Transcript for Signing Up for Mission to Mars With No Plan to Return
We cover all sorts of risk-takers and thrill-seek others this show. Tonight you're going to meet people taking it on an entirely new level. They are awe editiuditioning for a trip to Mars. Even though they've been told in advance, if they're chosen they cannot come back. He's hammish McDonald. Reporter: Kelly giraudi is training the mission of her life. We're suiting up to go on the Eva, extra-vehicular activity. Reporter: The suit, the head gear. Even a trip through an air lock. Kelly is no astronaut. But she's come here to the rocky plains of remote Utah to spend three weeks at the Mars society desert research center. It's an incredible environment out here. It really feels like Mars. Reporter: It might seem a bit extreme but this Florida native hopes it will give her an added edge among thousands of other applicants all vying for a trip to Mars. But there is one massive catch. It's a one-way ticket. The audacious idea from a new company called Mars 1, which says 200,000 ordinary humans from around the globe applied to leave life on Earth behind. Like Kelly. No matter what in my lifetime I'm going to face. Just 26 years old and newly engaged. Stefan Gunther, a German pilot and father of three. I want to go there. I'm willing to pay the price. Reporter: And sue Ann. I feel like it's my destiny to colonize Mars. Reporter: A tech worker from California. I think I would be completely crushed if I found out I didn't make it. Reporter: The three hopefuls competing to make the cut for the next Mars 1 selection round. Only 100 potential astronauts will be chosen. And they'll find out any day now. The first launch date is set for 2024. I've told so many people about this story. And the reaction that I get almost every time is, are you crazy? We're already doing this. So accept the new reality. Reporter: We bet landsdorf, the 38-year-old CEO of Mars 1, in his small office outside Amsterdam. He and his team of space experts claim they can do what nasa so far has not. The humans will leave effort arriving on Mars April 2023. Reporter: An entrepreneur by trade, he believes Mars 1's multi-billion dollar mission can be funded by selling TV rights to the reality show. Literally everybody on the globe will be watching, just like when Neil Armstrong and buzz aldrin landed the moon. How much of the science is missing? How many more advances are required to be able to make this happen? The technology is existing. But of course you can't buy it at Walmart. So we're hiring the established aerospace companies from all over the world. But no new inventions are needed to implement our program. Reporter: But because they don't have the technology for the return journey, a permanent colony will be formed. This is what butter would look like on Mars or similar to what chicken would look like on Mars. All freeze dried. Reporter: It is an irresistible opportunity for Kelly giraudi. You get it or you don't. I equate to it seeing Mt. Everest for the first time. Either you feel a yearning to climb it or you don't. If you don't, I don't know that I could ever explain that to you. Reporter: As for her wedding planned later this year? Kelly is facing the prospect of a very long-distance relationship. Everyone makes a joke to us, till Mars do us part. I couldn't be more in love. Do I still see myself going to space in the future? Yes, I would go. That's a hard reality. Reporter: So too is Martian cuisine. Where you really get dicey when is you start opening things like earthworms. Or zebra tarantulas. So this is going to be pretty gross. Reporter: Sue Ann pin is preparing for her potential launch into space by checking off a bucket list right here on Earth. So since I found out I was a Mars candidate it's kind of changed the entire trajectory of my life. So people who think that Mars is a suicide mission I have to say, if you're alive today, you're on a suicide mission. Reporter: Her family is supportive, feelings not shared by her girlfriend Cynthia. She's not going to lie about the fact that she doesn't like it. But, you something that would take me away from her. Reporter: 46-year-old Stefan Guenther knows his trip to Mars would take him away from his wife and three children. I always try to tell my kids, live your life. Don't live the life of others. But I hope they accept it the other way around too. Reporter: For him, it would be the culmination of his life's dreams. Actually, if I make it to the rocket, if I make it to the hatch, I'm climbing to the capsule. I had everything I wanted in this life. Join us in this great adventure. Reporter: But many are skeptical this mission to Mars will ever get off the ground, let alone succeed. This has the atmosphere of a circus where you have amateurs simply raising their hand, volunteering to be the first person on Mars. Given the fact that this will be untested technology, it's a tra tragedy waiting to happen. Reporter: A recent mit study hypothesized Mars 1 astronauts might suffocate within months of touching down on the red planet. Mars 1 says the mit study is flawed. That they won't risk human lives until they're confident in the technology. But still -- There is no safe mission to Mars, it's impossible to eliminate all the risks. Reporter: These risks won't deter dreamers like Kelly, sue Ann, and Stefan, each hoping they're among the 100 finalists chosen. My Mars 1 interview with Dr. Kraft, a little bit nerve-racking -- Reporter: First they need to pass an evaluation. By Mars 1's chief psychiatrist. What are the attributes that you're looking for? Imagine flying to Mars in quite a small little spaceship for seven months with three people. Seeing the Earth disappear. Knowing that you'll never see your friends, never talk to them in real life again. We're looking for people who can do that psychologically. Reporter: Back in Utah, Kelly isn't convinced her interview went well. This was more like a pop quiz. How much of minutiae of Mars 1 mission plan did you study? I'm anticipating that I didn't make it to the next round. Of Mars 1. Because -- specifically for that reason. Reporter: The disappointment she fears arrives in her inbox. I have the e-mail. Dear miss Kelly, we regret to inform you that you will not proceed to the third round in Mars 1's astronaut selection program. This is not the end of your cream -- Reporter: She takes the news pretty well. I'm already on Mars right now. I'm super excited to be still contributing to space settlement. Reporter: Stefan Guenther in Germany also didn't make the Mars 1 cut. Now he's intent on setting foot on the moon. As for sue Ann pin -- If I read the e-mail and it says that I didn't make it, I'm going to be pretty upset. I think -- definitely going to feel like my dreams are dashed. Oh my god, I made it, I made it, aahhh. ! Aahhh, oh my god, I made it! I didn't read it, what did it say? Dear miss sue Ann, congratulations. You and only 99 other aspiring astronauts around the globe have been invited to round three of the astronaut selection process! One step closer! Reporter: One small step for sue Ann, still a giant leap from reality. But it can't hurt to dream. I'm feeling elated. I feel like I'm in a dream. It feels like my dreams are coming true. Reporter: For "Nightline," I'm hammish McDonald in London. What do you think? Is the mission to Mars crazy? Or ahead of the curve? You can go to our Facebook page and tell us what you think about those one-way tickets.
This transcript has been automatically generated and may not be 100% accurate.