The launch of NASA’s $10 billion James Webb Space Telescope from French Guiana could mark a triumph in a tale that thousands of astronomers have been following for a generation. Or it could result in the deepest tragedy.

Either way, the climax is due to unfold beginning on Christmas morning — making for a plot worthy of a holiday movie.

“I’ve been waiting 23 years for this telescope to launch,” University of Washington astronomer Eric Agol told GeekWire.

Agol has been waiting so long that the focus of his research changed completely during the wait. Back in 1998, when the Next-Generation Space Telescope was still on the drawing boards, he was studying gravitationally lensed quasars.

“I was doing some science at the time with ground-based telescopes and, and specifically the Keck Telescope up in Hawaii,” Agol said. “We were spending half a night looking at distant quasars, and then we calculated that with the James Webb Space Telescope, it would take a few milliseconds to do the same observation.”

Now he’s studying planets beyond our own solar system — with an intense focus on TRAPPIST-1, a potentially habitable planetary system 39 light-years from Earth. It’s a testament to the telescope’s versatility that it promises to have just as dramatic effect on that project.

“James Webb is just going to give phenomenal data on this system of transiting planets,” Agol said. “Each of the transits will yield spectral information if there are any signs of atmospheres in these planets. This is the first time where we have a really good chance of probing atmospheres on potentially Earthlike planets.”

But first, the telescope has to get settled at its location in deep space, a million miles from Earth, at a gravitational balance point known as Sun-Earth L2.

The Christmas launch is the first step: Under an arrangement forged by NASA and the European Space Agency, JWST will lift off from ESA’s spaceport in French Guiana atop a European Ariane 5 rocket. After a series of postponements due to technical concerns and weather, launch is set for no earlier than 9:20 a.m. local time (4:20 a.m. PT) Dec. 25 — complicating holiday plans for astronomers around the globe.

“They have to, like, schedule their kids’ pancakes and presents so that their kids have a good Christmas, but also they need to watch James Webb deploy,” UW astronomer Emily Levesque said.

NASA is due to begin its streaming coverage at 3 a.m. PT Christmas morning.

Unprecedented risks

This launch is nothing to joke about: It’s coming after years of delay and billions of dollars in cost overruns. (When I wrote about JWST in 2007, the cost of what’s now a $10 billion observatory was estimated at $3.5 billion, with launch slated for 2013.)

Because of where the telescope is going, it can’t be serviced by a crew of astronauts after it’s launched. That’s different from the Hubble Space Telescope — which had to undergo a major repair by a space shuttle team three years after deployment, due to a flaw in its mirror.

Frequently asked questions: NASA’s quick rundown on the James Webb Space Telescope

Because JWST’s mirror is so wide — 6.5 meters, or 21.3 feet — it has to be folded up origami-style to fit inside the Ariane 5’s fairing. That means the mirror, and the multilayered screen that protects the telescope’s delicate instruments from the sun’s glare, have to unfold after launch. The spacecraft can be reprogrammed in flight if something goes wrong with the software, but if JWST experiences a hardware problem, there’s a chance the entire mission could be lost.

“If anybody can do this, NASA can,” Levesque said. “It’s an unbelievably complicated launch and deployment. There are so many steps that have to go perfectly. They’ve also spent years trying to make everything as perfect as possible. I think I’ll be biting my nails with everyone else, and nothing about a space launch or a mission of this complexity is ever routine, but if anybody can get it to work, it’s NASA.”

The drama is due to unfold, so to speak, over the course of several weeks. The last date that Levesque has marked on her calendar to worry about is in late January, when JWST is scheduled to arrive at the L2 point.

Because the gravitational pulls from Earth and the sun are aligned at that point, the spacecraft will require a minimum of thruster firings to remain in a stable location within Earth’s shadow. But it’ll take another few months to get the telescope commissioned for first light and full-scale science operations.

Unprecedented returns

For more than a decade, NASA has been talking up the James Webb Space Telescope as the successor to the Hubble Space Telescope, which has managed to last more than 30 years.

Like Hubble, JWST’s instruments are designed to make discoveries across the spectrum of astronomy — ranging from the worlds and mini-worlds in our own solar system to alien planets circling distant stars, from the supermassive black hole at the center of our own Milky Way galaxy to the edge of the observable universe.

The Webb telescope’s 18-segment mirror has almost seven times the light-gathering capability of Hubble’s mirror, and a significantly wider field of view. But Webb is different from Hubble in a far more fundamental way: It’s designed to see the universe in infrared light, rather than Hubble’s wider range of ultraviolet, visible-light and infrared wavelengths.

That means the pictures released to the public are more likely to be color-coded to reflect variations in the infrared spectrum, just as pictures from the Spitzer Space Telescope have been. Infrared telescopes are especially suited for peering through shrouds of obscuring dust to see what’s going on inside protoplanetary disks, or mapping cosmological frontiers affected by relativistic redshifting.

Levesque expects JWST’s infrared readings to contribute to her own research, which focuses on how the biggest stars in the universe evolve and die.

Geek of the Week: Emily Levesque looks out at massive stars and looks back at the history of astronomy

“Some of the dying big stars that I study, red supergiants, are actually fascinating to study in infrared light,” she said.

One example is the star Betelgeuse, which generated headlines a couple of years ago when it went through a mysterious cycle of dimming and brightening. Astronomers eventually determined that the dimming was probably caused by a cloud of dust.

“If James Webb had been able to observe Betelgeuse when that happened, it would’ve seen something very different, because that same dust that blocks the light we see with our eyes actually glows and gives off a pretty good amount of infrared light,” Levesque said. “It’ll be an entirely new way of looking at these stars that we’ve never been able to manage before, because we can’t get those types of observations from the ground.”

But the discoveries that Levesque is most looking forward to, assuming JWST survives its trip to L2, are the discoveries that astronomers don’t expect.

“There’s this famous Hubble observation, the Hubble Deep Field, where they pointed Hubble at what looked like an empty patch of sky, and they just let it take a very long picture,” she said. “And when the picture came back, it was just wall-to-wall distant galaxies. It was this stunning picture of what the distant universe looks like. And it surprised everybody, just how incredible the picture was. I can’t wait to see what the James Webb equivalent will be.”

Listening to Levesque talk about what Webb might bring, you can’t help thinking of a kid waiting for Santa Claus.

“I’m excited for Christmas,” she said.

Five fast facts about JWST

• The telescope was named after the late NASA Administrator James Webb, who led the space agency from 1961 to 1968. Some astronomers have called for Webb’s name to be removed, saying that he went along with government discrimination against LGTBQ employees in the 1950s and 1960s. But NASA says the name is here to stay.
• JWST was built by Northrop Grumman under the supervision of NASA’s Goddard Space Flight Center in Maryland, and had to be shipped from California to French Guiana via the Panama Canal. Details about the trip were kept under wraps, in part to frustrate pirates who might seek to hold the telescope hostage. Under the terms of its partnership with NASA, the European Space Agency was guaranteed at least 15% of the observing time. (It got 30%.)
• The telescope has four science instruments: the Near-Infrared Camera, or NIRCam; the Near-Infrared Spectrograph, or NIRSpec; the Mid-Infrared Instrument, or MIRI; and the Canadian Space Agency’s Fine Guidance Sensor / Near Infrared Imager and Slitless Spectrograph, or FGS/NIRISS.
• JWST’s mirror and detectors will have to be cooled down to a temperature of about 388 degrees below zero Fahrenheit (40 Kelvin or -233 degrees Celsius) to operate properly. That’s a big challenge, since solar radiation is expected to heat up the “hot side” of the telescope’s sunshield to near-boiling temperatures, as high as 185 degrees F (85 degrees C).
• The telescope is designed for at least five and a half years of operation (six months for calibration, plus five years of science operations), but scientists are hoping it’ll be around far longer. The limiting factor is expected to be fuel to maintain its halo orbit at L2. There’s enough fuel for at least 10 years, and it’s theoretically possible to refuel the spacecraft if NASA really, really wants to.

UW astronomer Emily Levesque is planning a series of in-person and virtual events to celebrate the release of the paperback edition of “The Last Stargazers,” her behind-the-scenes look at the people who use the world’s most powerful telescopes. The first event will be at Ada’s Technical Books in Seattle on Jan. 4. There’ll also be a virtual event presented by Third Place Books on Jan. 5, and a Jan. 21 event at Paper Boat Booksellers.