Harlan Spence began his Boston University undergraduate career in music studies until, one day, he realized he might need to shoot for the moon — quite literally — to achieve his truly astronomical dreams.

Spence, a College of Arts and Sciences astronomy professor and graduate of the Class of1983, said he realized his passion for the stars after taking an introductory astronomy class nearly 38 years ago.

“In some ways, it’s revealing the invisible, the forces that are in our midst on Earth but become very important in space,” he said.

Spence has overseen design and development of the Cosmic Ray Telescope for the Effects of Radiation – an instrument that will work with other devices to orbit the moon, map out its conditions and “enable an eventual man presence” – as the principle investigator since 2004, he said.

CRaTER, a $10 billion NASA project, will launch from Cape Canaveral this fall, Spence said. While other lunar devices search for water and map the moon’s surface, CRaTER will measure radioactive conditions on the moon to see if the environment is safe for human life.

CRaTER will attempt to measure the effects of the radiation field on human beings with “tissue equivalent plastic,” Spence said.

“It’s a plastic that has the material property of human flesh,” he said. “We’re flying that material as a symbol of what it would be like if that particle would move through your skin to your organs.”

He said he first became involved with CRaTER when he and his former Aerospace Corporation colleagues realized they “had a role to play in that mission.”

“A bunch of us worked together, and we just started brainstorming,” he said. “That afternoon we came up the idea for the instrument. Two months later, we proposed it, and a few months after that, we were selected.”

“People are inherently interested in space,” he said. “People are already buying tickets for the first flight.”

Anthony Case, a Graduate School of Arts and Sciences student, said an understanding of the radioactive conditions is necessary for establishing a human presence on the moon.

“If we know more about the radiation environment, we can send people to the moon with instruments to handle the radiation,” Case, who has worked as one of Spence’s research assistants for the past three years, said.

The information CRaTER collects will be sent directly to BU for further analysis, he said.

“It’s all based in CAS. All the data flows back to our Science Operation Center,” he said. “Hopefully after just a few days of launch, we can see all the data here.”

The cosmic ray radiation around the moon is extremely dangerous to humans and would be difficult to shield, GRS student Andrew Jordan, one of Spence’s teaching assistants, said.

Case said Spence’s attraction to the science during his college days reminds him a bit of his own path to becoming a scientist.

“I would say I wasn’t into science when I first came here,” Case said. “I was a student. I took classes and I learned. I wasn’t quite at the level, but I think being here and working with Professor Spence really helped me learn to think for myself as a scientist.”