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No, NASA's James Webb Space Telescope Isn't A Hubble Replacement
NASA's upcoming James Webb Space Telescope will not be a replacement for its Hubble telescope, despite how similar they might at first seem. Like Earth-based telescopes, space telescopes scan the galaxies, picking out clues that might help unlock the secrets of the universe. However, because such telescopes are not tied to Earth, they can roam, allowing them the freedom to peer into parts of space that might otherwise be out of view.
The space telescope concept dates back to the mid-1800s when German astronomers Wilhelm Beer and Johann Heinrich Mädler theorized the concept of building an observatory on the Moon. A little over a century later, U.S. astrophysicist Lyman Spitzer floated the idea of a massive telescope that would not be infringed by Earth's atmosphere. Then, over a four-year period spanning the late 1960s and early 1970s, NASA launched four space telescopes under its Orbiting Astronomical Observatory program. Not to be outdone, the Soviet Union established its Orion 1 observatory aboard its Salyut 1 orbital station in 1971.
Hubble launched in 1990, and in the three decades since, it has arguably become one of the most famous telescopes ever built. Hubble has identified new moons orbiting Pluto, helped researchers date the universe's age to more than 13.4 billion years, and shown markers for how rapidly it's expanding. But Hubble is struggling to keep up with demands, and there will inevitably come a time when it can no longer scan the skies. Of course, NASA has a plan — it's preparing to launch its James Webb Space Telescope next month. However, as the space agency positions it, James Webb is a successor to Hubble rather than a replacement.
Hubble Results Motivated James Webb Development
NASA says the goals of the James Webb telescope "were motivated by results from Hubble." The organization notes Hubble primarily gathers visible light, but the further away objects are, they become more "redshifted"— their light is near-infrared. Because of this, James Webb will focus on collecting infrared waves, allowing the telescope to pick up even more information from distant celestial bodies. James Webb will also feature a primary mirror with a diameter of 6.5 meters, which translates to a surface area of approximately 25 square meters. By comparison, Hubble's primary mirror has a diameter of 2.5 meters and a relative light-gathering area of 4.5 meters.
NASA describes James Webb as a chance to "go beyond" Hubble. And though James Webb is designed for the next era of space exploration, it's also clear the agency is not quite ready to put Hubble into retirement quite yet. NASA has projected Hubble will be operational until 2030. Based on its recent images, it's fair to expect the older telescope will have the capacity to make surprising discoveries for a while yet.
