The world's first space tourist, Dennis Tito, has announced plans for a manned fly-by of Mars - crewed, he suggests, by a married couple.
Tito's targeting the launch for January 2018 - although, he says, he doesn't yet have the $1 million funding required. He's putting in $100 million himself. If he manages it, the trip will pre-empt NASA by 17 years.
Tito says his Inspiration Mars Foundation is in talks with several commercial aerospace companies in the US about a launch vehicle - SpaceX is one likely option.
The timing is based on a particular set of circumstances. The Earth and Mars will be particularly close to one another, with the next such alignment not occurring until 2031. In addition, the sun will be at solar minimum, reducing the risk of radiation exposure for the two astronauts.
The 501-day mission would take the astronauts to within 100 miles of Mars, before using the planet's gravity to sling-shot the craft back to Earth.
"It's a lean - and over the course of 501 days, I am sure it will be mean - mission," says the project's Miles O'Brien. "There are no technical or financial show-stoppers that I can see. In fact, the beauty of this idea is its combination of simplicity, audacity and liquidity."
The selection of the crew may be a little less well-thought-out. Tito says he prefers a man and a woman, as they'd better represent the human race - we're not sure who he's expecting them to meet up there. And, he believes, a couple in a relationship would be better able to cope with the cramped conditions.
The successful candidates are also likely to be middle-aged, as older people will be less likely to develop cancers through radiation exposure.
The project's been welcomed by the Space Foundation, which has argued for more US investment in space.
"Less than three months ago, the Space Foundation released our report on the future of America's civil space enterprise. Entitled Pioneering: Sustaining US Leadership in Space, our report calls for NASA to return to its pioneering roots and embark upon a sustained and sustainable course of pioneering human presence throughout our solar system," says chief executive officer Elliot Holokauahi Pulham.
"Missions like this one, organizations like Inspiration Mars and all parts of our space industrial base, must be part of humankind's epic journey - not just for NASA to succeed, but for all humankind to benefit."
In 2001, Tito became the world's first person to fund his own trip to space when he visited the International Space Station in 2001. He won't be going along this time.