NASA’s James Webb Space Telescope is now ready to launch and become the most powerful space telescope in the world. But to what extent will the images of this telescope be comparable to the images of Hubble?
The Hubble Space Telescope was launched into Earth orbit in April 1990. Over three decades, the telescope helped expand our view of the universe and collected stunning images that attracted attention. What we once had a dark, light, and mysterious image became a universe full of many details and colors, and we were able to see stars and galaxies we had never seen before.
But the James Webb Space Telescope, which is scheduled to be launched on December 24, 2021, will do things a little differently. According to NASA, the Web, with its giant golden mirror and infrared observation instruments, is designed to detect objects that are ten to 100 times dimmer than what Hubble was able to observe. So how different is what James Webb gives us from Hubble? An obvious answer to this question is the presence of spectacular detail in web images.
James Web Telescope is no substitute for Hubble!
The Web is often described as Hubble’s successor. But despite the handful of shapes over the past three decades, Hubble and its tools are still powerful, so these two telescopes can be used to better discover the universe.
Hubble is in lower Earth orbit, closer to us. But the Web goes much further, to a gravitationally stable point 1.5 million kilometers from Earth. This point will be the Sun-Earth Lagrangian point 2 (L2).
Moreover, while Hubble and the Web are both large space telescopes (the Web is significantly larger than Hubble), they give us a very different view of the universe.
“The web will take amazing pictures,” Klaus Pontopidan, a web project scientist at the Space Telescope Institute in Baltimore, told a news conference last month. Definitely their quality will be different from Hubble images. “Although the web is better than Hubble in some ways, we should not compare it, because they shoot at different wavelengths.”
While Hubble detects light at ultraviolet wavelengths, the Web is designed to detect infrared light.
The beauties of the universe in infrared light
The web captures uniquely beautiful images by viewing infrared light. “I think the universe is very dazzling in infrared,” Pontopidan said. But it is very difficult to predict exactly what we will see. This is the first space telescope mission in infrared light. At this wavelength, the stars become dimmer – in other words, they fade – but the interstellar clouds become brighter and brighter. “Of course, some of the properties of gas and dust in the infrared spectrum are ignored, which is not necessarily a negative issue.”
“We may all be a little worried about what we will see in the end,” he said. “But the more we go to infrared, the brighter the dust will be, and hopefully we will see nebulae that shine brightly.”
Hubble can see light in the wavelength range of 200 nanometers to 2.4 microns. This is while the web will observe light from about 500 nanometers to 28 microns. NASA said in a statement that visible light has a wavelength between 400 and 700 nanometers.
Although the web is primarily designed to monitor infrared light, it can also see red / orange parts of the visible spectrum by matching wavelengths. The gold coating of its mirrors absorbs blue light from the visible spectrum, but reflects yellow and red visible light so that they can be detected.
Although this is not Hubble’s main task, it also has the ability to see some infrared light. In fact, in 2013, on the 22nd anniversary of the satellite’s launch, the Hubble team released a stunning infrared image of the Horsehead Nebula.
Hubble has provided the world with stunning images for decades and has a web-like resolution. According to NASA, the web is as clear as Hubble, but the web allows us to see more detail in images. For example, with the help of the web, you can see an object the size of a coin from a distance of 40 km.
Despite this resemblance, the web mirror is much larger – 6.5 meters wide compared to Hubble 2.4 meters wide. The telescope also has more advanced detectors designed to see deeper infrared spectra than Hubble.
The Web, with its infrared observations, allows scientists to see farther distances from the universe. Its larger mirror also allows more light to be collected, allowing us to see deeper into space. In other words, scientists will be able to look at the world billions of years ago.
The Web is designed to show the first stars and galaxies ever formed in the early universe. Observation means identifying objects that are up to 10 billion times fainter than the faintest stars visible without a telescope, and 10 to 100 times fainter than what Hubble can detect.
The Web is equipped with four scientific tools to assist with observations. These include the Near Infrared Camera (NIRCam), the Near Infrared Spectroscope (NIRSpec), the Mid-Range Infrared (MIRI), and the FGS-NIRISS.
“With these tools, the web can do what we call imaging spectroscopy – an image is taken and the spectrum of each pixel of the image is recorded,” Pontopidan said. In imaging spectroscopy, there is information about the wavelength spectrum in each small piece of the image. This information helps scientists identify what elements or chemicals may have formed that spectrum. The unique set of web imaging tools allows us to do a variety of other scientific work as well. For example, we can observe extrasolar planets passing in front of stars, or we can determine the chemical composition of clouds in the star-born region. “It may also be possible to look for ice, water or complex organic matter in the atmosphere of extrasolar planets.”
The James Webb Space Telescope is a joint effort between NASA, the European Space Agency and the Canadian Space Agency.
The Web will be launched on December 24, 2021, over the Ariana 5 Ariana Space rocket from the European space port of Coru گa, France.