EPISODE 158: HUBBLE: AN ENGINEERING MARVEL

Transcript

Andres Almeida (Host): The Hubble Space Telescope is one of the most iconic observatories in history. It’s not just for the stunning images of the universe and the groundbreaking science, but for the incredible engineering that keeps it working more than three decades after launch. How does Hubble work, and what’s in store for space-based astronomy? Let’s get into it in this episode of Small Steps, Giant Leaps. 

Welcome to Small Steps, Giant Leaps, the podcast from NASA’s Academy of Program, Project and Engineering Leadership, or APPEL. I’m your host, Andres Almeida. 

Today we’re diving into how Hubble has overcome technical hurdles with two people who know the space telescope very well, Morgan Van Arsdall, deputy mission operations manager, and Lynn Bassford, flight operations manager. Both are based out of NASA’s Goddard Space Flight Center in Maryland. 

Morgan, just what makes Hubble an engineering marvel? 

Morgan Van Arsdall: It’s part of, really some of the most historic telescopes. You think of Galileo’s telescope that opened us up to this whole new universe, and then Hubble really did, as one of the first major space telescopes, that helped us see exactly how beneficial it can be to have space telescopes, in general, to get above the atmosphere. 

And then for Hubble, specifically, some of the things that is very unique is obviously first that it’s in space, so that it gets to be above the atmosphere and above that distortion, but also it’s pointing is one of the really important and amazing engineering feats of it, so that it can point at an object and maintain that pointing while it is orbiting Earth, and then even drop that pointing and then pick it up again after it’s gone to the other side of the Earth, and then repoint again at the same target just as accurately over and over again. 

So, when you combine the pointing with being above the atmosphere, you get really revolutionary ability to explore the universe. 

Host: That’s wonderful. And Lynn, you have a different perspective. What to you makes it an engineering marvel? 

Lynn Bassford: The fact that it’s using solar panels and batteries rather than rocket fuel and joysticks, and it’s using calculations that are done well in advance.

As Morgan said, it’s pointing at these really, really distant objects, and it’s maintaining lock on it as it goes around the Earth.  A calculation done by a computer for how much its reaction wheels will spin up about the about a 100-pound bicycle tire, if you want to think of it that way, or a hamster wheel. It spins up just the right amount of momentum needed in order to move us. 

And then it’s also “the people’s telescope” as well, that anyone could put in a proposal if they wanted to, to look at something, if they understand the level of knowledge that’s needed. 

Host: So, what do Hubble gyroscopes do? And how have they changed over time, since we’re now coming up on 35 years of operations? 

Van Arsdall: So, Hubble’s gyroscopes are really a key part of the pointing and control system. And the original design for Hubble required it to use three gyroscopes at a time to point. 

When we first launched, we had six gyroscopes so that there were redundancy for each of the gyroscopes. But the initial gyro design actually had some issues so it would fail–, the gyros were failing relatively quickly. When we had servicing missions, we were able to replace them, so that really helped us keep the mission going. But the next generation of gyroscopes were, are a lot more stable and a lot more long lasting, which has been great. 

It did cause some other issues in how they operate, so we had to learn how to operate with these new gyros. But now that we’ve gone on for 35 years, some of several of the gyros on orbit have died, and obviously we don’t have servicing missions anymore to replace them. So recently, we were able to transition to a new science mode that only requires one gyroscope, which was really exciting, that all of the design and prep we had done for that was able to be so successful. So, now we are operating on orbit with just one gyroscope, and that has still been able to do all of the amazing science. 

So, at this point, we have one gyro that we’re using. We have another functioning gyro. That is available if this gyro that we’re using stops working, and then we actually have a third gyroscope that has some issues. So, it really isn’t ideal for you doing science operations, but we are thinking about ways that we could still use it if needed. 

Host: And space is such a harsh environment. How is Hubble protected from extreme conditions? Lynn, I’d love to ask you that. 

Bassford: The way that Hubble was envisioned was the bays and the compartments inside Hubble between the various equipment built to be optimal thermally. But really the key that we find is the multilayer insulation that’s this very thin layer on the outside of the telescope. So, silver on the outside, this black on the inside and against the Hubble shell. 

During that 90-minute orbit Hubble has around the Earth. That’s the temperature swing, because we’re like roughly 40% in night and 60% in day. And you can imagine those 350-degree delta in that one 90-minute orbit could crack rocks on Earth, in the desert, for example. 

Host: In the beginning, the images coming back were a little bit fuzzy. What did engineers learn from that? And how was that rectified? For Morgan, please. 

Van Arsdall: Yeah, so when Hubble was initially launched, our primary mirror was ever so slightly out of focus. It actually was less than the width of a human hair. Fortunately, because Hubble was designed to be serviced. In the very first servicing mission, we were able to install something called COSTAR, which was corrective optics for the space telescope. And basically, it’s a pair of glasses. 

So, as the light was bent incorrectly on the primary mirror, this COSTAR instrument would bend the light back in exactly the right amount so that the image would end up being as crisp and as pristine as it should be. That was the first servicing mission, and we had COSTAR installed for several years. But after that, all of the science instruments that were built from then on actually were designed with the optics to take into account the primary mirror’s actual shape. So, eventually we were able to replace COSTAR with another science instrument. So basically, we put glasses on Hubble. 

Host: How do engineers monitor Hubble’s health as it ages? 

Van Arsdall: So, we have a team on the ground here at Goddard Space Flight Center that is always monitoring the telemetry and, basically, for all of the things that come down. 

So, the telemetry is monitoring the temperatures and the power and our pointing and how everything, basically, how all of the components on orbit are working. And we have limits for those. We know what they should be. We know what they expect them to be, so our computers are always monitoring it. And whenever anything is either too high or too low, so too hot or too cold, for example, we are notified. 

Right now, Hubble is in automated operations, so the computers are monitoring all that telemetry for us, and then if something is out of limits, they send a page out to whoever is on call that week to go and look at it, for the humans to go and look at it. So that’s the sort of real time monitoring that happens with all our telemetry points. 

But we’re also always looking for trends over time, right? After 35 years, you would expect that different pieces of hardware are going to be functioning slightly differently, right, whether they’re operating more warmly or require more power or things like that. 

So, all of our systems engineers are also monitoring trending, and we’re looking at weekly trending and monthly trending and monthly trending and quarterly trending, but we’re also looking at all of these telemetry points literally over the lifetime. 

So, for some things that have been on orbit since launch, not only are we looking at the weekly trending, but we’re also looking at the lifetime, the last 35 years of the trends, so that we can see in advance if something might not be out of limits yet, but trending in the wrong direction or giving us some kind of concern. And Lynn’s group actually does a lot of the trending, so I’m sure she can add to that. 

Bassford: The cool thing is, what we did with that automation, because when I started my first eight years on Hubble, I was on console rotation 365 days a year. So, day shift one week, swings the next, third shift the next. And those 10,000 points of telemetry that we are looking at were on screens in front of us, and we were looking for red and yellow flagging of those particular items. 

And we would have to look it up. And sometimes we would have hundreds of them out at one time that we’d be looking into and then tracking down through manuals – paper – that were in back of us to see what it was. And it was marvelous to actually see a way to automate this so that the computer is now passing on to a system that can pass it on to the expert to look into. 

And that we can log on our phone and we can do a little bit [of] analysis if we’re the one on call, and then we can log on to the laptop remotely and say, “When was the last time this occurred? What were the seasonal conditions? What was the orbit of Hubble?” And try and figure out the severity of what’s going on and pass on that recommendation for how we should proceed. 

And also, we’re also starting to look at the recovery time. 

Host: So how does Hubble data transfer happen? How does it transmit images back to Earth? 

Bassford: Some neat thing about Hubble, too, is we get the data in general, our engineering data, back in less than a second. But when it comes to the images, whether they’re the visible images, whether infrared or whether the spectroscopy, we store those on board solid-state recorders, and that’s all automatically scheduled within the computer loads that we have. We’ll downlink that data to the ground through the TDRS system done out of White Sands, New Mexico, and then that comes to us, to NASCOM (NASA communications) and to Hubble.  

So basically, it’s coming through the IP line these days. 

And it’s zeros and ones that we’re seeing in house by my team. We look at the data for quality errors, and we fix those if necessary. That might be playing back the data from the spacecraft and piecing together things, or it could be taking little chunks of data that got repeated out. Again, we’re seeing the zeros and ones, and the data from us is automatically transitioned to Baltimore.   

Host: And that institute you mentioned, that’s the Space Telescope Science Institute, correct? 

Van Arsdall: Correct, yes. So, we work with them, hand-in-hand. 

Host: Morgan, I’d love to pivot to you for a little bit about risk management. How did you all handle the issue in 2021 when the onboard computer stopped Hubble from collecting data? 

Van Arsdall: In the summer of 2021, our science data computer stopped working. And really, we have two computers on board, main computers. One that is sort of more taking care of the satellite as a whole, and then our science data computer. And those computers are talking to each other. 

So, the science computer, when everything’s working perfectly, is always sending a signal to the main computer saying, “Hey, I’m here. Everything’s fine.” So, it stopped sending that signal. 

And because of our automated system, all of us were at home, right? Because this was the summer of 2021, so we were still in COVID protocols. We all got the text messages that something was wrong, and the science data going down into what we call fixed format. Obviously, it was a big deal. We knew that that was a problem. 

But at first, we, we hoped, I guess, that something, you know, something had happened, some sort of upset that we would be able to recover quickly from. So, the initial thing we did was, like pretty much everybody does when you have a computer problem, right, after we knew that everything else was safe and we understood what had happened, we basically tried to clear the errors and turn it back on. It wasn’t until that second time when it turned back on briefly and then “safed” itself again that we knew we had a really major problem with the science computer. 

And then, over the course of several weeks, actually, we gathered all of the experts. We even were able to call back people that had worked on Hubble years and years ago, who were experts on the science computer. We were able to call in people from other parts of NASA. And then, obviously, all of the Hubble team really dug in and investigated to try to understand what the problem might be, and we did several on orbit tests to try to isolate where the issue was coming from.

And, unfortunately, we weren’t able to keep the science computer working on the side that it had been on. The good news is that all of the critical components on Hubble have redundancy, and that’s really one of Hubble’s biggest risk management methods is that it was designed with an enormous amount of redundancy and ability to be cross-strapped. 

So, after several weeks of investigation, several weeks of on-orbit testing, we were able to switch the science computer from the side it had been operating on to the backup side. And there was definitely a lot of holding our breaths, because we hadn’t been operating on the backup side for years, right? So, we assumed and hoped that it was working. We didn’t have any reason to believe that it wasn’t, but after all those years, you just never know if there had been a failure that we just didn’t know about, right? 

So, we switched the side. Everything came up perfectly, and we were able to get back to our regular science operations on the redundant side of that computer. It was really an amazing, an amazing amount of teamwork during that time because we had every single member of the team working incredibly long days, mostly seven days a week, for several weeks to get this change happening just as soon as we could to get back to science. 

And again, this was in the middle of 2021, so we also had to worry about COVID issues, and we were really conscious about minimizing the people that had to come on site, to Goddard, making sure that when they did come on site, people stayed separated, things like that, so that added a whole ‘nother layer of complication to the response. But it was, it was really exciting to see everybody work together, really gratifying that anybody who asked for help just hop to it right away, without any, any hesitation, any questions. 

Host: That sounds like a team bonding experience. 

Van Arsdall: [Laughter] It really was! Yeah, definitely. Lots, lots of people working together. 

And now we are currently working on something called B-side science operations that we believe we have identified a way so that we can actually keep doing science on the side that had failed. It will be less efficient than what we’ve done in the past, and we’ll have some other kind of operational changes, but that’s something we’re always doing as far as risk mitigation is, okay, given where the telescope is now, how can we change and how can we prepare if there’s another anomaly in the future? 

Host: Yeah, and I see it’s paying off, because you go on nasa.gov/hubble, and you can continue seeing the latest from Hubble. It’s, it’s operating, bringing back science. 

So, Lynn, how has Hubble shaped the design of newer telescopes? 

Bassford: If you don’t mind, I’ll let Morgan answer that one. 

Host: Oh, sure. 

Bassford: Because there’s another secret, hidden hero aspect of Morgan that she’s actually going to be the operations manager for the Roman Space Telescope, which is spun off of Hubble. So, she’d probably be perfect for that. 

Host: Wonderful. Morgan, please go ahead. 

Van Arsdall: Absolutely! So, I think really [on] the most fundamental level, Hubble proved that having a space telescope is not just possible, but worthwhile, right? 

So, by Hubble’s very existence and the amazing science it’s been able to do, it’s really driven the whole concept of space telescopes forward. As far as specifics go, Hubble operates in mostly in the visible light, with a little bit into the ultraviolet and a little bit into the near-infrared, and a lot of the science that Hubble has been able to do in those wavelengths formed the basis of the further science that James Webb Space Telescope was able to do operating in the infrared. 

So, Hubble and JWST, working in concert throughout the different wavelengths, are able to do that much more science and understand things in that much more detail, because we can cover additional wavelengths. 

And then looking forward to the Roman Space Telescope, which will be launched in late 2026, that will also be mostly infrared with some visible light. And both James Webb and Roman are out at a point we call L2 or Lagrange point 2, which are much, much further away, right? Hubble is in low-Earth orbit around Earth. L2 is much further away from Earth. 

Host: A million miles away for us, right? 

Van Arsdall: Yep, absolutely, out beyond the Moon. So, being able to basically learn how to operate a space telescope, and learning how, what kind of science you can do with that has really fed into the design of the telescopes, as well as how we’re going to operate them, where they should be, what we should be looking at for all of the future space telescopes. 

Bassford: If I can add a visual to that, you see, the Pillars have been a picture that been out there since 1995 and then Hubble upgrade its instruments in 2009 for that near-infrared channel Morgan’s talking about. So, you see a picture that’s visible light. It’s beautiful, and they had predicted a long time ago, there will be a couple baby stars on the fingers. And then the next picture taken with the same camera, same time frame, with that near infrared shifts the spectrum a little bit to the right, and it’s able to push through all those gas and dust by doing that. And now you start to see thousands of stars that you couldn’t see in the visible light, but you can see in the near infrared. 

Host: That Pillars of Creation image is a classic and a favorite for many, including myself. So, Lynn, what do you hope Hubble’s legacy will be generations from now? 

Bassford: I hope that Hubble is still up there and still operating. At the moment, we’ve only seen [a] very small part of the universe over time, even though we’ve explored and we’ve discovered so many new things and changed so many books.

Host: Morgan, what is your take on that? How do you hope Hubble’s legacy will be generations from now? 

Van Arsdall: I think Hubble really, really did just completely change how humans understand the universe and how humans understand their place in the universe, right? 

If you look at science textbooks from the ‘70s and ‘80s, the images of what we thought was out there [is] completely different than the reality that we learned once Hubble was on orbit and doing science. And I think that that’s something that even generations from now, people will be looking back on and saying, “This is when we really started to be able to see what the whole universe looks like,” and completely changed our understanding. Completely changed, not just the science, but really kind of on a human level, what we’re part of, where we fit into this beautiful, gorgeous universe, right? 

You look at Hubble pictures, and the astronomers can get amazing data and science out of it, but as a human, you still look at the picture and say, “This is amazing. This is beautiful.” And the fact that Hubble was really the first telescope to, to open our eyes to what things looked like, I think, is something that will forever be part of science books and history books. 

And even now, it’s really a generational telescope, right? We have people who have worked on Hubble since it was, you know, since before launch, in the ‘70s and ‘80s, and have been on Hubble their entire careers. But we also have people working on Hubble who literally weren’t born when the telescope was launched in 1990 and just from that point of view, having this science instrument that has been through now really a whole generation of scientists and engineers also really makes a difference for how we can pass on that legacy. 

Host: It’s a strong legacy, for sure. To close this out, I’d like to go back to Lynn. What do you consider to be your giant leap? 

Bassford: My giant leap was being offered and taking the job to work on Hubble after I graduated from college with a physics degree, I continued to work at the college and into the summer afterwards, and I got a call on the answering machine that my mother called and told me. She said, “Mr. Adventure is offering a job for you working on a telescope in space, and is wondering if you’re interested.” I’d always wanted to be a NASA astronaut, so I was like, “Wow, that sounds really cool – Mr. Adventure!” I called him back and I found out his name was Mr. Ed or Edward Venter. 

[Laughter] 

And so, I was like, “Well, this is the start of something promising.” And it was indeed an adventure, and it has been an adventure, and it’s been great. So that’s, that’s really my step forward. 

Host: That’s really memorable. Morgan, what do you consider to be your giant leap? 

Van Arsdall: So, I think, like pretty much everybody at NASA, right, I always loved space as a kid. Growing up, I went to Space Camp. I did all the things. School and high school was relatively easy. I was a good student in high school, and then I got to college. 

Freshman year, I was majoring in aerospace engineering, and it just hit me like a ton of bricks, right? Classes were really hard. My grades weren’t great, despite working harder than I ever had at school. And there was definitely a point in freshman year of college where I said, “You know, this isn’t, this isn’t for me. I guess I’m not, not going to be an engineer.” And luckily, talking to my parents and talking to some professors, they, you know, gave me some support and gave me some encouragement to stick with it. And I think that that was the giant leap of saying, “You know, it’s okay to not for things to not be easy,” but it’s worth, it’s worth the effort and stick with it. And, you know, if 18-year-old me could see a grown up me now doing this job that was, that was definitely a giant leap. That was worth it. 

Host: That’s wonderful. Lynn and Morgan, thank you both so much for your time today. I hope couples legacy has impacted you the same way it impacts the public. 

Bassford: Thank you very much. 

Van Arsdall: Thanks so much. It was fun talking about it. 

Host: That wraps up another episode of Small Steps, Giant Leaps. For more on Morgan and Lynn, visit our resource page appel.nasa.gov. That’s A-P-P-E-L dot NASA dot gov. And don’t forget to check out our other podcasts like Houston. We Have a Podcast, Curious Universe and Universo curioso de la NASA, now in their third season. 

As always. Thanks for listening. 

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