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Dedicate hours to examine the ends of the universe

Dedicate hours to examine the ends of the universe

The James Webb Telescope will be launched into space on December 18, and the tension is already palpable among the scientists involved in his project as there will be many defining moments after this launch, including the deployment telescope and its various components.

When operational, the James Webb Telescope will occupy an area the size of a tennis court. But to move it into space, it will have to be more compact. And so it’s designed in such a way that we can bend it, like we do in origami, so that we can mount the biggest rocket we have right now, that rocket. Ariane 5 Its aerodynamic diameter is only 5.4 meters.

Therefore, the most sensitive part of the mission will be the part where the telescope will reveal itself once in space, mission craftsmen said during a virtual technology briefing organized by NASA. This deployment will include approximately 50 main stages and 178 release mechanisms will be required to function properly for the telescope to reach operational condition.

Shortly after launch, the solar panel and transmitter antenna to be deployed, respectively, will be to power the spacecraft and build it with the control center, Baléu site, Estados Unidos Da America. MISSEL Ariane 5 The Webb telescope will then be placed in a specific orbit from which it continues on its own path to its final destination, which will be the second point of Lagrange L2, located 1.5 million kilometers from Earth, four times the distance from the Moon. . Thus, the Webb telescope will be found farther from our planet than the Hubble telescope, which orbits the Earth at an altitude of 590 km.

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The point L2 was chosen because its temperature is stable, the effects of gravity are weak and the telescope can always be kept at a constant angle to the Sun’s position, unlike Hubble, which is affected even by large changes in temperature. The ones you’re exposed to because sometimes it’s in Earth’s shadow, sometimes on the bright side, explains Martin Bergeron, director of planetary exploration and astronomy missions for the Canadian Space Agency (CSA).

Since the instruments on board the Webb telescope can only function properly at very low temperatures (-233°C), it is fitted with a huge sun visor (21m by 15m) that acts as an umbrella to protect the mirrors and the Earth’s heat instruments. And the moon.

This sunscreen consists of five very thin layers (about the thickness of a strand of hair) made of a reflective material, which is vital to the proper operation of the telescope. Therefore, its spread represents another crucial moment for scientists to worry about. About 100 release mechanisms, 400 pulleys, 90 cables and a variety of hinges, springs and other devices will participate in the disclosure of this protective plate.

Next, we proceed to the aperture of the mirror, which consists of 18 hexagonal sections. These gold-plated beryllium units will be precisely aligned to form a large mirror with a diameter of 6.5 meters. The Hubble telescope was probably three times the size of its 2.4-meter diameter, but the Webb telescope’s ability to catch light would be 9 to 10 times stronger, Bergeron says. This power and the telescope’s position at point L2 will allow “more visibility into the early moments of the universe.”

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Thus, the telescope will search for the first stars and galaxies that formed after the Big Bang. “These very distant objects have very low luminosity, because their light has traveled so much that it has so far faded through. To see them, you would have to have a very large mirror, like a Webb telescope, and watch it for a long time to collect as much light as possible.” Low light spot for a long time, the mirror must be very stable. However, since this telescope is in space and has not been firmly planted on Earth, it was necessary to find a way to orient the telescope towards the target in a stable manner, and this is what the FGS would make of the pointing detector,” explains Bergeron.

“The FGS is a Canadian instrument that will keep the entire telescope stable with an accuracy of sixty degrees, or the equivalent of a coin four kilometers away, for hours on end,” even days, he explains.

The Canadian Space Agency also offers another instrument designed by René Doyon’s team at the University of Montreal: the Near Infrared Imaging Spectrometer (NIRISS) that will make it possible to determine the composition of the atmospheres of distant exoplanets.

This Canadian contribution to the James Webb Telescope mission, which is the result of a collaboration between NASA, ESA and the Canadian Space Agency, will ensure privileged access to the telescope for Canadians for the life of the telescope. “Canadians are entitled to 5% of the observing time, which is exceptional because this telescope will be in high demand,” Bergeron says.

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But these researchers will have to be patient, as the first lights captured by the telescope will not be sent back to Earth until next summer (in 2022) for analysis by scientists. “Because once launched, the James Webb Telescope will take four weeks to reach the second Lagrangian point, where it will be fully deployed. After that, it must be cooled so that the instruments do not contaminate the infrared signal coming from the celestial bodies. It will then be necessary to test and verify everything About his health. All this will take about six months for the telescope to start operating,” notes Bergeron.

The James Webb Telescope will be launched from the European base in Kourou, French Guiana, by boat on October 14 from California, where it was built and assembled. Scientists are currently running the last tests before D-Day.

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