He flew the space shuttle and has logged more than 700 hours in space.
"I was there because I wanted to go fly, it was a great adventure," he said.
But now Nagel is fighting for his life with stage 4 Melanoma.
"It got in my lymph system, they found some enlarged lymph nodes and it was there, that was the real punch in the gut," Nagel said.
But he now has new hope. Nagel is one of the first patients in the country to receive a new drug that fights the cancer.
"The drug is called the MK-34-75 and it helps the bodies immune system activate and it enables it to target the tumors," said Dana McDaniel, a nurse practitioner treating Nagel.
The drug is awaiting FDA approval, but is being administered as an expanded access drug at six hospitals around the country, including Heartland Regional Medical Center.
Nagel has high hopes the drug will be successful and help others as well.
"The space program is something that benefits everybody," said Nagel. "I was always really proud to be a part of it. I guess being in a drug test is kind of the same thing. There's a selfish part where I'm trying to help myself, but then again, this is helping everybody."
The drug is administered in three sessions in three-week increments.
Doctors will do a CAT scan after the three treatments to monitor its effectiveness.
If successful, Nagel may be on the fast track to one day being cancer free.
"It's a bad disease to have but if you're going to have it, now is better than five years ago or ten years ago. I mean there is a lot of cutting edge technology out there like this drug I am on now. And if you have to have it, heaven forbid, it will be better ten years from now," he said.