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Sunday, June 23, 2024
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Q&A: NASA’s Dr. Ken Sembach talks Webb Telescope and career trajectory

Dr. Kenneth Sembach’s infatuation with space began when he was a graduate student studying astronomy at the University of Wisconsin-Madison. He was a Hubble Fellow at the Massachusetts Institute of Technology (MIT) and eventually ascended to the role of director of the Space Telescope Science Institute (STSci) in 2015. 

In this position, Sembach directed the creation and subsequent launch of the James Webb Telescope or “The Webb.” The Webb Telescope was launched a million miles into space last December with the goal of looking back in time to provide the world’s leading astronomers with information about when the universe’s first galaxies were formed. 

This conversation has been edited for clarity and brevity.

I read that your journey to becoming one of NASA’s top astronomers blossomed from a fifth-grade book report. Tell me about that. 

When I was in fifth grade, we had a library class once every other week and they’d take you out to the library and you’d do a book report on it. As a kid, I loved to read so it was never a problem for me, but one afternoon when we went down there, I couldn’t decide what book to pick. The bell rang at the end of the class and I didn’t have a book so I picked up the nearest book on the shelf and it was “A Field Guide to the Stars,” a little book by Herbert Zim, one of the golden guides at the time, and it had pictures of the constellations in it. I took it home and decided to put it to use. I lived on the south side of Chicago, and the skies got really dark, but with that little field guide I could actually find my way around even in my backyard.

For those who are unfamiliar with your career trajectory, do you mind talking about your career path and how you ended up at STSci?

I graduated from UW-Madison in 1992. When I was a student there, I applied for the Hubble fellowship, which was a fellowship to help create future leaders. It was part of the Hubble Space Telescope program, and I took one of those fellowships for four years at MIT where I did research of my own choosing and worked with people in different departments.

Then, I went to Johns Hopkins to work on a project called the Far Ultraviolet Spectroscopic Explorer, which was an ultraviolet astronomy mission designed to look at waves that are bluer, or more violet than those that Hubble can see. Having been trained at Wisconsin as a spectroscopist, this was right up my alley. I became the deputy project scientist there for the mission. 

In 2001, I moved over to the Space Telescope Science Institute as an instrument scientist working on one of the new instruments for Hubble that was to be launched and replaced in the telescope with the final servicing mission, which was canceled after a few years. I worked my way up in the ranks and served in different offices before becoming director. 

Tell me a little about the launch of the Webb Telescope. Were you ever nervous about specific stages of the deployment? Was there ever a point where you knew the launch was going to be successful?

The launch day was on Christmas last year. It was a special day because we [at the institute] had waited for so many years and had so many launch dates. There was a sense of relief; it was actually going to happen. When the launch occurred, everyone was very happy —  myself included. Seeing the solar panel come out, which lets you know you have power, was a big step. Then we played a little bit of a waiting game for a day or two waiting for the actual deployments. 

The main deployments for the telescope occurred over the first two weeks when the sunshield was deployed, and the primary and secondary mirrors were put in place, at that point, we really breathed deep and knew we had a working telescope. The main things that could’ve gone wrong didn’t because of all the testing and planning. 

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Is there something you hope historians will take away from this ambitious project?

I hope that when people look back on this, they see what was necessary to actually accomplish something of this scale, such as the testing and the preparations. These ambitions take a lot of preparation given you have to get it right or else it doesn’t work. There are hundreds of single-point failures that could’ve derailed the mission, but the real legacy here is that you can actually do something complicated and ambitious if you really pay attention to all of the details and get it right. 

It’ll also completely change the way we view the universe — we’re looking at the universe in a whole new light. It’s a little cliche to say it’s a new window on the universe, but we really are looking at it in a different way and seeing things differently than we ever have before with other great observatories like Hubble. Having both of those observatories working together, I think people will eventually look back on this as a golden era in astronomy. I don’t know when we will have two such telescopes in space working together like that. 

I read that the Webb Telescope will be able to see further back in time than ever before. Can you explain how the telescope will do just that?

Webb looks at infrared light. The universe is expanding from the Big Bang, and as the universe expands, the light from distant objects gets stretched out on its journey to us. When the wavelengths of light get stretched out, they get redder. Eventually, some of those objects that are so far away get so red that we can’t see them from the ground with Hubble, and you have to actually look at infrared wavelengths. At a certain distance, the universe becomes dark to Hubble because all of the light has shifted out of its bandpass. That’s where Webb comes in; Webb can actually look into those regions to see where those first stars and galaxies are in the universe and when they started forming relative to the Big Bang. 

Has there been any data from the Webb Telescope that changed previous scientific findings?

One thing we’re finding is that galaxies seem to be forming very early, and that’s a little confusing. They were forming maybe even a little earlier than we thought, and so you need enough time between the Big Bang and those galaxies having formed to understand the galaxy formation. That’s not so much a problem with the Big Bang Theory as it is a problem in understanding how galaxies form in the first place. That process is faster than we potentially thought. That’s something worth studying and that we will be studying over the coming years. 

Do you know how long the Webb Telescope will stay in orbit?

Webb was designed to last a long time. It has enough fuel on board to last at least 20 years by our current estimates. You’ll be able to tell your kids about it, and they’ll be looking at pictures from Webb for a long time just like we had with Hubble. 

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