"You know, the Wright brothers flew 12 seconds and went nowhere. And our objectives are not quite exactly the same, but it does have a certain ring of that," Friedman said.
Friedman is a former aerospace engineer at the Jet Propulsion Laboratory (JPL) in California, an arm of the U.S. space agency NASA. If all goes according to plan, the "Cosmos 1" solar-sail spacecraft -- folded tightly inside the nose of a Cold War-era Volna rocket -- will be launched into orbit on 21 June from a submerged Russian submarine.
Once deployed, the privately funded spacecraft will remain in Earth's orbit, with no particular destination in mind. While the journey of "Cosmos 1" may be modest, the science is anything but.
As Friedman explains, sunlight contains packets of energy called photons.
"Only in the vacuum of space can we harness that energy into a force, because there are no other competing molecules, like wind and atmosphere, and we're flying in an otherwise weightless condition. So we harness the energy of sunlight in the form of the photons that come out of the sun. They hit a giant reflective mirror, which is how we make our solar sail -- into a very thin, aluminized, highly reflective sheet of plastic. And as the photons bounce off the mirror, they transfer their momentum to the mirror, and that gives you a force," Friedman said.
Since a solar-sail spacecraft doesn't need to carry fuel, the idea holds great promise for interplanetary travel -- even interstellar travel, far in the future. The technology could be especially efficient for returning soil or rock samples, or carrying cargo.
Friedman says he first got involved in solar sailing three decades ago, when he was working for JPL. The idea was broached to use the technology to rendezvous with Halley's comet in 1976. But the project was too ambitious and was abandoned. But Friedman never lost his fascination for solar sailing.
"People have come to me for years with ideas for test flights. But it wasn't until the Russians had a suggestion for a very low-cost launch vehicle -- the Volna launch vehicle, which is a submarine-launched ballistic missile, converted from its days as a weapon of war -- and then an idea for using inflatable tubes for making a low-cost spacecraft," Friedman said.
The solar sail is attached to inflatable tubes, which will deploy in space. Eight triangular sails will then unfurl, like a butterfly emerging from a chrysalis. The sails will have a total surface area of 600 square meters. That's about one-and-a-half times the size of a basketball court.
Mark Hempsell is a senior lecturer in astronautics at the University of Bristol in England. He says that, if the technology can be mastered, solar sailing could one day be used for inexpensive travel to other planets in our solar system, and beyond.
He believes the "Cosmos 1" project, while small, will help to advance science.
"There's a lot of detailed technology that you need to address, and [Friedman] seems to be tackling those sort of issues. So I think it is fair to say that it's a valid attempt and a useful start in getting this technology under our belts," Hempsell says.
The $4 million "Cosmos 1" mission is financed by private donors. About half of the money is coming from the U.S.-based Cosmos Studios, run by the widow of the late astronomer Carl Sagan. The "Cosmos 1" team is also working closely with the Lavochkin Association and the Space Research Institute, both in Russia.
Friedman believes the greatest space ventures -- missions to the moon or Mars, or probes such as "Voyager" or "Galileo" -- will always be carried out by governments. But private missions can also play an important part.
"There is a role, I think, for private groups like ours -- if we can get private funding -- to actually seed and innovate and sort of spur the whole process of exploration on," Friedman says.
He notes that NASA and the European Space Agency, as well as the Russian and Japanese space programs, all have solar sail projects. But he says they have more ambitious objectives and an approach that makes it a lot harder to commit to that risky first flight.
"They're doing everything right," Friedman says, "except they're not flying."
Last year, three Russian missiles of the kind being used to ferry "Cosmos 1" into space misfired during military exercises. One was blown up after veering from its flight path. But Friedman says the reliability of the Volna launch vehicle is the least of his worries.
"We are pretty confident. I mean, there's no question. There is a risk at launch. There is a risk at orbit insertion. There is risk with deployment of the sail, with the behavior of the sail. There is risk all the way down the line in this. No one in the space business takes these risks lightly," Friedman says.
Friedman hopes "Cosmos 1" will be deployed and in a stable orbit by 26 June. After that, experiments will be conducted to control the sails and expand the orbit. Friedman says the mission is designed to last only a few weeks -- the solar sail equivalent, perhaps, of the Wright brothers' 12-second flight.