The Hubble Space Telescope, the first major optical telescope ever hurled into space, broke down a lot. Since its launch in 1990, NASA has organized five separate missions to service the Hubble—and it was doable, even though the telescope is 300 miles away from Earth.
In the final servicing mission in 2009, the Space Shuttle Atlantis carried four astronauts to the observatory for a 12-day mission, when they replaced old batteries and equipment, while adding two new instruments to expand the capabilities of the Hubble, which is still going strong.
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Artist conception of the telescope in space. Image: NASA’s James Webb Space Telescope/Flickr
After its big brother, the James Webb Space Telescope (JWST), launches in 2018, those sorts of fixes-on-the-fly won’t be possible. Once the gigantic telescope—which is so big it can’t fit inside any of NASA’s rockets, and instead has to be folded up like origami to blossom once in space—is at its destination a million miles away, it’s gone. If it breaks, it’s done.
And that would be a shame. Hubble redefined the way we see the universe around us, and JWST—a partnership between NASA, the European Space Agency and the Canadian Space Agency—will be Hubble on steroids.
Astrophysicist Amber Straughn, who serves as the deputy project manager for the JWST Science Communications, is in Waterloo, Ontario to give an update on the telescope.
Her talk from the Perimeter Institute for Theoretical Physics can be watched here:
Excitement has only grown in the past week, with the announcement of a seven-planet system around a star called TRAPPIST-1, 39 light years away. The planets orbiting the star appear to be Earth-sized and rocky; some could even be habitable, so scientists want to find out more. Because TRAPPIST-1 emits light in infrared, the telescope will be perfect for observing it.
JWST will be able to study the thin atmospheres of cold planets that are dominated by carbon-based gases (like the planets of TRAPPIST-1). It’ll check for water vapor, oxygen, methane, and other signs of habitability.
It’s taken so long to build and test the telescope because NASA wants to get it right: the $8-billion price tag and million miles are unforgiving. For the last 10 years, the observatory’s parts have been put through their paces, one by one. They’ve now entered the most important on-Earth phase: being tested as a package under simulation of brutal launch and space conditions.
Image: Enna Kim
“We really have to make sure we get things right on the ground,” said Straughn, who is based at NASA’s Goddard Space Flight Center in Maryland. Researchers are subjecting the telescope to punishing sub-zero temperatures, blasting it with sound, and banging it around to mimic its launch and deep-space solitude.
“Webb is designed to answer the biggest questions in astronomy today that Hubble just can’t quite answer,” she told me in a phone interview before her public lecture, adding that the JWST will be one hundred times more powerful than Hubble.
Engineers cleaning the mirror with carbon dioxide snow. Image: NASA Goddard Space Flight Center/Flickr
Beyond learning more about exoplanets like those in the TRAPPIST-1 system, “we hope to be able to see some of the first galaxies that lit up the universe right after the Big Bang,” she said.
That’s 13.5 billion years ago, at least in theory. “Of course, they’ve never been able to actually observe that part of space because, though the Hubble has seen quite far, it’s never gone that far,” she explained. Hubble is an optical telescope, while these first galaxies are red-shifted so far that their light falls into the infrared part of the spectrum. To observe them, NASA needs an infrared observatory—the JWST.
After the Hubble telescope launched in 1990, scientists started talking about the next big telescope. By 2000, a machine with JWST’s abilities had been selected as the priority for astronomy, Straughn explained.
An engineer testing the thermal shield. Image: NASA Goddard Space Flight Center/Flickr
Aside from being an infrared observatory, the JWST has two main differences from Hubble. The first is its size: Webb’s mirrors are six-and-a-half times as big as Hubble’s—the primary mirror is made of 18 individual segments—while the telescope itself is the width of a tennis court (that’s the size of its massive Sun shield) and more than three stories tall.
Aside from the mirror and Sun shield, the JWST is comprised of science instruments (cameras and detectors to collect data) and a “spacecraft bus” where the controls and electronics lie.
While Hubble orbits the Earth, the JWST will be about a million miles away, orbiting the Sun along with the Earth. This spot is called the second Lagrange point, a “gravitationally semi-stable point.” In other words, Straughn said, it’s a pretty good place to park.
The current environmental testing is taking place at Goddard. They’ve just finished vibrational testing, Straughn said. “That’s where we basically shake it, to simulate the stresses it will encounter during launch.”
The next test, after vibration, is acoustic testing—when they put the telescope in a giant acoustics chamber and blast the JWST parts with loud noise to mimic the sound of the launch rocket.
Each mirror has been through a series of cryogenics (low-temperature) tests and other examinations, to make sure it will survive the rigors of deep space. Now, the mirrors and instruments are being put together and tested as a package, Straughn said.
Part of the telescope undergoing a “gravity sag test” in a NASA clean room. Image: NASA Goddard Space Flight Center/Flickr
After vibration and acoustic exams will be center of curvature tests, where scientists basically measure that the mirror hasn’t been hurt by the testing. Then the pieces will be shipped—via C-5 aircrafts, the largest military planes available—to the NASA Johnson Space Center in Houston, Texas, where the gigantic thermal vacuum chambers (same ones used to test the Apollo-era spacecrafts) will run a full, end-to-end optical test at really cold temperatures.
They’ll then move the mirrors and instruments to Northrop Grumman, a massive aerospace contractor in California, where everything will be put together with the Sun shield and spacecraft bus. Then, more testing.
Read More: This Hubble Video Shoots You to the Center of the Galaxy
After that, the JWST will be transported to a launch pad in French Guiana to embark on its final journey: on an Ariane 5 rocket, to a point in space that’s far, far away.
According to Straughn, scientists haven’t decided what they should look at first when they get there. But among the JWST’s priorities will be the universe’s earliest galaxies, along with distant planets, and objects in our own solar system. The JWST is designed to last at least five years, but the it’ll carry enough fuel for a 10-year mission.
“We have all these questions that we plan to answer, but the most exciting thing is what we haven’t thought of yet,” she said. “That’s what always happens when we build a big, ambitious observatory like this. We discover things that we never dreamed of.”
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