So what drives a game-changing figure like Elon Musk?

That's what Neil deGrasse Tyson was wondering when he got the chance to interview Musk for the March 22 episode of his StarTalk Radio podcast.

Musk enrolled at Queens University in 1990, where he studied for two years before transferring to the University of Pennsylvania. There, he spent three years getting a bachelor of Science degree in physics and one in Economics, graduating in 1995.

Most college graduates in those days had heads full of dreams of grandeur and world-changing innovations. Musk was just the same, he told Tyson in the podcast.

Here's what Musk said:

When you are starting out in college, in your freshman and sophomore year, you have these sort of sophomoric philosophical wanderings. And I tried to think of ok, what are the things, that seem to me that would most affect the future of humanity?

There were really five things, three of which that I thought would be interesting to be involved in. And the three that I thought would definitely be positive: the internet, sustainable energy — both production and consumption, and space exploration, more specifically the extension of life beyond Earth.

Though I never thought I would actually be involved in that, it was something I'd thought would be important in the abstract. But not something I would ever have an option to be involved in.

The fourth one was artificial intelligence and the fifth one was rewriting human genetics.

These are just the five things I thought would most affect the future of humanity.

Musk has been involved in three of these industries, so far.

First, he made millions from his involvement in online payment company PayPal.

Musk is now chairman and CEO of Tesla Motors, which makes fancy electric cars — decreasing our reliance on oil and promoting sustainable energy options.

He's also Chairman of SolarCity, a company created by his cousins Peter and Lyndon Rive. Solar City provides energy services by selling and leasing solar panels to provide sustainable energy to home and business owners.

Beyond all those accomplishments, Musk also dove headfirst into the one goal he didn't think he'd be involved in: space exploration.

In 2002 — just 7 years after he finished university — he founded Space Exploration Technologies, commonly called SpaceX, using $100 million of his own money from selling PayPal to Ebay. The mission? To build a human colony on Mars.

In 2010, SpaceX became the first privately funded company to successfully launch a spacecraft, called the Dragon capsule, have it orbit the Earth, and recover it after the flight. Later, SpaceX became the world's first private company to send a spacecraft (that same one — the Dragon) to the International Space Station in 2012. Since then they have successfully run several more cargo missions to the space station for NASA.

They are currently working on making their rockets reusable — an incredible accomplishment that would cut space travel costs drastically. They also have plans for a Mars mission, to set up an off-Earth colony of humans to do precisely what Musk wanted — the extension of life beyond Earth. SpaceX will reportedly unveil their "Mars Colonizing Transporter" to do just that later this year.

Listen to the entire episode of StarTalk, also featuring Bill Nye the Science Guy and comedian Chuck Nice, here: