By Emily Levesque, University of Washington
There are many powerful telescopes, coronagraphs, and intensive light curve surveys that are already being used to study planets. However, to study them in detail and probe their atmospheric chemistry to look in more depth, there is a need for another new telescope, one that is more powerful than any other—the James Webb Space Telescope.
The Idea of the James Webb Space Telescope
A successor to the Hubble Space Telescope was on astronomers’ minds as early as the late 1980s, before Hubble even launched.
This imagined next-generation telescope went through a number of design iterations and updates, but the basic gist has remained the same: a new telescope, larger than Hubble, further from Earth than Hubble, and operating at longer wavelengths—in this case, the infrared.
Infrared Telescope
An infrared space telescope has a wide range of scientific applications. These longer wavelengths make it possible to study incredibly distant galaxies—galaxies so far away that their light has been redshifted by the expansion of the universe to make them appear particularly bright in the infrared.
Second, infrared wavelengths are perfect for studying exoplanet host stars, exoplanets themselves, and the all-important chemical properties of these planets’ atmospheres.
These plans eventually culminated in the James Webb Space Telescope, named after NASA’s administrator during most of the 1960s who led the agency through the development and launch of the crewed Mercury, Gemini, and early Apollo missions.
Features of the James Webb Space Telescope
Like Hubble, Webb will carry multiple instruments capable of taking infrared photographs and capturing infrared spectroscopy of everything from nearby planets to record-breaking-distant galaxies. These instruments will be gathering light captured by a 6.5 meter, or over a 21-foot mirror, designed specifically to reflect and focus infrared light.
The mirror is so large—by far the largest telescope ever sent into space—that it will need to be launched in a folded configuration, unfurling into a classic curved mirror shape only after it’s reached its final destination. For reference, Hubble’s mirror is 2.4 meters or 7 feet-10 inches across.
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Far-reaching, Quite literally
Unlike Hubble, which was launched into orbit around Earth, the Webb telescope will be sent further into space—much further. It will ultimately sit near a gravitationally stable point beyond the Moon, where the combined mass of the Earth and Sun create a local gravitational well called a Lagrange point where a spacecraft can maintain a stable position.
Once there, Webb will be shielded from any light coming from the Sun, Earth, and Moon, keeping it cold enough to effectively detect infrared light without any errant signal interfering with the data.
Complexities with the James Webb Telescope
The combination of Webb’s complex mirror and its distant position (the one we can’t currently reach with crewed spacecraft) make it an incredibly complicated telescope to design and launch. Hubble launched with a slightly misshapen mirror, but that error was corrected through the heroic efforts of a ground crew and a team of shuttle astronauts. Webb offers us no such option.
As a result, the heroes of the Webb telescope were the team members working tirelessly on the ground, day after day, month after month, for years, testing everything they can test and exploring every possible scenario to ensure that Hubble’s successor will work perfectly, over and over again.
Challenges and Delays
The Webb telescope had become infamous for its delays and budget struggles. Development of Webb began in 1996 with an originally planned launch date of 2007 and a budget of 500 million dollars, but the budget has since ballooned to over 9 billion dollars and the launch date has been continually delayed, slowed down by everything from engineering challenges to the COVID-19 pandemic.
Still, the costs and delays, and challenges are all a part of this level of scientific research. Most astronomers agreed that it’s better to launch Webb late and working than to launch it early and risk a preventable failure.
Regardless of how Webb’s story unfurls, the teams of researchers who conceived of, designed, built, and tested this telescope are unarguably heroes of astronomy, who have dedicated years of intensive effort to giving us an incredible new look at the cosmos.
Common Questions about the James Webb Space Telescope
A successor to the Hubble Space Telescope was on astronomers’ minds as early as the late 1980s, before Hubble even launched. Their idea behind the James Webb Space Telescope was to have a new telescope, larger than Hubble, further from Earth than Hubble, and operating at longer wavelengths—in this case, the infrared.
The Webb Telescope will carry multiple instruments capable of taking infrared photographs and capturing infrared spectroscopy of everything from nearby planets to record-breaking-distant galaxies. These instruments will be gathering light captured by a 6.5 meter, or over a 21-foot mirror, designed specifically to reflect and focus infrared light.
The combination of Webb’s complex mirror and its distant position make it an incredibly complicated telescope to design and launch. Unlike the misshapen mirror of the Hubble which was rectified by the crew after it was launched, the Webb telescope cannot be corrected.
