NASA revives plans to build huge solar power plants in space

Fifty years ago the idea of capturing renewable solar energy using space based platforms and then beaming that energy to base stations back on Earth was regarded as a crackpot idea, and now, after China’s recent announcement that they’re going to start building solar power plants in space that will beam gigawatts of electricity back to Earth starting in 2024, teams at NASA look like they’re finally ready to put the case forwards for their own version of the technology at this year’s UN Climate Change (COP25).

Solar satellites, as NASA are calling them, were first conceptualised in 1968 by Peter Glaser, a NASA engineer, and these huge arrays, which would be lightweight frames several miles across that would hold tens of thousands of solar panels, would orbit 22,000 miles above the equator in a geosynchronous orbit where they’d be constantly exposed to sunlight which they’d convert into electricity.

They would then use a cellphone-like microwave signal to beam that electricity safely down to equally large antennas on the ground below them where it would then be fed into the grid with each of these satellites transmitting 3 to 15 gigawatts each - enough to power several cities. For example,  today, 1 gigawatt will supply 1 million American homes with constant power.

Over the years since the initial idea companies such as Boeing and General Dynamics proposed that astronauts could build Skylab-like space stations in Low Earth Orbit 200 miles up, where crews and robots would assemble the enormous satellites, and then rockets could boost the arrays into their final orbit 22,000 miles above the Earth.

The General Dynamics proposal even suggested that factories, like the ones Amazon founder Jeff Bezos is now suggesting, could be built on the moon, 220,000 miles from Earth. They would manufacture solar satellite components from local materials, then launch them back toward earth and into their geosynchronous orbit, and because of the moon’s very low gravity and lack of atmosphere the costs would be 10 percent of launching from Earth – although, admittedly, that doesn’t account for the costs and complexities of setting up manufacturing facilities on the moon in the first place which obviously wouldn’t be cheap.

As these engineers knew all too well though the real limit wasn’t the sky, it was the federal budget. These plans would have cost more than the entire Apollo program. But the real showstopper was that solar satellite electricity would have cost far more than electricity produced on the ground, so eventually all of those proposals and designs were shelved.

In every decade since then though the companies and sponsors of the ambitious project have been re-running the numbers using improved rockets and lighter satellite components, and needless to say the costs have been plummeting…

Last year, Paul Jaffe at the US Office of Naval Research, another Glaser fan, developed solar satellite components that weigh a tenth as much as they did just five years ago, and a group at Caltech did the same. Glaser’s proposed 10-mile-wide satellites would be 1,000 to 3,000 yards across, depending on the design.

Today, private rocket companies such as SpaceX and Blue Origin use reusable rockets to launch satellites for a third of the 2014 cost, and a hundredth of the 2004 cost, and according to NASA, the Block 2 versions of their huge new SLS rocket, if mass-produced for this market, could match or beat those costs.

Many within NASA also believe that the current plan to return astronauts to the moon in 2024 could be modified to seek out sites to manufacture the solar satellites. During the past decade, satellites orbiting the moon have discovered enormous caves, called lava tubes, which could house these factories and protect them from the radiation and wild temperature swings on the surface.

The interiors of some of these caves are over a mile high and many miles long. Other lunar satellites have analysed metal ores on the surface that can be processed and used to build solar satellite components. They’ve even found ice in deep craters, and once processed, this would sustain the astronauts, and also provide rocket fuel to launch the components back into orbit.

So, will NASA enter the race and join China in building these giant orbiting power stations? Well, time will tell so keep your eyes peeled.