How Bay Area scientists designed the most powerful telescope in history

Scientists seek to understand what happened between the Big Bang and today

As astrophysicists gazing into the cosmos attempt to explain what happened between the Big Bang and the present day, they’ll be relying on some far-out technology developed in San Francisco’s own backyard.

The James Webb Space Telescope — the most complex space science observatory ever built, according to NASA — launched into space on Christmas Day and is now on a million-mile journey from Earth. The mission? Capture infrared light to see what galaxies nearly 13.5 billion years ago might have been like in an effort to better understand our place in the universe today.

“There really is nothing like the excitement when you’ve worked to build something, then you turn it on and you’re getting data and its something mankind never knew before,” said Thomas Roellig, chief of the Astrophysics Branch at NASA’s Ames Research Center, who has been working on the detector technology for nearly 20 years. “It is a real rush.”

Scientists at the center in Mountain View have been developing the cutting-edge detector technology that sets the $10 billion Webb telescope apart from other space observation missions. Now that the telescope has launched into space, the Bay Area researchers will also join others around the globe to investigate and analyze the never-before-seen evidence that Webb gathers.

Thomas L. Roellig, of the NASA Ames Research Center in Mountain View, has been working on the Webb telescope for nearly 20 years.

Thomas L. Roellig, of the NASA Ames Research Center in Mountain View, has been working on the Webb telescope for nearly 20 years.

Compared with its predecessor, the Hubble Space Telescope, Webb is about 100 times more powerful and has nearly six times the light-gathering capacity.

Its mirrors gather light and direct it to scientific instruments, which then filter and focus the light on the detectors. Those detectors then absorb photons and convert them into electronic voltages that can be measured and analyzed.

The larger and more sophisticated detectors on Webb allow observers to measure light outside of the visible range, including infrared and mid-infrared wavelengths. In comparison, the Hubble could only detect visible light. That key difference will allow scientists to observe molecular clouds, dust and events in otherwise hidden parts of space.

“A star that’s far away is flying away from us very rapidly,” Roellig explained. “So if you want to look at the very first stars, you have to do it in infrared because it won’t be very visible.”

While Hubble orbits Earth from relatively close, Webb will be 1.5 million kilometers away once it reaches its destination in what’s called the second Lagrange, or L2 point, a position in space where objects remain in orbit.

The five-layer sunshield of the James Webb Space Telescope, which will keep the optics and sensors cold in order to search deep space while another part of the telescope faces the Sun to absorb its rays for energy use. (Photo by Chris Gunn/NASA)

The five-layer sunshield of the James Webb Space Telescope, which will keep the optics and sensors cold in order to search deep space while another part of the telescope faces the Sun to absorb its rays for energy use. (Photo by Chris Gunn/NASA)

In addition to the earliest galaxies, Webb scientists will also scan known planets outside of our solar system, called exoplanets, for evidence of life by looking for chemicals that life forms produce such as methane, nitrous oxide and ozone.

“What we see now is what happened billions of years ago, and we have reasons to believe the universe was very different back then. People like us wouldn’t exist,” said Roellig. “Now, with the sensitivity of James Webb, we can for the first time see if there is any evidence if there is life on them.”

A joint effort between NASA, the European Space Agency and the Canadian Space Agency, Webb launched into space on a rocket out of French Guiana in South America on Dec. 25. The first images are expected to come in after about six months.

In the weeks since launch, Webb has been unfurling its massive plastic, tennis court-sized sun shields that protect the mirrors, detectors and other equipment from sun radiation. It’s among the most challenging milestones for the mission, but only one of about 10 delicate procedures that Roellig calls “single point fails,” where any misstep could end the mission.

Parts of the observatory require self-assembly, and other elements are led by an operations team based at Johns Hopkins University in Baltimore. After unfolding the sunshades, the next big step will be assembling the telescope’s main mirror, which extends about 21 feet across.

“Once we get these first 29 days I can sleep much more soundly,” said Roellig.

sjohnson@sfexaminer.com

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