Over the next few weeks, we will be exploring different aspects of the James Webb Space Telescope in anticipation for its upcoming launch later this month. This is part one of our series on this incredible mission.
In the span of ten days between December 18-28, 1995, one of humanity’s most successful telescopes gave us a glimpse back in time. The Hubble Space Telescope, orbiting high above Earth, peered into a small patch of sky in the constellation of Ursa Major, and took what is now called the Hubble Deep Field. With more than 3,000 galaxies, some appearing as they were just 500 million years after the Big Bang, the Hubble Deep Field was one of our first glimpses into the early Universe.
Since then, Hubble’s career has only grown more illustrious, but scientists know that this career will not last forever. Various successor telescopes have been in the planning stages for almost as long as Hubble has been around, and with the upcoming launch of the James Webb Space Telescope (JWST), this succession plan is on the verge of taking a giant leap forward. A project more than two decades in the making, the JWST will soon become the most powerful space telescope yet, taking us even closer to the edge of the observable universe.
In the span of ten days between December 18-28, 1995, one of humanity’s most successful telescopes gave us a glimpse back in time. The Hubble Space Telescope, orbiting high above Earth, peered into a small patch of sky in the constellation of Ursa Major, and took what is now called the Hubble Deep Field. With more than 3,000 galaxies, some appearing as they were just 500 million years after the Big Bang, the Hubble Deep Field was one of our first glimpses into the early Universe.
Since then, Hubble’s career has only grown more illustrious, but scientists know that this career will not last forever. Various successor telescopes have been in the planning stages for almost as long as Hubble has been around, and with the upcoming launch of the James Webb Space Telescope (JWST), this succession plan is on the verge of taking a giant leap forward. A project more than two decades in the making, the JWST will soon become the most powerful space telescope yet, taking us even closer to the edge of the observable universe.
It seems odd that the story of the James Webb Space Telescope would begin with the first line of a lullaby, but this is for good reason. The lines “Twinkle, Twinkle, Little Star” may seem innocuous to the ordinary child, but for astronomers, it’s a line that constantly annoys them all because of our planet’s dynamic atmosphere. In the lower levels of the atmosphere, we experience this dynamicity most commonly in the form of airplane turbulence, but the effects go much further than that. Atmospheric instability also causes variations in the way light is refracted, which is why stars appear to twinkle.
For ground-based telescopes, this twinkling disrupts the view of faraway stars, and the only way to get around this is to reduce the amount of air that a telescope has to peer through. This is why many observatories, like the Mauna Kea Observatory in Hawaii, are situated on the peaks of tall mountains. However, this is still only a partial solution because even the highest mountain is still separated from space by dozens of kilometers of air. Plus, even the tiniest bit of atmospheric interference can throw off astronomical observations, especially in the infrared part of the spectrum. This is why in 1946, American astrophysicist Lyman Spitzer proposed putting a powerful telescope into space. Of course, his ideas were ahead of his time, but as rocket technology improved, more and more scientists began to believe in Spitzer’s vision.
In the 1960s and 70s, Spitzer’s telescope gained powerful supporters like the National Academy of Sciences, which published a report outlining the potential scientific uses of such a telescope. The successes of the first space telescopes in this period also pushed support forward. Although these early observatories were small and less powerful than those that would follow, they vindicated Spitzer’s concept. Finally, in 1977, Congress approved funding for what eventually became the Hubble Space Telescope.
However, scientists wanted more. Why study just visible light when there is so much more to the electromagnetic spectrum? This idea quickly gathered steam and birthed what we now call the 4 Great Observatories, each of which focused on a particular type of light: Hubble, the Compton Gamma Ray Observatory, the Chandra X-Ray Observatory, and the Spitzer Space Telescope.
Unfortunately for Hubble, things went wrong from the very start after its launch in 1990. The telescope’s mirror, made using state of the art grinding techniques, had been ground incorrectly, making the pictures it returned utterly useless. Luckily, Hubble’s ability to be serviced by crewed missions allowed engineers to devise a solution by essentially giving the telescope a pair of “glasses.” The fix worked, and ever since, Hubble has produced some of the most spectacular views of the cosmos. Combined with data from Chandra, Compton, and Spitzer, it’s safe to say that our understanding of the universe has been revolutionized by the 4 Great Observatories.
As of today, only Hubble and Chandra are still operating, but the legacy of the Great Observatories will live on with a new generation of telescopes led by the JWST. First envisioned just 6 years after Hubble’s launch, the JWST has taken a rather twisted road to reality. From cost overruns to repeated delays totaling more than 14 years, there’s a lot that can be criticized about this project, but it has overcome all of these challenges to stand as a beacon of human ingenuity. Indeed, the JWST is the closest thing that humanity has to a time machine that can see to the beginning of the universe itself, and with launch day fast approaching, it won’t be long before the revelations begin to emerge.
...to be continued
Sources & Further Reading
Lyman Spitzer's vision
Great Observatories