The James Webb Space Telescope should be launched on December 22, although previous delays suffered by the project do not ensure that it is the final date.
We only know of one planet Earth, but outside our Solar System there are countless stars that host exoplanets, and that the James Webb telescope will help to scrutinize with its powerful instruments. It is one of the main missions of this gigantic apparatus that has needed three decades and about 10 billion dollars to build. Its launch is scheduled for December 22.
Since the discovery of “51 Pegasi b” in 1995, scientists have discovered about 5,000 exoplanets. For life to exist in one of them, as we know it, these exoplanets must not be too close or too far from the star in which they orbit.
Some of those space objects are gigantic gaseous masses, like Jupiter or Neptune, others are rocky, like Earth. They are all too far away to be observed directly, and also the ones that arouse the most interest, the rocky ones, are small and difficult to locate.
So far astronomers have only managed to detect them when they pass in front of their stars, since variations in luminosity occur.
With that observation they have barely been able to determine its size and density, but scientists cannot find out its atmospheric composition, or what happens on its surface.
See her insides
That is the task of Webb, who will deploy a masterpiece of astronomical technology: the Middle Infrared Instrument (MIRI), equipped with a camera and a spectrograph to detect that type of light emission that is invisible to the human eye.
“It will revolutionize the way we see the atmospheres of the planets. We are going to be able to see their insides!” exclaims Pierre-Oliver Lagage, from the French space agency, who has worked at MIRI.
Pierre Ferruit, another scientist from the Webb project and member of the European Space Agency, explained that the MIRI will be able to analyze the infrared trail that light leaves when it filters through the atmosphere of a planet, as it passes in front of its star .
In this way, Ferruit explained to AFP, scientists will be able to find out if that atmosphere contains molecules such as water vapor, carbon monoxide or methane. Those three substances are present in Earth’s atmosphere and could potentially show biological activity on the surface of the exoplanet in question.
“To imagine that twenty years ago we barely knew exoplanets, and that now we will be able to know the composition of their atmospheres, that is enormous,” added Ferruit. “My dream would be to discover an atmosphere around a rocky planet in a habitable zone, with water molecules,” explains René Doyon, from the Institute for Exoplanets Research in Montreal, who is responsible for another instrument on board the Webb.
But that path is uncertain. Astronomers recently believed that they had discovered phosphane, a gas associated with biological activity, on Venus. But analysis later showed that lead to be false.
Although the Webb telescope will be able to detect biological molecules, knowing their origin will likely be “out of reach,” says Doyon.
“For now we are looking for conditions that are favorable to life, such as the presence of liquid water,” he says. For starters, Webb is already set up to examine the Trappist-1 planetary system, some 40 light-years from Earth.
That system has seven planets, seven of them in a habitable zone, near a dwarf star that is not excessively bright. Webb could spark a new astronomical classification. “The discovery of exoplanets is full of surprises,” warns Doyon.