The James Webb

Jean-Louis Santini/AFP (Agence de Presse Française)

April 21, 2015

translation: doxa-louise

THE WEBB TELESCOPE: FINDING THE ORIGINS OF THE UNIVERSE

The space telescope James Webb Space Telescope (JWST) will be100 more powerful than Hubble, 

which it will replace in 2018, and will allow us to go back in time to the birth of the first galaxies.

«The Webb ....will be able to go back at least to 300 million years after the Big Bang

(which gave birth to our universe some 13,8 billion years ago) when the very first stars 

and galaxies appeared», explains mark Clampin, an astronomer member of the scientific 

team attached to the telescope.

It will allow us to get much nearer the birth of the universe than Hubble, launched 25 years ago, April 24 1990.

It will also be able to see through couds of gas and cosmic dust, to gain access to the furthest and 

most hidden corners of the universe.

The JWST - which will be launched in 2018 - heralds a great advance from Hubble with a principal 

mirror three times as large (6,5 meters in diameter) and the capacity to observe in the infrared range» 

to discern far objects today invisible, he explains in an interview with AFP at Nasa’s Goddard Center 

situated at  Greenbelt Maryland, near Washington.

That is where, in a huge partly windowed hall, with pure air without the slightest speck of dust, 

the telescope is being put together by engineers in white suits, who look like surgeons.

In order to capture images of these objects from the far reaches of the cosmos one must leave the

objectives of the cameras exposed for long periods and a large mirror is

necessary to capture their faint luminosity, discloses Matt Greenhouse, one of those

in charge of the JWST instrumentation. The Webb will see 70% more light than Hubble.

«The Webb will also contribute to research on exoplanets - in orbit around stars in our own galaxy, 

the Milky Way - thanks to capture devices and  equipment capable of analysis of their atmosphere 

to deduce their composition», he tells the AFP.

Looking for extraterrestial life

Thus, «this telescope will open a new window on these planets» of which more than 5000 have 

been discovered. Among these, a handful the size of the earth, are potentially habitable, neither 

too hot, nor too cold, where water could exist in liquid state and thus make life possible.

According to this astronomer, «the Webb could permit making serious progress in the search for

life in the universe because this telescope is sufficiently powerful to detect biosignatures in the 

atmosphere of these planets». In effect water and oxygen molecules and perhaps even pollution 

from extraterrestial civilizations.

«The Webb represents  enormous progress with respect to Hubble for research on the origin and 

evolution of the universe, exoplanets, and extraterrestial life... and like Hubble it could rewrite our 

astonomy books», he summarizes.

In order to function perfectly in the infrared - an invisible range of emissions whose colour is lower 

than red in the colour spectrum - the telescope needs to be kept at a very low temperature of minus 

223 degrees Celsius. It is thus not blinded by its own infrared emissions.

«We have concluded that we could not create such an environment in Earth orbit, because radiation 

from our own planet is too strong, which led to the decision to place the Webb at 1,5 kilometers form 

Earth at the Lagrange 2 Point, a very stable place in the direction opposite to the Sun», explains 

astronomer Matt Greenhouse. Hubble is in orbit 570 kilometers from Earth.

Nasa engineers are running a series of tsts with mirrors, the four camearas and spectometers and 

other elements of the telescope to insure their capacity to function in the emptyness of space and 

at very low temperature.

A good porportion of these tests have already been made in a vacuum chamber at the Goddard 

Center where temperature was lowered close to absolute zero and will be repeated.

An immensable folding parasol, the size of a tennis court once deployed, will protect the telescope 

indefinitely which is essential for the very lenghty observations on such far objects emitting faint radiations.

Weighin 6,4 tons and at a cost of 8,8 billion dollars, the Webb will be launched by an Ariane V 

rocket of the European Space Agency (ESA) from the Kourou Center in French Guiana. ESA 

contribures to its developement as does the Canadian Space Agency.