Ever since the James Webb Space Telescope was announced, astronomers have been desperately
trying to be awarded the time to use it. This spectacular machine promises to take us into all
new territory when it comes to looking at space. And so, excitement builds for the official start
of the Webb’s scientific observations. But, in the meantime, it has already been in space for months…
so, what’s it been up to? This is Unveiled and today we’re
exploring everything the James Webb Space Telescope has achieved so far.
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At this point, the telescope isn’t exactly a new invention in itself.
We’ve had it for centuries now, and perhaps more than any other astronomer in history,
it was Galileo Galilei who first decided to point one skyward… to begin in earnest
studying the stars. For Galileo, and for so many years after him, however, these were
simple, ground-based setups. It wasn’t until the mid-twentieth century, as technology fast-tracked,
that science realized how observatories positioned in space offer a much better view
of the universe. The first successful space telescope was launched in 1968, the American
Orbiting Astronomical Observatory 2. And, since then, we’ve seen increasingly advanced variations,
up to and including some of the supremely powerful instruments that are still in orbit today – like
the Chandra X-Ray Observatory and the Hubble. But none of these can accomplish quite what the
James Webb Telescope can, which is why it’s one of the most anticipated space missions (period)
ever to launch… and has been variously heralded as ushering in a new age for cosmos exploration.
In short, the Webb is so important because it’s the most powerful space telescope ever built and,
operating in the infrared spectrum of light, it will enable us to see further than ever before.
Webb is also the largest space telescope ever launched, which brings with it a unique challenge,
given its infrared speciality. Tools that see in infrared need to be kept extremely cold…
and that’s somewhat difficult as the sun is obviously an ever-present in the solar system.
In order to stay cold, then, the Webb requires an advanced cooling system and a massive shield – on
account of its size. At the same time, though, Webb depends on solar energy for power,
so it’s a huge and complex balancing act. The telescope has to juggle gathering direct sunlight
while also staying cool. And yet, thanks to that shield, and the cutting-edge engineering
that runs right the way through it, there have been no problems so far.
The Webb successfully launched on Christmas Day, December 25th, in 2021, from the European Space
Agency’s Kourou launch site in French Guiana. And the payload’s long path ahead began on an
extremely positive note. Due to a very successful and accurate launch, NASA announced post-launch
that Webb would have enough fuel left in the tank to effectively double its mission life
expectancy – with it now expected to run for “significantly more than” a decade. So, right
from the beginning, success was in the air. As Webb left the atmosphere, a camera onboard the
Ariane 5 rocket that carried it into space caught sight of it one last time, disappearing into the
darkness. Its destination wasn’t a planet or star, though, but something called a Lagrange point,
which is an area in space where the gravity and centripetal force of the Sun and Earth effectively
cancel each other out – which creates a kind of “stable zone”. The specific Lagrange point that
Webb traveled to is called L2. It arrived in late January 2022, and is now located as though behind
the Earth, and therefore further from the sun than we are. This particular position means that the
telescope will follow Earth in orbit and will stay a constant almost-one-million miles away from us.
A massive distance that’s also necessary to ensure that Earth’s own heat and light emissions
don’t contaminate Webb’s view of space. The journey to L2 wasn’t simply a case of A to B,
however. The Webb was launched in an initially compact form, so mission runners have had to pull
off a series of complicated and unprecedented unfurling processes to get the machine into
its target shape and operational. One of the most important steps came just three days after
launch when the sunshield was deployed. This is that key part of Webb tasked with providing
a barrier between it and the sun’s intense heat, or else the telescope would not be able to retain
its vision. With the fully extended sunshield being about the same size as a tennis court,
it took some four days in total to get it ready, with the final tensioning of its membrane
taking place about a week post-launch. The next major milestone came with the
deployment of the telescope’s mirrors, which serve to reflect light directly into its central eye.
There were eighteen primary segments to deploy as well as a handful of secondary mirrors, and it was
announced that all had been successfully initiated on January 19th, 2022. There next followed a main
trajectory burn to alter Webb’s course, and to ensure it stayed on the right track, which was yet
another crucial moment that could have easily gone wrong… but was executed perfectly.
In total it took 30 days for the telescope to reach its destination
and settle into what’s known as a Halo orbit at L2. At that point, it was ready to begin final
preparations to start its main mission objective – gazing into the universe. This meant aligning,
calibrating, and cooling all the instruments… and Webb achieved these feats over the next few
months. On March 16th it was announced that it had successfully aligned its mirrors and officially
turned on its optics. And then, on April 13th, the Mid-Infrared instrument on-board was cooled to a
sufficient temperature for the first time, at just a few degrees above absolute zero,
and essentially the coldest that anything can get. Clearly, the sunshield was working.
So now, with the everything in position, optics aligned, and key instruments cooled, was the Webb
finally ready to begin? Not quite. There are more tools on board – including cameras, spectrographs,
and imagers – which all have different modes of operation that need to be checked,
rechecked, and tested. And, in the remaining months before final switch on, this was what
the team on the ground busied themselves with. Meticulously trialing and fine-tuning all of
Webb’s gadgets before finally “pressing play” for real on one of the most innovative, exciting,
and expensive astronomy missions ever seen. Often, a mission as big and budget heavy as this
one can find itself dogged by problems, niggles, and false starts. And let’s not forget that this
was the case before Webb got off the ground, with various issues causing delays to the launch
itself. But, since then, it’s been remarkably plain sailing for astronomy’s new favorite
toy. There were countless things that could have gone wrong at almost every step of the way. The
launch could have failed; the sunshield might’ve collapsed; the ejection burn could have messed up
its position entirely. But, so far so good. The Webb has performed every action near perfectly.
And while there are still many problems that could arise from this point onward,
confidence in Webb is growing and growing. From here, it’s little wonder that there’s
such a race amongst astronomers to get some time working with Webb. NASA has outlined its four
main objectives as 1) exploring the very beginning of the universe 2) viewing the birth and formation
of early galaxies 3) seeing the birth of stars and protoplanetary systems, and 4) uncovering
more about the origin of life itself. Those are extremely high targets, but ones that Webb is
expected to meet. It’s been a long time coming, but we’re very nearly ready to see completely new
parts of the universe. And that’s everything the James Webb Space Telescope has achieved so far.
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