Jame's Webb Space Telescope NASA mockup

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The James Webb Space Telescope Will Expand Our View of the Universe

The James Webb Space Telescope or Webb is a large, space based observatory. It’s intended to complement and expand on the discoveries of the Hubble Space Telescope.

Webb has a longer wavelength coverage and improved sensitivity over the Hubble. This increased wavelength coverage let’s the Webb look farther back in time than the Hubble to the time the first galaxies were being formed and inside the dust clouds where stars and planets are being formed today. Ultimately this brings us closer to understanding the origins of our universe and where we came from.

Orion Nebula

Credit: ESO/NASA/JPL-Caltech/S. Kraus

Stacking Webb up to Hubble

The JWST is a vast improvement on the Hubble’s capabilities due in part to its mirror being 6x larger in area which gives it significantly more light-gathering power. Webb also has infrared instruments with a longer wavelength coverage and sensitivity than Hubble.

What’s most impressive is that Webb is being operated much farther from Earth than Hubble. Hubble operated in Earth orbit around 570km above sea level. The Webb will operate 1.5 million km beyond Earth. As the diagram below shows that’s well beyond even the Moon.

Credit: NASA

Webb’s Location in Space

This immense distance allows the Webb telescope to maintain a colder operating temperature, more stable pointing and a higher observing efficiency than Hubble.

It operates at the Earth-Sun Lagrange point. Named after a 1772 mathematician,

“A Lagrange point is a location in space where the combined gravitational forces of two large bodies, such as Earth and the sun or Earth and the moon, equal the centrifugal force felt by a much smaller third body. The interaction of the forces creates a point of equilibrium where a spacecraft may be “parked” to make observations.” (Neil English)

The diagram below show’s the gravitational forces of the various bodies which will serve to stabilize the Webb’s orbit.

Credit: NASA

Seeing Back to the Beginning

At the L2 point Webb will orbit with the Earth around the Sun, staying fixed in spot with relation to the bodies it’s orbiting. The centrifugal force of the Moon acting on this orbit is what will stabilize Webb and give it the stable pointing needed to see the vast distances it’s capable of.

A solar shield on Webb will block the light from the Sun, Earth and Moon. This helps Webb to stay cool which for an infrared gathering telescope is vital.

The universe is constantly expanding causing the most distant and youngest galaxies to move away from us. This causes the emitted light from these galaxies to be shifted towards the red end of the spectrum. The youngest galaxies in the universe are moving so quickly they’re known as “high red-shift” galaxies and require a telescope with infrared capabilities like the Webb to be observed.

Seeing back into the cosmos

Credit: NASA and and Ann Feild [STScI]

New Insights Into the Hunt For Life

With Webb’s unmatched ability to view into our universe’s past we’ll be able to measure the first galaxies and stars with an unmatched precision. We’ll rapidly expand upon the exoplanet discoveries currently underway by measuring the atmospheric contents of Earth-like planets orbiting the smallest, low mass stars. Like the incredible TRAPPIST-1 system.

We’ll be able to learn how the universe became transparent to visible light by viewing radiation from the earliest galaxies. As NASA puts it:

“This process of particles pairing up is called “Recombination” and it occurred approximately 240,000 to 300,000 years after the Big Bang. The Universe went from being opaque to transparent at this point. Light had formerly been stopped from traveling freely because it would frequently scatter off the free electrons. Now that the free electrons were bound to protons, light was no longer being impeded. “The era of recombination” is the earliest point in our cosmic history to which we can look back with any form of light.”

By viewing this period we’ll be able to learn much more about the origins of our universe and ultimately where we came from.



Written by Andrew Walls

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