In the third century BCE, King Hiero II of Syracuse asked Archimedes to devise a number of death traps to thwart Roman invaders. Among the many designs spun up by the great inventor was a solar death ray. The basic idea was to build an array of mirrors that could reflect rays of light into a central blast, causing Roman ships to burst into flame. It's unlikely the weapon ever made it past the blueprint stage, but it became an incredibly influential model nonetheless. Archimedes was perhaps the first solar power convert, searching for a way to take advantage of the inconceivable amount of energy our friendly neighborhood star barfs up every second.
The only thing that would make Archimedes' solar death ray more fascinating is if it was technically feasible, socially benevolent, and in space. That's where John Mankins comes in. A NASA veteran, aerospace entrepreneur, and space-based solar power (SBSP) expert, Mankins designed the world's first practical orbital solar plant. It's called the Solar Power Satellite via Arbitrarily Large PHased Array, or SPS-ALPHA for short. If all goes to plan, it could be launched as early as 2025, which is sooner than it sounds when it comes to space-based solar power timelines.
Scientists have been aware of the edge the “space-down” approach holds over terrestrial panels for decades. An orbiting plant would be unaffected by weather, atmospheric filtering of light, and the sun's inconvenient habit of setting every evening. SBSP also has the potential to dramatically increase the availability of renewable energy.
The SPS-ALPHA could revolutionize disaster relief, give developing countries access to reliable power, and provide the planet with an affordable green energy option.
I recently caught up with Mankins to discuss the SPS-ALPHA's progress and potential. “Because the power plant is in orbit, it can deliver power to any place on the ground that it can see,” he said. “A single solar power satellite would deliver power to on the order of a third of humanity—not all at the same time, but any of that market could, in principle, be addressed.” The SPS-ALPHA could revolutionize disaster relief, give developing countries access to reliable power, and provide the planet with an affordable green energy option. Plus, it's shaped like a margarita glass. What's not to love?
Most aerospace professionals would tell you there is, in fact, a lot not to love. When space solar was first suggested in the 1970s, the projected costs were gargantuan, giving the concept something of a quixotic reputation that holds strong today. “Most people in the aerospace industry learned, when they were coming up as new engineers, that solar power satellites are impossible, wildly expensive, and that anybody who works on them is a nut,” said Mankins. And it's no wonder. The old-school vision of such a satellite would weigh about 50,000 tons, cover an area of 5 x 10 km, and require a budget of at least half a trillion dollars. That exiled it firmly into the land of aggressively wishful thinking, where O'Neill cylinders and Martian terraforming hang out.