us to sneak peek into farther galaxies.
NASA further specifies that Webb will primarily look at the Universe in the infrared, while Hubble studies it primarily at optical and ultraviolet wavelengths (though it has some infrared capability). Webb also has a much bigger mirror than Hubble. This larger light collecting area means that Webb can peer farther back into time than Hubble is capable of doing. Hubble is in a very close orbit around the earth, while Webb will be 1.5 million kilometers (km) away at the second Lagrange (L2) point.
WHY IS IT IMPORTANT TO STUDY INFRARED LIGHT?
Infrared light is noted to be important to astronomy in three major ways: