The Most Powerful Telescope Ever Built Is Ready to Unlock the Mysteries of the Cosmos
French Guiana does not often get the chance to be the center of the world, to say nothing of the universe—or at least humanity’s understanding of it. At 7:20 am ET on December 24, the small and forested South American country will rise with an Ariane V European Space Agency rocket. The payload, which is $9.5 million worth of hardware and 25-years of work and is what the future of scientific research about the origins and evolution of the cosmos is dependent, is expected to take off. Ariane 5 will receive the spacecraft that was entrusted to them on this morning. James Webb Space Telescope (JWST), NASA’s—and the entire astronomical community’s—follow-on to the aging Hubble Space Telescope, which has widely been considered the greatest space observatory ever built—until now, at least.
The Hubble’s work is most powerfully captured in the A vast collection of stunning photos it’s sent back in the 31 years it has been flying. But those pictures also reveal its sole shortcoming: Hubble sees in the ultraviolet and visible spectrums, allowing it to peer approximately 13.4 billion years back in time—or just 400 million years after the Big Bang (because light from the cosmos can take a heck of a long time to reach us, looking up at the night sky is effectively looking into the past). A lot happened in those missing early years—galaxies began to form, stars began to flicker on—but the expanding universe and the great distance the light from that epoch is traveling to reach us cause its wavelength to stretch from the visible spectrum and into the infrared, to which Hubble and human eyes are blind.
But the infrared band is the exact one that the Webb was created to see. The Webb’s sensitivity increased 200m years earlier, to 13.6billion years ago. That’s just 200 million year after the Big Bang. That comparatively small improvement is enormously significant, opening the door to the universe’s babyhood—a period in which it matured spectacularly quickly.
“The difference between what Hubble and Webb will see is not like comparing someone who’s 70 years old to somebody who’s 71 years old,” says Scott Friedman, commissioning scientist for the Webb team. “It’s like comparing a baby who’s one day told to a baby who’s one year old, and that’s a huge difference.”
Webb had to overcome a lot of hurdles to get as far as it’s come. It was first proposed in 1995, with a $500 million price tag and an expected launch date of 2007. However, it repeatedly exceeds budget deadlines and limits. In 2012, the telescope almost died when Congress threatened with pulling funding. However, Webb was saved by the late delivery of the mirror which convinced lawmakers to hold their ground. There have been some last-minute delays, too—it was previously set to launch Dec. 22—and takeoff could be pushed back further still.
The telescope must face the sun before it can work. There are also technological obstacles. Contrary to the Hubble which flew in an Earth orbit of just 545 km (338 mile) it is a tight space. Webb would have to fly 1.6million km (1 million mi) above the earth. from the planet, where it will station-keep in what’s known as a Point Lagrange—It is an area in space that the Earth’s gravity and the sun cancel one another out. This invisible point allows objects to move around it as though they were orbiting solid bodies like planets. Also unlike the Hubble, which was small enough to fit comfortably inside a space shuttle’s cargo bay, the Webb is far too big to fit fully extended inside even the biggest rocket now flying, and will thus have to be folded multiple times, loaded aboard the Ariane and then unfold once in space.
“It’s like an origami object,” said Alphonso Stewart, the Webb deployment systems team leader, during a November NASA press conference. “Only we’ll do origami in reverse.”
Similar to the Hubble but with a Webb as its main focus, it promises to be an astronomical historian. The Webb will unlock portions of our cosmos that have been hidden and uncover secrets that once were not only unknowable, but impossible to predict. “There are all of these things that lurk out there that we haven’t even imagined,” says Klaus Pontoppidan, a Webb project scientist. “That is one of the things that makes it really, really exciting.”
It’s quiet now in mission control at the Space Telescope Science InstituteJohns Hopkins University Baltimore campus. As mission controls go, this is a small one—a dozen seats at a dozen consoles in a glassed-in room for the lead controllers, and at least an equal number in an auxiliary room. But on Dec. 23, the day before launch, the room will fill with astronomers and engineers preparing for the 12-hour shifts they’ll be working once the Webb goes into operation. The first and biggest job they’ll have to do is the one of unfolding. This is not simple reverse origami. It will take six months for the telescope to be fully assembled, ready to use, and operational.
Due to its ability to view into the infrared it requires complex designs, the JWST is extremely complicated. It’s easy to tell at a glance what the Hubble does, simply because it looks like a telescope—a metallic tube with a wide aperture at one end to admit light and a main mirror inside to gather up inflowing photons. It acts as a shield by blocking any light which could flood the image. Webb is quite a different kind of telescopic animal. Observing in the infrared, it needs protection not from light but heat, which would ruin its vision as surely as light would Hubble’s. JWST doesn’t have any housing. A sun shield protects the JWST from ultraviolet radiation as well as the heat generated by the hardware. The mirror of the satellite flies free in space.
The mirror, by itself is an amazing piece of engineering. Hubble’s mirror, which measures 2.4 m (7.9 ft) across, is a single, circular piece of highly milled and polished glass that, like the telescope itself, looks exactly like what it is. Webb’s is much more complex—a far larger 6.5 m (21.3 ft) across, and assembled from 18 separate hexagonal segments. The segments are made of beryllium—a metal that functions like glass but can be more highly shaped and polished—and covered in a thin layer of gold for reflectivity. NASA is I am fond of being pointed outThe gold is able to cover the whole 25 square. 25 sq. m (or 269 sq. The mirror measures 269 square meters. It is polished to a smooth finish that even if the mirror were extended to the dimensions of the United States would have only a meter-high imperfections. Each of the mirror segments can move in seven different directions—up, down, left, right, in, out and a diagonal tilt—to focus and refine the infrared energy being captured across the entire mirror surface.
“We have such a large primary mirror because what we want to do is look deep into the universe, so you need a bigger photon bucket,” says NASA associate administrator Thomas Zurbuchen.
That bucket has to stay cold—one reason the telescope is not in Earth orbit, where it would have to contend with the constant day-night-hot-cold cycle satellites experience as they circle the globe. But the sun still shines at the Lagrange points, and that’s where the Webb’s sunshield comes in. The shield, which is roughly diamond-shaped and has a size of a tennis court in it, is made up of five layers of Kapton. This foil-like film, as thin as your hair, can be as thick as 5 mm. On the outer layer, the side exposed directly to the sun, the temperature will be about 110º C (230º F, 383 Kelvin). On the inner layer, closest to the mirror, it will be -237º C (-394º F, 36 Kelvin).
“[The sunshield] is going to be irradiated by 200,000 watts of solar radiation and it should allow only about .02 watts through,” said Mike Menzel, the Webb team’s systems engineer, at the NASA press conference. “So if we’re suntan lotion, that would have an SPF of 10 million.” And both the mirror and the sunshield—plus the power-providing solar panel, the onboard computer, the maneuvering system and more—have to fold up small enough to fit into the Ariane 5’s payload bay, which measures less than 5 m (16 ft) across. The engineers designed the telescope so it is indeed neatly stowable, but the unstowing—and unfolding—is another job entirely.
Friedman’s role as the commissioning scientist means he is responsible for opening up and configuring the telescope over the course of the mission’s first six months. The rest of Friedman’s team must work exceptionally carefully and well. By the engineers’ calculations, the telescope’s unfurling process has a staggering 344 so-called “single point failures”—each involving a hinge, actuator, pulley or other system or procedure that, if it goes awry, could all by itself spell the end of the mission. Flying with a single failure can be dangerous. One failure can lead to an exponentially greater number; 344 are hair-raising.
“There is some redundancy built into the system of release mechanisms,” said Friedman during a recent walkabout with TIME in the mission control building. “They have multiple wires in and only one has to work right. But one way or another, all of the releases do have to fire.”
“Many of these things are actuators that do have back-up systems,” says Zurbuchen. “But make no mistake, I could easily imagine things that we have no fallback on.”
It is possible to assume that any of the single points fails.There is much that the James Webb Space Telescope can do, and more it could discover during the decade-long work ahead. It will be able to see as far back as possible in the past, which will allow it to reveal a wide range of phenomena and astronomical objects. For starters, it might be able to glimpse, or at least get close to, the universe’s literal let-there-be-light moment—peering back to the point when stars first began to form among the dust and gas clouds that made up all there was to the cosmos just after the Big Bang. It was at this moment that the newborn universe became illuminated. The stars had enough mass to start to ignite their fusion engines.
“There was a period of time when the universe wasn’t able to form stars or galaxies yet, so there wasn’t any light yet,” says Pontoppidan. “Then you form galaxies and they form stars and that happens about 100 million years after the Big Bang, but we don’t know for sure.”
These stars did not look like our current-day ones. They were huge, for starters—300 times more massive than our sun—and relatively short-lived. That was actually a blessing: The stellar giants that exploded in supernova explosions helped to create the heavy elements which made the universe modern and elemementally complicated.
Webb could also contribute to the study of gravitational waves—ripples in the fabric of spacetime caused by collisions of massive objects. The first gravitational waves had been detected2015. This proved a theory Albert Einstein had first proposed a century ago. Those waves, and others that have been detected since, were caused by pairs of black holes or neutron stars colliding—cosmic crack-ups that would also have produced massive amounts of heat and other radiative energy. Webb would detect any infrared signals from those emission.
Closer to home, the new telescope will conduct observations within our own galaxy, studying the atmospheres of exoplanets—planets circling other stars—looking for signs of biology. The transit method is the most common way to spot more than 400 exoplanets. When an orbiting planet crosses in front of a star it blocks some starlight. This can be seen by observatories such as the. Kepler Space Telescope. The amount of dimming gives you a good estimate of the planet’s diameter, and the frequency with which that little flicker repeats tells you how fast the planet is orbiting. But that’s all you can get from the transit method. With Webb, scientists will be able to analyze starlight as it passes through—and gets distorted by—a given planet’s atmosphere. The precise nature of that distortion can reveal the makeup of the atmosphere’s chemistry, including the presence of oxygen, carbon, methane and other elements and compounds that are requirements for—and perhaps fingerprints of—life as we know it. Similar chemistry measurements can be made by the JWST on moons and planets that have atmospheres within our solar system. This includes Titan, the giant, gaseous satellite from Saturn.
“[Webb] won’t find new planets, so much as it will characterize those we already know,” says Pontoppidan, “in particular, smaller exoplanets with rocky surfaces and maybe relatively temperate temperatures.”
Webb will likely not have the same lifespan as Hubble, despite its great potential. Hubble launched back when there was no Soviet Union. One risk is that it’s far more vulnerable. Hubble has a metal body that protects the fragile instruments within from harmful micrometeorites. Webb does not have such protection and its sun shield and mirror will likely be damaged. Webb engineers appear to be surprisingly optimistic about the fact that NASA has done hypervelocity simulations and fired micrometeorite ordnance at mirror materials, finding minimal damage.
“Luckily for us, the micrometeorites will put nice little well-defined bullet holes in [the mirror],” said Webb project manager Bill Ochs at the NASA press conference. That, he says, will detract a little bit from the overall mirror’s light collecting area, but not enough to make a meaningful difference. Its five layers of sun protection are very useful. Ochs states that micrometeorites will likely disintegrate upon impact with the first layer, and might strike the second. However, it is unlikely to puncture all five layers.
Webb will still face other operational problems. Hubble is kept alive partly by maintenance and servicing run done by astronauts. Webb’s great distance from Earth makes that kind of house call impossible. What’s more, in order to remain stable at its gravity-balanced Lagrange point, Webb needs a thruster system, and a thruster system requires fuel. A full tank will allow the telescope to launch, however it won’t be enough fuel for its operation beyond five years. It can only operate up to 10. In theory, a refill ought to be possible, and the telescope is actually equipped with a docking target to accommodate an incoming spacecraft that could conduct a refueling and extend the JWST’s life. It’s an appealing idea, especially considering the telescope’s dizzying price tag. The spacecraft has not been built yet, although it may in the next ten years.
“At this moment in time, we’re putting tunnel vision focus on getting this launched,” says Zurbuchen. “There is nothing to refuel if it doesn’t deploy. But I think refueling is not out of the realm of possibility, especially considering technological progress.”
Webb won’t live very long, but it will still fly in a tiny fraction of the time it is studying the cosmos. However, it will allow us to learn a lot in its short life span. The universe has long kept parts of its earliest epoch hidden from us—but no more. The Webb, says Pontoppidan, will be nothing less than “a discovery machine.”