Why James Webb Telescope Is Better Than Hubble

The James Webb space telescope (JWST) is named after the longest serving NASA administrator and is the official successor to the Hubble space telescope. JWST is the costliest astronomy project having spent nearly three decades in the making.

The largest and the most powerful telescope in the world is scheduled to be launched in December 2021 after many delays since completion. The JWST will be able to look back in time closer to the Big Bang than ever before.

Comparison

JWST was built by NASA in collaboration with European Space Agency and Canadian Space Agency. It will explore the universe in the infrared region, something that Hubble space telescope is incapable of doing. The mirror size is 6.5 meters - three times the size on the Hubble telescope but it weighs half of Hubble.

Protection

To make observations in the infrared part of the electromagnetic spectrum, JWST must be kept under 50K or −223°C which is extremely cold. It uses a cryocooler and a large five-layer sunshield to block light and heat from the Sun, Earth and Moon to maintain a stable temperature.

Mission

The objectives of JWST include detecting clues to the origins of the universe, like observing infant galaxies and their evolution. As well as locating earth like planets outside the solar system and study the origins of life.

Hubble space telescope is capable of observing events that happened in space some 500 million years after the Big Bang, whereas Webb telescope can go back even further to around 100 million years after that event.

Instruments

JWST has a near infrared camera for observation of faint extrasolar planets very close to the bright stars. It also has a near infrared spectrograph capable of measuring spectrum of faint stars and galaxies. A fine guidance sensor helps the telescope stay pointed at whatever it is commanded to look at.

Challenges

It was scheduled to launch before but accidental tears in the delicate sunshield in 2018 delayed the project. Controversy also erupted over naming of the telescope as activists alleged that James Webb had discriminated against LGBTQ scientists during his term.

The mirror in JWST will be folded before launch. It is made up of 18 hexagonal segments - shaped so to join without gaps in between them. The mirror will unfold after the launch and it will take at least two weeks before the telescope becomes operational in orbit.

How it works

When picture of a galaxy is taken we see it the way it was millions of years ago because light takes time to travel. It is like finding a picture of a child dated from 1900 but if that child was still alive, they would be among the oldest people on the planet.

As the light travels, it becomes red-shifted due to expansion of the universe. So, objects at extreme distances are easier to see in the infrared. We can see these objects the way they were millions of years ago, that is, when that galaxy was fairly young.

JWST's infrared capabilities will allow humans to see back in time to the first galaxies for the first time. Infrared astronomy will also help us to learn how stars and galaxies have evolved over time. By overcoming all the challenges, JWST is set to launch in December 2021.