Designing a space ship and with the dust shield

[DHF]

Hello everyone, I am designing a ship for my sci fi story and I need input regarding the shield. I am trying to make my story as hard sci fi as I can get away with. The story takes place a few centuries from now and details the first expedition to Alpha Centuri. The ship will have a cruising velocity of 12-15%c and I am currently trying to figure the best way to protect it from collisions with dust and other schpleh it encounters along its merry way. Would the shape of the shield have any baring? Lately I have wondered if it was possible to construct the shield in such a shape that it deflected impacts rather then absorbing them. would this work or would it not make any difference when you are moving at those speeds?

Any other ideas for the shield? I am open to ideas.

 

[newjerseyrunner]

What other technologies do humans have at the time? Can they create exotic matter? A shield made out of neutronium should be able to handle pretty much anything.

 

[GTOM]

I thought about a strong magnetic field deflect charged particles.
And use X-lasers, or electron and proton beams to charge uncharged ones.

 

[DHF]

Yes Nutronium would be a super shield but it is off the table for my characters for a few reasons, This is their first exploration outside of the Sol system so they wouldn't have access to Neutron stars. I also feel that fabricating such a material would be well beyond their technical capabilities. fabricating Neutron material and you are talking about a society that is likely tens of thousands of years ahead of us. I was trying to keep my tale within a few hundred years because I want the world the characters come from to be recognizable to the reader.

I also wanted to keep mass and fuel within reasonable limits. I am capping the ship's speed at no more then .15c because I want to keep the fuel consumption within believable limits. Most of the ship's mass is already going to be the fuel, I was hoping there was a way to get off with having a less massive shield. I was thinking that if the shield were cone shaped or had channels built into it, it might be able to deflect most of the kinetic energy of impacting dust and micro meteors at a significant portion of the speed of light. I just don't know if this is feasible or just wishful thinking on my part.

 

[DHF]

I thought about a strong magnetic field deflect charged particles.
And use X-lasers, or electron and proton beams to charge uncharged ones.

I had considered that as well but I was wasn't sure about energy based shields because the trip will take around 30 years and I wasn't convinced they could afford to keep a powered shield running for decades at a time.

 

[Nidum]

Use clear path technology . Look ahead and collision avoidance systems backed up with seek and destroy defensive systems .

 

[GTOM]

I had considered that as well but I was wasn't sure about energy based shields because the trip will take around 30 years and I wasn't convinced they could afford to keep a powered shield running for decades at a time.

Compared to propulsion requirements, i think its affordable, besides, ionization don't need to be constant, I'm not sure whether superconductors can upheld the magnetic field without constant energy supply?

 

[mfb]

Fuel can act as shield.

Your particles hit the spacecraft at 10 MeV/nucleon. You will get nuclear reactions and some interactions with electrons, all directed towards the ship (as seen in the frame of the ship) in a shallow angle. While you cannot deflect the incoming particles themself, a very long nose cone might be able to have some reaction products escape without damaging the shielding further.

Every 1 milligram speck of dust will have the same energy of ~240 kilograms of TNT, and I don't see how you can detect or destroy them in any realistic way. You will get some explosions at the front.

 

[DHF]

Fuel can act as shield.

Are you referring to using some of the hydrogen as a shield by spraying it in front of the ship and letting incoming dust impact the mist of fuel particles to absorb the impact?

 

[GTOM]

Fuel can act as shield.

Wont that result in fuel tank leak?

In another topic, we speculated about liquid/ferrite dust/nano armor, that held by a magnetic field, so it immediately restores damages.

 

[newjerseyrunner]

I had considered that as well but I was wasn't sure about energy based shields because the trip will take around 30 years and I wasn't convinced they could afford to keep a powered shield running for decades at a time.

Wouldn't you need one anyway? Interstellar space is full of cosmic rays that would have to be deflected as well.

You say neutronium is too far off for you, what about superheavy elements? Are your people advanced enough to synthesize these? We have no idea if the physics are correct or not, but theoretically there should be stable elements around number 146: https://en.wikipedia.org/wiki/Island_of_stability#Hypothetical_second_island. It's still not very dense compared to neutronium, but should provide some shielding.

 

[DHF]

Wouldn't you need one anyway? Interstellar space is full of cosmic rays that would have to be deflected as well.

You say neutronium is too far off for you, what about superheavy elements? Are your people advanced enough to synthesize these? We have no idea if the physics are correct or not, but theoretically there should be stable elements around number 146: https://en.wikipedia.org/wiki/Island_of_stability#Hypothetical_second_island. It's still not very dense compared to neutronium, but should provide some shielding.

A very dense and massive shield is certainly within the limits of the society I am While the ship is being privately funded it will still need to take into account that every kilogram of mass I add to the ship is going to cost more fuel to move it. I am not putting a figure down for how much it all costs but I wanted to be respectful of realism. So yes the shield will need to be made strong enough to withstand countless contact explosions of nuclear strength. Constructing the shield out of a very dense metal was one idea. Carving a cylinder of ice several hundred meters thick and pushing it ahead of the ship is another idea. Ice is pretty cheap and easy to come by in space and a very thick layer would absorb a lot of radiation. In this particular post I was exploring ways to reduce the mass of the shield while still making it tough enough to withstand the punishment it will undergo.

 

[mfb]

Are you referring to using some of the hydrogen as a shield by spraying it in front of the ship and letting incoming dust impact the mist of fuel particles to absorb the impact?

I'm not sure if that would help, and gas would disperse.

A thin shield in some distance to the remaining ship might help. Individual molecules would induce some radiation damage to the lattice, but that can be repared. Specks of dust would produce holes, and the debris is then scattered sufficiently to reduce the impact on the main ship.

Wont that result in fuel tank leak?

Solid fuel?

In another topic, we speculated about liquid/ferrite dust/nano armor, that held by a magnetic field, so it immediately restores damages.

Macroscopic forces can be too strong for magnets, and for things like lattice defects those structures are too large.

Wouldn't you need one anyway? Interstellar space is full of cosmic rays that would have to be deflected as well.

There is no realistic way to deflect cosmic rays. Use shielding.

You say neutronium is too far off for you, what about superheavy elements? Are your people advanced enough to synthesize these? We have no idea if the physics are correct or not, but theoretically there should be stable elements around number 146: https://en.wikipedia.org/wiki/Island_of_stability#Hypothetical_second_island. It's still not very dense compared to neutronium, but should provide some shielding.

Even if they are stable, which is highly questionable: are you limited by space? Twice the number of lead atoms do the same job for the same mass.
"Neutronium" in the way neutrons stars have it is stable in neutron stars only.

 

[Ryan_m_b]

A thin shield in some distance to the remaining ship might help. Individual molecules would induce some radiation damage to the lattice, but that can be repared. Specks of dust would produce holes, and the debris is then scattered sufficiently to reduce the impact on the main ship.Solid fuel?

I was going to say this too. Deploy a thin shield far ahead of the ship (perhaps push/keep it there with lasers). It's not going to stop debris but if something problematically big (>10 micrograms) hits it then the resulting explosion would hopefully be enough to deflect/spread debris over a much wider point. Then you either repair the Sail Shield or leave it and deploy another.

 

[DHF]

I was going to say this too. Deploy a thin shield far ahead of the ship (perhaps push/keep it there with lasers). It's not going to stop debris but if something problematically big (>10 micrograms) hits it then the resulting explosion would hopefully be enough to deflect/spread debris over a much wider point. Then you either repair the Sail Shield or leave it and deploy another.

I am liking this idea.

 

[Ryan_m_b]

I have no idea how to work out how feasible the sail shield idea is, given the speeds involved any debris (I'm guessing) would shoot straight through without interacting. But if the tiny portion of the sail material that is hit explodes into a plasma it would hopefully be enough to knock the whole thing off course, maybe in pieces.

If anyone knows a quick and dirty way to putting numbers to that it would be cool.

 

[mfb]

Individual atoms would get stopped within a millimeter for anything at least as dense as water. I don't think it will be different for dense massive objects - the collisions happen at timescales where the motion of the atoms in transverse direction is negligible. They won't get fully stopped, but they interact sufficiently to get a relatively uniform motion of the collision products.

For order of magnitude estimates, let everything have the density of water. Taking the milligram object from above again, let it collide with a shield 1 cm thick. I would expect most atoms in the millgram object to interact with the shield material. We get a small ball of plasma with a mass of roughly 11 mg mass, probably with some charge separation (electrons get accelerated easily, the nuclei not so much), so the whole thing makes a coulomb explosion. The available energy for transverse motion should be way in excess of 10 eV per nucleon, which is 1/100,000 of the total energy. That would give a speed of at least 1/1000 of the spacecraft velocity. But the mass of the plasma comes mainly from our shield, so it just moves at 1/10 the spacecraft velocity relative to the spacecraft . So we have a velocity ratio of 1 to 100. A shield at a distance of a few hundred times the diameter of the spacecraft should work. Probably less.

 

[DHF]

So by the time that ball of plasma hits the cone shaped main shield of the ship, it is hitting it at a much slower velocity then the original object. So instead of 1mg striking the ship at .15, you instead have a 11mg mass hitting the main shield at .015c?

 

[Loren]

One trend I see is the use of ram scoops. Right now it is one of the best alternatives for interstellar travel we know and the ram scoop takes care of the problem pretty well.

Other solutions I have heard about is a good layer of ice.

Lastly, the best solution is simply don't reveal the technology. It just works (whatever it is) and the less you write about it, the better.

 

[mfb]

So instead of 1mg striking the ship at .15, you instead have a 11mg mass hitting the main shield at .015c?

Ideally you have most of it missing the spacecraft . But even that change reduces the energy by 90% and spreads it over the front.

 

[DHF]

One trend I see is the use of ram scoops. Right now it is one of the best alternatives for interstellar travel we know and the ram scoop takes care of the problem pretty well.

Other solutions I have heard about is a good layer of ice.

Lastly, the best solution is simply don't reveal the technology. It just works (whatever it is) and the less you write about it, the better.

Agreed on that last part, most of the numbers and finer details that we discuss here won't be laid out in the story, I will focus on the characters and story. Most of this is for my benefit, I want to have a full understanding of how my ship works, if I understand how all the parts fit together then I can write more effectively.

As to the Ram Scoop, but I abandoned it early on as I feel there are far too many hurtles to overcome, the least of which is the fact that it relies on P+P+P+P fusion which I really don't think humans will master for many centuries to come, there is a good chance we never may. My story is set a couple hundred years forward so I am trying to stick to tech that we have on the drawing board now. like D-T fusion and a star Tram like launch system to get things in orbit.

 

[DHF]

Ideally you have most of it missing the spacecraft . But even that change reduces the energy by 90% and spreads it over the front.

Excellent, thank you very much for that.

 

[Loren]

Agreed on that last part, most of the numbers and finer details that we discuss here won't be laid out in the story, I will focus on the characters and story. Most of this is for my benefit, I want to have a full understanding of how my ship works, if I understand how all the parts fit together then I can write more effectively.

As to the Ram Scoop, but I abandoned it early on as I feel there are far too many hurtles to overcome, the least of which is the fact that it relies on P+P+P+P fusion which I really don't think humans will master for many centuries to come, there is a good chance we never may. My story is set a couple hundred years forward so I am trying to stick to tech that we have on the drawing board now. like D-T fusion and a star Tram like launch system to get things in orbit.

I think the rate of technological advance is going to startle most people.

Once we start getting self-learning machines we will see explosive growth in our technology once super-intelligence takes place.

I think a conservative estimate of 50 years before we hit that knee in the curve. From there it will be nearly impossible to predict what comes next and when.

Kind of bad news for science fiction.

 

[GTOM]

I think the rate of technological advance is going to startle most people.

Once we start getting self-learning machines we will see explosive growth in our technology once super-intelligence takes place.

I think a conservative estimate of 50 years before we hit that knee in the curve. From there it will be nearly impossible to predict what comes next and when.

Kind of bad news for science fiction.

Someone said about that singularity stuff, that this is the intelligent design theory of high Iq people. I agree. It isn't like someone is so super genius and there will be explosive growth. Einstein couldn't develop theory of relativity in middle ages, even if all the church supported him. In order to advance lots of people are needed, who discover, invent things, design and build new machines, gather resources etc.

 

[Loren]

Someone said about that singularity stuff, that this is the intelligent design theory of high Iq people. I agree. It isn't like someone is so super genius and there will be explosive growth. Einstein couldn't develop theory of relativity in middle ages, even if all the church supported him. In order to advance lots of people are needed, who discover, invent things, design and build new machines, gather resources etc.

I'm just looking at the historical pace of growth in human knowledge and technology. It clearly isn't a linear function. The last 100 years has advanced us more than the sum of all time before it.

50 years ago we were just scratching at using machines to solve problems. Now people do that every day with the tools in your pocket.

 

[GTOM]

Growth always has it limits, even today too much pollution, fossils eventually run out, unemployment, first world problems etc. Some supermachine alone won't solve that... Maybe it even creates more problems than it solves.

 

[Loren]

Growth always has it limits, even today too much pollution, fossils eventually run out, unemployment, first world problems etc. Some supermachine alone won't solve that... Maybe it even creates more problems than it solves.

It could create more problems. The church has been saying that for a millennia.

 

[mfb]

Growth always has it limits

We are far away from fundamental limits , even if the limits we see today are fundamental (which we do not know). Not a factor of 10 or 100, but tens of orders of magnitude.

even today too much pollution, fossils eventually run out, unemployment, first world problems etc.

All those problems are not impossible to solve. It is by no means guaranteed that we solve them, but humans have a great track record of solving problems. Our ancestors survived an ice age without any modern technology. And all that is without superintelligent computers.

There is no indication that Einstein-like people would be the upper end of intelligence. It is possible that a computer might become as intelligent compared to humans as we are to ants. Humans routinely solve problems ants cannot even comprehend.I think this is drifting away from the original topic.

 

[Loren]

We are far away from fundamental limits , even if the limits we see today are fundamental (which we do not know). Not a factor of 10 or 100, but tens of orders of magnitude.All those problems are not impossible to solve. It is by no means guaranteed that we solve them, but humans have a great track record of solving problems. Our ancestors survived an ice age without any modern technology. And all that is without superintelligent computers.

There is no indication that Einstein-like people would be the upper end of intelligence. It is possible that a computer might become as intelligent compared to humans as we are to ants. Humans routinely solve problems ants cannot even comprehend.I think this is drifting away from the original topic.

The neat thing is we really won't have long to wait to see the results at this point. The next 10 to 20 years will be a pretty reliable vector.

 

[GTOM]

We are far away from fundamental limits , even if the limits we see today are fundamental (which we do not know). Not a factor of 10 or 100, but tens of orders of magnitude.All those problems are not impossible to solve. It is by no means guaranteed that we solve them, but humans have a great track record of solving problems. Our ancestors survived an ice age without any modern technology. And all that is without superintelligent computers.

There is no indication that Einstein-like people would be the upper end of intelligence. It is possible that a computer might become as intelligent compared to humans as we are to ants. Humans routinely solve problems ants cannot even comprehend.I think this is drifting away from the original topic.

I don't doubt that, i just highly doubt that explosive growth stuff. Ants can't even comprehend many problems, because they are overspecialized and highly deterministic, just like machines. Sorry for derailing is there any topic more suitable to continue this?

 

[Loren]

Agreed on that last part, most of the numbers and finer details that we discuss here won't be laid out in the story, I will focus on the characters and story. Most of this is for my benefit, I want to have a full understanding of how my ship works, if I understand how all the parts fit together then I can write more effectively.

As to the Ram Scoop, but I abandoned it early on as I feel there are far too many hurtles to overcome, the least of which is the fact that it relies on P+P+P+P fusion which I really don't think humans will master for many centuries to come, there is a good chance we never may. My story is set a couple hundred years forward so I am trying to stick to tech that we have on the drawing board now. like D-T fusion and a star Tram like launch system to get things in orbit.

Have you considered the RAIR (ram-augmented interstellar rocket)?

The idea is to use the interstellar material as reaction mass rather than propellant. This requires a significant amount of anti-matter, but the reaction process is not only more efficient, it happens at a lower temperatures.

The main problems are securing enough antimatter and to a lessor degree, a mechanism to boost the space vehicle (SV) to a velocity where the ram scoop provides reaction mass. However, if you resolve the antimatter problems, you probably won't be too stuck with a mechanism to get the SV moving fast enough for the ram scoop to become operational.

Lastly, if the ram scoop drive is not your thing, maybe the scoop is all you need to resolve your shielding needs. A laser could be used to create an ionization field in front of the SV and the scoop is used to create a powerful EM field. You would essentially have a magnetic bottle at its throat, but periodic pulsing the field at the throat could release the material to pass through the central core of the SV.

You need large amounts of energy to work the laser and its EM field, but you are already at that technological point if you have some form of drive that can reach .15C.

I'll also reiterate what I said earlier. Alastair Reynolds created a star drive using Chebesa physics. What's Chebesa physics? He made it up and never explained a word of how it works. I get the feeling that if you could see his detailed notes on the subject it would probably be no more than a paragraph long and he never addressed the issue of how to avoid interstellar matter, either.

But if you want to create a hypothetical system I think the EM scoop might be a good way to start. You could always write that the Bussard Ram Scoop was a failed idea, but it did lead to the development of something called the EM Scoop (EM = Electro-Magnetic), which opened the door to the first interstellar spacecraft s by providing a protective shield... bla, bla, bla.

Just thinking out of the box a little.

 

[Sirsh]

Any chance of using artificial gravity generators to alter the trajectory of any incoming foreign objects? if they're a technology that is within the era of your book.

 

[DHF]

Any chance of using artificial gravity generators to alter the trajectory of any incoming foreign objects? if they're a technology that is within the era of your book.

When you say artificial gravity, I envision something providing the interior of the ship with an environment for the crew to move about normally, I don't see how that would effect incoming objects. Please let me know what you had in mind.

Ultimately I think I will be going with the shield design mfb suggested, over all it would be the cheapest option and require minimal power to maintain. It relies on using physical objects and dispersion over distance to deflect incoming matter. I quite like the elegance in that.

 

[Noah J]

I agree that the shield is your best and most realistic option. To quote off of the Atomic Rocket Website,

"As a side note, a Whipple shield is very effective at stopping hypervelocity weapons. With kinetic weapons at closing velocities in excess of 10 km/sec, you're getting into the realm where armor is less important than blow-through. For armor, you want something that will resist being turned into a plasma for as long as is possible, followed by gaps made of vacuum to make it a Whipple shield." http://www.projectrho.com/public_html/rocket/spacewardefense.php

Considering that space debris will basically be hyper-velocity projectiles, a Whipple shield will be one of the better options. As for material, it doesn't have to be super fancy, even carbon will do. My suggestion is to read up on the atomic rocket site for more information on basically anything you need.

 

[tobyr65]

ooo make a ship out of diamond. Not clear, still opaque but light and shiny.