njh, an anonymous commenter mentioned the following in the comment section of the recent SKA job announcement:
This seems as good a place to suggest this as any, with a non-zero chance of someone who can answer actually hearing: I recall that radio telescopes don't operate during the day due to the noise from the sun. If the surface were 'visible light reflective' these telescopes would focus sunlight and these already have a tracking system built in. Is it practical to make this array have dual purpose of radio telescope by night and solar generator by day?
Back of the envelope says that the SKA would produce 700TJ = 200GWhr if it is located mostly in desert areas with clear skies.
(photovoltaic panels have a conductive layer on the front, perhaps even the non-tracking arrays could serve dual purpose)
I responded with:
What surface area did you take for that back of the envelope computation ? Plus, there is the whole line loss between this location in the desert amd more populated areas
Let us also not forget that a power infrastructure would probably have some impact on the science aspect of the project even if they don't work at the same time.
to which njh responded added:
I was using their claim of 1 square kilometer - I was under the impression that for photon capture the resolution is set by the baseline (hence the idea of using telescopes around the world), but the sensitivity is set by the aperture, which is the amount of mirror area. Thus, when they call it a square kilometer array they mean it has a surface area of 1km^2, rather than its effective diameter. I agree about the power infrastructure, but I figured that the array itself would probably require a considerable amount of power. Long distance power transmission has improved steadily and 2000km is now considered very tractable - that's Algiers to London.
To keep this on topic, consider the dual problem: can we use the power fluctuations of large scale PV and window power to measure climate change?
njh must be refering to The Accidental Single Pixel Camera which in that case is really about imaging the Sun and the atmosphere in between. There ought to be some interesting information out of that. But without looking at the Sun and the power station capabilities, normal operation of the SKA during daylight ought to provide some information on the atmosphere above it.
Photos credit: SKA Project Development Office and Swinburne Astronomy Productions (through wikipedia)
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