As part of a new video series, retired NASA astronaut Scott Kelly got real about life in space, "Star Trek" and a creepy ball of urine.

Kelly appeared today (July 18) in the first video of a digital series developed by Biography at A+E Networks and Reddit. The series aims to bring Reddit AMAs (short for "ask me anything") to life with intimate interviews and captivating footage. Reddit's AMA series features well-known figures or people in interesting situations taking questions from commenters on the platform.

The video starts with a question for Kelly that has historically divided science fiction fans: "'Star Wars' or 'Star Trek'?" Kelly said that while he likes "the idea of 'Star Trek,' where you're visiting these places, you don't interfere with what's going on," there's "something about that lightsaber that I really like, too. … I would want one of those." [Welcome Home! Year-in-Space Astronaut Scott Kelly's Earth Return in Photos]

Kelly talks about the creepiest thing he experienced working on the space station (left). Kelly deals with what is (presumably) a ball of urine (right). (Image credit: A+E Networks/Biography/YouTube)

In true AMA style, Kelly answered a wide variety of questions. When asked to name the creepiest thing he's encountered while working on the space station, he answered, "a gallon-sized ball of urine mixed with acid" that he had to clean up. "Essentially," Kelly added, "it's sulfuric acid that is mixed with the urine — basically keeps the toilet from clogging up."

Kelly also got a little bit deeper and spoke about how spending time in space has changed him. He described his space experiences, starting from when he first launched and thought, "Wow, I'm just ready to do the coolest thing I've ever done. And oh, by the way, I could get killed doing it." The astronaut also discussed how his experiences in space have given him a new perspective, or "a sense of being more empathetic to the environment and the human condition."

Email Chelsea Gohd at cgohd@space.com or follow her @chelsea_gohd. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.