- 3597 - JAMES WEBB TELESCOPE: what next generations will learn? Hubble was built to detect visible and ultraviolet light. These early galaxies do emit visible light, but because of their distance, the wavelength of this light gets stretched into the infrared part of the electromagnetic spectrum caused by their redshift. Infrared detectors is a technology that has now reached its culmination in four cutting-edge scientific instruments of the James Webb Space Telescope.
- 3597 - JAMES WEBB TELESCOPE: what next generations will learn?
- There were many things about the universe we don’t know. One of these unknowns is how stars and galaxies existed already a few hundred million years after the Big Bang.
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- By the time Hubble was built , science had moved on, science had changed. One of the things that astronomers discovered in the 1980s ,shortly before Hubble's 1990 launch, was that galaxies formed much earlier than expected.
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- It became obvious that another, even grander, space observatory will be needed to get to those early stars and galaxies. Those that had lit up the universe after hundreds of millions of years of darkness that followed the Big Bang when the expanding space was only filled with hydrogen atoms.
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- The technology that would eventually enable the James Webb Space Telescope to see that mythical first light in the universe had yet to be developed. This missing piece of technology was infrared detectors that would be able to collect the faint light coming from those early stars and galaxies more than 13 billion light-years away.
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- In the 1980s, infrared pictures were taken with one detector scanning the sky one pixel at a time. The first camera which could take 2D infrared images. It had 58 times 62 pixels, and that was 4,000 times more than everybody else had, because they only had one.
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- The “Near Infrared Camera and Multi-Object Spectrometer” (NICMOS) was the first infrared detector fitted on the Hubble Space Telescope during its second servicing mission in 1997. NICMOS, consisting of three infrared detectors, each of which had 256 by 256 pixels, opened the first door for Hubble into the infrared universe.
NASA's James Webb Space Telescope (JWST), will orbit the sun 1 million miles from Earth. The technology has come a long way since Hubble's early years, and the James Webb Space Telescope project has been pushing it further along the way. The detectors on JWST have 2000 by 2000 pixels.
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- The James Webb Space Telescope's giant mirror will feed the light of stars and galaxies into four cutting edge instruments designed not only to take images, but also to analyze the chemical composition of the near and distant universe.
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- This is done with a technique known as “spectroscopy“, which looks at how matter in the universe absorbs light. As different chemical elements absorb light at different wavelengths, astronomers will be able to reconstruct what stars, nebulas, galaxies and planets within James Webb's Space Telescope's sight are made of.
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- The James Webb Space Telescope instruments are a factor 10 to 100 times better than anything previously available. These improvements in the resolution of infrared imaging are critical for imaging the furthest reaches of the universe.
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- Where the Hubble Space Telescope, or the recently retired infrared telescope “Spitzer“, could provide only a rough estimate of an ancient galaxy's age and chemical composition, Webb will deliver with precision.
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- The “Spitzer Space Telescope” is trolling for huge, early galaxies in areas of the sky such as this COSMOS field, which is short for Cosmic Evolution Survey. It was its Wide Field Camera 3 that opened some of the best views into the early universe.
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- However, when it comes to these distant galaxies, the Wide Field Camera 3 runs out of wavelength. Some of those detections get kind of iffy and it will be very interesting to see which ones turn out to be right. Webb will be able to say exactly what we see for this particular galaxy 250 million years after the Big Bang.
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- Hubble can see up to 13 billion years into the past. And it already sees galaxies that by that moment in their evolution may have formed several generations of stars. If we are seeing that material some 500 million years after the Big Bang, it must have been made even earlier by stars we haven't yet seen. Big stars form and die quickly, in only a few million years, so after 500 million years, you may have had lots of generations of massive stars.
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- Astronomers know that the early universe had a very different chemical composition from what we see today. It consisted only of hydrogen, helium and a little bit of lithium. All the other chemical elements that we see now, including those that make life possible, were cooked up throughout eons inside those stars.
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- A lot of the chemical synthesis in the universe is around massive stars when they explode, or low mass stars in their final stages of evolution. There's lots of interesting, slow process chemistry that can happen in their atmospheres because of the temperatures and pressures. How can we go from having only three chemical elements to the vast array of diversity we see around us today?
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- The spectroscopes aboard the James Webb Space Telescope will be able to probe the -chemical elements of those early galaxies seeing what was cooking inside individual stars and what they fertilized the wider cosmos with when they exploded in powerful supernovas.
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- While the James Webb Space Telescope and the Hubble Space Telescope are frequently compared, their images will be quite different, revealing different aspects of the universe. While Hubble's strength is imaging the visible universe, Webb's infrared superpowers will enable the telescope to see through dust right into the heart of nebulas, galaxies and star-forming regions that are hidden from Hubble's view.
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- We know that stars are being born in places like the Orion Nebula and other nebulae in the sky. But we can’t see into them in the optical because optical light gets absorbed by dust.
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- Previous infrared observatories, such as NASA's Spitzer Space Telescope, were much smaller than Webb. Therefore, they couldn't see as far as Webb, and when they did, they only glimpsed those star-forming regions in a limited resolution.
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- Previously, when we could see the site of star formation, we would see multiple objects all mushed in together. Webb will be able to separate them all out individually. We would be able to see multiple stars being born in clusters where previously we could only detect those clusters.
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- We could only see stars about 8 times the mass of the sun but now we should be able to see the formation of stars about as big as the sun and that process has never been observed before.
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- With JWST astronomers can't look inwards towards the sun, but they will be able to look outwards. They can look at planets like Mars, Jupiter, Saturn, Uranus and Neptune also into the Kuiper Belt.
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- The Kuiper Belt is a repository of comets, asteroids and other debris that encircles the outer solar system beyond the orbit of Neptune. It's a dark and cold region that is very difficult to explore because these objects reflect very little light.
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- These objects are really cold, they don't reflect much light, so you need a big infrared telescope. We know they have ices and various molecules on their surfaces, and we hope to be able to see that.
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- Just like with Hubble, science has moved forward since the conception of the James Webb Space Telescope and new areas have emerged that may not have been foreseen when the first light machine was first conceived.
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- In 1995, the first two planets orbiting another star than our sun were discovered. Since then thousands of exoplanets of various sizes and kinds have been detected. And while not designed with these potential other Earths in mind, the James Webb Space Telescope turns out to be positioned to not only discover many more, but also to tell us much finer details about their nature than any other mission before.
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- These planets have atmospheres that have various molecules in them, like carbon dioxide, oxygen and nitrogen. To look at these molecules, that's really best done with infrared spectroscopy.
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- One of JWST's instruments, the “Near Infrared Camera” (NIRCAM) is fitted with extra implements called “coronographs“, which block out the light of a star to see more clearly what is happening around it. That might involve alien systems of planets, some of which might be habitable, with water and atmosphere that could support life just like Earth.
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- Thirty years ago, nobody would have imagined that we could study the composition of atmospheres of planets around other stars.
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- The James Webb Space Telescope was built to revolutionize astronomy. Ten years from now, many of its most ground-breaking discoveries may come from realms that are still completely unknown today.
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- Both Hubble and Webb have a broad range of capabilities that enable them to make discoveries that were not in the areas that you designed the telescopes for. If you do Hubble's top 10 greatest hits, half of them were things they knew they were building it for and half of them were things that people had no idea about, like dark energy and exoplanet studies. The same will be true for Webb.
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- The Near Infrared Camera (NIRCAM) will be crucial for accomplishing Webb's flagship goal: detecting the light from the earliest stars and galaxies. It's not just a simple infrared camera, but is fitted with some extra implements called coronographs. The coronographs will enable astronomers to block out the light of a star and look at what's happening around it, which makes it great for discovering orbiting exoplanets.
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- NIRSpec is the main tool for cracking the chemistry of the universe. It will split the light coming from the distant universe into spectra, revealing the properties of the observed objects, including their temperature, mass and chemical composition.
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- Because some of these objects are extremely distant and the light coming from them will be extremely faint, the James Webb Space Telescope, despite its giant mirror, will have to stare at them for hundreds of hours. To make those observations more efficient, NIRSPec will be able to observe 100 such distant galaxies at the same time.
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- It basically lets you open little doors and let the light through from one galaxy, but then block off all the light from everything else. But you can open 100 doors at once. So that's very sophisticated and that's never been flown in space.
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- The Mid-Infrared Instrument (MIRI) is a combination of a camera and a spectrograph, but unlike the previous two, it observes in the longer wavelengths of the mid-infrared part of the electromagnetic spectrum, which will make it a go-to instrument for everyone looking to study everything from comets and asteroids at the outskirts of the solar system to newly born stars and distant galaxies. The images of MIRI will be the most akin to those that turned the Hubble Space Telescope into a legend.
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June 9, 2022 JAMES WEBB TELESCOPE: what next generations will learn? 3597
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