Rocket Ship

Notice: The telescope that will replace Hubble will be launched at Christmas. Here’s why it’s important

By Chris G. Robinson


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The James Webb Space Telescope (JWST) is a next-generation instrument designed to scan the cosmos, with capabilities that exceed and complement the venerable Hubble Telescope. It has been a long time coming, but it is a very exciting prospect to see the astronomical community take another step forward.

The Webb Telescope is an international enterprise, led by NASA, but with significant contributions from European and Canadian space agencies. It comes with a substantial price tag – around $ 10 billion – and it was originally slated to launch over a decade ago. But the cost and the wait are well worth it.

The company has supported expensive astronomical projects like space telescopes because of the huge return on investment in knowledge of the universe – and is expected to continue to do so. Hubble, for example, has proven time and time again that the investment is worth it. It answered questions that weren’t even asked when it launched, while also shedding light on old questions such as: How fast is the universe expanding? And how old is he?

Hubble discovered the moons of Pluto and proved that most galaxies have a supermassive black hole at their core. And he created a three-dimensional map of dark matter in the universe. These are amazing discoveries that are a great return on your investment.

But there are other questions to be answered which require new capabilities. This is why the Webb telescope, so important is named after James Webb, who led NASA from 1961 to 1968 as the agency prepared for the Apollo missions to the moon. It will go further back in time than Hubble can, and it will answer questions that Hubble cannot.

The main difference between the Hubble and the JWST is the wavelength of light they are designed to image. Hubble is sensitive to ultraviolet, visible and near infrared light (200-2400 nanometers). In contrast, JWST mainly focuses on the infrared spectrum (600-28,000 nanometers), with a limited ability to see visible red / orange light, but not other colors. This change in technology will allow us to look deeper into the past and gain insight into how our universe came to be.
In 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. As the initial conditions of the cosmos glowed white, as the universe expanded and cooled, the cosmos vanished into darkness, containing only clouds of hydrogen and helium. . What followed is a period that astronomers call the Dark Ages.
For the next hundred or two hundred million years, gravity compressed these clouds until their densities became high enough for nuclear fusion to begin and they became stars. These stars were huge and bright and shed a light that was predominantly blue and ultraviolet – something the JWST cannot see directly. However, since its formation, the universe has expanded, stretching the short ultraviolet wavelength emitted by these early stars into long wavelength infrared light.
the oldest galaxy that the Hubble Telescope photographed existed about 400 million years after the Big Bang. With its improved ability to image infrared light, JWST will be able to see much older stars and galaxies – those that arose just 200 million years after the Big Bang – perhaps even older. In short, the James Webb Telescope will be able to see when the cosmos has passed from a dark, invisible void to the star-filled universe we see today. It will be a huge step forward for astronomy.

Seeing the evolution of the universe is not the only mission of JWST. Its ability to image infrared light will allow it to directly see certain planets orbiting distant stars. While it is highly unlikely that the facility will be able to see Earth-like planets, it will be able to see infrared light reflection on Jupiter-like planets, and it will be able to see young planets hot enough to be molten. – much like the Earth was when it first formed. Detailed information on 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 humanity alone in the universe?

Unlike the Hubble Telescope, which orbits a few hundred kilometers above the Earth’s surface and is relatively accessible for maintenance missions, the JWST will be located at what is called the point L2, a place about a million kilometers farther from the sun than Earth. This location was chosen because it protects sensitive JWST instruments from infrared (ie heat) emitted by the sun, earth and moon. Without this shield, the JWST telescope would not work.
Of course, with JWST’s location so far from Earth, it’s impossible for astronauts to maintain the establishment. It just has to work. And due to the remote location of the telescope, it will not be possible to replenish consumables like instrument coolant and rocket fuel to keep the telescope in the correct location and correctly oriented. This means that unlike Hubble’s 30+ year (and over) mission, JWST is expected to run for five years, although the engineers and scientists who built it hope it will have a lifespan of ten years. These five additional years would be a huge boon for the astronomical community.
Once the James Webb Space Telescope leaves Earth’s atmosphere, it won’t be quite ready to go. When fully deployed it is about the size of a tennis court, but everything is bent to fit inside the rocket shroud. The telescope will take approx two weeks unfold. As it unfolds, it will travel to point L2, a journey that will take about a month. Once the instrument is in place, JWST technical staff will spend approximately six months performing tests to ensure that it will perform as expected.

And then the fun begins. While researchers have a clear plan for what the telescope will look for, it’s almost certain that astronomers will also discover things they didn’t anticipate. We can only guess what we might learn about the universe over the next five years. However, I’m sure the James Webb Space Telescope will turn at least a few centuries-old questions into modern answers.

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Chris G. Robinson
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