James Webb Space Telescope to Launch in Search of Earth-like Exoplanets
The James Webb Space Telescope, the most powerful space observatory ever built, will launch in late December from the European spaceport in French Guiana after decades of waiting. An engineering marvel, the telescope is expected to convey new clues about the origins of the Universe and Earth-like planets beyond our solar system.
There is only one Earth … that we know of. But outside of our own solar system, other stars give heat and light to planets and possibly life. The discovery of exoplanets, that is, planets outside the solar system, is one of the main missions of NASA’s James Webb telescope. You will also investigate the potential for life on these worlds by studying their atmospheres.
The first observed exoplanet, 51 Pegasi b, was discovered in 1995 and since then nearly 5,000 more have been observed, from Jupiter- or Neptune-like gas giants in our solar system to rocky planets like Earth.
Some are within habitable distance from their suns, in a range fancifully called the Goldilocks Zone.
But beyond being neither too close nor too far from the stars they orbit, little is known about these planets or what they are made of.
They are too far away to be directly observed and rocky planets, which are more likely to be capable of supporting life as we know it, tend to be even smaller and more difficult to observe.
So far, astronomers have detected them as they pass in front of orbiting stars, capturing small variations in luminosity.
This has allowed astronomers to determine their size and density, but the rest, their atmospheric composition, what happens on their surfaces, remains to be discovered.
‘To take a look at his insides’
Astrophysicists hope the Webb telescope will help fill in some of these gaps.
Equipped with a new piece of technology called the Mid-Infrared Instrument (MIRI), it will use a camera and spectrograph to view light in the mid-infrared region of the electromagnetic spectrum, invisible to the human eye.
“It will revolutionize the way we view the atmospheres of planets. Let’s take a look at their insides!” said Pierre-Oliver Lagage of the French space agency who worked on MIRI with a US and European team.
Pierre Ferruit, a scientist with the European Space Agency’s Webb project, explained that MIRI will be able to read the infrared signature of light filtered through various substances in the planets’ atmospheres as they pass in front of their stars.
In this way, Ferruit told AFP, scientists should be able to tell if they contain molecules such as water vapor, carbon monoxide and methane.
Those three substances are present in Earth’s atmosphere and could potentially indicate biological activity on a planet’s surface.
“To think that twenty years ago we knew almost no exoplanet and now we are about to discover what their atmospheres are made of, is huge,” said Ferruit.
Looking for a rocky planet with water particles.
Rene Doyon is director of the Exoplanet Research Institute in Montreal and lead scientist on another of Webb’s instruments, the near-infrared imager and the slitless spectrograph.
“My dream would be to find an atmosphere around a rocky planet in a habitable zone with water molecules,” Doyon told AFP, describing three conditions that would make life as we know it possible on Earth.
But there are pitfalls: on Venus, for example, scientists recently thought they had found phosphine, associated with biological activity on Earth.
However, subsequent investigations showed that there were no traces of the gas.
Doyon said finding the origin of biological molecules will likely be “beyond the capabilities” of the Webb telescope.
“That will be for later,” Ferruit confirmed. “For now we are looking for favorable conditions for life, such as the presence of liquid water.”
Such clues will narrow the focus of future missions that aim to discover “whether the Earth is unique or not.”
Webb is now ready to probe a system around the Trappist-1 planetary system, some 40 light-years from Earth, that was discovered by Belgian scientists named after famous brewing monks.
It has seven planets, of which three are in a Goldilocks zone and orbit a dwarf star, whose light that is not too bright will make it easier to detect the composition of the atmosphere.
Other direct observation instruments will allow Webb to examine the atmospheres of “hot Jupiters” or “mini Neptunes,” Doyon said.
He said he hopes new categories of exoplanets will be discovered along with many surprises.
“The surprise is what exoplanet discovery is made of,” he said.
( Jowhar with AFP)
