James-Webb telescope ready to launch

Weather permitting, the launcher’s tanks have been filled with a total of 210 tonnes of hydrogen and liquid oxygen, the final count has started. NASA’s James-Webb Space Telescope (JWST), designed to provide a glimpse of the first moments of the universe, is due to be launched on Saturday, December 25 from the launch site in Kourou, French Guiana. This revolutionary infrared telescope at a cost of nine billion dollars (7.9 billion euros) has been encapsulated in an Ariane-5 rocket which is due to take off at 9:20 a.m. (1:20 p.m. in Paris) and will have a thirty-two minute firing window.

If all goes as planned, the telescope will exit the rocket after a twenty-six minute trip into space. It will then take a month to reach its destination in orbit around the Sun 1.5 million kilometers from Earth, about four times the Earth-Moon distance. It will be protected from solar radiation by a thermal shield of five flexible sails which will dissipate the heat, lowering the temperature (which is 80 degrees) to – 233 degrees, telescope side.

Named after a former NASA administrator, the Webb telescope is about a hundred times more sensitive than its predecessor, Hubble, and is expected to revolutionize astronomers’ understanding of the universe. It should make it possible to see the glimmers of “cosmic dawn”, when the first galaxies began to light up the Universe since the big bang, 13.8 billion years ago.

It will allow us to better understand the formation of stars and galaxies and to observe exoplanets, of which astronomers are discovering more and more specimens, in an attempt to identify, perhaps one day, other Earths. It should also allow a closer observation of Mars and Titan, one of Saturn’s moons.

Imagined by NASA from the launch of Hubble in 1990 and built from 2004, with the collaboration of the European (ESA) and Canadian (CSA) space agencies, the JWST differs in more than one way.

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Entry into service scheduled for June

The size of its mirror, with a wingspan of 6.5 meters, gives it a surface area and therefore a sensitivity seven times greater, sufficient to detect the thermal signature of a bumblebee on the Moon. Another difference: its mode of observation. Where Hubble observes space primarily in the domain of visible light, James-Webb ventures into a wavelength escaping the eye: near and mid-infrared. A radiation that any body, star, human or flower emits naturally.

This light will be studied by four instruments, equipped with imagers and spectrographs to better dissect it. Their development mobilized a plethora of engineers and scientists, under the leadership of American and European laboratories and industrialists. The prerequisite for the correct operation of the JWST is an ambient temperature so low that it does not interfere with the examination of the light.

We will know after twenty-seven minutes if the propelled phase of the flight went well. This would further seal the cooperation between NASA and its European partners. For space, “Strong cooperation is essential to accomplish great things”ESA and NASA officials told Kourou. It will, however, take several weeks to find out if the telescope is ready for use. With entry into service officially scheduled for June.

Le Monde with AFP and Reuters

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James-Webb telescope ready to launch

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