It's the size of the radiators and the expense of getting them up into orbit (along with maintenance) Most of my assumptions come from discussions like: https:

It's the size of the radiators and the expense of getting them up into orbit (along with maintenance) Most of my assumptions come from discussions like: https://news.ycombinator.com/item?id=46876105 https://news.ycombinator.com/item?id=46876105