> there is a source of volatiles "close" by - earth The spacers weren't near earth, they were out at the (former) moon's orbit. Getting to and from Earth or an

> there is a source of volatiles "close" by - earth The spacers weren't near earth, they were out at the (former) moon's orbit. Getting to and from Earth or anywhere not near moon's orbit would require considerable propellent. This is even assuming that the thrusters continue to work - they only have so many parts. The book makes reference to hundreds if not a 1000 years before the spacers really started to develop things again - well past the base case for solar cells. For the diggers, the sunshade would have been way after and even if in place would have provided no help as all the energy of consequence was coming from the bolides burning up in atmosphere and hitting ground. This worst of the hard rain lasted for at least a few hundred years in the book, although the OP analysis suggests maybe the peak hard rain may have been shorter. For the pingers, another big issue would be corrosion. I imagine the ocean would eat away at most of their stuff long before they could develop the capacity to make more.