6 min read.Updated: 16 Dec 2021, 10:52 PM ISTDilip D’Souza
From that vantage point, using its mirror that’s three times larger than the HST’s, the JWST promises even greater astronomical triumphs than the HST has brought us
Listen to this article
Not long ago, the Hubble Space Telescope (HST) turned its gaze on an explosion. Astronomers had witnessed the death of a star inside the so-called Butterfly Galaxies in the constellation Virgo, about 60 million light years away. At the end of their lives, stars explode, forming what’s known as a supernova. So as soon as this supernova (called SN 2020fqv) was detected, a team of astronomers “triggered our ultra-rapid target-of-opportunity program with HST to obtain very early-time" observations of SN 2020fqv (Last Year Before Death: Observations of SN 2020fqv by TESS and Friends, bit.ly/3q5hcGB).
The result was a ringside view—as much as being 60 million light years away can be described as one—of the early moments after the star’s death. HST was on the job within hours of this one’s death. This meant that the telescope could examine what the star ejected in the last months of its life. As you might imagine, that’s not a frequent occurrence. While stars are dying all the time, it’s rare that we can see a supernova. It’s rarer still that we have a powerful telescope handy to observe it.
But this is just what happened with SN 2020fqv and the HST. The result is that we know more about the final moments of stars, maybe even enough to detect signs that one is about to die and go supernova. In fact, astronomers have taken to calling SN 2020fqv the “Rosetta Stone" of supernovas. The original Rosetta Stone, remember, was what led to the deciphering of Egyptian hieroglyphics in 1799. In the same way, SN 2020fqv has taught us plenty that we didn’t know about supernovas.
There’s a lot more to tell in this story. But my point here is really about the “final moments" of the HST. It has been a workhorse of astronomy for three decades now. It shows no signs of letting up on that pace of astronomical discoveries—this Rosetta Stone is just one example. But its days as that workhorse of astronomy are now numbered.
Though it’s not that the HST is about to explode or fall into disuse—not at all—but as I mentioned in my last column here, there’s a new kid on the block: the James Webb Space Telescope (JWST) will soar into space on 24 December. It will settle into an orbit about 1.6 million km beyond the moon. This is a spot in space known as a Lagrange point. Where exactly it is, is defined by the presence of the Earth and the Sun. It is that point at which, for any object, the force required to keep it in orbit equals the pull of gravity from the Earth and the Sun. Because of this, the object can stay essentially in place without needing much fuel.
From that vantage point, using its mirror that’s three times larger than the HST’s, the JWST promises even greater astronomical triumphs than the HST has brought us. Astronomers expect to use the JWST to learn more about the universe as it was very soon after the Big Bang—a time that we know about more via speculation and inference than via real data. How will they do that? By observing extremely distant objects, so distant that we see them now as they existed in those early years.
The HST showed us galaxies up to about 13 billion light years away, meaning that light from there has taken that long to reach the HST, meaning, in turn, that we are seeing them as they existed 13 billion years ago. The JWST will take us even further back in time. It should be able to show us stars and galaxies as they were forming in those infant first few hundred million years of the universe’s existence.
But with the JWST, astronomers also want to progress towards answering that ancient question—are we alone? This is because JWST will allow much closer examinations than we have ever managed of exoplanets, planets that orbit other stars. By now, we know of thousands of exoplanets. The challenge is to examine them for signs of life or signs that might support life. It’s not so much that astronomers expect to discover whether life does exist, or even could exist, outside our planet. Instead, they are excited by the unexpected findings such a search will throw up. The astronomer and SETI (Search for Extra-Terrestrial Intelligence) veteran Jill Tarter spoke of this spirit in an interview with the Washington Post some months ago. She hopes the JWST will “continue with [the] legacy" of every other telescope humankind has ever built, in this sense: that it “will show us something that none of us had in mind when the telescope was proposed."
In a real sense, that’s the great worth of the JWST.
Yet all that peering into the void, at distant planets, into the past, is in the future—not billions of years, but about six months. This is because it will take that long for the JWST to settle into orbit and begin operation. The HST was assembled by astronauts aboard the Space Shuttle. In contrast, the JWST will assemble itself. Unfolding its huge mirror, firing up its instruments, deploying a plastic “sunscreen"—all these manoeuvres will happen automatically, certainly without any human helping hand. In the whole months-long process, there are what scientists refer to as “single points of failure"—specific operations that will doom the JWST if they don’t happen as planned. If any of them fail, there’s no way to send a repair team out to set things right.
There are 344 such single points.
So you can imagine why scientists the world over are going to be chewing their fingernails over the next several months. Not that there hasn’t been such chewing over the last several years: the project has been through delays and budget overruns, a pandemic and even a threat of cancellation.
Topping those for sheer drama, there was a particular worry prompted by where it will be launched from. That’s the European Space Agency’s launch facility in French Guiana. Now the JWST is too large to fit on a plane. So it went to South America by ship, sailing through the Panama Canal. The exact date of this trip was kept secret because of, yes, pirates—modern pirates, who might salivate at the prospect of hijacking this incredibly valuable piece of machinery. Starting with its gold-plated mirror and moving on to its intricate, elaborate instrumentation, this is an object worth over $10 billion. Unlikely, you might think, but what if there was a gang of such pirates? Thus the simple precaution of keeping the journey secret. There’s too much riding on the JWST, and the $10 billion is, arguably, the least of it.
Yet the stakes are enormous, and scientists worldwide are also aware of that. At Yale University, the astrophysicist Priyamvada Natarajan told the New York Times this week: “Remarkable enduring achievements of human hand and mind, be it the temples of Mahabalipuram, the pyramids of Giza, the Great Wall or the Sistine Chapel, have all taken time and expense. I truly see JWST as one such monument of our times."
Once a computer scientist, Dilip D’Souza now lives in Mumbai and writes for his dinners. His Twitter handle is @DeathEndsFun
Subscribe to Mint Newsletters
* Enter a valid email
* Thank you for subscribing to our newsletter.
Never miss a story! Stay connected and informed with Mint.
our App Now!!