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Seeing Power Beaming
A really interesting article at Centauri Dreams
The Benfords are doing some really interesting stuff on boostbeaming.
[Image: Fig-1-Benford.jpg]
Quote:Figure 1. Schematic of Mars cargo mission via microwave beaming, not to scale. The path of the sailship is the dashed arrow. The inset is the beam profile shown in green overlaying the sail of diameter Ds. The beam always overlaps the sail to some extent.

Quote:How to See Power Beams

At 100 parsecs (326 light years), beam intensity is estimated to be of order 1 Jansky, which is about 100 times the typical detectability of SETI radio searches. The sweeping action of the beam in Figure 2 has implications for observers. The receiving radio telescope will typically see a rising signal because the beam is beginning to sweep past, then a drop in signal as the sail’s shadow falls on the receiver, then a rise as the beam reappears, followed by a decline. In other words, the time varying history of intensity is a symmetric transient with two peaks with much less (or even nothing) in between. They estimate the timescale for the transit to be of order 10 seconds.
Boostbeams are so useful for interplanetary and interstellar travel that I'd expect any civilisation that didn't have reactionless drive (which, in the real universe may be all of them) to use them extensively. Even in the OA universe many or most factions and xenosophont civilisations do not have access to reactionless drives.

Forget anti-asteroid radar; the most easily detectable emissions could be boostbeams.
Note the similarity between Benford's image and this one I made ten years ago; a distant observer would tend to see a double peak, depending on exactly which part of the beam they intercepted.

[Image: Bearmrider2.jpg]
It's a shame that we don't have access to data accumulated by radio telescopes in past decades.
If we had it, we could run relatively simple algorithm to find candidate signals, otherwise it will require lot of resources and time to get any results.

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