It is a road trip that could test the best of marriages — one to Mars.

A tycoon announced plans on Wednesday to send a middle-aged couple on a privately-built spaceship to slingshot around the Red Planet and come back home — hopefully with their bodies and marriage in one piece after 501 days of no-escape togetherness in a cramped capsule. Under the audacious but bare-bones plan, the spacecraft would blast off less than five years from now and pass within 160 km of the Martian surface. The cost was not disclosed, but outsiders put it at more than $1 billion.

“This is not going to be an easy mission,” chief technical officer and potential crew member Taber MacCallum said. “We called it the Lewis and Clark trip to Mars.”

The trying circumstances include — no showers; limits on toilet paper and clothing; drinking water made from recycled urine and sweat; and almost no privacy. But the flight comes with never-before-seen views of Mars. And there’s ample time for zero-gravity sex, something NASA doesn’t like to talk about.

As for why a man and a woman will be selected, “this is very symbolic and we really need it to represent humanity”, said Mr. MacCallum.

The private, non-profit project, called Inspiration Mars, will get initial money from NASA engineer-turned-multimillionaire investment consultant Dennis Tito, the first space tourist.

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