Webb Space Telescope - An engineering Marvel.
Article by Chirag Lunker (Hyderabad,India) ; Published by NRI Herald Australia 24 January 2022
ABOUT THE WEBB TELESCOPE:
The James Webb Space Telescope is the world’s largest, most powerful, and most complex space science telescope ever built. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.
Webb is the biggest and the most advanced space observatory ever constructed. About 100 times more powerful than Hubble, Webb is the size of a 70-foot tennis court. Its massive 21.6-foot primary mirror (to Hubble’s 8-foot primary mirror) is made from super-strong beryllium and comprises 18 hexagonal segments.
Webb’s journey to L2 is nearly complete. On Monday, Jan. 24, engineers plan to instruct NASA’s James Webb Space Telescope to complete a final correction burn that will place it into its desired orbit, nearly 1 million miles away from the Earth at what is called the second Sun-Earth Lagrange point, or “L2” for short.
Launch date: 25 December 2021
Cost: $10B USD (as per 2016 data)
Dimensions: 20.197 m × 14.162 m (66.26 ft × 46.46 ft), sunshield
Bandwidth: S-band up: 16 kbit/s; S-band down: 40 kbit/s; Ka-band down: up to 28 Mbit/s
Power: 2 kW
Rocket: Ariane 5 ECA (VA256)
Manufacturers: Northrop Grumman, Ball Aerospace & Technologies
The James Webb Space Telescope (JWST) is expected to cost NASA $9.7 billion over 24 years. Of that amount, $8.8 billion was spent on spacecraft development between 2003 and 2021; $861 million is planned to support five years of operations. Adjusted for inflation to 2020 dollars, the lifetime cost to NASA will be approximately $10.8 billion.
That is only NASA’s portion. The European Space Agency provided the Ariane 5 launch vehicle and two of the four science instruments for an estimated cost of €700 million. The Canadian Space Agency contributed sensors and scientific instrumentation, which cost approximately CA$200 million.
The James Webb telescope, which is set to replace the Hubble Space Telescope, will study the origin of the universe. Equipped with sophisticated cameras, James Webb will look at the celestial objects by capturing infrared light from them. In addition to studying our solar system, it is expected to learn more about distant worlds too.
The scientists said the telescope is now entering “a period of cooldown” and they will be less frequent with their updates but their work will continue.
The James Webb Space Telescope is the next chapter in spaced-based telescope astronomy.
The Webb mission builds on the legacy of the Hubble Space Telescope’s powerful imaging capability and the Spitzer Space Telescope’s ability to detect light beyond the visible spectrum, into the mid-infrared range. Because infrared light travels through dense gas clouds that block visible light, Webb will reveal previously hidden regions of the universe: early galaxies, forming planets, brown dwarfs, and much more.
These instruments include new technologies, like the micro shutter 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 fundamentals questions.
Webb’s groundbreaking engineering will facilitate groundbreaking science.
Will Webb really look back in time?
All telescopes are time machines. The light from every single star you see is old and has travelled very far to reach you. Even the Sun’s light is 8 minutes and 20 seconds old. The brightest star in the night sky, Sirius, is 8.6 light-years away. That means its light has travelled for 8.6 years at 186,000 miles per second to reach your eyes.
Every photon Webb will detect is old light, but since it’s an infrared telescope it will detect the very oldest, most ancient light. Infrared light is electromagnetic radiation with wavelengths longer than visible light, so it is imperceptible to the human eye.
The very oldest light in the universe – emitted soon after the Big Bang 13.8 billion years ago, when the first stars and galaxies formed – has been stretched by the expansion of the Universe, so it is deeply red. So red in fact that it falls off the visible light spectrum entirely and into the infrared spectrum.
Webb will be able to study those very first stars and galaxies a few hundred million years after the Big Bang, something no other telescope has been able to do. That is why Webb was built.
What will Webb do now?
With the mechanical unfolding of the observatory complete, the engineers got on with aligning the mirrors. Remotely moving each of the 18 primary mirror segments and the secondary mirror out of their launch configuration, they tinkered with the curvature of each mirror segment to set the overall shape of Webb’s primary mirror.
NASA says it could take until April 24 to align the 18 hexagonal gold-covered beryllium segments to create Webb’s primary mirror.