NASA Space Telescope Unfolds Mirrors, Advances to Final Stage
GREENBELT, Md. — NASA’s James Webb Space Telescope successfully metamorphosed into its final and most critical stage after unfolding the last of its enormous golden mirrors in outer space on Saturday.
The mission’s latest developments were shared with the world during NASA’s livestream of the mirror deployments on Saturday, one of the vehicle’s most critical milestones as it cruises on course to its orbit at Lagrange point two. NASA scientists collectively breathed a sigh of relief as the data came back nominal and the mission is now in the hands of NASA’s engineering team to calibrate its delicate imaging technology as it continues on towards its orbit destination.
Two panels of NASA experts discussed the difficulties of launching the world’s biggest and most complicated space observatory in a press conference following the livestream of the Webb’s final mirror deployments. The first-of-its-kind telescope could not have come to fruition without contending with unprecedented challenges, all of which required a painstaking amount of designing, testing and verification to ensure the mission’s success.
Lee Feinberg, optical telescope element manager at NASA’s Goddard Space Flight Center, said that mission systems engineers will be phasing each of the Webb’s 18 hexagonal mirrors over the course of the next two weeks. Once the vehicle reaches Lagrange point two and its instruments sufficiently cool, NASA scientists can begin fine-tuning the Webb’s imaging technology to capture and transmit the telescope’s first clear images.
“Starting on Tuesday, we’ll start deploying the mirrors,” Feinberg said during the press conference. “So, they’re [currently] in a launch configuration and there’s about a 10- to 12-day process to get all of the mirrors forward by roughly half an inch, and that puts them in a position where we can do the detailed optical alignment. So, this is sort of the first step we call mirror deployment, but then after that, there’s actually a three-month process to align the mirrors starting with the very first light on all 18 segments. And at roughly four months into the mission, right around day 120, is when we think the entire telescope will be aligned.”
This phase of the mission will happen side by side with the commissioning of instruments, meaning NASA scientists will begin activating and testing components of the observatory prior to the mirror becoming fully operational. Should all go according to plan, the first clear images of distant exoplanets and stars will be transmitted from the Webb back to Earth sometime in June.
“One of the things that we’re paying very close attention to is how the telescope and the instruments are cooling,” Feinberg said. “Because … what prevents us from getting images even sooner is how long they take to cool. It turns out, actually, early in the mission, we did find things were cooling a little bit faster than our models had predicted. And so, it does look like there’s the potential of [receiving them] maybe a day or two faster but not significantly faster. So, basically, our original timeline is close.”
When the Webb’s mission was first conceived and began developing in 1996, much of the technology it now uses did not yet exist and required countless feats of ingenuity. Over many years of development, the mission’s success is a testament to the work and collaboration by thousands of scientists and engineers from around the globe.
With all in-flight performances returning as expected according to NASA models, a new standard has been set for future human space endeavors. However, the apparent ease of NASA’s launch and subsequent deployments is misleading, Bill Ochs, Webb project manager at NASA Goddard, said.
“It is not as easy as it looks,” Ochs said. “But the thing is, what you saw [during the NASA livestream] is just a tribute to the folks. We went through what I feel now is the exact right amount of testing, the exact right amount of engineering audits, the exact right amount of tweaks to the design as we’ve gone through this journey of manufacturing in launching this telescope. The fact that it looks easy just emphasizes that we did all the right things leading up to this moment.”
In addition to the hours spent designing, fabricating and testing each component of the vehicle, billions of dollars were also spent in the process. One of the most significant concerns of the mission was the projected lifespan of the Webb given that it would launch with a finite amount of propellant and it’s impossible to refuel due to its vast orbital distance from Earth.
At the mission’s onset, estimates of the telescope’s lifespan varied between five and 10 years of useability, vastly limiting the return on the investments made. But now that data has come back signaling the accuracy of the Webb’s launch and its midcourse corrections, that estimate has increased dramatically from what was once expected, Scott Willoughby, vice president and Webb program manager at Northrop Grumman, said.
“When we launched, by design our limiting resource was propellant,” Willoughby said. “And right now, because of the efficiency with which [the Ariane 5 launch vehicle] put us in orbit, and our accuracy and effectiveness in implementing our midcourse corrections, we have quite a bit of fuel margin right now relative to 10 years. Roughly speaking, it’s around 20 years of propellant, and that’s [to be determined.]”
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