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First person: A scientist's discovery puts space into focus08:09
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This photo provided by NASA, the James Webb Space Telescope is separated in space. (NASA via AP)
This photo provided by NASA, the James Webb Space Telescope is separated in space. (NASA via AP)

Listen to our hour on the remarkable story of the James Webb Space Telescope here.


The James Webb Space Telescope is NASA, the European Space Agency and the Canadian Space Agency's most ambitious space observatory ever. A million miles away from Planet Earth, it is designed to look back to the beginnings of the universe.

MEGHNA CHAKRABARTI: Now, one of the things that I love most about science and discovery is that it is the purest kind of team collaboration. I mean, very, very rarely can we pinpoint one person who revolutionized what science knows and understands about the world. Instead, it's a process, as we definitely heard about the Webb telescope. A process that takes decades, or sometimes centuries, and evolves due to the life's work of thousands of people.

Now, you will never know the names of everyone who worked on the Webb. You'll likely never know the thousands more scientists whose innovations and discoveries in fields from material science to mathematics were instrumental in getting a human telescope one million miles from Earth. So let's turn one of those unknowns into a known.

Allow us to introduce you to Professor Robert Gonsalves, creator of an imaging technique known as phase retrieval.

ROBERT GONSALVES: I invented this stuff in 1975 at age 30. I helped NASA fix the Hubble telescope in 1990 at age 50. And JWST is going to use the same phase retrieval algorithm in 2022 at age 87.

CHAKRABARTI: His innovation is a boon to astronomy for a number of reasons. For example, it doesn't require any ancillary hardware.

GONSALVES: Phase retrieval is the very last step to make sure that everything is tuned up sharp as can be.

CHAKRABARTI: And if images from a space telescope aren't as sharp as they can be, all you've got is an extremely expensive hunk of mirrors and instruments returning super fuzzy and virtually useless pictures. Much like the Hubble Space Telescope first did back in 1990. NASA couldn't replace Hubble's giant mirror.

Instead, they built replacement instruments that fix the flaw much in the same way a pair of glasses correct the vision of a nearsighted person. And it was Gonsalves's phase retrieval technique that snapped Hubble's images into razor sharp focus and allowed humanity for the first time ever to see clearly spectacular images like the birthplace of stars.

GONSALVES: Well, first of all, phase retrieval is an algorithm. It's an unconventional imaging technique which clarifies an unknown flaw in an imaging device. It's similar to autofocus. Without these corrective improvements, images will be blurred. So really, what phase retrieval does is it gives you a prescription to fix what's wrong in the telescope. That's what it does.

When I went to Northeastern University to get my Ph.D., I learned about a lot of things that really I thought were going to be kind of useless. Because that's usually what happens when you write a Ph.D. thesis. You have these things that demonstrate that you know how to do research, but you're not anticipating that will ever be anything that's interesting. Well, my research when I got my Ph.D. was on phase diversity. It really didn't have any application then, and nobody cared about it, until they did. And that's when they found a problem with the Hubble.

[Archival Tape]: Engineers have discovered that the giant telescope has a warped mirror. One of the mirrors in the Hubble Space Telescope is out of shape.

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GONSALVES: And it really it was a simple matter. Namely, what they needed was a prescription. All you do is you have to put a lens in front of the camera that you use and it'll fix it, but you need to know what's wrong with it. And some people were just astonished that we could do what's called phase diversity. We could take an image and from that image, figure out the prescription that would fix this telescope. And it was very easy for me. The reason it was very easy for me because I was teaching my students how to do that. I didn't know it was going to be used for this purpose.

It was just something that I was interested in. We nailed it within a month or two. And then we had to wait three years until two astronauts could get up in the sky and actually put the prescription in place. And then at first light a few days later, the images were beautiful. My students, they were yelling and screaming ... look at how  good we did it!

The errors that were made on the Hubble telescope were one 50th the size of a hair, so I mean, that is really tiny. Well, the tolerances for the James Webb are 10 times higher than that. Because they are looking so deep into space and it's really incredible. I'm interested in algorithms, I'm interested in fixing things, and I'm interested in doing research, and that's about what I've done.

Of course, I'm also interested in teaching. In fact, I taught at Northeastern University for 23 years. I taught at Tufts for another 30 years. I've always really known that I'm a teacher, and it came from the fact that my parents were teachers. And so I started helping people learn math and other things at around age 14, and I learned quickly what I had to do to help people to understand things.

And I've done that my whole life. My whole life I've been helping people and I love it. I mean, I had 10,000 students and I'm still in touch with a lot of them. One of my students wrote, Bob, you were the best teacher I ever had in grad school at Northeastern University. Your skill is in being able to make us understand mathematics behind optics and mathematical physics was key in my training and everyone else lucky enough to have you as a professor. It's no surprise that you were the father of the wonderful technology for the JWST.

CHAKRABARTI: Robert Gonsalves, professor emeritus at Tufts University and father of the phase retrieval imaging technique now being used by the James Webb Space Telescope.

This segment aired on April 1, 2022.

Tim Skoog Sound Designer and Producer, On Point
Tim Skoog is a sound designer and producer for On Point.

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