From Nyrath's twitter: "Adam" quantifies interstellar dust. This is to constrain starshot-like journeys to Alpha Centauri. If we could actually, like: do that.
No less a blogger than Centauri Dreams is saying that we should start smaller that is, closer. If we are resigned to low-mass high-speed flybys, we might as well strike out to - say - Eris. Or to Sedna, which clearly started out much further than its perihelion. We could mass-produce several of these and rideshare them on a Falcon 9. Several dozen if on the Super-Heavy / Starship plan.
Beyond the 30-100 AU Kuiper region, Centauri flags 550 AU as a sweet spot for using the Sun for a lens. (Yay Einstein!) These craft would fly hyperbolically to that point opposite the target system, turn around toward the Sun, and take their snapshot. Although such missions aren't inherently ecliptic; near-ecliptic trajectories are preferred for time-shaving planet-boosts. So: expect zodiacal or near-zodiacal initial targets. Like 55 Cancri.
I don't know how we quantify 100s AU dust which is not interstellar, although heated more from interstellar radiation than from solar. Although I can take some initial guesses, from trigonometry. (Yay Euclid!)
Out in 550 AU we get interstellar medium in radiation but not in dust. The dust - ice flakes mostly - would be orbiting the Sun, like Sedna does, so (on average) at slightly-less than the right-angle to the craft's near-straight curve but very slowly. (Yay Kepler!) Its sensitive equipment would be facing Sunward, so not in the line of the snowflakes, which I expect will be ramming the back of the craft with a (very) slight angle. Non-ecliptic missions will be taking that dust at larger angles and perhaps higher speeds if they aren't flat taking longer; another reason to start ecliptic.
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