why the honorverse would be full of dead planets

Annachie wrote:Thinking about it.

Sand would burn up in atmosphere wouldn't it?

But it would make a mess of orbital infrastructure, well unshielded.

Sounds like a safish way to destroy orbitals, assuming the launching/detection roblems could be handled.

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Takes time to burn up though, we could send up one of those useless shuttles up into orbit with a load of sand and release it on a sub orbital flight path, and all it'd do is make a really big fireworks show. Too little velocity, and tiny size so they'd burn up really fast and wouldn't make it deep into the atmosphere.


Sand scorching in at anything upwards of 0.4c or so, would be moving so fast that between hitting the outer atmosphere and hitting the surface, it only has time to get hot but not actually burn up.

Somtaaw wrote:

Annachie wrote:Thinking about it.

Sand would burn up in atmosphere wouldn't it?

But it would make a mess of orbital infrastructure, well unshielded.

Sounds like a safish way to destroy orbitals, assuming the launching/detection roblems could be handled.

Sent from my SM-G920I using Tapatalk

Takes time to burn up though, we could send up one of those useless shuttles up into orbit with a load of sand and release it on a sub orbital flight path, and all it'd do is make a really big fireworks show. Too little velocity, and tiny size so they'd burn up really fast and wouldn't make it deep into the atmosphere.


Sand scorching in at anything upwards of 0.4c or so, would be moving so fast that between hitting the outer atmosphere and hitting the surface, it only has time to get hot but not actually burn up.

It's also a question of concentration of mass. Estimates vary, but the largest I've seen is that the Earth might scoop up up to 300 tons of space dust per day. But scattered over the whole earth, and spread a little over time that's insignificant.
But I bet if a 4 megaton freighter dumped a couple million tons of loose sand out at medium orbital height - then you'd get some impressive effect even if that spreading ball of sand hit the atmosphere at low velocity (say less than 1000 kph) - each individual grain is insignificant but enough of them in a relatively concentrated area is going to be a bigger problem.

Somtaaw wrote:Takes time to burn up though, we could send up one of those useless shuttles up into orbit with a load of sand and release it on a sub orbital flight path, and all it'd do is make a really big fireworks show. Too little velocity, and tiny size so they'd burn up really fast and wouldn't make it deep into the atmosphere.

Sand scorching in at anything upwards of 0.4c or so, would be moving so fast that between hitting the outer atmosphere and hitting the surface, it only has time to get hot but not actually burn up.

Never underestimate the amount of energy relativistic projectiles can dump. This is an interesting read on the subject. (TL;DR: The particle itself is the least of your concerns in this regard, it's what the atmosphere is starting to do once those particles pass through that's the issue)

The E wrote:

Somtaaw wrote:Takes time to burn up though, we could send up one of those useless shuttles up into orbit with a load of sand and release it on a sub orbital flight path, and all it'd do is make a really big fireworks show. Too little velocity, and tiny size so they'd burn up really fast and wouldn't make it deep into the atmosphere.

Sand scorching in at anything upwards of 0.4c or so, would be moving so fast that between hitting the outer atmosphere and hitting the surface, it only has time to get hot but not actually burn up.

Never underestimate the amount of energy relativistic projectiles can dump. This is an interesting read on the subject. (TL;DR: The particle itself is the least of your concerns in this regard, it's what the atmosphere is starting to do once those particles pass through that's the issue)

I actually kept that in mind, but that comic is also assuming a speed of 0.9c, and a baseball has far more atoms in its makeup than a grain of sand. At too low a velocity, the sand is simply going to burn up before it gets deep into the atmosphere and is unlikely to even impact the ground.

That's ignoring what would happen to the atmosphere itself, jet streams, weather and the like, a sufficiently sized bombardment that wasn't travelling fast enough would still wreck havoc to a planet's life sphere, but it isn't close to approaching declaring Exterminatus


But once that magical threshold speed gets crossed, sand turns into Exterminatus, and just trashes everything on the surface of the planet.

Annachie wrote:Thinking about it.

Sand would burn up in atmosphere wouldn't it?

It's moving at 210,000 km sec. assume the atmosphere is 100 km thick, the sand will pass through the atmosphere in .0004 seconds. So I don't think it will burn up. It will certainly be visually exciting, but I suspect it will more or less convert the upper atmosphere into a superheated shock front that visually resembles the core of a fusion bomb.

It's a lot more complex than that, although your description of the effect is probably pretty close.

My own guess [and it _is_ a guess, I don't have the tools to calculate this] is that all the sand will be stopped at least 50km up - and by the time it is stopped, that layer will be incandescent. And the shock wave will have broken every window on the planet several times over.

kzt wrote:

Annachie wrote:Thinking about it.

Sand would burn up in atmosphere wouldn't it?

It's moving at 210,000 km sec. assume the atmosphere is 100 km thick, the sand will pass through the atmosphere in .0004 seconds. So I don't think it will burn up. It will certainly be visually exciting, but I suspect it will more or less convert the upper atmosphere into a superheated shock front that visually resembles the core of a fusion bomb.

Louis R wrote:It's a lot more complex than that, although your description of the effect is probably pretty close.

My own guess [and it _is_ a guess, I don't have the tools to calculate this] is that all the sand will be stopped at least 50km up - and by the time it is stopped, that layer will be incandescent. And the shock wave will have broken every window on the planet several times over.

The shock waves are unlikely to put out all the fires that were created by the incandescent layer of the atmosphere...

It will be a bad day.

I mentioned this before but no one commented so I may have not explained it properly. Under relativity, when you start getting up to 0.9C or so it takes a lot of energy to go faster. The energy goes into increasing the mass in a reversal of E=MCsqr. So a 1000kg projectile at say (too lazy to do the high end maths) 0.95C might weigh 201ton, of which 200ton would be converted back to energy on impact with a planatry core.
Small radar section and less likely to hit space dust. Impossible to do without Honorverse free wedge energy.
An old SiFi joke on this is that it is possible to get to C, but only one ship per universe once, as at C it has infinite mass & we all become a black hole.

Ok, I admit I have not read every post so far, but I must say that the problem is much, much larger than OP indicated. You do not need to consider relativistic effects or the problem of cargo.
Think about it some more, please.
You do not need to load a ship up with anything.
You do not need to get it to 0.9c.

You need to capture a freighter, any freighter, of some size, with any cargo at all. Then accelerate it at 200g for 60 seconds...

You now have an near extinction level impact on the order of 50 Gt. At least.

Something as small as a pinnace impacting at 0.5c would make the Krakatoa eruption look like a sneeze.


This aspect of the Honorverse technology is the one that bothers me most, since impact energy increases by the square of the change of relative velocity for long enough before you ever approach the relativistic.

And as David Weber himself has said in this very thread, that is why most planets that have traffic control also have very strict rules about the use of impellers anywhere near them, including lethal responses if it looks like a ship intends to disobey orders to shut down its impellers.