Zodiacal Dust and Spaceship Detection

[vicky_molokh]

Greetings, all!

In a thread far away a long time ago, upping the amount of zodiacal dust in the setting's solar system(s) was mentioned as a way of making detection of objects in space harder. The question is: how much can it be upped without having other unforeseen/undesirable consequences and how much would it reduce the detection bonuses?

Also, if there are other plausible ways to achieve a similar outcome, they're welcome.

Thanks in advance!

[johndallman]

Well, trying to figure this out, the dust is responsible for the brightness of the sky in the 5-50 micron infra-red band. Increasing the amount of dust will start to reduce the +24 bonus for a target silhouetted against deep space (Spaceships, p44-45). However, I don't know how to work out how much dust you need to reduce the bonus.

The mass of the solar system's dust cloud is small on a solar system scale (about a 15-killometre asteroid), but quite large on a human industry scale. You also have to grind it remarkably fine, and disperse it very widely, which sounds expensive. I think you'll need to be really quite high-tech to do enough of this to be noticed, never mind to have any side-effects other than annoying astronomers.

[Anthony]

Originally Posted by johndallman

The mass of the solar system's dust cloud is small on a solar system scale (about a 15-killometre asteroid), but quite large on a human industry scale. You also have to grind it remarkably fine, and disperse it very widely, which sounds expensive. I think you'll need to be really quite high-tech to do enough of this to be noticed, never mind to have any side-effects other than annoying astronomers.

That's assuming we're talking our solar system, and deliberate action. A protoplanetary disk is probably something like 10^12 times the density of our dust cloud.

As for the effects on detection: it depends on detector details, because it varies with sensor resolution, but a decent rule of thumb is to reduce range by the fourth root of sky brightness, so 10,000 times brighter would be 1/10 detection range (side note: the +24 should really replace the +10 for in plain sight, not add to it).

[vicky_molokh]

Originally Posted by Anthony

That's assuming we're talking our solar system, and deliberate action. A protoplanetary disk is probably something like 10^12 times the density of our dust cloud.

As for the effects on detection: it depends on detector details, because it varies with sensor resolution, but a decent rule of thumb is to reduce range by the fourth root of sky brightness, so 10,000 times brighter would be 1/10 detection range (side note: the +24 should really replace the +10 for in plain sight, not add to it).

And how much denser and how much brighter can it reasonably get without upsetting planetary formation, climates, requiring a very specific solar history etc.?

[johndallman]

Originally Posted by vicky_molokh

And how much denser and how much brighter can it reasonably get without upsetting planetary formation, climates, requiring a very specific solar history etc.?

Dust has quite a short lifespan in the inner solar system, compared to the lifespan of the solar system. A dust grain will usually be gone within ten million years: they get swept away by the solar wind and radiation pressure, collide with planets, and so on.

The sources of present-day dust include short-period comets, collisions between asteroids and Kuiper Belt Objects, and interstellar dust grains.

[Calvin]

There's a book by Ian M. Banks called Feersum Ennjin which has an incoming interplanetary dust cloud as one of the major plot points for the book. The idea being that it's substantial enough to block a substantial amount of sunlight, which does all sorts of bad things to crops.

If you wanted a hard(ish) sci-fi way of having a thick enough dust cloud for your needs, you might set the campaign during such an event. The dust might not stick around very long on a stellar level, but that could still mean several generations of people living with the dust cloud as a reality.

Granted, being thick enough to make agriculture much more difficult probably goes against your desire to avoid "unforeseen/undesirable consequences", but you could tone it down a little.

As for a scientific basis for reducing the modifiers to detect something, I couldn't really give you a proper answer.