Interstellar debris

[jaf]

When travelling at reletivistic speeds even a grain of rice could be fatal to your starship that is why Project Daedalus has that "sheild" at the front of the second stage, my point is what do you think about interstellar debris in ksp 2.

[Catto]

12 minutes ago, jaf said:

When travelling at reletivistic speeds even a grain of rice could be fatal to your starship that is why Project Daedalus has that "sheild" at the front of the second stage, my point is what do you think about interstellar debris in ksp 2.

Probably asteroids

[t_v]

I think it was mentioned in the Purdue space interview back in like 2020 that interstellar debris was not a part of the game. The Daedalus project would never actually slow down, as turning around to burn retrograde would destroy the engine. To avoid that, they chose not to simulate interstellar debris. 

[Jcklemme]

21 minutes ago, t_v said:

I think it was mentioned in the Purdue space interview back in like 2020 that interstellar debris was not a part of the game. The Daedalus project would never actually slow down, as turning around to burn retrograde would destroy the engine. To avoid that, they chose not to simulate interstellar debris. 

Maybe I'm just not thinking about it enough, but why would that preclude adding interstellar debris?

[darthgently]

28 minutes ago, t_v said:

The Daedalus project would never actually slow down, as turning around to burn retrograde would destroy the engine.

I wonder if once the engine is firing if the debris could reach the engine to damage it given the thrust.  Like if there were some way to shield it during the turn and lose the shield just as the engine comes up to full power or something.  I'm talking hypothetical real world here, not KSP. 

If the braking thrust can prevent debris damage, the shield wouldn't have be as bulky as the fore shield as it would only have to last a short time.

[t_v]

Just now, darthgently said:

I wonder if once the engine is firing if the debris could reach the engine to damage it given the thrust.  Like if there were some way to shield it during the turn and lose the shield just as the engine comes up to full power or something.  I'm talking hypothetical real world here, not KSP. 

If the braking thrust can prevent debris damage, the shield wouldn't have be as bulky as the fore shield as it would only have to last a short time.

I think that the engine's exhaust is linear enough that it wouldn't hit nearly any debris coming its way. One solution is to have a massive conic shield with the tip of the cone near the engine to allow the exhaust to slip past the engine into space but block the particles coming in from the other side Then you would just have to shield while rotating the craft mid-course. As for the first question, I can't remember exactly what it was, I think it was a convenience thing where they didn't want players to have to encapsulate their craft in concrete. 

[darthgently]

14 minutes ago, t_v said:

I think that the engine's exhaust is linear enough that it wouldn't hit nearly any debris coming its way.

Ok, I guess I was thinking the dangerous debris would be something the ship was running into as it ran aft-first into it, so the thrust would be aim right at the debris.  Are you saying the debris would survive the thrust and make it to the engine because it would slip between the particles in the exhaust as the vectors are so parallel?  As for debris coming in at an angle to the craft's velocity vector with a high relative velocity, I have no ready answer.

The conic shield is interesting; or even just a normal shield, but far enough away that the exhaust had no effect on it.  In fact, why does the shield have to connected to the craft at all and why does it have to slow down with the craft?  As long as the main craft follows the path the shield has cleared out it should be mostly clear, I'd think.  So the fore shield could be detached prior to flipping, then the main craft flips, and slows slightly to allow the shield to get ahead of it a safe distance, then the braking burn starts.

I still wonder if the exhaust alone could be used even if it means having it intentionally less laminar and more of a spread so the debris has to cross its flow at some point; maybe.

Edited April 14, 2022 by darthgently

[t_v]

3 minutes ago, darthgently said:

Ok, I guess I was thinking the dangerous debris would be something the ship was running into as it ran aft-first into it, so the thrust would be aim right at the debris.  Are you saying the debris would survive the thrust and make it to the engine because it would slip between the particles in the exhaust as the vectors are so parallel? 

You should be able to see this in the trailer- the Daedalus engine's exhaust is a rather thin line extending from the center of a large engine bell. It expands, but not in a short enough time to stop all the particles ahead of the engine. It would basically be like having a shield far in front of the engine, which I'll explain with the other point:

5 minutes ago, darthgently said:

As for debris coming in at an angle to the craft's velocity vector with a high relative velocity, I have no ready answer.

The conic shield is interesting; or even just a normal shield, but far enough away that the exhaust had no effect on it.  In fact, why does the shield have to connected to the craft at all and why does it have to slow down with the craft?  As long as the main craft follows the path the shield has cleared out it should be mostly clear, I'd think.  So the fore shield could be detached prior to flipping, then the main craft flips, and slows slightly to allow the shield to get ahead of it a safe distance, then the braking burn starts.

I still wonder if the exhaust alone could be used even if it means having it intentionally less laminar and more of a spread so the debris has to cross its flow at some point; maybe.

So, the speed of the craft means that a piece of debris traveling horizontally pretty fast would still be traveling in practically a straight line, so you don't have to worry about them coming in from an angle. However, you do have to worry about it when the shield is very far in front. If the shield (or exhaust shield) is a non-negligible time ahead of the main craft, a particle traveling sideways can use that time to start outside the shield and move into the path of the engine bell. To get full coverage, the exhaust would have to expand every rapidly to catch any particles that are traveling sideways, which is not ideal for Isp, as that is a lot of energy that you could have used for thrust. So, sweeping out the path wouldn't really work, you probably would do best with a shield only a few dozen km away from the craft at most. 

[darthgently]

5 minutes ago, t_v said:

So, sweeping out the path wouldn't really work, you probably would do best with a shield only a few dozen km away from the craft at most. 

Ok, then if the exhaust is thin, what about the shield having a port in it for the exhaust (yeah, I know, heat heat heat) but the remaining disc of the shield would protect the engine where the exhaust didn't cover it.  That boundary between the exhaust and the shield port edges is highly problematic though, lol.  Still, the cone shaped shield would have the same concerns with heat

[t_v]

That could work a lot better, but I can’t remember why the Daedalus engine is a dome (since the actual reaction is in a rather small area the engine could easily be much smaller) and I’m just going off of the hypothetical that there are a lot of neutrons and other fun stuff bouncing around and you don’t want to bottle that up. But definitely a hole would be better than deflecting the exhaust. 

[Vl3d]

5 hours ago, darthgently said:

I wonder if once the engine is firing if the debris could reach the engine to damage it given the thrust.

How much thrust would it actually have, considering a long duration constant acceleration?

For Daedalus the internet says a mass of 54,000 tons and a thrust of about ~700,000 Newtons with an engine exhaust velocity of 10,000km/s.

Minimum TWR: 700 kN / 54,000 tons = 0.013

Maximum TWR: (second stage weight + payload = ~1,500 tons) meaning 700 kN / 1,500 tons = 0.46

But I know that calculation is not right in a 0g environment.

So TWR would actually be 1 for a long duration constant 1g acceleration. That's not enough for a relativistic speed force shield.

Another approach:

You can accelerate 1 gram of matter to 10% speed of light with 30 kN applied for 1 second. So even if you focus the whole engine bell in a circle occupied by a 25 grams object, you still wouldn't have enough to slow it down in 1 second.

Edited April 14, 2022 by Vl3d

[darthgently]

5 hours ago, Vl3d said:

How much thrust would it actually have, considering a long duration constant acceleration?

For Daedalus the internet says a mass of 54,000 tons and a thrust of about ~700,000 Newtons with an engine exhaust velocity of 10,000km/s.

Minimum TWR: 700 kN / 54,000 tons = 0.013

Maximum TWR: (second stage weight + payload = ~1,500 tons) meaning 700 kN / 1,500 tons = 0.46

But I know that calculation is not right in a 0g environment.

So TWR would actually be 1 for a long duration constant 1g acceleration. That's not enough for a relativistic speed force shield.

Another approach:

You can accelerate 1 gram of matter to 10% speed of light with 30 kN applied for 1 second. So even if you focus the whole engine bell in a circle occupied by a 25 grams object, you still wouldn't have enough to slow it down in 1 second.

This is interesting.  I'm thinking the exhaust velocity would be the relative velocity of the debris and craft combined with the exhaust velocity relative to the engine.  I mean if the debris is enough to damage the engine via relative velocity, then wouldn't the exhaust have an effect on it given the exhaust velocity + the relative velocity of the craft and debris?  And the exhaust is much hotter also, so vaporization of debris gets a head start prior to any impact with the bell, and up to some size and composition of debris, would complete prior to impact with the bell

[Vl3d]

I guess it depends on size. I wouldn't go one-on-one with a piece of rock 1 m in diameter at 0.1c or more.

That's about a half kiloton airburst at 18 km/s... 0.1c is ~30.000 km/s. I don't think it would even have time to vaporize.

Edited April 14, 2022 by Vl3d

[darthgently]

41 minutes ago, Vl3d said:

I guess it depends on size. I wouldn't go one-on-one with a piece of rock 1 m in diameter at 0.1c or more.

That's about a half kiloton airburst at 18 km/s... 0.1c is ~30.000 km/s. I don't think it would even have time to vaporize.

Agreed.  At some point, at those velocities, there will be a size/density that will wipe out whatever shield you have, exhaust enhanced or not.  There is definitely a risk analysis roll of the dice involved in relatively timely interstellar travel.  But I think that risk is to be accepted and baked in, so it really comes down to knowing the risk within some error level I suppose.  Life is risk

Edited April 14, 2022 by darthgently

[Vl3d]

That type of project is a Darwinian experiment. You would have to send a lot of ships.

But I'm sure there will be some legendary player that will leapfrog the Oort cloud to another star. Just to make it realistic.

[SciMan]

You know how part failure mods aren't a part of KSP 1 (and almost certainly that mechanic is not part of KSP 2)?

The same logic applies against the inclusion of interstellar debris.

RNG of "your ship is crippled or entirely destroyed" is not something I myself would consider "fun and engaging gameplay". In fact, if I encountered such a thing, I'm so against it that I'd probably become a mod author SPECIFICALLY to eliminate that one particular feature from the game.

Nobody likes it when the single mission you spent 20+ in game years building up to, fails because "RNG says so". Not even if you can do things to "reduce the chance of it happening".

And if you CAN entirely eliminate it, you could balance the game WITHOUT that mechanic, by de-rating the engines just enough to compensate for the mass savings of not having to carry debris shielding, which means that the entire mechanic is pointless to include in the first place.

That's also why I think life support won't be a thing. If you can get to fully closed-loop life support where literally everything is recycled and the only requirement is energy (and to even consider going interstellar you're going to need to do just exactly that), why even include all those parts and extra code in the first place if 99% of the time it's just going to be sitting there doing essentially nothing? That would be just one more thing hogging precious CPU resources in an already quite computationally-demanding game.

[darthgently]

2 minutes ago, SciMan said:

You know how part failure mods aren't a part of KSP 1 (and almost certainly that mechanic is not part of KSP 2)?

The same logic applies against the inclusion of interstellar debris.

Yeah, you missed the introduction to this part of the thread where we stipulated that this was about real space travel hypotheticals, not KSP 1 or 2 game play.  Sorry for any confusion

[SciMan]

OK, then my next question becomes "If this is about real space travel hypotheticals, and not about KSP 1, then why is it in the "KSP 2 Discussion" forum sub-section?"

[darthgently]

4 hours ago, Vl3d said:

That type of project is a Darwinian experiment. You would have to send a lot of ships.

Well, that is kind of what life is, right?  Sending a lot of ships, as well designed as possible, perhaps differences in design across the group, and hoping some gets through.  There is no safe space

1 minute ago, SciMan said:

OK, then my next question becomes "If this is about real space travel hypotheticals, and not about KSP 1, then why is it in the "KSP 2 Discussion" forum sub-section?"

Because the topic of interstellar came up here, then diverged.  A mod can move it if is a problem.  People are not machines and socializing doesn't occur by way of some algorithm.  Well, not the good kind any way.  No harm, no foul, right?

[SciMan]

As far as "how do you shield against interstellar debris", the best solution I personally know of is to use Oort body ices to make your shield, something like this:
Take the ice and volatiles from a lot of Kuiper belt and/or Oort cloud bodies, and melt it into one gigantic (million metric tons sounds like a good place to start) sphere of ice and volatiles (if you're using a Fusion-driven vessel, you could make the sphere do double duty by making it out of Deuterium ice, so you can also use it as fuel).
Then add the habitat module and any other payloads, by melting a hole deep into the created sphere, 1/3 of the diameter of the ice sphere deep. This encases the habitat module and any other payloads in a deep layer of ice, thicker on one side than the other.
Attach the drive system on the side of the ice sphere where you melted the hole to put the habitat module and any other payload in, this leaves the other 2/3's of the ice sphere to protect the habitat module (and payload) from interstellar debris.
Now add a bunch of ice-crawler and ice-burrowing robots, to manage the mass distribution and harvest the ice ball for various consumable needs (might work best if the ice is just "all heavy water", not sure about the toxic effects of heavy water on human beings but I don't think it's too bad, heavy water is just normal water with one or both of the Hydrogen atoms being replaced by Deuterium, so it's either HDO or D2O).

Now if you did the calculations of how much ice you need correctly, you should be consuming the ball of ice constantly as you travel, but still arrive at your destination with enough left over that you have a safe area to shelter from solar storms from the destination star.

And to return to your starting star, you just harvest the icy bodies in the Kuiper belt and/or Oort cloud of the system you arrived in.

Simple and elegant, and there's a certain irony that one of the largest ocean liners (Titanic) was sunk by an iceberg, but the first Star Liners are essentially pushing around an iceberg as a critical part of the vessel.

[Vl3d]

13 hours ago, SciMan said:

best solution I personally know of is to use Oort body ices to make your shield

That would be way too heavy for the engine to push.

Original Daedalus solution: "the ship would be protected from the interstellar medium during transit by a beryllium disc, up to 7 mm thick, weighing up to 50 tonnes. This erosion shield would be made from beryllium due to its lightness and high latent heat of vaporisation."

[pandaman]

Ok... Assuming that random., naturally occurring debris (dust or small wanderings rocks etc) is not modelled or simulated, either within star systems or in interstellar space.   Excluding defined asteroids, comets and planets' rings etc.

What about ship debris in interstellar space? (it's KSP, we all know this is inevitable) .

Will it be treated the same as in KSP1?  Whereby it does it's own thing until it hits something or reaches the 'max limit'.

[Minmus Taster]

This ship seems to have some sort of heat shield on the front, I don't really see any reason it would be there other than for debris protection:

Also I'm guessing the engine on a Dedalus that has to face the debris would have it's sides coated in armor & the inside is probably already beefed up just so it can run.

[t_v]

That's actually a big detail, which probably does mean what you're saying. After all, the interview was a while ago, so new information takes priority. Also, in the first shot, I see the Crucible's plume. It is really more diffused than I expected, I thought it would be very linear due to the high efficiency. 

[Ozzy.R]

You can also employ active protection systems. Like, an array of really powerfull lasers for vaporizing the debris and either a really powerfull radar or lidar system for tracking them. You could combine this with a (or multiple) static shield for dealing with small debris and save the lasers for debris that are to big for the shield to safely handle. And for anything bigger you just need to move out of the way, which isn't to bad because the bigger something is the easier it is to see it from far away. 

Combine this with multiple ships for redundancy and you have a pretty good chance of making it to your interstaller destination safely.

Edited April 18, 2022 by Ozzy.R