NASA, the U.S. departments of Energy and Defense, the European Space Agency, the Japanese Aerospace Exploration Agency (JAXA), a handful of companies and a gaggle of academic scientists all have taken hard looks at stellar power technology, and they concluded that, from a technical point of view, it is feasible.
Yet one obstacle has seemed insurmountable: the cost to get up to 10,000 tons of components all the way to geosynchronous orbit. Rockets today are not reusable, and that makes them so expensive — currently around $4,600 for each kilogram of payload lofted into low orbits — that the economics of putting solar modules in space just don’t pencil out, even if the modules use solar-electric propulsion to lift themselves into their final orbit. For stellar power to compete with other kinds of renewable energy, those costs need to drop to around $400 a kilogram, Mankins estimates. Rocket launches would have to become a lot more frequent as well. Building a large plant would require hundreds of launches a year.
A tenfold drop in price and a manyfold increase in launch frequency might seem like wishful thinking. But SpaceX, a private company whose Falcon rockets now resupply the International Space Station, recently announced ambitious plans to make that happen. The company has designed a reusable booster that it believes can return to Earth, land gently on its feet and take off again within weeks. Elon Musk, the company’s audacious billionaire founder, has said that when rockets can be reused like airplanes, launch costs will fall by up to 99 percent.
The first attempt to land a Falcon after it delivered its payload to orbit, in January, ended in a near miss and an explosion. But in a more recent test in April, the rocket returned upright to the correct coordinates. (It landed, but then toppled over in high winds.) Musk has vowed to perfect the process.
He apparently has set his sights on near-daily launches, too. That is key to his plan, announced in January, to enrobe the planet with 4,000 communications satellites — more than triple the number of satellites now in orbit — starting around 2020. Musk has shown little interest in space-based solar power; his goal is to rebuild the backbone of the Internet in space. But if SpaceX succeeds with its reusable rockets and ramps up its launch rate as planned, it “could reduce launch costs enough to make SBSP cost-competitive,” says Susumu Sasaki, a veteran of JAXA’s stellar power program.