This article by Martin Barstow, University of Leicester originally appeared on The Conversation and is republished here with permission. After decades of development and many trials and disappointments along the way, the James Webb Telescope has finally begun to deliver what it came for. On July 12, NASA released the first scientific observations made by the suite of instruments it carried on the mission, marking what we eagerly expect to be the beginning of a new era in astronomy. After the launch on Christmas Day, a series of critical deployments followed to open the telescope and its shadow. If any of these functions had failed, James Webb would have been an unused disaster. But the program was executed flawlessly, a process that went more smoothly and successfully than any of us had dared hope, let alone expected. This is not just a testament to the skill of the project’s engineers, technicians and scientists. It also underscores the enormous importance of the testing program conducted on Earth to verify procedures, which occasionally revealed problems that needed to be fixed before launch. While this sometimes resulted in schedule slippage and cost overruns, it ultimately produced a perfect telescope. In July, the telescope moved from procurement and operational testing to the amazing observatory it had long been planned to be. Those of us who have been involved in the journey and will work with the data, look forward to it. Sharp images The new “early release observations”, selected by an international panel of representatives from Nasa, Esa (European Space Agency), CSA (Canadian Space Agency) and the Space Telescope Science Institute, are part of a program designed to to highlight the wide range of science the telescope will perform. It is very exciting to see the new images – I was not prepared for the level of sharpness and detail that can be seen. It is a pleasure to finally have such high quality data. Unveiled by US President Joe Biden, the stunning image of SMACS 0723, a cluster of thousands of galaxies, was released on July 11. The massive galaxy clusters in the foreground magnify and distort the light of objects behind them, helping us look back in time at very faint objects. The image shows the galaxy cluster as it appeared 4.6 billion years ago. But the most distant galaxies in the image (the ones that look stretched) are about 13 billion years old – and we already have more data on them than on any other ancient galaxy. Images like this will help us understand how the first stars and galaxies formed. Some of them may be among the most distant objects known, from the beginning of the universe. The image is a composite “color” image derived from observations made at different wavelengths. It was taken by the telescope’s Near Infrared Camera (NIRCam). James Webb also caught a glimpse of the Stephano Quintet, a group of five galaxies merging about 290 million light-years away in the constellation Pegasus. The image also suggests that there is a supermassive black hole at the center and shows stars being born. The data will tell us more about how galaxies evolve and the rate at which supermassive black holes grow. The next image shows the Carina Nebula, shown in the image below, which is one of the largest and brightest nebulae (clouds of dust and gas in which stars are born). James Webb can probe deep into the dust in infrared light to reveal the interior of the stellar nursery – never seen before – to discover more about how stars are born. The Carina Nebula is located about 7,600 light-years away in the southern constellation Carina. The image shows hundreds of brand new stars (each dot of light is a star) and jets and bubbles created by them. We can also see details that we cannot yet explain. The next striking image is of the Southern Ring or Eight Burst Nebula, a planetary nebula, which is an expanding cloud of gas surrounding a dying star, or in this case two dying stars orbiting each other. the other. It is almost half a light-year in diameter and is about 2,000 light-years away from Earth. The frothy orange shell in the image is molecular hydrogen (a gas formed when two hydrogen atoms bond together), while the blue center is an electrically charged gas. In the right image, you can see the two dying stars in the center, giving us the opportunity to study stellar death in unprecedented detail. The new data is the result of months of painstaking measurements and testing to make James Webb ready for use as a post-deployment scientific instrument. The first steps were to focus and align the images of each of the mirror sections. Each of the telescope’s science instruments – NIRCam, The Near InfraRed Spectrograph (NIRSpec) and the Mid-Infrared Instrument (MIRI) – were also activated and tested. All these instruments, looking into deep space at different wavelengths, had to be cooled, along with the telescope, otherwise they would radiate background heat that would interfere with sensitive observations of astronomical objects. The last to be activated was MIRI, which operates at the lowest temperature, just seven degrees above absolute zero, which took several months to achieve. The size of a telescope – its aperture – is the key element that determines the ultimate quality of images and the detail that can be observed. Bigger is better. Large telescopes with apertures up to ten meters in diameter have been built on the ground. However, atmospheric interference, which disrupts the light reaching the telescope, makes it difficult to achieve the final resolution. Also, on Earth, the background light from the night sky limits the telescope’s sensitivity, the faintest objects we can see. With its six-meter aperture, the James Webb is the largest telescope ever launched into space, and from its vantage point a million miles from Earth, free of Earth’s atmosphere, it is expected to provide the best, most detailed views of the universe that we have. has ever seen. There is no doubt that it will revolutionize our understanding of the universe, just as its predecessor, the Hubble Space Telescope, once did. Martin Barstow, Professor of Astrophysics and Space Science, University of Leicester This article is republished from The Conversation under a Creative Commons license. Read the original article.
