The fact that a mission to send humans to Mars could be a one-way trip hasn't stopped thousands of people volunteering for such an effort, says a group hoping to send a crew to the Red Planet in 2024.

A Dutch not-for-profit organization, Mars One, says more than 200,000 people responded to its call for volunteers for a mission to establish a permanent human settlement on Mars.

From that group it has selected 660 who will face a stringent astronaut selection process for the one-way trip to the Red Planet, Mars One says.

Interviews and group challenges will attempt to find out how well people work together, a final group of candidates well be tested to see how they can cope with living together in harsh and remote Mars-like habitats mocked up here on Earth.

Sending a crew of two men and two women to Mars will, of course, require a rocket, and Mars One says it would contract with a manufacturer such as Lockheed Martin or SpaceX to build it for them.

Once on their way to the Red Planet, there would no turning back for the crew, and once on Mars they would be there to stay, Mars One acknowledges.

"The Mars One crews are people that want to settle on Mars," the group says on its website. "Absence of a return mission reduces the mission infrastructure radically.

"For the astronauts, Mars will be a new home, where they will live and work. While this may seem unreasonable to some, others have no greater ambition in their life. Such dedicated settlers will be chosen by Mars One as their crews."

The manned mission would be preceded in 2022 by six unmanned cargo missions that would place rovers, living units and life support equipment on Mars.

Once the crew arrived after a journey of 8 to 9 months, they would begin efforts to grow their own food on Mars.

Each stage of mission plan employs technology already existing and validated, Mars One says.

"While complex, the Mars One Mission is feasible. The science and technology required to place humans on Mars exists today.

"Much of what was learned from Skylab, Mir and the International Space Station has resulted in vital data, experiences with systems and related know-how -- all of which are applicable to living on Mars."

Mars One is attempting to fund the $6 billion mission through sponsorship deals, sales of broadcast rights, crowd-funding and licensing intellectual rights to technology and inventions growing out of the program.