Editor’s Note: Don Lincoln is a senior scientist at the Fermi National Accelerator Laboratory. He is the author of several science books for general audiences, including the best-selling audio book “The Theory of Everything: The Quest to Explain All Reality.” He also produces a series of science education videos. Follow him on Facebook. The opinions expressed in this commentary are solely his. View more opinions on CNN.
In April of 1990, the space shuttle Discovery lifted the Hubble Space Telescope into orbit just a few hundred miles above the Earth’s surface. For over 30 years, the telescope has been the go-to facility for those interested in unlocking the mysteries of the universe. However, on Christmas morning, a new orbital telescope is scheduled to be launched that will challenge Hubble’s claim to supremacy and allow astronomers to photograph the very first stars and galaxies that came into existence.
The James Webb Space Telescope (JWST) is a next-generation instrument designed to peer at the cosmos, with capabilities that both outstrip and complement the venerable Hubble telescope. It’s been a long time coming, but it’s a very exciting prospect to see the astronomical community take the next step forward.
The Webb Telescope is an international endeavor, helmed by NASA, but with important contributions from both the European and Canadian space agencies. It comes with a substantial price tag – some $10 billion – and it was originally intended to be launched over a decade ago. But both the cost and the wait are totally worth it.
Society has supported pricey astronomical projects like space telescopes because of the huge payback in knowledge about the universe – and should continue to do so. Hubble, for instance, has proven itself worth the investment again and again. It has answered questions that weren’t even being asked when it was launched, while shedding light on old questions like: how fast is the universe expanding? And how old it is?
Hubble discovered moons of Pluto and proved that most galaxies have a supermassive black hole at their core. And it created a three-dimensional map of the dark matter in the universe. These are amazing discoveries that are a great return on investment.
But there are more questions that need answering, which require new capabilities. That’s why the Webb Telescope, named for James Webb, who ran NASA from 1961 to 1968 as the agency prepared for the Apollo missions to the moon, is so important. It will look further back in time than the Hubble can, and it will answer questions that the Hubble can’t.
The primary difference between the Hubble and the JWST is the wavelength of light that they are designed to image. Hubble is sensitive to ultraviolet, visible, and near-infrared light (200-2,400 nanometers). In contrast, JWST is focused mostly on the infrared spectrum (600-28,000 nanometers), with some limited capability of seeing some red/orange visible light, but not the other colors. This change in technology will allow us to peer more deeply into the past and get a firsthand look at how our universe came to be.
Over the last century or so, scientists have determined that the universe began about 13.8 billion years ago in a cataclysmic event called the Big Bang. While the initial conditions of the cosmos glowed white hot, as the universe expanded and cooled, the cosmos faded into darkness, containing only clouds of hydrogen and helium gas. What followed is a period that astronomers call the Dark Ages.
For the next one or two hundred million years, gravity compressed these clouds until their densities became high enough that nuclear fusion began, and they became stars. These stars were enormous and bright and poured out light that was predominantly blue and ultraviolet – something that the JWST can’t directly see. However, since its formation, the universe has expanded, stretching the short ultraviolet wavelength emitted by those early stars into long wavelength infrared light.
The oldest galaxy that the Hubble telescope has photographed existed about 400 million years after the Big Bang. With its enhanced ability to image infrared light, JWST will be able to see stars and galaxies that are much older – ones that were born a mere 200 million years after the Big Bang – maybe even older. In short, the James Webb telescope will be able to see when the cosmos transitioned from a dark and invisible void, to the star-filled universe we see today This will be a tremendous advance for astronomy.
Seeing the evolution of the universe isn’t the JWST’s only mission. Its ability to image infrared light will allow it to directly see some planets orbiting distant stars. While it is very unlikely that the facility will be able to see Earth-like planets, it will be able to see the reflection of infrared light off planets comparable to Jupiter, and it will be able to see young planets that are hot enough to be molten – much like Earth was when it was first formed. Detailed information about exoplanets will allow scientists to better understand how planetary systems are formed and give us a better idea of whether our own solar system is unusual. This will have profound implications for the question: Is mankind alone in the universe?
Unlike the Hubble telescope, which orbits a few hundred miles above the Earth’s surface and is relatively accessible for servicing missions, the JWST will be located at what is called the L2 point, a location about a million miles farther away from the sun than the Earth. This location was chosen because it makes it possible to shield the JWST’s sensitive instruments from infrared (i.e. heat) emitted from the sun, Earth and moon. Without that shield, the JWST telescope wouldn’t work.
Of course, with JWST’s location so far away from Earth, it is impossible for astronauts to service the facility. It simply has to work. And because of the telescope’s remote location, it will not be possible to replenish consumables like coolant for the instruments and rocket fuel to keep the telescope in the correct location and oriented properly. This means that unlike the Hubble’s 30+ year (and counting) mission, JWST is expected to operate for five years, although the engineers and scientists who built it hope it will have a ten-year lifespan. Those extra five years would be a huge boon to the astronomical community.
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Once the James Webb Space Telescope leaves the Earth’s atmosphere, it won’t be quite ready to operate. When fully deployed, it’s about the size of a tennis court, but it is all folded up to fit inside the rocket shroud. The telescope will take about two weeks to unfold. While it’s unfolding, it will be traveling to the L2 point, a journey that will take about a month. Once the instrument is in place, the JWST technical staff will spend about six months performing tests to make sure that it will work as designed.
And then the fun begins. While researchers have a clear plan on what the telescope will search for, it’s a near certainty that astronomers will also discover things they didn’t anticipate. We can only hazard a guess at what we might learn about the universe in the next five years. However, I am sure that the James Webb Space Telescope will turn at least a few age-old questions into modern answers.
For more about the telescope, you can watch the CNN Film “The Hunt For Planet B” on CNNgo. The documentary follows scientists as they build and plan for the launch. It also looks at the search for life on planets outside of our solar system.