Concepts for gargantuan space-based solar power plants have swung back in vogue. But the engineering to make them a reality still lags far behind.The accelerating buildout of solar farms on Earth is already hitting speed bumps, including public pushback against the large tracts of land required and a ballooning backlog of requests for new transmission lines and grid connections. Energy experts have been warning that electricity is likely to get more expensive and less reliable unless renewable p...