Two months ago, we told you about Baiju Bhatt, one of the co-founders of the investing app Robinhood, who launched a new company called Aetherflux. This startup has a bold plan: to create a network of satellites in space that can send power back to Earth using powerful lasers. Sounds like science fiction, right? But it could change how we get and use energy—especially in hard-to-reach places.

The idea of space solar power isn’t new. Back in 1941, science fiction writer Isaac Asimov first...