The Webb telescope’s 1.5 million journey of heart-stopping complexity has begun
By Linda Shiner|December 25, 2021
After running a 25-year gauntlet of technical and political challenges, the telescope’s most difficult tests lie ahead
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This story has been updated.
The weary world finally had reason to rejoice this morning when the largest, most powerful, most awaited space telescope ever built rode an Ariane 5 rocket into space, the telescope separating from the rocket’s upper stage and deploying its solar array.
NASA’s $9.7 billion James Webb Space Telescope was launched from French Guiana on the first leg of a one-month trip to its workplace in solar orbit, a point where the combined gravity of the sun and Earth will keep it aligned with Earth as the telescope and the planet move around the sun. After a smooth countdown in French, NASA’s launch commentator Rob Navias declared on NASA’s livestream that Webb had begun its journey from a tropical rain forest to the edge of time, and minutes later he called the launch a perfect ride on the Ariane 5. Twenty-seven minutes after liftoff, Webb separated from the upper stage, and the mission control room at the European Spaceport erupted in applause and cheers as the range operations manager Jean-Luc Voyer called out, “Go, Webb!”
When it reaches its destination, Webb will answer humanity’s biggest questions: Where did we come from and are we alone?
To answer the first question, NASA and its chief contractor Northrop Grumman created a telescope that, after a complex set of deployments, will be 100 times more powerful than the Hubble Space Telescope. Its primary mirror is the largest ever launched into space, and its four instruments will detect extraordinarily faint infrared radiation, the universe’s first light emitted more than 13 billion years ago as the first stars formed and assembled into primitive galaxies. The expansion of the universe has stretched that ancient light into infrared wavelengths. The oldest known galaxy, discovered in a Hubble deep-field observation, is 13.4 billion years old.
“We see it as a red blob,” said Swara Ravindranath, an instrument scientist with the Space Telescope Science Institute. “We will now be able to resolve this galaxy’s structure.” Ravindranath also believes that within the first year of observation, Webb will find galaxies even older than 13.4 billion years.
“Webb was set up from the beginning to answer one important and difficult question,” said senior project scientist and Nobel prize-winning cosmologist John Mather. “That’s the early universe question. [It will show us] the first objects to grow from the Big Bang. That’s where there’s a possible big surprise coming. We’ve never seen this era before.”
Catching the weak infrared light from the early universe requires a giant, hyper-sensitive telescope, and that type of telescope makes possible all sorts of other observations as well, Mather said.
These include answering the second question — Are we alone? Webb will give scientists the chance for the first time to analyze atmospheres of small, rocky Earth-like planets orbiting other stars. With its spectrographs, the telescope may discover that those atmospheres contain oxygen, methane, or other molecules that could signal life. But we’re getting ahead of ourselves. The telescope has a long way to go before it can begin observations.
With the powerful push by the Ariane rocket, Webb will cruise for the next 29 days to its destination, abetted by two mid-course corrections made by small thrusters. A third final shove by the thrusters will insert Webb into a halo orbit around the equilibrium point. (These thrusters will fire during the five- to 10-year life of the mission to maintain the orbit and control the telescope’s attitude.)
As Webb travels outward, controllers at the mission operations center at the Space Telescope Science Institute in Maryland will send it commands to trigger an astonishing transformation from a tight chrysalis stuffed in a rocket fairing to a structure with an 18-segment primary mirror—almost three times larger than that of Hubble —and a sunshield the size of a tennis court. This Kapton shield of five hair-thin layers will keep the heat of Earth and the sun from interfering with Webb’s infrared instruments, which are sensitive enough to detect the signature of a bumble bee a quarter of a million miles away.
As the Northrop Grumman Webb alignments engineer, Amy Lo oversaw a team that made sure the sunshield was positioned to fully protect the telescope. She also supervised the alignments of its star trackers and sun sensors. Later, as the Northrop Grumman lead for vehicle engineering, Lo spent years with her team simulating Webb’s myriad deployments. She will stay at the Space Telescope Science Institute over the next month making sure “the vehicle is behaving properly,” she said, and standing by to help the team trouble shoot in case it doesn’t.
The metamorphosis is fraught with risk: NASA has identified 344 individual operations that it calls “single-point failures,” any one of which has the potential to ruin the mission.
John Mather trusts the process followed by the 10,000 people who designed, built, and tested Webb. He told Joel Achenbach of the Washington Post, “We sketched, we argued, we worried, we analyzed, we made a plan, we wrote down everything, we made checklists, we built the parts, we put them together, we tested as though our lives depended on it.”
Having spent the last 10 years seeing the telescope every day, Lo said she will miss its physical presence now that it’s in space.
“But it’s going where it’s supposed to be,” she said. “A space telescope belongs in space. In a way, it’s going home.”
Related TopicsSpace Science
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- Track the journey to L2: https://jwst.nasa.gov/content/webbLaunch/whereIsWebb.html
- AIAA says “we look forward to the new discoveries from JWST that will help us understand the origins of the universe.”