The first week of the year that we are launching began with one of the greatest challenges of science in terms of astronautics: the deployment of critical structures of the James Webb Space Telescope, the More powerful released to date. Gently they began to separate and tense their hands. five individual layers that make up the shield of the telescope, containing the Mirrors and to sunscreen of the Webb.
Silent, delicate, almost origami mission: The Webb had to overcome 344 of what engineers call “single point failures”, i.e. actions that if they did not happen at the right time and in the right order could have crippled the entire project . Yes, 344.
And it is that the mirror of the Webb (6.5 meters) and its enormous parasol they had to retract and fold in on themselves to get into a 5 meter diameter rocket. Therefore, the deployment phase was vital.
Now the James Webb Space Telescope will enter the orbit in which it will park (so to speak) to almost 1,609,344 kilometers away from Earth (the Moon is about 384,000 kilometers), an ideal place to scan the skies in search of the faint infrared light from the first generation of stars and galaxies. Getting there, and successfully deploying a giant umbrella, mirrors, and other props along the way is just part of the whole quest.
What happened
On the first day of launch, the heat shield the size of a tennis court that owns the space telescope. The Webb specializes in infrared observations, which are sensitive to heat, making the sunshield a vital component of the observatory.
In particular, experts focused on controlling the temperature levels of a set of motors used during sunshade tensioning, the process that separates and smoothes the five delicate layers of the kite-shaped sun deflector. The entire process took 15 days, until the deployment of the main mirror.
Most of the steps in that procedure are controlled from the ground. Now, scientists and engineers have to turn the James Webb into a working telescope, precisely aligning your 18 primary mirror segments for what work together as a single mirror almost 7 meters wide, the largest ever launched.
History
The James Webb Telescope was launched into space on Saturday, December 25, 2021 on an Ariane rocket from French Guiana, in the Caribbean. The device is the successor to the Hubble Space Observatory, already elderly (he is 31 years old), which is approaching the end of its operational life.
The team of scientists who devised and who tworked for 25 years in the construction of the Webb expect that the telescope manages to detect the first stars to light up after the Big Bang o Big Bang more than 13.5 billion years ago. That is will observe an epoch of the universe never seen before, when the first galaxies and stars were forming.
There were three space agencies that participated in the construction of the super observatory of the past: the POT (from the United States), the THAT (from the European Union) and CSA, of Canadian origin.
The three have been working together since 1996, when a committee of experts recommended developing a space telescope to observe the universe in infrared light. This wavelength allows you to see through clouds of dust and gas, stretching your vision further back in space and time. until about 13.5 billion years ago, compared to what Hubble allows operating with visible light (about 12.5 billion years).
Components
The set sits on an aircraft on which is the gigantic solar shield or parasol, as big as a tennis court and divided into five layers, which protect it from the light and heat that come from the Sun and the Earth. The temperature in the part facing our star can be around 100 degrees centigrade while behind, on the cold side where the instruments work, reaching the 235 degrees below zero.
On top of the multi-coated lens hood sits the telescope itself, made up of the 6.5 meter primary mirror with 18 hexagonal pieces. It is made of gold Clad Beryllium, a precious metal that reflects weak infrared light very well for later detection.
Behind the great mirror the scientists set up a scientific module (ISIM) with four instruments. A secondary mirror will reflect the light of the primary on them. In addition, the ship has other elements, such as antennae, stabilizers and a fine guidance sensor (FGS) to orient itself very precisely and keep the observatory stable.
Of the four instruments, three operate in the near-infrared (NASA’s NIRCam, entirely European-made NIRSpec, and Canadian NIRISS), and one in the mid-infrared (MIRI, built 50/50 between NASA and ESA). inside they carry cameras for taking images of astronomical objects, spectrographs that decompose light in its colors to analyze it and coronagraphs to block starlight, which allows us to observe the planets that orbit around them.
The Webb is reaching its destination, 1.6 million kilometers away, in the so-called Lagrangian point L2, an optimal place in the Sun-Earth system where to stabilize and place this type of observatories. In such a way that the telescope ever has a fault no astronaut will be able to go repair it, how if it was done with the Hubble. The idea is that the James Webb be on that site observing the universe for at least five yearss, with a choice of ten in all. The overall budget for this complex space observatory is around $10 billion.
Infrared
Even though 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 in imaging the visible universe, the infrared superpowers of the Webb will allow the telescope see through dust right into the heart of nebulae, galaxies, and star-forming regions that are hidden from Hubble’s view.
The Hubble Space Telescope was built to detect visible and ultraviolet light. McCaughrean, then a doctoral student at the University of Edinburgh in Scotland, was one of those scientists who developed early infrared detectors, a technology that is now part of four cutting-edge scientific instruments that make up the James Webb Space Telescope.
“In the 1980s, infrared images were taken with a detector that scanned the sky one pixel at a time,” McCaughrean explained to space.com. “It took me forever. My doctoral thesis was about the first camera that could take 2D infrared images. We had 58 times 62 pixels, and that was 4,000 times what everyone else had, because they only had one.” He adds: “The detectors on the Webb are 2,000 by 2,000 pixels. And we have a lot of them.”
What will all those pixels do for the James Webb Space Telescope? James Webb’s giant mirror will feed light from stars and galaxies into four state-of-the-art instruments designed not just to take pictures, but to analyze the chemical composition of the near and distant universe.
This is done with a technique known as spectroscopy, that analyzes how matter in the universe absorbs light. As different chemical elements absorb light at different wavelengths, astronomers will be able to piece together what stars, nebulae, galaxies and planets within James Webb’s observational range are made of.
These improvements in the resolution of infrared images are essential for imaging the farthest reaches of the universe. Where the Hubble Space Telescope might give only a rough estimate of an ancient galaxy’s age and chemical composition, Webb will do just that.
But, in addition, it will be able to analyze what chemical substances were in those very distant stars in time. Current hypotheses indicate that the early universe had a chemical composition very different from today. It consisted only of hydrogen, helium and a little lithium. Every other chemical element seen today, including those that make life possible, was cooked up for eons inside those stars.
In addition, with the Webb the experts may see (yeah see) the birth of multiple stars in clusters. Until now, they could only detect them. And that, in very distant places in the universe, where the environmental conditions are very different from those that have been detected in the Milky Way. The hope is even see the formation of stars the size of the Sun, something never before achieved.
exoplanets
It was the year 1995 when the first two were discovered. planets orbiting a star other than the Sun. Since then they have been found thousands of exoplanets of various sizes and types. And while it’s not designed with these other potential Earths in mind, the James Webb Space Telescope is poised to discover many more. And also to show details that have never been accessed before.
They are planets with atmospheres containing molecules such as carbon dioxide, oxygen, nitrogen. And to observe them it is better to do it with infrared spectroscopy. One of JWST’s instruments, the Near Infrared Camera (NIRCAM) is equipped with additional implements called coronagraphs, which block the light of a star to see more clearly what is happening around them.
That, in fact, could involve the possibility of studying the atmospheres of planets around other stars, some of which could be habitable, with water and atmosphere that could support life like Earth.
Image gallery
