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The Challenges of Building the Hubble Telescope’s Replacement

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NASA

Since 1990, the Hubble telescope has brought us photos that are as beautiful as they are scientifically important. But there’s a limit to what Hubble can see—so space agencies from around the world are collaborating to create a better, more powerful, and literally bigger telescope: the James Webb Space Telescope (JWST), which is projected to launch in 2018. In the SXSW panel “Beyond Hubble: Building NASA’s Next Great Telescope,” scientists and engineers discussed what the Webb telescope will look for and all the engineering challenges that go into actually building the instrument.

What JWST Will Do—And How It Will Do It

According to Alberto Conti, Innovation Scientist at the Space Telescope Science Institute, the Webb telescope is a versatile instrument that has four main goals: To find the first stars, study galaxy evolution, study planet formation, and find habitable planets that might contain water (and, therefore, might also have life). “We build telescopes because they’re time machines,” Conti says. “They tell us about how the universe came to be, and how it works.” Scientists hope that Webb will answer questions like: How did the universe form? Is our solar system unique? Are we alone?

In order to answer these questions, JWST needs to be big—really big. One hundred times more powerful than Hubble, the four-story-tall, infrared optimized telescope will be comprised of 18 hexagonal mirrors that total 21.3 feet in diameter which will allow it to take pictures of faraway worlds, and an 80-foot-long sun shield that will keep the telescope’s eyes cold enough to snap those photos.

While Hubble can capture images of planets the size of Jupiter, JWST will be able to look for planets from the size of Neptune down to the size of Earth, according to Charles Mountain, the director of the Space Science Telescope Institute. And it will do it by looking for infrared spectrums. “On the infrared spectrum, there are three planets that we know a lot about: Venus, Mars, and Earth,” Mountain says. If, using JWST, they can find planets with infrared signatures similar to Earth’s, they might be goldilocks planets—just right to have life. “If we find life, it’ll be as profound as Darwin and Copernicus rolled into one,” Mountain says. “It will bring about a change in our world—we’ll realize we’re not as special that we thought, that evolution happened elsewhere.”

Looking for life begins by looking for stars, because planets that can harbor life will be orbiting around stars. JWST can also use infrared to peer through clouds of gas. “The idea is that we can see thousands of stars embedded in gas clouds because we have the right set of eyes,” Conti says. By looking at the spectra of the disks, Webb will be able to determine what constituents of those disks create planetary systems.

The Engineering Challenges

Building JWST hasn’t been a cakewalk. It has required both creativity and tons of collaboration between scientists, engineers, and companies in the private sector to get it done. Here are the engineering challenges behind key elements of the telescope.

Mirror

In order to see distant objects, JWST needs a big mirror. Blake Marie Bullock, the campaign lead on JWST at Northrup Grumman Corporation, explains the need for a big mirror this way: If you leave a coffee can out overnight in a storm, in the morning, the water in the can will be two inches deep. If you leave out a kiddie pool in the same scenario, the pool will also have water two inches deep—but there will be a lot more water in it. In a telescope, “the same thing is happening with photons,” Bullock says. “If you have a bigger bucket, you can have more photons, and see fainter objects.”

This mirror is so big that it won’t fit in a traditional rocket (Webb will go up in one of the European Space Agency’s Ariane 5 rockets), so engineers had to create a mirror that will fold. “There are 18 hexagons, but three of the hexagons [on each side] are folded down like leaves on a dining room table when it’s stowed,” Bullock says. Once in space, the telescope “unfolds like a flower. Figuring out how this process works takes a lot of engineering.”

Even more complicated is figuring out the prescription. “As you’re manufacturing that mirror on the surface of the Earth, gravity pulls it down and bends that structure,” Bullock says. But when the mirrors are up in space, the gravity is gone—so on Earth, the prescription actually has to be perfectly wrong so that it will be right once the telescope goes into space. As you can imagine, it takes a lot of calculations.

In order to be as precise as the mission requires, JWST’s mirrors have to be very, very smooth. So smooth, Bullock says, that “if you took one of these hexagons and stretched it out to the size of the state of Texas, the biggest bump would be 1 centimeter tall.”

Hot vs. Cold

Infrared is sort of like heat, Bullock says, and because JWST is looking for heat, it doesn’t want to see heat. So engineers are building a five-layer, 80-foot long sun shield that will take photons away from the telescope’s eyes, which much be cold to function. And because there’s such a huge difference in temperature between the hot side of the observatory, where temperatures will reach 185 degrees Fahrenheit, and the cold side, which will be a chilly -388 degrees Fahrenheit, engineers have to think about things like how glue and other materials might behave. Engineers also have to wrestle with how to handle things like the sun shield so that it doesn’t have any creases once it’s deployed.

Weight

The bigger something is, the heavier it is—and the more difficult it is to get it out of Earth’s orbit. JWST is no exception. “As the telescopes get bigger, engineers have to think about how to make it light enough to get into space,” Bullock says. Hubble is just a couple of hundred miles above Earth’s surface, but Webb will be a million miles away, where it is both dark—to make imaging planets and stars easier—and cold (so the telescope functions properly).

Testing

No facility is big enough to test Webb in its entirety, so its components are being tested at Johnson Space Center in Houston, Texas. The facility’s cryogenic chamber, according to Bullock, hasn’t been used since the Apollo missions, so it’s been retrofitted to test JWST’s components. The gold-coated mirrors are being tested six at a time, but the chamber isn’t big enough for the 80-foot sun shield. “That means a lot more math to make sure everything will work the first time,” Bullock says.

Given all of these challenges, how can scientists be sure JWST will work? Nothing is 100 percent, but engineers are working hard to make it happen. “Every piece is tested incrementally, verified, put into a larger system and tested again,” Bullock says. “We’ll spend two years testing it to make sure that it works.”

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Bruce Weaver / Stringer / Getty Images
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NASA Is Posting Hundreds of Retro Flight Research Videos on YouTube
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Bruce Weaver / Stringer / Getty Images

If you’re interested in taking a tour through NASA history, head over to the YouTube page of the Armstrong Flight Research Center, located at Edwards Air Force Base, in southern California. According to Motherboard, the agency is in the middle of posting hundreds of rare aircraft videos dating back to the 1940s.

In an effort to open more of its archives to the public, NASA plans to upload 500 historic films to YouTube over the next few months. More than 300 videos have been published so far, and they range from footage of a D-558 Skystreak jet being assembled in 1947 to a clip of the first test flight of an inflatable-winged plane in 2001. Other highlights include the Space Shuttle Endeavour's final flight over Los Angeles and a controlled crash of a Boeing 720 jet.

The research footage was available to the public prior to the mass upload, but viewers had to go through the Dryden Aircraft Movie Collection on the research center’s website to see them. The current catalogue on YouTube is much easier to browse through, with clear playlist categories like supersonic aircraft and unmanned aerial vehicles. You can get a taste of what to expect from the page in the sample videos below.

[h/t Motherboard]

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U.S. National Archives and Records Administration, Public Domain, Wikimedia Commons
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5 Things You Didn't Know About Sally Ride
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U.S. National Archives and Records Administration, Public Domain, Wikimedia Commons

You know Sally Ride as the first American woman to travel into space. But here are five things you might not know about the astronaut, who passed away five years ago today—on July 23, 2012—at the age of 61.

1. SHE PROVED THERE IS SUCH THING AS A STUPID QUESTION.

When Sally Ride made her first space flight in 1983, she was both the first American woman and the youngest American to make the journey to the final frontier. Both of those distinctions show just how qualified and devoted Ride was to her career, but they also opened her up to a slew of absurd questions from the media.

Journalist Michael Ryan recounted some of the sillier questions that had been posed to Ride in a June 1983 profile for People. Among the highlights:

Q: “Will the flight affect your reproductive organs?”
A: “There’s no evidence of that.”

Q: “Do you weep when things go wrong on the job?”
A: “How come nobody ever asks (a male fellow astronaut) those questions?"

Forget going into space; Ride’s most impressive achievement might have been maintaining her composure in the face of such offensive questions.

2. SHE MIGHT HAVE BEEN A TENNIS PRO.

When Ride was growing up near Los Angeles, she played more than a little tennis, and she was seriously good at it. She was a nationally ranked juniors player, and by the time she turned 18 in 1969, she was ranked 18th in the whole country. Tennis legend Billie Jean King personally encouraged Ride to turn pro, but she went to Swarthmore instead before eventually transferring to Stanford to finish her undergrad work, a master’s, and a PhD in physics.

King didn’t forget about the young tennis prodigy she had encouraged, though. In 1984 an interviewer playfully asked the tennis star who she’d take to the moon with her, to which King replied, “Tom Selleck, my family, and Sally Ride to get us all back.”

3. HOME ECONOMICS WAS NOT HER BEST SUBJECT.

After retiring from space flight, Ride became a vocal advocate for math and science education, particularly for girls. In 2001 she founded Sally Ride Science, a San Diego-based company that creates fun and interesting opportunities for elementary and middle school students to learn about math and science.

Though Ride was an iconic female scientist who earned her doctorate in physics, just like so many other youngsters, she did hit some academic road bumps when she was growing up. In a 2006 interview with USA Today, Ride revealed her weakest subject in school: a seventh-grade home economics class that all girls had to take. As Ride put it, "Can you imagine having to cook and eat tuna casserole at 8 a.m.?"

4. SHE HAD A STRONG TIE TO THE CHALLENGER.

Ride’s two space flights were aboard the doomed shuttle Challenger, and she was eight months deep into her training program for a third flight aboard the shuttle when it tragically exploded in 1986. Ride learned of that disaster at the worst possible time: she was on a plane when the pilot announced the news.

Ride later told AARP the Magazine that when she heard the midflight announcement, she got out her NASA badge and went to the cockpit so she could listen to radio reports about the fallen shuttle. The disaster meant that Ride wouldn’t make it back into space, but the personal toll was tough to swallow, too. Four of the lost members of Challenger’s crew had been in Ride’s astronaut training class.

5. SHE DIDN'T SELL OUT.

A 2003 profile in The New York Times called Ride one of the most famous women on Earth after her two space flights, and it was hard to argue with that statement. Ride could easily have cashed in on the slew of endorsements, movie deals, and ghostwritten book offers that came her way, but she passed on most opportunities to turn a quick buck.

Ride later made a few forays into publishing and endorsements, though. She wrote or co-wrote more than a half-dozen children’s books on scientific themes, including To Space and Back, and in 2009 she appeared in a print ad for Louis Vuitton. Even appearing in an ad wasn’t an effort to pad her bank account, though; the ad featured an Annie Leibovitz photo of Ride with fellow astronauts Buzz Aldrin and Jim Lovell gazing at the moon and stars. According to a spokesperson, all three astronauts donated a “significant portion” of their modeling fees to Al Gore’s Climate Project.

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