(CNN) -- Years before Bill Nye became the Science Guy, he was a mechanical engineering student at Cornell University, where he took a course with astronomer Carl Sagan.
Sagan, who was instrumental in the planning of NASA missions to other planets and became widely known for his research, writing and public television series, was one of the founders of the Planetary Society. And his student dutifully signed up to become a member.
"I've been a member for over 30 years. And now I'm the head guy. It's quite odd," a surprised-sounding Nye told CNN in an interview in March at the TED2012 conference in Long Beach, California.
So today, the bow-tied, jauntily professorial Nye has a new role aside from his television work as a popularizer of science: As the society's chief executive, he's become a leading voice against the Obama administration's proposed $300 million cut in NASA's planetary exploration budget. And it's a subject about which he's passionate.
"This is a deep, deep concern. All the budgets are being cut. We gotcha, budgets are being cut, budgets are being pulled back, yes, yes, all good," he says, acknowledging the pressure to cut spending.
"But investment in space stimulates society, it stimulates it economically, it stimulates it intellectually, and it gives us all passion. Everyone, red state, blue state, everyone supports space exploration. So I understand the budget has got to be cut, but something has gone a little bit wrong."
Nye says the planetary exploration budget, facing a reduction of 21% from this fiscal year's budget, is taking a deeper cut than other parts of NASA.
"This wouldn't matter. except it's not a faucet. It's not a spigot you can turn off and on. You stop planetary exploration, those people who do that extraordinary work are going to have to go do something else."
His worry is that the U.S. is in danger of losing its unmatched scientific expertise to plan and execute missions to other planets.
"To try to really land a spacecraft really on another world is really difficult, and if we lose that ability, it's going to be heartbreaking," says Nye, who adds that it could take decades to recoup.
Nye makes another argument for investing in exploring the solar system. He says there are two kinds of natural disasters that can be prevented: One is climate change, and the other is the Earth getting hit by an asteroid.
"If the Earth gets hit by an asteroid, it's game over. It's control-alt-delete for civilization." Nye says he figures "sea jellies, squid, cockroaches will be fine," but an asteroid could wipe out humankind.
"So what we want to do is to develop the capability to redirect, to deflect an asteroid, ever so slightly. If you're going to do that, you've got to have space exploration. And sooner or later, you're going to want to send people out there to look around. It's just our nature, and one day it would be exciting to send people to Mars."
NASA is in the midst of active exploration of Mars.
In August, Curiosity, the Mars Science Laboratory rover, is due to land on the planet's surface. David Weaver, NASA's associate administrator for communications, says the rover is the "Hubble of Mars missions" and "the most sophisticated scientific system ever sent to another planet."
Its mission is to determine whether the red planet could have ever hosted life. Weaver said in June that the agency is reformulating its Mars strategy in light of budget constraints and scientific priorities and "the president's challenge of sending humans to Mars in the 2030s."
Nye says his concern isn't about current missions but about whether the next series of missions and the ones beyond that will have enough funds to proceed.
Taking a larger view, Nye says there are two questions everyone should ask themselves at some time in their lives: "Where did we come from? And are we alone?"
"To seek the real answers to those questions, you have to explore space, and if you stop exploring, if you say, 'I don't care; I'm not going to look up and out and beyond the horizon,' what does that say about you? It's not good," Nye said.
"If we found life on Mars, or evidence of life on Mars, it would change the way everybody thinks about everything. It would change the way you think about your place in space."
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