The largest and most powerful space telescope James Webb is being launched today


After five consecutive postponements, corresponding excesses of its original budget and 30 years after its initial design, it is finally time – and on Christmas day – to launch the James Webb Space Telescope, Hubble’s successor, the largest and the most advanced ever sent into space, thus opening a new era in astronomy and astrophysics. It is a joint mission of the US Space Agency (NASA), the European Space Agency (ESA) and the Canadian Space Agency.

The launch is scheduled to take place with a European Arian 5 rocket shortly after noon on Saturday, at 14:20 Greek time, from the European spacecraft in Kouros, French Guinea in northeastern South America. If all goes well, the $ 10 billion telescope will orbit the Sun at the second Lagrange or L2 point, staying at a fixed distance of about 1.5 million kilometers from Earth or about four times farther from the Moon. By comparison, the Hubble Space Telescope – launched in 1990 – is about a third of that distance from our planet (almost 550 kilometers).

James Webb is expected to reach L2 a month after its launch. Then there will be an installation and adjustment period of six months. He is expected to start collecting data and making the first observations in mid-2022.

The telescope, built mainly by the American company Northrop Grumman and named after the head of NASA in the 1960s, is much more sensitive than the Hubble and will “see” mainly in the infrared part of the spectrum, which will allow it to observes through clouds of dust and gas, while Hubble operates mainly in the optical and ultraviolet part of the spectrum.

According to an article in the online magazine “Kosmos” of the National Observatory of Athens, Dr. E. Saridakis, Principal Investigator of the Institute of Astronomy, Astrophysics, Space Applications and Remote Sensing (IAADET / EAA), the new telescope will provide Hubble and will be used in a vast array of research in astronomy, astrophysics and cosmology, from the atmospheric characterization of potentially habitable exoplanets to the observation of some of the most distant and oldest events and objects in the Universe, such as the formation of the first galaxies.

The James Webb has a mass of 6 tons and 6.25 times larger collector area, hence the sensitivity, compared to the Hubble. In addition, it has a significantly larger field of view, covering 15 times the area of ​​the sky. Its primary mirror consists of 18 hexagonal sections, made of gilded beryllium, which unfold and adapt to form a mirror 6.5 meters in diameter. Its largest component is the five-layer solar shield, which reduces the sunlight that reaches the telescope by a million times and is the main cause of its large size (20 by 14 meters).

Unlike the Hubble Telescope, which made observations in the ultraviolet, visible and near-infrared region of the electromagnetic spectrum (0.1 to 1 μm), the James Webb will be able to receive data at a lower frequency range than in long-range visible light. medium to infrared (0.6 to 28.3 μm), which will allow it to observe objects with high displacement to red, and therefore much older and much farther away than Hubble could observe.

Space telescopes have the advantage that they can make observations without the obstruction of the Earth’s atmosphere. James Webb, according to Mr. Saridakis, will be able to observe the most distant objects in the observed Universe, seeing 13.5 billion years back in time, recording the light of the first stars and galaxies after the Big Bang, thus allowing the control of cosmological and gravitational theories. In addition, it will be able to observe the large black holes that exist in the centers of galaxies, providing evidence for their formation and evolution. It will also collect data on the formation of stars and new planetary systems, phenomena that because they occur in dense clouds, are difficult to see.

Another category of observations that James Webb will make is related to exoplanets. Its spectrometers are capable of collecting and analyzing radiation passing through the atmosphere of exoplanets, in order to draw conclusions about their chemical composition as well as possible traces of life. At the same time, James Webb will make observations in our own solar system, related to the atmospheres of the planets and the satellites that have them. It will be able to focus on the study of Jupiter and its satellites, especially Ganymede and Europe, with possible oceans beneath the icy surface, Virus with hidden sulfur volcanoes, and Saturn Saturn’s satellite with hydrocarbon lakes. Finally, as the rings of Saturn, but also those of Poseidon,of Uranus and Jupiter, are much better observed in infrared, the Webb is expected to provide a wealth of information about their formation.

Astrophysicist Dr. Alexis Delivorias, a collaborator of the Eugenides Planetarium, points out in a related post on the Foundation’s website that it is “perhaps the most important space telescope of the next decade”. “Having far exceeded both its initial budget and its originally scheduled launch date, there have even been thoughts of canceling the entire program. Fortunately for astronomical research, this has not happened, and the international scientific community is anxiously awaiting it. its successful launch and orbit around a point about 1.5 million km from Earth. “

He emphasizes that “with the data he will collect, he will help astronomers to investigate almost every” era “of the evolution of the Universe, from the first luminous structures formed after the Big Bang, to the formation of planetary systems and the detection of exoplanets, favorable for the appearance of life “.

“It will allow astronomers to penetrate areas that are opaque to optical telescopes, such as dust-filled and gaseous stellar maternity hospitals and newborn planetary systems. But it will also collect data on the most distant galaxies in the universe. contributing decisively to the investigation of the great cosmological questions that remain unanswered: with his penetrating gaze, he will travel us even further in space and even further back in time, compared to the now-old Hubble, helping astronomers to expand their knowledge significantly for the creation and the first stages of evolution of the first stars and the first galaxies of the Universe “.

The launch will be broadcast live on NASA ( and ESA ( TV, and anyone can watch it as well via Facebook (, YouTube ( and other applications.

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