#Breckenridge, Colorado.
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| Special to the Daily |
When Rebecca Espina was a kid in Summit County, she wanted nothing more than to leave the ski slopes far, far behind and become an astronaut.
Since the dawn of the space program, millions of students have shared that dream, and like those science-minded youngsters, Espina was endlessly fascinated by the mysteries of outer space. In the 1980s and early ’90s, space stations were all the rage and Espina — then Rebecca Hage — saw an opportunity to delve into the nitty-gritty mechanics of space exploration.
“I was very interested in becoming an astronaut,” says Espina, whose family moved to Summit County when she was in the fifth grade. “There were a lot of concepts out there about building space stations, and at that point, even with Hubble, the idea was that astronauts were going out and building things. I wanted to be a construction worker in space.”
Espina never made a trip to low-Earth orbit, home of the International Space Station and the majority of satellites, but she found a way to be part of the select group perfecting NASA’s next big thing: the James Webb Space Telescope, a massive, 14,300-pound instrument that will replace the 25-year-old Hubble Space Telescope.
On Tuesday, Espina will give a presentation to the Rotary Club of Summit County about JWST, the intricacies of space exploration and her life after leaving Summit County. In 1992, she won scholarships through the Rotary Club and several other local organizations that helped her go from Summit High School valedictorian to the University of Colorado-Boulder’s aerospace engineering program and, finally, to her current home at Goddard Space Flight Center in Maryland.
At Goddard, Espina is one of more than 1,000 scientists from 17 countries working on JWST, the newest and most complex satellite NASA has ever built. And it has to be: Once it’s launched in 2018, it will sit in what’s called an L2 orbit, roughly 1.5 million kilometers above Earth. That’s past the moon, which will make JWST the remotest telescope ever launched.
The distance also makes it difficult to maintain. For most of its life, Hubble was regularly repaired and updated by teams of two to three astronauts on space shuttle missions — Espina’s dream as a child. But when the shuttle program was discontinued in 2011, NASA engineers no longer had a way to maintain the aging telescope.
The solution for JWST is to over-engineer every component. Since astronauts can no longer replace and repair parts on a regular basis, the telescope is built to survive at least 10 years in J2 orbit, operating in temperatures of less than 50 degrees above absolute zero, or roughly negative-370 Fahrenheit.
“With Hubble, we could replace batteries, replace solar panels, change and fix parts,” Espina says. “But this telescope (JWST) will be so far out to do its work that we can’t reach it for service. It will be much larger and much more complicated than Hubble.”
BUILDING A BETTER TELESCOPE
For the past two years, Espina has been a structural dynamics analyst for the JWST program. Her job is straightforward: Make sure every mechanical component, from solar panels to mirror, will endure the stresses of the initial launch. After all, circling the Earth is the easy part — breaking free of its gravity is where things get tricky.
“The launch environment is your most severe environment,” Espina says. “You have to over-design telescopes to handle several Gs during launch. That’s the most important part, is to make sure this delicate hardware will survive.”
NASA has hundreds of Earth-based tests to simulate the stresses of space. Take the test for acoustic vibrations: When any satellite launches, sound waves resonate through every component. If they aren’t built perfectly, they’ll bend and loosen and even break long before the satellite and its primary mirror are in position. The mirror is 21 feet in diameter, roughly 2.7 times larger than Hubble’s mirror; protecting such a massive investment is paramount.
“Once we’re confident the hardware is built to survive these conditions, we put them on a shaker table and shake them like they would during a launch,” Espina say. “We have all these environments to pre-test equipment to make sure it won’t fail when it counts, and you want your failure to still be here when you’re done.”
The testing process appeals to Espina’s inner construction worker, albeit in a less hands-on way than she imagined as an astronaut hopeful. She spends most of her time in front of a computer looking at graphs and algorithms.
“Now, I rarely get close to actual hardware,” Espina says. “I just analyze — about the closest I get to hardware is when I put it on the shaker table. I envisioned more of that hands-on work, but I’m now doing more number crunching, making sense of squiggly lines.”
But Espina’s inner astronaut is more than satisfied. She’s on the ground floor at NASA, and if she does her job well, her handiwork will survive indefinitely: In L2 orbit, JWST will likely never succumb to the Earth’s pull.
“This is a very high-risk project, so we have more stringent requirements on us,” Espina says. “It has all sorts of risk requirements attached to it. You have to be redundant, keep testing, keep reviewing every last component.”
Courtesy of the Summit Daily News.
