I was asked to write up some thoughts on Space Solar Power, so here they are – stream of conscious and all that. I wrote this even though the last time I had the gall to say such things (in Space News) i was excoriated by members of alt.space for attacking one of the holy grails of space development.
In the sure to be immortalised words of our current War President – “Bring ’em on!”
SSP advocates point to the ability geostationary based SSP stations to provide clean abundant energy by harnessing solar power and retransmitting to Earth in the form of microwave energy, to be converted at ground-based stations into cheap energy for terrestrial uses.
There are a large number of factors which, at this time, call into question the feasibility of SSP – these can be grouped into two primary categories: economic and technological.
As I am not an engineer by trade, i will refrain from getting into power efficiency, conversion ratios, or other factors which others have pointed to when comparing SSP to existing terrestrial-based power systems (such as nuclear and wind). These tradeoffs in efficiency and the economics of the power generated by SSP vis a vis terrestrial means are fairly well argued out by others. There is one glaring unknown which also forms the basis for my position against the viability of SSP at this point in time.
Simply put – with today’s space technology, we are supremely unprepared for the task of building a SSP generating station. Current designs that have been put out to the masses call for a facility at geostationary orbit which is many times the size & mass of the ISS. There are significant major problems that immediately come to mind:
1) we’ve never designed and built even a prototype SSP. So even if we wanted to, we couldn’t just “build” one today from scratch without first going through numerous teething pains designing, building, and testing prototypes until we finally had it working correctly. And that includes building and testing IN SPACE, not just on the ground.
2) which leads to the second issue – R&D and Operations are two very different things. These are often confused by true believers, or the difference is knowingly trivialised as “just an engineering problem”. But work I did studying commercialisation of ISS highlights the same problem. The ISS was touted as a great R&D facility – as was the Wake Shield Facility before it. However, what was never examined was the practicality of production of a material that was first discovered during zero-G research. A practical example: WSF demonstrated that it was possible to create an ultra-pure vacuum environment, which could be used for making better raw materials for computer chips. However, there is a huge gap between making a few test raw material articles in basic R&D and building a zero-G chip fabrication facility in space…
3) so let’s assume for a moment that we can actually design and fly a few prototype power stations (big assumption). There do not exist today any launch vehicles capable of lifting a complete item to GEO that is as large or larger than ISS. Which means that we’d need MANY large launch vehicles (likely hundreds) to put the components of this hypothetical SSP into GEO. Then we’d have to assemble it. Except that this assembly would have to be automated, as the last time we had an astronaut at GEO or beyond was in 1972. Which means developing brand new capabilities, as the assembly and ongoing construction of ISS continues to demonstrate just how difficult it is to build a relatively small facility only a couple hundred miles up.
Some day, when we have solved the single most important aspect that is critical to all long term space development – that is cheap, realiable, reusable, access to space (under $100/lb to orbit), THEN things like SSP (and space elevators, and L5 colonies, and insert your favourite space development idea here) will be possible. But for now, it is just another bit of science fiction — because of economics and existing engineering know how.