Progress takes time and money. Imagine they needed to take an 8 month break and raise 20M to fix a battery heating issue. Each component of a complex solution, like a solar plane, makes slow but steady progress: lighter&#x2F;stronger materials, lighter&#x2F;more durable batteries, etc. Software will also play a huge role automating and making resource efficiency better. The fact is that step one is cleared: flight around the world on solar power :)