Apollo Archive

Space / The Moon

The man behind that Apollo boot print

Lunar soil expert David Carrier is to thank for the iconic photo of some of the first steps on the moon.

Mar 13, 2019

In the months leading up to the 50th anniversary of the Apollo 11 mission, we will be sharing the stories of the people who made the moon landing possible as part of our Airlock space newsletter. First up is David Carrier, the mission’s lunar soil expert.

When William David Carrier went off to college at MIT, his dad advised him to do anything but go into aerospace. His father was a pilot and knew just how cyclical the industry was. But, as most college students do, Carrier ignored his father’s advice. “I ended up drawn like a moth to a flame to go work on the Apollo program,” he says.

During the Apollo missions, he served NASA as a lunar soil mechanics specialist and a principal investigator—an expert in moon dirt, in other words. Before the Apollo 11 moon landing, lots of crazy rumors were flying around about what lunar soil would actually be like. Would astronauts sink into the surface when they touched down? What if it wasn’t solid? Carrier decided he was going to brief the astronauts himself and settle any nerves.

Carrier helping with a drilling simulation at Cape Canaveral with Apollo 13 Astronaut Fred Haise.
Courtesy of David Carrier

Down the hall from where he was working in Houston was the team of geologists tasked with giving them on-site training in El Paso. “The astronauts got the equivalent of a master’s degree in geology, basically, before they went to the moon,” says Carrier. “I made friends with the geologists and said, ‘Don’t you want me to help with the training?’ And they said, ‘Sure, come on—help us.’” He figured this could be his chance to grab the astronauts and impart his lunar soil wisdom.

But life got in the way. His wife was due to give birth before the training date, but as Carrier put it, “Our child wouldn’t be born.” With reluctance, he had to cancel on tagging along with the Apollo crew.

When the day of the astronaut training rolled around, Houston’s weather was dreary. He drove to the NASA Manned Spacecraft Center through the fog, expecting a boring day in an empty office. The day before, everyone else had flown out to El Paso to prepare for the astronauts to arrive. Or at least they were supposed to arrive. Luckily for Carrier, it was so foggy that they had been grounded at his home base. “The crew and the backup and the backup’s backup were still in Houston and suddenly had nothing to do,” he says.

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Carrier had been hoping for a few minutes. Now he had an entire hour one on one with the whole Apollo 11 team to share the inside knowledge he had gained researching the density of lunar soil at MIT and for NASA. “I told them their boot print was going to be about a half-inch deep and that the core tubes [sampling equipment] they were using were not very good. They in turn challenged me to make better ones,” says Carrier. “I think I gave them a certain level of confidence, in contrast to some of the things they had heard and been told by others.”

That conversation was also an impetus for one of the most iconic photos from the mission, which documented the soil mechanics experiment he asked Armstrong and Aldrin to do. “I asked them to photograph an undisturbed portion of the lunar surface, then step on the soil, back up, and take another photograph of the boot print,” he recalls. Voilà—the famous photo was made.

A recent photo of Carrier holding his grandson Beckett at an indoor soccer game.
Courtesy of David Carrier

While he didn’t get to sit down with the astronauts after their mission to hear about the experience firsthand, he did get some feedback after a chance encounter. “I pulled into the gas station that was near our apartment, and who stopped in front of me at the pump but Neil Armstrong. He’s getting gas and was also buying some Coca-Cola,” says Carrier. “The first thing he says to me is, ‘There are more rocks there than you said!’”

Carrier now lives in Lakeland, Florida, and has built a career in construction and mining (Earth dirt versus moon dirt, you could say). In the pictures above, he can be seen helping with a drilling simulation at Cape Canaveral with Apollo 13 astronaut Fred Haise, and on the right is a recent photo of him holding his grandson Beckett at an indoor soccer game.