"Is it going to happen? Who knows? I feel like I've been disappointed so many times I refuse to get excited," said Roger Launius, a longtime space historian.
Pence pledges that US will go to the moon, Mars and beyond →
"As this history recedes into the background and fewer and fewer people remember it, the more mythological it becomes," he said. "The majority of the human race has been born since we've left the moon so they don't have knowledge of it."
9 prominent early astronauts carrying on US space history →