One couple will have the chance to take a honeymoon expedition on a high-risk manned flight to Mars in 2018, organized by a wealthy space tourist. The trip will be a bare-bones 501-day round-trip flyby, passing just 100 miles above Mars before heading back to Earth, CBS News reported.

Dennis Tito, the first private citizen to fly aboard the International Space Station, said he would provide two years of funding to support a non-profit called the Inspiration Mars Foundation, which he founded to execute the venture. Remaining funds will be raised from private sources.

"We have 50 years of experience," Tito told reporters during a news conference, according to CBS. "We can do things a lot faster; we just need a commitment. I'm not worried about getting this done from that standpoint. The vehicles are there, we have time to get it together."

He added in a statement issued to CBS that his organization is "engaging the best minds in industry, government and academia to develop and integrate the space flight systems and to design innovative research, education and outreach programs for the mission."

"This low-cost, collaborative, philanthropic approach to tackling this dynamic challenge will showcase U.S. innovation at its best and benefit all Americans in a variety of ways," he added.

Building the spacecraft in five years will be difficult, but that's not the only challenge. It's risky for the couple to spend nearly one-and-a-half years in the weightless environment of space, with an increased risk of cancer because of space radiation. Also, it could be extremely stressful for the couple to spend all that time confined in such a small place, CBS reported.

Homer Hickham, author or "Rocket Boys/October Sky," said in a Twitter posting: "A married couple in a bathroom for 501 days? I love my wife but rather take my cat and some good books," CBS reported. He joked that a book about the trip might be titled "Murder on the Martian Express."

Jon Clark, a former NASA flight surgeon whose wife, Laurel Clark, died during the 2003 Columbia disaster, told CBS that the selection process will be thorough, looking for candidates with excellent health, technical abilities and psychological stability.

Pre-flight training and well-established exercise protocols will aid in mitigating any negative results of extensive exposure to microgravity, but space radiation is still a concern. Clark said NASA will not consider a mission potentially causing a 3 percent excess cancer mortality rate over a lifetime, according to CBS.

This Mars mission is "in that ballpark," said Clark, who is also working with the Inspiration Mars Foundation. "So, the real issue here is understanding the risk in an informed capacity. The crew would understand that. Ultimately, that is going to be the decision based on that informed consent," CBS reported.

Taber McCallum, the chief technical officer for Inspiration Mars and CEO of Paragon Space Development Corp., told CBS this expedition is "the kind of risk America used to be able to take," and the country should step up and take another risk.

"There are lots of options and ways to get this done," he told CBS. "We have an amazing industrial base and it's about time America stood up and proved to the rest of the world we've got, bar none, the best industrial base in the world. Let's show it to them. Let's do this mission."

McCallum noted that mission planners are looking into a 1,200-cubic-foot spacecraft, half-full with food, water, life support equipment and spare parts -- leaving approximately 600 cubic feet of living space.

If the spacecraft launches on Jan. 5, 2018, it could reach Mars in 228 days and circle around the planet, employing gravity to bring it back to Earth. The return trip, lasting 273 days, would end with re-entry on Earth on May 21, 2019, at a record velocity of 31,000 mph, CBS reported.

Although Tito could not yet give a cost estimate, he told CBS he expected it to be in the range of a robotic Mars mission. NASA's twin Mars Exploration Rovers cost about $400 million each and the Curiosity rover currently on Mars was much more expensive -- some $2.5 billion.

"It uses low-Earth orbit architecture and we're just adapting it, in effect, to a very large Earth orbit that ... just happens to go out pretty far," Tito told CBS. "But you're really flying this mission without a propulsion system on the spacecraft, it's in the most simple form.

Whatever the price tag, Tito thinks this Mars honeymoon will also be a chance to raise money.

"Dr. Phil solving their marital problems," Tito told CBS. "It will be great."