Golden Spike

An artist's conception from the Golden Spike Company shows a lunar lander in the foreground, and a moonwalking astronaut in the background.

Selling trips to the moon? Sending astronauts to Mars and back? These sound like 1960s-era science fiction adventures, but they're actually in the works for later this decade. Will these privately backed projects get off the ground? That's the billion-dollar question.

The Golden Spike Company says it's in talks with one corporation and more than one space agency about sending a two-person expedition to the moon in the 2020 time frame, at a cost of $1.4 billion per mission. Meanwhile, the Inspiration Mars Foundation is getting ready to launch a man and a woman, preferably a middle-aged married couple, on a round-trip flyby past Mars in 2018.

The two ventures are the focus of Wednesday night's installment of "Virtually Speaking Science," a talk show that airs online via BlogTalkRadio with a live audience in the Second Life virtual world. I'm your host, and my guests are Taber MacCallum, Inspiration Mars' chief technology officer; and Doug Griffith, general counsel for Golden Spike.

The hour-long show starts at 9 p.m. ET (6 p.m. PT), but if you miss the live program, never fear: You can always download the podcast from BlogTalkRadio's archive or iTunes.

Both Golden Spike and Inspiration Mars are getting advice and moral support from NASA, but the financial support is coming from elsewhere. The lunar venture expects to bootstrap its way to profitability by selling its services — and initially through an Indiegogo crowdfunding campaign aimed at raising $240,000 (one dollar for each mile to the moon) by late April. So far, more than $7,500 has been contributed.

To Mars and back
Inspiration Mars is relying on seed money from California millionaire Dennis Tito, who became the first tourist to visit the International Space Station in 2001. Tito said his effort to send a spacecraft zooming past Mars during a favorable planetary alignment in 2018 is purely philanthropic, with the goal of inspiring future generations of Americans.

MacCallum, who took part in the Biosphere 2 experiment in 1991-1992 and went on to become a co-founder of Paragon Space Development Corp., said he's already noticed the inspirational effect.

"I keep hearing people say, 'This is the kind of thing America used to do, and maybe now we can do it again.' It's like we touched on a sore spot, and the reaction has been ... almost too positive," MacCallum said.

He said Tito's aim was merely to get some introductory exposure for the concept, in hopes that all the kinks can be worked out in time to make the 2018 deadline. Tito has committed to supporting the venture for its first two years, but he needs to raise the rest of the money for what's rumored to be a billion-dollar mission.

The team hasn't yet worked out the procedure for selecting the crew, but MacCallum said more than 100 applications have already been sent in — including some candidates with jaw-dropping credentials. "There are some where you say to yourself, 'Oh, my gosh!'" MacCallum told me. "Hey, listen, it's suddenly cool to be a middle-aged couple."

To the moon
Unlike Inspiration Mars, Golden Spike is set up as a business, which will ultimately have to be supported by paying customers. The idea is to provide two-person trips to the moon for roughly the same cost as today's robotic missions to the moon. Golden Spike aims to do that by employing high-tech, low-cost hardware as well as a relatively low-risk mission architecture. The company plans to pre-position a lander in lunar orbit, and only then send the crew and their moon-and-back booster on a subsequent pair of launches.

"Before it even launches, we know that the lander is working," said Griffith, who is drawing upon years of experience in space and aviation law.

Griffith said Golden Spike will serve as the outer-space analog of, say, United Airlines, contracting with other companies for flight hardware. The company is working on design studies for launch vehicles, landers and other equipment. It's also talking with potential customers — and trying to convince the skeptics that it's really possible to put people on the moon, almost half a century after NASA did it in 1969.

"The consensus seems to be that it's doable within the prices we're talking about," Griffith said. "All of the skepticism seems to be about whether there are space agencies or billionaires who are willing to pay the price. That is the big unknown. ... I think we'll know in fairly short order whether the skeptics are right or wrong."

Griffith said Golden Spike's game plan calls for signing up its first customers for "right of first refusal" deals by the middle of the year, and getting its first flight contract by the end of this year.

"Our operating premise is not that we keep sliding things back," Griffith told me. "Our operating premise for now is, it's go time."

Are Golden Spike and Inspiration Mars ready for takeoff, or will we have to wait for NASA to send astronauts to a near-Earth asteroid in the mid-2020s, and to Mars and its moons in the mid-2030s? Listen in to "Virtually Speaking Science" and feel free to weigh in with your own views, either by taking part in the live show or by leaving your comments below.

'Virtually Speaking Science' podcasts:

• Sean Carroll and Matt Strassler on physics' X Files
• Ig Nobel's Marc Abrahams on weird science in 2012
• Paul Doherty on Curiosity and the year in science
• Shawn Lawrence Otto on the election and the climate issue
• Sean Carroll on what lies beyond the Higgs boson
• Alan Stern on the Uwingu mystery space venture
• George Djorgovski on the future of immersive virtual reality
• JPL's Dave Beaty previews Curiosity's mission on Mars
• SETI Institute's Seth Shostak about aliens and UFOs
• Paul Doherty on solar eclipses and the transit of Venus
• Veronica Ann Zabala-Aliberto on spaceflight and Yuri's Night
• JPL's Dave Beaty on the search for life on Mars
• Shawn Lawrence Otto on science and politics
• Ig Nobel impresario Marc Abrahams on silly science
• Rocket scientist Robert Zubrin on Mars exploration
• Propulsion expert Marc Millis on interstellar spaceflight
• Sean Carroll on the puzzles facing physicists
• Rand Simberg on the private-enterprise vision for spaceflight
• Martin Hoffert on the future of energy policy
• George Djorgovski on science in virtual worlds
• Alan Stern on suborbital research and NASA's mission to Pluto
• Col. 'Coyote' Smith on the outlook for space solar power
• Tim Pickens on rocket ventures and the Google Lunar X Prize

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

"Virtually Speaking Science" airs on Wednesdays on BlogTalkRadio, with a live audience in the Exploratorium's Second Life auditorium. In addition to Alan Boyle, the hosts include Tom Levenson, director of MIT's graduate program in science writing; and Jennifer Ouellette, science writer and "Cocktail Party Physics" blogger.