Why solar panels are being launched into space

Among the many space-bound satellites aboard the SpaceX rocket launched earlier this week was a small prototype designed to harvest the power of the sun.

Scientists are hoping to show that space-based solar power is more than a futuristic concept, and potentially the next big thing in clean energy. 

Weighing in at just 110 pounds, the prototype satellite called the Space Solar Power Demonstrator (SSPD) is part of a larger effort to test out space-based solar power called the Space Solar Power Project (SSPP). 

Built by engineers at CalTech, the demonstration mission blasted off into space on Tuesday morning. The team is hoping to see if the technology is capable of working in the harsh environment of space, and ultimately launching a constellation of solar panels that would form an orbital power station, beaming energy harvested from the sun back down to Earth. 

Humanity has been harnessing the sun's power since the advent of the first solar cells in 1880. Solar energy is clean, it's cheap and we have an almost never-ending supply of it. Yet only about 5 percent of the world's energy is supplied by the sun. That's because solar panels are expensive and unreliable as a main energy source. 

And they have historically been too big and bulky to launch into space — but that's changing, along with the affordability of those satellite launches generally. 

In 2015, SpaceX shook up the aerospace industry when the company proved that rockets could be reusable. To date, the company has launched 200 rockets and recovered 161 of them. This feat continues to drive down launch costs as more and more companies aim to make their rockets reusable.

On Tuesday, SpaceX launched SSPD as part of its Transporter-6 mission, a sort of cosmic Uber pool that allows many smaller satellites to share the cost of the rocket. This in turn enables more access to space.

Solar panels are designed to take energy from our star and convert it into energy we can use here on Earth to power our lives. However, there are some limitations: weather and the fact that the sun doesn't shine at night. As such, the power we receive from these devices is not consistent. 

But by moving solar power stations to space, we could produce electricity from solar power around the clock. That's because the power would not be obscured by the day-night cycle or cloud cover, or affected by the changing seasons. 

So what does a solar power station look like? 

The SSPP team has developed one idea. To create its satellite, the engineers had to create a craft that was light enough for it to be scalable and cost-effective, while also being durable enough to withstand the harsh environment of space. It also had to be able to convert solar energy into energy that could be used on Earth. This called for the creation of new materials and technologies, resulting in the satellite we see today. 

The SSPD is composed of three different experiments rolled into one. The Deployable on-Orbit ultraLight Composite Experiment (DOLCE) will test the mechanisms needed to deploy solar panels in orbit. Another experiment onboard, known as ALBA, will analyze 32 different types of photovoltaic (PV) cells to see which cells perform better in the harsh environment of outer space. Finally, the Microwave Array for Power-transfer Low-orbit Experiment (MAPLE) will evaluate an array of 32 different microwave transmitters. 

The SSPP hopes its satellite will lead to the development of a constellation of modular spacecraft that collect sunlight, transform it into electricity, then wirelessly transmit that electricity over long distances wherever it is needed — including to places that currently have no access to reliable power.

John Mankins, a former NASA researcher, says that harvesting sunlight in space and delivering it wirelessly to Earth would be more feasible than one would think, noting that NASA has been exploring it for decades.

And he said recent studies have shown that a modular, mass-produced approach to building the necessary hardware would make it economical. 

"Combine low-cost launches with modular technology, and suddenly the economics of space solar power become obvious,” he said. 

Phil Metzger, a planetary scientist and former NASA researcher, said this technology could be game-changing not only to those who don't have access to traditional power sources, but also for planetary missions and other activities in low-Earth orbit. 

"We should be developing off-planet mining and manufacturing which will make space-based solar power even more economic and scalable," Metzger said. 

"The cost of building things in space drops faster than launch costs and the impact of fossil fuels on the environment will continue to go up, so space-based solar power will become economical."

Mankins says that one of the biggest hurdles — after cost — will be to ensure that we can beam as much of the power collected back to Earth as possible and that it ends up where we want it. Earth's atmosphere can prove tricky, but the more this technology is tested, the more refined it will become. 

To that end, CalTech isn't the only enterprise tossing around the idea of space-based solar power. The European Space Agency, Japan and China are also conducting studies into its feasibility. 

"Space-based solar power would be an important step towards carbon neutrality and energy independence, not only for Europe, but for everyone," said Josef Aschbacher, director general of the European Space Agency. "Our studies have shown that." 

The U.S. military also recently conducted its own solar power experiment in space, contained inside the X-37B spaceplane, which evaluated the sunlight-to-microwave conversion process. SSPD will help take it one step further.