December 4, 2023


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NASA’s John Mather continues to redefine our understanding of the universe

NASA’s John Mather continues to redefine our understanding of the universe

Space isn’t just difficult because of rocket science. The task of moving NASA’s mission from development and funding to construction and launch — all before we use the object for scientific purposes — could span decades. Their entire careers have been spent putting a single satellite into space. John Mather, a Nobel Prize-winning NASA physicist, has already helped send two.

In their new book, Inside the Star Factory: The Construction of the James Webb Space Telescope, NASA’s largest and most powerful space observatory, Author Christopher Wanjek and photographer Chris Gunn take readers on a behind-the-scenes tour of the James Webb Space Telescope’s journey from inception to orbit. Textile examinations of the radical imaging technology that enables us to delve deeper into the early universe than ever before with profiles of the researchers, consultants, managers, engineers, and technicians who made it possible through three decades of effort. In this week’s excerpt from Writing, a look at JWST project scientist John Mather and his unlikely journey from rural New Jersey to NASA.

MIT Press

Adapted from “Inside the Star Factory: The Construction of the James Webb Space Telescope, NASA’s largest and most powerful space observatoryCopyright © 2023 by Chris Gunn and Christopher Wanjek. Used with permission of the publisher, MIT Press.

John Mather, project scientist

– Steady hand in control

John Mather is a patient man. It took thirty years for him to receive the 2006 Nobel Prize in Physics. That prize, for definitive evidence of the Big Bang, was based on a bus-sized machine called COBE, another NASA mission that almost never happened. Drama design? I was there. Are you navigating unexpected delays? I did that. NASA’s selection of Mather as JWST project scientist was pure insight.

Like Webb, COBE – the Cosmic Background Explorer – was intended to be a time machine to reveal a snapshot of the early universe. The target era was just 370,000 years after the Big Bang, when the universe was still a fog of elementary particles with no discernible structure. This is called the Epoch of Recombination, when the hot universe cools to a point that allows protons to bond with electrons to form the first atoms, mostly hydrogen with a sprinkling of helium and lithium. As the atoms formed, the fog cleared, and the universe became clear. Light penetrated. This ancient light, from the Big Bang itself, is with us today as a remnant of microwave radiation called the cosmic microwave background.

Tall but never imposing, demanding but never mean, Mather is a study in contrasts. He spent his childhood just a mile off the Appalachian Trail in rural Sussex County, New Jersey, where his friends were busy with mundane matters like farm chores. However, Mather, whose father was an animal husbandry and statistics specialist, was more interested in science and mathematics. At the age of six, he grasped the concept of infinity when he filled a page in his notebook with a very large number and realized he could go on forever. He loaded himself with books from a mobile library that visited farms every two weeks. His father worked at Rutgers University’s Agricultural Experiment Station and had a laboratory on the farm with radioisotope equipment to study metabolism and liquid nitrogen tanks with frozen bull semen. His father was also one of the first users of computers in the area, around 1960, keeping milk production records for 10,000 cows on IBM punch cards. His mother, an elementary school teacher, was also quite educated, and fostered young John’s interest in science.

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Ultimately, the opportunity for year-round warm weather brought Mather in 1968 to the University of California, Berkeley, for graduate studies in physics. He would have joined a crowd of people fascinated by the newly discovered cosmic microwave background radiation, which was discovered by chance in 1965 by radio astronomers Arno Penzias and Robert Wilson. His thesis advisor devised a balloon experiment to measure the spectrum, or color, of this radiation to see if it actually came from the Big Bang. (It is.) The next obvious thing is to map this light to see, as the theory suggested, whether the temperature changes slightly across the sky. Years later, this is what he and the COBE team discovered: anisotropy, an uneven distribution of energy. These small temperature fluctuations indicate fluctuations in the density of matter, sufficient to halt the expansion, at least locally. Through the influence of gravity, matter will collect in cosmic lakes to form stars and galaxies hundreds of millions of years later. In essence, Mather and his team have captured an audio blueprint of the nascent universe.

However, the COBE mission, like Webb’s, has suffered setbacks. Mather and the team proposed the mission concept (for a second time) in 1976. NASA accepted the proposal, but that year, announced that this satellite and most others from then on would be delivered into orbit by the Space Shuttle, which itself was still Running. In development. History will reveal the folly of such a plan. Mather understood immediately. This linked the COBE design to the cargo bay of the unbuilt shuttle. Engineers will need to meet the exact mass and volume requirements for a ship that has not yet flown. Even more troublesome is that COBE requires a polar orbit, which is difficult for the Space Shuttle to deliver. The COBE team was then burdened with budget cuts and compromises in the COBE design as a result of cost overruns for another pioneering space science mission, the Infrared Astronomical Satellite, or IRAS. However, hard work has continued to design instruments sensitive enough to detect temperature changes that are only a few degrees above absolute zero, about minus 270 degrees Celsius. From 1980 onwards, Mather was busy creating COBE all day, every day. The team needed to cut corners and make risky decisions to stay within budget. COBE was reported to have been launched on the Space Shuttle mission STS-82-B in 1988 from Vandenberg Air Force Base. All the joins are coming.

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Then the Space Shuttle Challenger exploded in 1986, killing all seven crew members. NASA has suspended shuttle flights indefinitely. COBE, now restricted to shuttle specifications, was unable to launch on any other rocket system. The COBE was too large for a Delta rocket at this point; Ironically, Mather had Delta in mind in his first drawing in 1974. The team looked to Europe for a launch vehicle, but that was not an option for NASA. Instead, project managers led a redesign to cut hundreds of pounds, trimming the launch mass to 5,000 pounds, along with fuel, which would bring it within the delta limits by a few pounds. Oh, and McDonnell Douglas had to build the Delta rocket from spare parts, after having to discontinue the series in favor of the Space Shuttle.

The team worked around the clock for the next two years. The final design challenge was… wait for it… the sunshade, which now had to be folded up inside the rocket and launched once into orbit, a new approach. COBE got the green light to launch from Vandenberg Air Force Base in California, a location originally requested because it would provide easier access to a polar orbit than launching a shuttle from Florida. Launch was scheduled for November 1989. COBE was delivered several months early.

Then, on October 17, the ground of California shook violently. A 6.9 magnitude earthquake struck Santa Cruz County, causing widespread damage to buildings. Vandenberg, 200 miles south, felt the tremor. Fortunately, the COBE was only securely installed because two of its supervising engineers secured it that day before going to the wedding. The machine suffered no damage and was successfully launched on November 18. More drama came with high winds on launch day. Countless concerns followed in the first weeks of operation: the cryostat cooled down too quickly; Sunlight reflecting off Antarctic ice has wreaked havoc on the energy system. Electrons and protons trapped in Van Allen belts disabled electronics; And so on and so on.

All the delays, all the drama, faded into a distant memory for Mather as the COBE trial results came in. It may take four years to collect data. But the results were amazing. The first result came weeks after the launch, when Mather showed the spectrum to the American Astronomical Society to a standing ovation. The Big Bang was safe as a theory. Two years later, at a meeting of the American Physical Society in April 1992, the team showed their first map. The data matches the theory exactly. This was the afterglow of the Big Bang that revealed the seeds that would grow into stars and galaxies. Physicist Stephen Hawking described it as “the most important discovery of the century, if not of all time.”

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Mather spoke humbly about this discovery in his Nobel Prize acceptance speech in 2006, giving full credit to his brilliant team and colleague George Smoot, with whom he shared the prize that year. But he did not downplay the importance of the achievement. He noted that he was thrilled by the “broader recognition that our work was as important as people in the world of professional astronomy have long known.”

Mather maintains this realism today. Although he was concerned about delays, threats of cancellation, cost overruns, and not-so-subtle hostility in the broader scientific community over “the telescope that ate astronomy,” he did not let it consume him or his team. “There’s no point in trying to manage other people’s feelings,” he said. “A lot of community feedback is, ‘Well, if I had a nickel, I would spend it differently.’” But it’s not their nickel. The reason we have the nickel in the first place is because NASA faces incredibly big challenges. Congress has agreed “We face great challenges. And great challenges are not free. My feeling is that the only reason there is an astronomy program at NASA for anyone to enjoy — or complain about — is because we do amazingly difficult projects. We push to the edge of what’s possible.”

Mather added that Webb is not a bit better than the Hubble Space Telescope; It’s a hundred times stronger. However, his biggest concern while designing the mission was not the advanced astronomy instruments, but rather the massive sun shield that had to open. Redundancy is built into all tools and all deployment mechanisms; There are two or more ways to make it work if the basic method fails. But this is not the only problem with sunscreen. It either works or it doesn’t.

Now Mather can focus fully on the science to be acquired. Expect surprises. He’d be surprised if there were no surprises. “Almost everything in astronomy comes as a surprise,” he said. “When you have new equipment, you will get a surprise.” His hunch is that Webb might reveal something strange about the early universe, perhaps an abundance of never-before-seen short-lived objects that says something about dark energy, a mysterious force that appears to be accelerating the expansion of the universe, or an equally mysterious force. Dark matter. He also can’t wait for Webb to turn his cameras to Alpha Centauri, the closest star system to Earth. What if there was a planet suitable for life? Webb is supposed to have the sensitivity needed to detect what molecules, if any, are present in its atmosphere.

“That would be great,” Mather said. Hints of life from the nearest star system? Yes, really cool.