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Cory Nealon:
Dr. John Crassidis was just a toddler when astronauts first landed on the moon. But by the time he was five, he was obsessed with the moment.

John Crassidis:
My first Halloween costume was an astronaut. So I wanted to be an astronaut.

Cory Nealon:
It sparked a passion for space that only grew with time. Today, Crassidis is the Moog Professor of Innovation and SUNY Distinguished Professor of Aerospace Engineering at the University at Buffalo. More importantly to you and me, he's the guy keeping satellites and objects in space from crashing into each other. Welcome to "Driven to Discover," a University at Buffalo podcast that explores what inspires today's innovators. My name is Cory Nealon and I will be your host for episode one, "Space Junk."

Dr. Crassidis, can you take us back to your childhood and tell us what first inspired your curiosity with space?

John Crassidis:
Absolutely. My father had a National Geographic magazine.

Apollo 11 Audio:
We have a lift off. Lift off on Apollo 11.

John Crassidis:
And my twin brother and I played that over and over again about the Apollo landing.

Apollo 11 Audio:
That's one small step for man, one giant leap for mankind.

John Crassidis:
It had a little record on it that we would listen to over and over again until it actually broke and we couldn't listen to it anymore. That's what really drove my passion into space.

Cory Nealon:
Over time, though, you’ve become a professor. When did you make this pivot to academia?

John Crassidis:
I got my dream job as a postdoc at NASA Goddard Space Flight Center. I got to work on real missions. At the time I was applying to be an astronaut. Didn't make the cut. For mission specialists, the vision requirement was 20/200. I have much worse than that, so I couldn't even pass the eye test. And that's fine. So I wanted to see what else I can do. I loved working at NASA. The opportunity came to be a professor. And NASA wanted to keep me on, but I said, "Hey, can I try this academia and see if I like it? If I don't, can I come back to NASA?" They said, "Yes, you can." I went out to academia, loved it. I get the best of both worlds. I get to work with NASA, and all these other agencies, and do the research that I enjoy as a professor too.

Cory Nealon:
Now, 20 some years into your career in academia, you work tracking space debris, otherwise known as space junk. What led you into this field?

John Crassidis:
It’s just a natural progression. I do a lot of work in estimation theory. When I worked at NASA, I developed systems that not only track satellites, but determine how they turn, is basically more where my main area of research is. That requires a lot of neat theoretical work that I liked. It was just a natural progression that I would go into, looking into space junk. I saw that this was going to be a problem, like a lot of us, and it was an area that excited me. It was something that I have a passion for because I know where this is going to lead if we don't fix the problem.

Cory Nealon:
Let's backtrack a bit. Can you tell us what exactly space debris or space junk is, and why we should be concerned about it?

John Crassidis:
Yeah. Space junk is defined as anything that's not useful anymore. So it can be something that fell off of a satellite, or it could be an actual satellite that's no longer working. It's a pretty broad definition. So for example, Ed White lost a glove that floated away when he did his first spacewalk. At that time, that glove was considered space junk.

Cory Nealon:
That gets to another question I wanted to ask. Roughly how many objects are we able to track in space right now?

John Crassidis:
Currently we track over 30,000 objects that are about softball-sized or bigger. That's the limit of what we can do with our current sensors. What we're really worried about is the stuff we can't see. It's estimated anywhere between one centimeter and 10 centimeters, there could be up to 900,000 of those objects. And you asked about the issue, what the problem is. They're traveling very fast, at 17,500 miles per hour. I like to always use the car lane analogy. If they're in the same orbit, meaning they’re in the same lane in terms of cars, they're not going to collide. But we have different orbits. We can have an orbit around the equator, we can have one around the pole, and now you're at the T-bone intersection case. So you can imagine two objects at a T-bone intersection going at 17,500 miles per hour. That would be a very violent collision. That's the stuff that we're very worried about.

Cory Nealon:
Just to put that speed in perspective, you're talking 17,500 miles per hour. Faster than the speed of sound?

John Crassidis:
Yes.

Cory Nealon:
Faster than a speeding bullet?

John Crassidis:
Yes.

Cory Nealon:
Can you tell us how long a typical object might stay in space?

John Crassidis:
That's another problem. We really can't tell how long stuff is gonna stay up there. In low Earth orbit, talking a couple hundred miles, it'll eventually come back down, depending on a lot of factors, unfortunately. But we just don't have very accurate models of how many air molecules are up there. We can do some predictions, but unfortunately they're not as accurate as we want to be. The Iridium-Cosmos, so those are two big satellites that we didn't think were gonna collide, and they did. So that's a problem. It sent a message that we're not tracking the stuff as well as we thought. Even the big stuff. We do a calculation called the probability of collision. It's based on a lot of math, but we can estimate that. And anything greater than one in 10,000 chance of colliding, we will tell one of those satellites, you should maneuver away. Those two satellites did not meet that threshold. I always like to say they won the bad lottery that day. It just happened. It's only... probability. They collided and caused about 500 pieces of debris.

Cory Nealon:
That gets us to another topic I was hoping to discuss, which is the Kessler Syndrome. Could you describe that to our audience and what it means?

John Crassidis:
Yeah. So Donald Kessler in 1978, a NASA engineer, had come up with this theory that said, basically, if a couple objects collide with each other, it's gonna cause more debris, and that debris is gonna collide with other debris. And now we're gonna get a cascading effect where we get to the point of having so much debris up there that it's not worth it to put satellites up there. Also we have to think about, we have to get through that debris field to get to the moon and Mars to get our astronauts. So we're putting our astronauts in harm's way too.

Cory Nealon:
And astronauts have been in harm's way before on the International Space Station with space junk, correct?

John Crassidis:
Correct. There have been a couple of instances where the astronauts had to go to the escape hatch. Fred Whipple in 1947 invented what's called now the Whipple Shield. That can handle little small impacts. There's over a hundred Whipple shields in a space station to protect it from small stuff. But astronauts out there doing their missions, they're completely vulnerable to it.

Cory Nealon:
Is that something that keeps you up at night?

John Crassidis:
I'm actually very worried about astronauts being exposed when they're out there in space and doing their missions outside of the space station, doing space walks. I don't mean to sound pessimistic about it, but I also like to be a realist. I don't think it's a question of if it's gonna happen, I think it's a question of when. If we keep doing this, someday an astronaut's gonna be hurt in space.

Cory Nealon:
One of the things I think people think about is, is this space debris gonna fall from space and hit me while I'm walking around in my day-to-day life.

John Crassidis:
When the satellites come back in, most of the stuff burns up as it comes back in. We, and most countries follow this. We don't build satellites with materials that won't do that. So the satellites that we're building here at University at Buffalo are all made of aluminum. That's gonna burn up. We don't make them out of titanium because that generally won't burn up. The bigger satellites, and not every country follows this, unfortunately, we know the two ones that don't are Russia and China. But our allies and us, any satellite that has thrust remaining has to do a controlled entry over the Pacific Ocean in an area that's very, very unpopulated. We can very much control this. Now obviously, all the stuff that China's been doing lately, with uncontrolleds getting people worried. And some of it did come close to some populated areas. One in particular. But this thing, the chances are small. And really, what can you do about it? Live your life. No human has been hurt by anything coming back in to this point and we're 60 years into the space age.

Cory Nealon:
Is there any way to clean up or remove space junk?

John Crassidis:
Again, a lot of great ideas and a lot of great experiments that are really nice in the sense of showcasing this, but nothing practical, unfortunately. And I don't see anything practical for at least the next 10 to 20 years.

Cory Nealon:
You recently received a $5 million grant to help in your efforts tracking space debris. Can you tell us about that?

John Crassidis:
Sure. So it's called a Space University Research Initiative and it was sponsored by the Air Force. Multiple universities are involved, myself and Moises Sudit from UB. We also have some great partners. We have partners from Purdue, MIT, Pennsylvania and Georgia Tech. I think we have a very strong team to tackle this problem. It was an extremely competitive effort and we ended up winning it. So the grant's gonna look at a number of things, but we want to look at space domain awareness as one of the issues. So adversaries are doing things right now. For example, there's an attack on our satellites every day. Now it's not a major attack in terms of a missile attack, but they're doing more annoyance type stuff, and we have to try to overcome these issues. One of the things with space is, it's very difficult to get that domain awareness.

So the research questions are, "What do we need to do to be able to do that? How do we need to optimize our sensors? Put sensors in space?" The other issue: The moon is starting to get very popular in terms of strategic assets, and to be able to do that out on the moon. That makes the problem a thousand-fold bigger than it is right now. So we're looking at that. The Air Force is not without their sense of humor. They have this thing called the ‘cone of shame,’ and you can't see anything within that cone of shame. So if our adversaries were to put objects within that cone right now, we can't see them. So how are we gonna do this? We're not particularly worried about the moon right now, but in 10 to 20 years it might be an issue. So we have to start doing that basic research that universities do well, to be able to help to the point where we start transitioning that basic research into more applied, and getting technology to be able to do that domain awareness.

Cory Nealon:
How are students involved with this work?

John Crassidis:
We have both undergraduates and graduate students involved in this. The graduate students are doing the research we're trying to do in that space domain awareness. The undergraduates are building satellites for the Air Force. One also, this program called the University Nanosat Program with the Air Force. We're getting ready to deliver our first satellite. That satellite's all done by undergraduates. They're learning tremendous things. What I tell the undergraduates is all the design reviews that I went through at NASA when I was working on satellites, the Air Force is making them go through the same thing.

Cory Nealon:
And it's students, the future generation, who's going to be helping solve this problem with space debris, right?

John Crassidis:
They're gonna have to. That's what I say. The space age didn't start until 1957. So we're talking 65 years ago. And look at what we're talking about right now. Imagine what it would be in another 65 years if we don't do anything. I think for sure Kessler Syndrome is gonna be true. Unfortunately, like a lot of things, we pawn off our problems onto our children. So this generation is going to have to solve this problem.

Cory Nealon:
What in general do you see as the future of aerospace exploration?

John Crassidis:
I think this is a great time to be an aerospace engineer and to get in the field. Look at the excitement that Apollo created. Right now, with all these satellites that we're building, it's giving a tremendous opportunity for aerospace engineers. I think it's the second Apollo. And we're talking about going out to Mars and things like this. So this is a very exciting time. A lot more exciting time than when I was a student. So I would've loved to have been a student right now. I think the excitement that these students bring are going to bring us at a forefront for space exploration. And also solving the space junk problem.

Cory Nealon:
Dr. Crassidis, thank you for joining us.

John Crassidis:
Thanks for having me. It's been a great time.