In October 2018, if all goes as planned, an Ariane 5 rocket will lift off from French Guiana, just north of the equator, carrying the most sophisticated, deepest-peering space telescope ever conceived.
But first, the $8 billion James Webb Space Telescope must pass a final grueling test to ensure it can survive the harsh environment in which it will be deployed.
That test is scheduled to begin Monday and to last 93 frigid days.
At the moment, the Webb telescope sits in a multistory, contaminant-free room just feet away from NASA’s famed Chamber A inside the Johnson Space Center’s Building 32, where the imaging device arrived last month aboard a C-5 cargo plane from NASA’s Goddard Space Center in Maryland.
In the Building 32 clean room, engineers shrouded in white suits from head to toe recently attached sensors that will monitor the Webb’s precision mirrors and other components during cryogenic testing, in which it will be subjected to temperatures about 35 degrees above absolute zero, the temperature at which atoms all but cease to move.
“This is the most complex, the most complicated, cryotest in the history of the world,” Randy Kimble, the NASA astrophysicist in charge of overseeing the telescope’s exhaustive testing, said of the three-month ordeal the telescope faces.
The test will mimic the environment in which the Webb will be deployed nearly a million miles from Earth, shielded from the heat of the sun by a five-layer “sunscreen” — in essence a heat sink that will allow the telescope’s mirrors to operate at 370 degrees below zero, at which it needs to be to capture the infrared images it is designed to obtain.
This summer’s test will be conducted inside the world’s largest cryogenic vacuum chamber, sealed behind a 40-ton steel door 40 feet in diameter.
“There are two large nested shrouds inside the chamber,” Kimble said of the equipment that will achieve the extreme cold. “The outer shroud, part of the original assembly, is cooled with liquid nitrogen to around 316 degrees F below zero.
“The inner shroud, which was developed for the Webb, is cooled with gaseous helium to 424 degrees F below zero.
“Things cool very slowly in space; much quicker in the chamber. So, in a sense, what we’re about to do is an over-test.”
Chamber A is one of two such thermal-vacuum structures inside the Space Environment Simulation Laboratory, as Building 32 is officially known and in which the Apollo capsules were similarly tested.
The building is listed on the registry of National Historic Landmarks in honor of its role in advancing the mission to land man on the moon.
Not Webb’s first ordeal
Already, the Webb has been subjected to drastic convulsions atop a so-called shaker table whose motion mimicked the extreme violence the telescope will experience during its launch aboard the heavyweight Ariane 5.
And, too, scientists have exposed the telescope to a certain sonic torture to ensure it can withstand the launch’s acoustic abuse.
“We blasted it with noise at super rock-concert volume,” Kimble said. “The telescope handled both tests perfectly.”
Webb’s successful completion of those ordeals gave the scientific and engineering teams involved in the project a high degree of confidence that the telescope will survive the trauma of flight aboard a rocket traveling about 25,000 mph — nearly seven miles a second — to escape Earth’s pull.
Now the question is, can the telescope survive the brutality of the vacuum and frigidity in which it will operate during its deployment 932,057 miles from Earth?
Named for Apollo overseer
The James Webb Space Telescope is named for NASA’s second administrator, who oversaw the development of the Apollo program while serving as the agency’s chief from February 1961 — three months before President John F. Kennedy’s call to land a man on the moon before the decade was out — to October 1968, nine months before Neil Armstrong stepped onto the lunar surface, taking “one giant leap for mankind.”
The Webb will be far more powerful than the Hubble Space Telescope, which collects visible and ultraviolet light and continues to provide spectacular images and valuable data.
The Webb, operating at the infrared end of the spectrum, will be able to peer nearly 13.5 billion years back in time to shortly after the dawn of the universe — the beginning of everything. Additionally, it will be able to peer through clouds of interstellar dust to witness the births of emerging star systems.
“The Webb will allow us to observe the most distant galaxies as they are first forming,” Rice University professor of Physics and Astronomy Patrick Hartigan said. “Expect some spectacular images of regions where stars form — things no one has seen before.”
Moreover, the telescope will assist in the search for life beyond Earth.
“There have been many recent discoveries of planets around other stars,” Hartigan said. “Webb will begin the process of trying to study their atmospheres. The infrared is optimal because we can see signatures of molecules there, and the planets are brighter relative to their host stars in the infrared than they are in the optical. Part of the effort will be to look for possible signs of life.”
The Webb’s 18 six-sided mirrors, seated in a grid 21 feet wide, are fashioned of beryllium, a brittle, lightweight element, and thinly coated with 24-karat gold.
The mirrors form a shallow, convex saucer, which will gather infrared light and reflect it into a single, smaller mirror mounted on a tripod above, which in turn will beam the gathered image to instruments capable of digitally transmitting it to Earth.
While the Hubble circles some 375 miles above our planet in what is known as low Earth orbit, where repair missions have been able to go, the Webb will be marooned in an orbit four times as far from Earth as the moon is.
So it is that the telescope will have to function almost perfectly from the get-go; the only possible adjustments will be those relayed to Webb’s computers by ground controllers.
The Webb will separate from the European Space Agency-provided Ariane 5 half an hour after liftoff and then will fly another month under its own power to its designated orbit.
Six months later, Webb, a collaborative project among the European Space Agency, the Canadian Space Agency and NASA, will begin its perusal of the universe.
It is expected to operate for at least five and a half years. The international team hopes that it will continue to scan the cosmos for more than 10 years, depending on how much of Webb’s minimum 10-year fuel supply is burned in maintaining its position.
“It’s not a perfectly stable orbit,” Kimble said. “It will take some propulsion to maintain Webb’s orbit.”
Scientists are putting together plans for the telescope’s use.
“The first call for observations is out,” Hartigan said. “Proposals are due in a few months.”
Imperiled, yet not
While Webb in its distant orbit will be beyond man’s reach, it is safe there from the millions of pieces of man-made space junk whirling through low Earth orbit, a constant threat to Hubble, the International Space Station and satellites relaying everything from Netflix downloads to hurricane tracks.
After its three-month stay inside Johnson Space Center’s Chamber A, Webb will travel to Northrop Grumman Aerospace’s facility in Redondo Beach, Calif., where its sunscreen, which provides what Kimble calls “SPF 1 million,” will be tested, the telescope’s final grand test.
Now, on the eve of Webb’s penultimate test, that at Johnson, Kimble is guardedly optimistic.
“At Goddard, we checked those things that we could check warm,” he said of the vibration and acoustic tests.
“I don’t want to be overconfident, but I’m feeling really good at this point; the team and the equipment are very ready,” he said, and then the Maryland resident did his best to summon up a newfound Texas spirit: “This isn’t our first rodeo, so to speak.”