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The James Webb Space Telescope (JWST), awaited for thirty years by astronomers around the world to examine the Universe with unequalled resources, took off on an Ariane 5 rocket on Saturday to reach its observation station. It was successfully injected into its final orbit, announced the director of launch operations at the Guiana Space Centre.

"Good separation Webb telescope, Go Webb", announced Jean-Luc Boyer from the control centre in Kourou. After 27 minutes of flight, the upper stage of the Ariane rocket released the telescope, which will now take around a month to reach its observation post 1.5 million km from Earth.

His ambition: to shed light on the creation of the universe

The JWST will become the most advanced instrument ever sent into space to observe the cosmos. Its ambition is to shed more light on the two questions that plague humanity: "Where do we come from? and "Are we alone in the universe? And to catch a glimpse of the "cosmic dawn", when the first galaxies began to illuminate the universe from the Big Bang, 13.8 billion years ago.

It will enable us to better understand the formation of stars and galaxies, and to observe exoplanets, of which astronomers are discovering more and more specimens, with a view to perhaps one day identifying other Earths.

In the footsteps of Hubble

The James Webb will follow in the footsteps of the Hubble telescope, which revolutionised observation of the universe: it was thanks to the telescope that scientists discovered the existence of a galactic black hole at the centre of all galaxies, or water vapour around exoplanets.

Conceived by NASA when Hubble was launched in 1990, and built from 2004 onwards in collaboration with the European Space Agency (ESA) and the Canadian Space Agency (CSA), the JWST is different in more ways than one.

The size of its mirror, with a span of 6.5 metres, 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 is the way it is observed. Whereas Hubble observes space mainly in the visible light range, James Webb ventures into a wavelength that the eye cannot see: the near- and mid-infrared. This radiation is emitted naturally by all bodies, stars, humans and flowers.

This light will be studied by four instruments, equipped with imagers and spectrographs to better dissect it. Their development has mobilised a plethora of engineers and scientists, under the leadership of American and European laboratories and manufacturers.

Need cold to see clearly

The imperative condition for the JWST to function properly is an ambient temperature so low that it does not interfere with the examination of the light. Hubble is in orbit some 600 km above the Earth. At this distance, the JWST would be unusable, heated by the Sun and its reflection off the Earth and Moon. It will therefore be placed 1.5 million km away. And it will be protected from solar radiation by a heat shield made up of five flexible sails that will dissipate the heat, lowering the temperature (which is 80°C) to -233 degrees on the telescope side.

But before that could happen, the machine and its designers had to achieve a real feat: its flawless deployment, with a series of operations involving, for example, 140 opening mechanisms, 400 pulleys and almost 400 metres of cable for the shield alone. The observatory, 12 metres high and with a shield the size of a tennis court, had to be folded to fit inside the Ariane 5 fairing. The "encapsulation" was carried out using laser guidance to avoid any damage to the instrument, which cost some ten billion dollars to develop.

Absolutely clean

For these manoeuvres, NASA has also imposed draconian cleanliness measures to avoid any contamination of the telescope's mirror by particles or even contaminated breath. Finally, Arianespace has installed a customised fairing depressurisation system to ensure that no sudden change in pressure will damage the beast when it separates from the launcher at an altitude of 120 km. "An ESA official in Kourou explained on Thursday that "exceptional 'customers' require exceptional measures".

It will be several weeks before we know whether the telescope is ready for operation. Official commissioning is scheduled for June.

Text by Le Matin.ch (AFP)

One variant, several responses. At a time when Europe is facing a resurgence of the Covid-19 epidemic, due in particular to the appearance of the Omicron variant, which the WHO considers to be "worrying", Our neighbours are implementing very different policies to break the chains of contamination and avoid overloading their hospitals.

Franceinfo brings you an overview of the new health measures in Europe.

Reconfinement in the Netherlands

For the time being, this is the most restrictive measure in Europe. On Saturday 18 December, Dutch Prime Minister Mark Rutte announced a national lockdown from 19 December to 14 January. This means that all non-essential shops, restaurants, bars, cinemas, museums and theatres will be closed for four weeks. Schools, which were closed a week early, will remain closed until 9 January.

The Dutch government is particularly concerned about the Omicron variant. "This forces us to reduce our contacts as quickly as possible, and as much as possible.explained Mark Rutte during his speech. Although leaving the house is not regulated, it is still forbidden to have more than two guests at home. This rule will only be relaxed for the Christmas weekend and the New Year period, when the maximum number of guests will be four.

In Portugal, caution and vaccination for children

Portugal is Europe's leading country in terms of vaccination rates, with 88.9% of its population of 10.3 million vaccinated. The country strictly controls travellers entering its territory, even if they come from European Union countries. Since December 1, all travellers to Portugal must present a negative PCR test less than 72 hours old, or a negative antigen test less than 48 hours old. This measure is accompanied by a form for tracing passengers in order to trace the chain of contamination. As the French embassy in Portugal points out on its website, the isolation of people identified as contact cases can go from "up to 14 days or more in certain situations"..

On Saturday, Portugal also extended its vaccination campaign to children aged between 5 and 11, using the Pfizer paediatric vaccine. The move was justified by the sharp rise in the epidemic among this age group, explained Portuguese Prime Minister Antonio Costa. The government's stated aim is to limit as far as possible the spread of the Omicron variant, which should still account for 80% of new infections between now and the end of the year, according to the country's health authorities.

To reduce contact after the Christmas and New Year rallies, the Socialist executive has also decided to extend the school holidays and make teleworking compulsory during the first week of January.

Mandatory teleworking and holiday restrictions in Switzerland

The Swiss Federal Council has announced that teleworking will once again be compulsory in the country from 20 December. "We're trying to avoid an explosion of cases and the situation going off the rails. The alternative, closures, is what we don't want".Federal Health Councillor Alain Berset explained to RTS. Additional measures have also been taken in certain cantons.

From 20 December, access to restaurants, cultural establishments, sports and leisure facilities and indoor events will be restricted to people who have been fully vaccinated or cured of Covid-19. This tightening of the ban has long been called for by health experts, in order to counter the fifth wave of the epidemic already being felt in the country. Private gatherings are now limited to 30 people indoors or 50 outdoors, including children. But if one of the guests (aged 16 or over) is neither vaccinated nor cured, the limit is reduced to 10 people.

Tighter controls on travellers in Italy, Greece and Germany

Vaccination alone is no longer enough to travel to certain European countries. Since 16 December, Italy has required a negative Covid test for all travellers, regardless of their vaccination history. As for those who have not been vaccinated, they must observe a compulsory five-day quarantine. From Sunday, the same applies to entry into Greece. This rule should remain in force for at least "for the holidays Mina Gaga, the Greek deputy health minister, explained on the RFI website.

In Germany, a quarantine is now imposed on unvaccinated travellers from certain countries classified as "high-risk". Since Sunday, France has been on this red list, alongside Denmark, Norway, Lebanon and Andorra. The German authorities specify that this is a self-quarantine that must last a minimum of 5 days, and can only be terminated by a negative PCR test. Failure to comply with this requirement can result in a fine of up to €25,000.

In Ireland, lights out at 8 p.m. for many establishments

From Monday, it will no longer be possible to go to the cinema, the theatre, pubs or restaurants after 8pm in Ireland. Once again, this drastic measure is justified by the spread of the Omicron variant, described by the Irish Prime Minister, Micheál Martin, as an "epidemic". "serious threat which already accounts for a third of new infections in Ireland.

Gatherings will now be subject to restrictions. Weddings are limited to 100 people, and indoor events must not exceed 50% of their capacity, up to 1,000 people. The same rule applies to outdoor events, with a maximum capacity of 5,000 people.

Denmark closes cultural and social venues for a month

The curtains will remain down for a long time in Denmark, which is witnessing a historic surge in the number of cases of Covid-19, largely attributable to the Omicron variant. In the week from 13 to 18 December, the average number of new infections was 8,666 per day, twice as many as in the last epidemic wave, according to the OurWorldInData website.

Faced with this explosion in the number of cases, the Danish government has ordered the closure of cinemas, theatres and concert halls from Sunday, for a period of one month. Museums, swimming pools, zoos and amusement parks are also affected by this decision. Restaurants and bars will remain open for the time being, but will be required to limit their capacity and close at 11pm.

Text:
Pierre-Louis Caron
France Télévisions

Month: December 2021

The James Webb Space Telescope is on its way to the edge of the universe