Short Wave - Hal Walker: The Man Who Shot The Moon

Episode Date: March 25, 2022

In addition to flying, landing, and returning from the moon in 1969 — NASA's Apollo 11 crew helped with a series of scientific experiments. One of them was to leave a special instrument with lots of little reflectors on the surface of the moon. The goal of that experiment was to beam a laser at the moon. Today on the show, Scientist-In-Residence Regina G. Barber talks to host Aaron Scott about the lunar laser ranging experiment — and how shooting that laser helped us better understand one of Einstein's theories. Follow Aaron on Twitter @AaronScottNPR and Regina @ScienceRegina. Reach the show by beaming an email to [e-mail] pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. For the eyes of the world, now look into space to the moon and to the planets beyond. In the early 60s during the space race, President John F. Kennedy set a national goal. We have vowed that we shall not see space filled with weapons of mass destruction, but with instruments of knowledge and understanding. The promise was simple. send a crew of U.S. astronauts to the moon, land, and return to Earth. So on July 20th, 1969, much of the world stood still as NASA's Apollo 11 crew fulfilled this national vow.

Mangility base here. The Eagle has landed. Becoming the first group of astronauts from any nation to land on the moon. That's one small step for land. And in order for us to see it, the crew actually had to set up a television camera to transmit the signals back to Earth. But that iconic video we've all seen of the astronaut bouncing in low gravity doesn't show the astronauts other objectives, like collecting samples from the moon. Because, you know, what's a trip to the moon without some souvenirs?

Right? And the Apollo 11 crew also left some scientific equipment on the moon so that we could study the moon from Earth. And one of those was an instrument with a lot of little reflectors. Okay, Regina, I love this because there's actually a pinky, in the brain episode in which the brain tries to shoot a bunch of little reflectors at the moon and turn it into a giant disco ball. But I'm going to guess that wasn't their mission here. So why reflectors? So we actually needed the reflectors there so that we could shoot a high-powered

laser beam of light at the moon. Okay, so this actually is very pinky in the brain. Yes. Why are we shooting lasers at the moon? Aaron, this is the story I brought for you today. All right, you get my phone up to my ear. There it is. The story of the man who shot the moon. My name is Hildredth, Hal Walker Jr. I'm known as Professor Hal.

Hal was actually the person charged with leading the effort in building and operating the laser that reflected off the equipment the astronauts left on the moon. Today on the show, we go pinky in the brain on you by shooting a laser at the moon. But not for evil, for science. With an experiment led by scientist Hal Walker that helped verify one of Einstein's biggest theories. I'm Aaron Scott. And I'm Regina Barber and you're listening to Shortwave, the Daily Science podcast from NPR. All right, Regina. So this is a story about space. Where are we starting? I mean, Houston, Cape Canaveral. So Aaron, Hal is actually calling from Cape Town, South Africa. Okay. A different

Cape. Right. I like it. These days, Hal is working with his foundation. He started with his wife, Betty Walker, called the African American Male Achievers Network, or A-Man, which is based near L.A. and works to help black youth get excited about space. But then California is out long ways from Cape Town. So what's he doing there? Yeah, I love this story. So he's actually in South Africa because in the late 90s, President Nelson Mandela met with Hal and Betty,

along with kids from A-Man, and asked them to promise to bring programs like A-Man to South Africa. And in 2019, they actually fulfilled that promise by starting a National Space Society chapter in Cape Town. Oh, right, very cool. But actually, Howell's science journey begins accidentally in the mid-50s at Douglas Aircraft in Southern California. I have to admit, I don't know that I feel good about a space story beginning with an accident,

but I'm with you. How do we start? It's like all Hollywood movies, right? Well, Hal's fresh out of the Navy. He's deciding what to do next with his life. But he's not quite looking for a totally new job, but his buddy is. And asked him for a ride to Douglas Aircraft for a job interview. And Hal is sitting in the office waiting for his first.

friend, when one of the interviewers pokes his head out of the door and says, Hey, next. And I said, oh, I'm not looking for a job. And he had this look like, well, what are you doing in the employment office? I said, well, I'm on leave from the Navy right now. I said, I worked aboard aircraft carrier.

He said, what do you know about airplanes and board the carriers? I said, I worked on those also. He said, well, look, come in and let me have a chat with you and the rest is history. So Hal gets the job, and the job is installing and testing radar. on plates. What a great story. The radar job makes him qualified for an even bigger job. So he starts

working on the ballistic missile early warning system. And this is around 1960. It's the middle of the Cold War. And he's part of building a state-of-the-art radar detection system that would give us enough warning if a ballistic missile was fired from the Soviet Union to the U.S. Yeah, okay. No pressure whatsoever. Yeah, I actually asked how. I'm like, were you scared? And he was like, all the time. And this story just keeps on going. He finishes up in Alaska, and now he has all this experience with high-powered radar, and he's thinking about his next career move. I noticed one day in the paper that there was a company called Corrad that was looking for engineers with experience in the high-powered radar. So Corrad is actually a company led by

Theodore Maimon, and Theodore Maimon is the man who built the first working laser. And back then scientists were dreaming up all sorts of possibilities for lasers, from surgery to physics experiments. Working with high power technology, this is power supplies, high energy discharge systems. This is something you have to have a lot of experience. You only get one mistake. We were building a ruby pulse laser. A ruby pulse laser. I love the sound of that. Yeah, I love them because they're outrageously powerful. This laser he's working on is about a billion watts. Okay. Think about a household item like a light bulb. That's 100 watts. So a gigawatt, or one billion watts, that would be 10 million light bulbs. 10 million light bulbs. Very, very bright. It

sounds like this laser could, I mean, basically turn night into day. But it also gets us to this pivot point where Hal moves from working on radars to working on lasers. Right. I mean, he's really good at it. He rises in the ranks and gets opportunities to hire up-and-coming engineers. And, of course, I had the fortunate experience that I found three African-American guys that really met the qualifications. So I hired them. And after maybe about a couple of weeks, the personnel manager came down and asked me. He says, I noticed you were hiring all these new technicians in the lab.

They're all African-American. Can you explain that? I said, no, they're just some guys applied for. jobs and I hired them and I thought other people, you know, were not as qualified. He says, well, I think you probably shouldn't do that anymore. That is so discouraging. Yeah, it's pretty heartbreaking and it's clearly something he carries with him in his life, even when Corad, the laser company, becomes a contractor for NASA.

We as African Americans during that period of time, were still facing those challenges of the policies of the country's racial politics, but still, trying to get a job done for a nation's benefit. And that job was to get humans to the moon. Right. That's what, you know, the book and film Hidden Figures was talking about. But Howell's job was working on one of the Apollo 11th scientific experiments, the lunar laser ranging experiment. This was the first time ever we could measure the distance from the Earth to the Moon within a matter of inches. What, we're going to be breaking out one giant yardstick to measure the distance between the Earth and the Moon?

So as an astronomer, like cosmic distances, that's actually a big whole thing. But let's just make this simple today. If we could shoot a laser using visible light from the Earth to the moon and have that light bounce back, we could actually measure how long it took and therefore get the distance. However, the moon dust is not super reflective. So astronauts had to leave a reflector on the moon to up the chances we would get any of that light back. I love this because I'm used to these missions having. all sorts of super complicated science.

I can barely understand. But this, this sounds pretty straightforward. Yeah, you would think that. But in 1969, things didn't actually go as plant. I think that's Murphy's Law or something. Well, as you can imagine, we had lots of little problems that affected our operation that continuously kept us on our toes. Yes.

I'm guessing little problems in space can quickly get amplified into big problems down here on Earth. So what went wrong? Well, Neil Armstrong didn't quite land where they had planned. I think it was maybe 30 seconds of fuel left. And you've got to go somewhere safe and sit down or you're dead. So he took the command and took the module someplace and set it down safely. Thank goodness. But that led to the problem called where did they put the reflector for us.

So we didn't quite know exactly where it was. So all the calculations and all the preparation for the lunar ranging experiment were kind of thrown out of a whack. Keep in mind this reflector was about the size of a baseball home base. Where it was now was a mystery. But it was up to Hal and his team to figure out how to find the reflector and to run the experiment before anyone else did. Wait, stop. You are telling me that there are other people trying to shoot lasers at the moon? Well, of course, different scientists and countries around the world were trying to find the reflector because they also know it was down, most likely not where we thought it would be. Okay, so forget finding it.

a needle in a haystack, Hal found a home base on the moon. Yeah, and what's really interesting about light is that this laser light beam actually widens as it's traveling through space and getting dimmer and dimmer. So by the time the pulse gets back to Earth. So what you're looking for now is not a lot of light back. You're just counting, as we would describe it, photons. How many did we see? We saw five.

Just five particles of light. That's all that made it back to us from this super powerful laser. That really gives you a sense of how far this light had to travel. So what was the distance? It's about a quarter of a million miles. And keep in mind that orbits aren't perfectly circular. So it depends on when you shoot the laser, what distance you're going to get. But that's how far the moon is from Earth, roughly.

And it takes the light beam roughly 1.3 seconds to travel from the moon back to Earth. This whole experiment takes about 2.5 seconds. And what we should say is that the experiment happened for the first time in 1969, but it actually still happens today, which is why we know the moon is slowly moving away from us about an inch and a half every year. Wow. And this experiment also verified Einstein's theory of general relativity, how time works differently the further you get from Earth. We need precise measurements of distances so we can have accurate times within our satellites. Your GPS wouldn't work without this theory. So you're saying that How's Path, which began just with that accidental job interview,

it ended up verifying the theory of relativity and set the stage for satellites and GPS. That is really something to aspire to. Yeah, this man's life. I mean, he carried all these experiences with him to today, and he still wants to give back. My experience during those years of the 60s and 70s was a lonely journey, because it was only myself and a few other African-Americans involved in what was called the laser industry. that time. His story is fascinating because it weaves through so many social and political movements,

but like he said, he was just doing his job. And now he's doing the job of making it less lonely for black kids who loves space. Thank you, Regina. I'm so grateful that you shared House story with us. Yeah, I think this story should be known by everyone. This episode was produced by Major Thomas Liu, edited by Lady Stardust Rebecca Ramirez, and fact-checked by Catherine Ground Control Cipher. audio engineer for this episode was Starman, Josh Newell.

Jazele Grayson is our mission control. Andrea Kisick is the head of the science desk, and Edith Chapin is the executive editor and vice president of news. I'm Aaron Scott. And I'm Regina Barber. And you've been listening to Spacewave, the Daily Science Podcasts from NPR.