Astronauts in a privately-funded expedition to Mars in 2018 will use their own feces to protect themselves against cosmic radiation.

New Scientist reported on Friday that the Inspiration Mars project, funded by multimillionaire Dennis Tito, will develop a radiation shield for the 1166-cubic-foot spacecraft by lining its walls with, among other materials, human waste.

"It's a little queasy sounding, but there's no place for that material to go," said Taber MacCallum, a member of the Inspiration Mars project. "And it makes great radiation shielding."

MacCallum said that the two-person crew's waste products would also be dehydrated, with the water drained out for recycling and put into bags on the walls. Food would also be stored in shielding containers, he added, saying that using it as a shield would not put it at risk of becoming radioactive.

The goal would be to use the bags create a liquid shield that would be 40 centimeters thick, with the crew swapping and recycling materials as needed, using a program known as Water Walls, which follows researcher's suggestions to combine life-support and waste-processing functions with radiation shielding.

"Water is better than metals for protection," said one researcher, Marco Durante of the Technical University of Darmstadt in Germany, since water has a higher volume of nuclei -- natural radiation shields -- than metals.

A processing system using bags to convert urine to water for the NASA space shuttle Endeavour in 2011 was found to be 50 percent less effective in microgravity than in tests conducted on the ground.

The crew for the yoyage, which Inspiration Mars said it hopes to begin on Jan. 5, 2018, has not been named, but organizers said on the project's website that they will choose a man and a woman from the U.S. to take part n the 501-day trip, which will bring the spacecraft within 100 miles of Mars' surface before using the planet's gravity to "slingshot" it back toward Earth.

"This exceptionally quick, free-return orbit opportunity occurs twice every 15 years," the project website stated. "After 2018, the next opportunity won’t occur again until 2031. The mission will provide a platform for unprecedented science, engineering and education opportunities, using state-of-the-art technologies derived from NASA and the International Space Station."

[Image via Agence France-Presse]

[h/t The Verge]