MIT's Department of Aeronautics and Astronautics is marking its centennial this week, with a symposium examining the past, present and future of aviation and space exploration.
Wednesday's opening session brought eight Apollo-era astronauts together.
Now ranging in age from 76 to 84, the former astronauts may have slowed somewhat physically, but they took part in a spirited discussion on the future of space exploration.
All seem frustrated by the apparent stagnation of the current U.S. space program, but they said they are encouraged by the entry of private ventures into the field.
Rusty Schweickart flew on Apollo 9 back in 1969. He says commercial space flight is the best thing to happen to space exploration since the days of Apollo.
"When you go today to any gathering of people involved in private space initiatives, the juices are flowing. It's exciting. I mean, it's a rock concert, man. I mean things are really bubbling," Schweickart said.
Retired astronaut Charlie Duke, 79, is the youngest man to ever walk on the moon. He says he respects the innovative work of companies like Elon Musk's SpaceX, and said those types of firms will have to be profitable in order to stay in the game.
"I think he [Musk] has some great ideas with his automobiles and his spacecraft. But it's going to take NASA's money or the government money to get it done," Duke said.
The astronauts also tackled the question of sending humans to Mars.
Apollo 11 Astronaut Buzz Aldrin advocates a trip to the Red Planet, even if it means the voyage is one way.
"What are they going to do when you bring them back here that can possibly compare in the value that they would be if they stayed there and Mars wasn't empty?" Aldrin said. "And now we are establishing an outpost on another planet. That is a big deal."
The MIT AeroAstro Centennial Symposium continues Thursday and concludes with a discussion Friday with SpaceX's Musk.
This segment aired on October 23, 2014.