When the freshly launched James Webb Space Telescope fully deploys and comes online, it won’t just be another tool for astronomers to explore the universe. Thanks to its advanced spectroscopy technology, it will be able to scan the darkness of space and see distant objects in greater detail than ever before, much more than its predecessor, the Hubble Space Telescope. This will revolutionize our understanding of exoplanets, and it might even help us know where we came from and where else in the universe might be habitable.
To find out how the James Webb Space Telescope will help us study spinning rock balls trillions of miles away (and why astronomers want it), we spoke to two researchers who will be working with James Webb after deployment. : Néstor Espinoza from the Space Telescope Science Institute and Antonella Nota from the European Space Agency (ESA).
A giant step forward
In recent years, researchers have identified planets outside our solar system using telescopes such as the Transiting Exoplanet Survey Satellite (TESS) or the Kepler Space Telescope. These are able to look at the brightest stars and see changes in their brightness as a planet passes between them and us using a technique called the transit method. It’s an impressive feat of scientific observation, but it doesn’t tell us much about what these planets look like – just their approximate size and sometimes their mass.
If we want to know what a planet looks like, does it have an atmosphere? what is it made of? are there clouds in the sky? is there water there? – we have to look much, much more in detail. That’s what Webb is going to do, but it’s a huge technical challenge. This is why NASA, ESA and the Canadian Space Agency (CSA) are all working together on this project.
“Webb is a hundred times more sensitive than Hubble, and because of that, Webb will be able to reveal the smallest details in the farthest corners of the very distant universe, with exquisite resolution,” explained Nota.
While Hubble has been used to learn more about exoplanets, Espinoza said, “the view it gives you is very narrow. It gives you functionality, maybe. By comparison, he said, Webb is going to be “mind-blowing”, allowing us to see multiple features at once and look at smaller planets. “This will be our first change to examine small planets in detail. “
Hubble also operates in the visible light wavelength, capturing images in the range of light that we can see. But James Webb will be working in the infrared wavelength, which can select different characteristics and look through the obscuring dust, “opening a window to the universe that will be completely new,” as Nota said.
Hubble and Webb will be able to work together, bringing together additional data on the same targets. So if you like the beautiful images of space captured by Hubble, don’t worry, they won’t go away. We’re just going to gain another tool for even deeper understanding.
“James Webb is going to be revolutionary. Literally revolutionary, ”Espinoza said. “It’s going to allow us to see things that we’ve been expecting to detect for a long time but didn’t have the technology to see, and I’m pretty sure it’s going to detect things that we don’t think about.”
1980s Hubble Technology Update
Researchers have done a remarkable job finding and learning about exoplanets using currently available instruments, discovering more than 4,000 exoplanets to date. However, this field is very recent, the first planets outside our solar system having been identified in the 1990s. This means that many instruments of the current generation, like Hubble, were never designed for studies of exoplanets. .
“Hubble is the technology of the 80s,” Espinoza said. “Nothing against the 80s – I love the 80s, especially the music! – but technology has evolved a lot. The type of detectors we had back then is nothing compared to the type of detectors we have now.
James Webb, on the other hand, was designed with the specific intention of being used for the characterization of exoplanets, and this has been at the forefront of his design principles. For example, when Webb points to a star, it points to a particular pixel with very high precision and it doesn’t move at all, allowing researchers to measure very precisely any drop in brightness that could give clues about an orbiting planet. . .
This level of precision allows Webb to accomplish its most exciting function related to exoplanets: detecting if an exoplanet has an atmosphere and what that atmosphere is made of. “The little details that matter a lot when trying to detect exoplanet atmospheres,” Espinoza explained.
Investigate exoplanets using infrared light
Although researchers have come up with some very creative ways to detect the atmospheres of exoplanets, this is not something that current instruments were designed for. This is why Webb’s capabilities will be so revolutionary.
To scan the universe, Webb has four instruments that will look into the infrared wavelength. They include the near infrared camera (NIRCam) and the near infrared spectrograph (NIRSpec). Then there is the Fine Guidance Sensor / Near Infrared Imager and Slitless Spectrograph (FGS / NIRISS), which, as their names suggest, will look in the near infrared band. Finally, there is the Mid-Infrared Instrument (MIRI), which examines a wide range in the far infrared.
But they are sensitive instruments, and they require a carefully maintained environment to function. The technology around them must therefore also be at the cutting edge of technology.
“Webb is full of new and complex technology, from sensitive infrared detectors to the tennis court-sized five-layer Kapton sunshield that will shield instrumentation from solar radiation and allow the telescope and detectors to reach temperature.” cold needed to observe in the infrared, ”said Nota.
She also pointed out the fine details of the instruments, like NIRSpec’s micro-shutter array, which is a set of tiny shuttered windows the size of a few human hair. This will allow the instrument to observe hundreds of objects at the same time. “An absolute first in space astronomy, where spectroscopy is traditionally performed one object at a time,” Nota said.
Understand where we come from
The impulse to see if a faraway planet has an atmosphere isn’t just a scientific blossoming, or a vain curiosity about what those faraway places look like. Rather, it is the key to understanding how the planets, including our own, are created.
When it comes to understanding how our solar system formed, researchers run models and try to see how we might have ended up with the makeup of the planets we see. “But currently we have a sample size of one,” Espinoza said. “Our solar system. That’s it. We’re now in a time where we can look at the compositions of other solar systems. And the way the planets are formed defines their chemical makeup.
So when we look at the atmosphere of a distant exoplanet, we learn how it was formed. And from there, we can build a picture of the formation of planets and solar systems based on more cases than our backyard. “So getting these clues of formation signatures in these exoplanets through the chemistry that we observe in their atmospheres is absolutely fundamental for us to understand how they came to be, and therefore how we came to be,” he said.
Hunting for habitability
Perhaps the most exciting reason to watch the atmospheres of exoplanets is to understand where else in the universe life could flourish. “One of the key questions that Webb will be studying is the origin of life,” Nota said. “There are huge varieties of exo-worlds, more than we could ever imagine. There are gas planets the size of Jupiter orbiting very close to their star, huge rocky “super-Earths” and “hot Neptunes”. Some of them might have the right temperature conditions and the right composition to accommodate life.
But to determine if a planet is habitable, Espinoza said, it is not enough to know its size and mass. After all, when we find a planet the size of Earth and of similar mass, people often assume that it will be an Earth-like place. But Venus and Mars are roughly similar in size and mass to Earth, and they have atmospheres that are extremely inhospitable to our life form. “Venus is the worst place to go on vacation! he joked, with its immense pressure and toxic atmosphere full of carbon dioxide. Mars is not much better, with its extremely fine and unbreathable atmosphere which represents only 1% of the density of our atmosphere on Earth.
So we need to know the atmospheres to know if an individual planet is habitable. And more importantly, to get an estimate of how many habitable planets there might be, we need to know what types of atmospheres are typical for planets the size of ours. “What is the most common atmosphere that nature forms? Espinoza asked. “It could be similar to Venus or Mars, and Earth is an outlier.” Or it could be that Earth-like atmospheres are typical and the number of potentially habitable planets is huge.
Go to the unknown
Webb won’t just be looking at exoplanets. He will perform a wide range of research, from examining the early phases of the universe to see the first galaxies forming, to observing the birth of stars from swirling dust and gas. With its first year of science operations planned, we are only scratching the surface of what this new tool could be used for. We will have to wait and see what other astronomical wonders he can unravel.
“I think the biggest discovery will be one that nobody expects,” Nota said. “The one who will change the way we see the universe, the one who will define, perhaps once and for all, our place in the universe.”
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