On April 24, 1990, humanity began a scientific revolution.
I mean “Launched” literally means: the spacecraft on that date Search Roared into the sky with the Hubble Space Telescope housed in its cargo bay. The telescope was on a mission to change our view of the universe forever.
Hubble wasn’t the largest telescope ever built — its 2.4-meter mirror is actually considered small these days — but being above the atmosphere gave it superpowers. Our air boils and shakes, blurring the view from ground-based instruments. It also shines – dimly but enough to limit how dim an object astronomers can see. And third, our air absorbs most of the ultraviolet and infrared light, where cosmically interesting things happen. Getting up, up and away from all that atmosphere makes Hubble one of the most important telescopes ever built.
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And it revolutionized astronomy. Hubble saw objects fainter than before. The telescope discovered how fast the universe is expanding, Weather changes observed on outer planets And it proved that at the heart of every large galaxy is a supermassive black hole, the names of three amazing feats stand out at the top of my mind. The major breakthroughs and discoveries that have come out of this magnificent machine are so numerous, in fact, that even listing them here would be overwhelming (and even a little tedious, if incredible astronomical exploration can ever get tiresome).
And yet, despite these successes, I see a lot of talk online (and even in the news) somewhat casually dismissing Hubble, saying that NASA’s James Webb Space Telescope (JWST) is a “replacement” for Hubble. This is not just unfair; Its Wrong.
JWST was never intended to replace Hubble, and in fact can’t, Given that it was designed for very different observations.
Hubble is optimized to observe the universe in visible light, the type of light we see with our eyes. It can also detect some wavelengths in the ultraviolet and infrared, but Hubble cannot see most of the spectrum. JWST detects infrared light at much longer wavelengths, where various astrophysical processes dominate.
It is true that JWST is a very large telescope. It has a 6.5 meter wide mirror, so it collects about seven times more light than Hubble. In general, a larger mirror also means higher resolution, a better ability to see finer details in an observation. Yet it also depends on the wavelength observed, and in fact, at its best, Hubble beats JWST by a smidgen! But that’s not really the point; Both are extraordinary telescopes that are at the forefront of every type of observation.
Understanding Hubble’s power in visible light serves to highlight one key area where the JWST’s infrared vision excels: glimpses of the universe’s first galaxies.
Hubble’s deepest observations revealed an unexpected richness of galaxies in the distant universe, but the telescope has a limit. The more distant the galaxy, As cosmic expansion moves a galaxy away from us, its light becomes redder. At some point, most of the galaxy’s light is emitted in the infrared, where Hubble can’t see it – but where JWST keenly observes. That’s why the new observatory has been so successful in breaking distance records and giving us unprecedented views of the early universe.
There is an irony here. idea of ​​space telescope First proposed by astronomer Lyman Spitzer in 1946And in the 1960s astronomer Nancy Grace Roman began advocating for NASA to build a telescope – she later became known as the “mother of Hubble” and a space telescope planned for launch this year is named after her. However, delays and budget overruns plagued the Hubble project and in the end, it cost more than $10 billion and was launched much later than originally planned. Same thing happened with JWST; Initially proposed to cost less than $1 billion and launch by 2004, its final cost was also estimated to be around $10 billion, and it was not launched until 2021. In this way, both telescopes have a similar history.
Then, from a different perspective, their histories are extremely different. Hubble launched with a flawed mirrorVery flat on the edges by a micron or two – much less than the thickness of a human hair but more than enough to ruin the binocular vision. I remember those hazy years well: my Ph.D. During. During the research, I spent a lot of time working with software that mathematically corrected some of Hubble’s out-of-focus images. thankfully, This problem was overcome with the launch of corrective optics in 1993.And later instruments had built-in corrections to ensure that observations were focused.
Today few people know about that difficult time (there were congressional hearings on NASA’s mistake!), and many now focus only on Hubble’s success. And I guess that’s okay, as long as the lessons learned prevent similar glitches for later space telescopes.
In JWST’s case, they mostly did. That $10 billion figure I listed above is only half-correct; When the costs of that telescope and Hubble are compared in inflation-adjusted dollars (especially if you take into account the cost of Hubble’s shuttle-servicing missions, which you should), the much larger JWST is actually cheaper despite its delays and technical problems. And of course, all that money bought a telescope that performed almost flawlessly from the start, even after going through a seemingly impossible Rube Goldberg-esque series of steps to get it operational in space.
JWST’s planned primary mission length is more than five years, which it will reach in 2027, but its expected lifetime is at least 20 years due to careful management of the onboard supply of fuel. Note that Hubble’s primary mission lasted only 15 years or so, and it is in its 35th year in space. It has been viewed over 1.7 million times since its launchVery.
So Hubble is hardly obsolete. In terms of cameras, accessories and even its solar power panels, it is much better now than when it was launched! Suppose that, Its aging gyroscopes, which were necessary to keep the observatory pointed precisely, have experienced several mission-failures.. But still, engineers on the ground have found ways to squeeze every last drop of efficiency out of Hubble’s sole operating gyro.
NASA has a habit of making its missions last longer than their nominal lifetimes. Chandra X-ray Observatory is in the 26th year of its five-year mission spitzer space telescope Lasted up to 11 years past its “use by” date, and Fermi Gamma-ray Space Telescope It is still operating after twice the length of its original mission.
If JWST lasts as long as Hubble, I’ll be glad to see it still peeking into infrared skies in 2057. Hubble will be long gone by then, but hopefully by that time we will have other grand observatories in space, not replacing it but carrying on its legacy.
