Even if the venture, which has ambitious plans and many doubters, never gets off the ground, it poses an interesting, if, for now, mostly hypothetical question: what would compel someone to permanently give up life on Earth for extraterrestrial adventure?
For McLain, 30, a Maria Carrillo graduate, the motivation is advancing human society.
"My goal is to impact the world in as powerful and positive a way as I can," he said. "Going to Mars would be the most inspirational and positive thing I can do in my lifetime. I can't think of a more powerful way to help humanity grow than by helping humanity leave this planet."
Mars One, a Dutch company, hopes to put a settlement on the planet within a decade by tapping into human fascination with our closest neighbor. Part "Space Camp," part "Survivor," the company plans to raise money by staging an elaborate reality show and letting a worldwide audience help whittle down the applicants to 24 finalists through a series of challenges over the next two years.
The final two dozen will be trained as astronauts over the following eight years.
The company's website says it will need $6 billion to send a team of four to Mars.
"The next several selection phases in 2014 and 2015 will include rigorous simulations, many in team settings, with focus on testing the physical and emotional capabilities of our remaining candidates," Norbert Kraft, chief medical officer of Mars One, said in a statement. "We expect to begin understanding what is motivating our candidates to take this giant leap for humankind. This is where it really gets exciting for Mars One, our applicants and the communities they're a part of."
A Mars One spokesperson declined to answer questions and referred a reporter's inquiry to press releases published on the company's website.
The company has yet to secure a television deal for its reality show.
McLain, who is currently a musician and actor in Los Angeles, has approached the application process cautiously, and he is aware that many think Mars One's plans seem a bit far-fetched. But curiosity and a desire to leave his mark on humanity has led him to pursue this dream in the hopes that it does take off.
"Skeptically optimistic is the way I'm approaching this," he said. "Helping humans get off this planet is something I'd give my life for. I think there is a romanticism in being a pioneer. But I've kept my heart a little bit at bay. I will fall in love with this and devote my life to this and will be extremely disappointed if it doesn't happen."
McLain said he spent two days working on the application essay and video and paid a $20 application fee. The next step in the process is a comprehensive physical exam followed by a round of interviews.
"They are going to vet the crap out of us if we're going to Mars," he said. "Not just physically but mentally. I'm not going to lie, it's not going to be easy in any way."
According to Mars One, the company plans to launch a rover and supply capsules to Mars in 2020. The first four-person crew would lift off on a 210-day voyage to the planet in 2024.
The crew would live in the apartment-sized supply modules. They would get water by melting ice found under the planet's surface, and extract oxygen from the water.