Famed scientist and science popularizer Neil deGrasse Tyson talked about the importance of space exploration today during his keynote at South by Southwest Interactive. Despite advances by private companies, particularly SpaceX, he said they won’t be the ones making the biggest breakthroughs.

Tyson admitted that for him, the appeal of space travel is the simple fact that it’s “a frontier.” However, there are more practical reasons to go into space. For one thing, we need to be able to respond if we find out that an asteroid is headed for Earth.

“You know the dinosuars would have if they could have,” Tyson said. He joked that failing to pursue a space program when we have the scientific and technological capability would make us “the laughing stock” of other intelligent species: “They’d have human bones on display in their museum. ‘Here they are, not building a spaceship.'”

He also suggested that space travel is tied to other forms of significant innovation like transportation, energy, and health — which he contrasted with people “who innovate because you want to make a buck” and are trying to figure out “the next app.”

Tyson described space travel as “a long-term investment”: “It’s an investment that private enterprise cannot lead.” He recalled the excitement around SpaceX’s delivery of cargo the International Space Station, which sparked discussion about whether private companies would replace government as the main engine behind space travel. Tyson’s response? “They brought cargo to the space station! NASA’s been doing that for 30 years!”

The problem, he said, is that it’s hard to predict the risk and return on investment on “doing anything big and expensive first.” He noted that the first Europeans to come to America were not the Dutch East India Company, but Christopher Columbus and his crew, whose expedition was paid for by Spain. After the initial exploration, there will be opportunities for private companies.

“The first trillionaire in the world is going to be the person who first mines the asteroid belt,” Tyson said.