Best Theoretical Spaceship

[Spacescifi]

 

Barring a way to do warp/FTL, nothing tops antimatter catalyzed nuclear pulse.

It's basically project Orion using antimatter to trigger nuclear explosions.

Given the vast energy of antimatter reactions, little in the way of reaction mass is needed.

And by little... I mean wayyy less than a kilogram.

So this:

In the mid-1990s research at the Pennsylvania State University led to the concept of using antimatter to catalyze nuclear reactions. In short, antiprotons would react inside the nucleus of uranium, causing a release of energy that breaks the nucleus apart as in conventional nuclear reactions. Even a small number of such reactions can start the chain reaction that would otherwise require a much larger volume of fuel to sustain. Whereas the "normal" critical mass for plutonium is about 11.8 kilograms (for a sphere at standard density), with antimatter catalyzed reactions this could be well under one gram.

Several rocket designs using this reaction were proposed, some which would use all-fission reactions for interplanetary missions, and others using fission-fusion (effectively a very small version of Orion's bombs) for interstellar missions.

 

Long story short: So long such a ship had some spare SRB's for relaunch, it could go just about anywhere, land, and return.

 

The TWR compared to propellant mass is ridicolously high here.

 

What do you think?

I think it beats any torch ship...especially in a race to the moon or even mars.

Care to challenge that?

What do you think?

Since I am betting that the heat rejection mass or propellant mass will make the torchship lose the race anyway.

Having more thrust with less mass with less waste heat is generally excellent for any spaceship.

 

EDIT: Not sure if KSP has antimatter catalyzed nuclear pulse but it should,I think.

Edited June 18, 2020 by Spacescifi

[cubinator]

The best theoretical spaceship is one where I just fly wherever I want, as fast as I want. No fuel, no heat, no rules!

[K^2]

The best power source for a reaction drive is a tiny black hole. It takes absolutely any matter as fuel and produces almost pure photon exhaust. A relatively modest ship, just a few thousand metric tons, can go anywhere in the galaxy with such a drive within lifetime of the crew. Taking time dilation into account, of course, and disregarding the fact that we don't really have any way to shield the crew from interstellar medium turning into hard radiation at these speeds. Setting that aside, as an in-system ship, you can torch absolutely anywhere, and only have to refuel once every few months. The only downside is that if you stop refueling the ship, it will, eventually, undergo a very spectacular explosion as the black hole evaporates.

[Spacescifi]

1 hour ago, cubinator said:

The best theoretical spaceship is one where I just fly wherever I want, as fast as I want. No fuel, no heat, no rules!

 

That's scifi not theory.

Even so, I dare say it would make spaceship's kinda obsolete. I can ship everything to me via FTL drone ship then.

Conquer worldsvia drone while I take a bathroom break.

Makes it all... too easy would you not agree?

59 minutes ago, K^2 said:

The best power source for a reaction drive is a tiny black hole. It takes absolutely any matter as fuel and produces almost pure photon exhaust. A relatively modest ship, just a few thousand metric tons, can go anywhere in the galaxy with such a drive within lifetime of the crew. Taking time dilation into account, of course, and disregarding the fact that we don't really have any way to shield the crew from interstellar medium turning into hard radiation at these speeds. Setting that aside, as an in-system ship, you can torch absolutely anywhere, and only have to refuel once every few months. The only downside is that if you stop refueling the ship, it will, eventually, undergo a very spectacular explosion as the black hole evaporates.

 

That last part is... a bit of inconvience for some people.

I still like the first one more, since you can at least land it if properly equipped with SRB's.

Black hole spaceship?

Sounds like an orbiter maybe landing on low g moons.

1g Earth?

Doubt it. Unless you know otherwise.

Nevermind all the radiation.

[cubinator]

6 minutes ago, Spacescifi said:

Makes it all... too easy would you not agree?

Fine, maybe it's powered by a spherical cow.

[Spacescifi]

1 minute ago, cubinator said:

Fine, maybe it's powered by a spherical cow.

 

That eats stars to refuel.

Needs to eat a star every 7 LY traveled.

So expect other scifi civilizations not to like you lol.

Even if you do not eat their sun, they won't rest knowing you could.

[Bill Phil]

An antimatter initiated nuclear reaction would be a torchship with a large enough thrust power. If you took @MatterBeam‘s Epstein drive concept and initiated the reactions with antimatter you would basically have a high power torchship. A fission-fusion hybrid using Lithium-Deuteride as its main fuel could potentially work extremely well, using the neutrons from uranium or plutonium fission to fission the Lithium into Tritium and Helium and provide enough energy to kickstart the fusion reaction. Plus Lithium-Deuteride would be denser than D-T ice or gas and could be cheaper since Tritium production is difficult. However the drive would be highly radioactive because it would emit neutrons, though some of that energy could be absorbed by propellant.

[adsii1970]

Best theoretical ship? If this game has taught me anything, the best theoretical ship I can think of is the U.S.S. Discovery out of the movie, 2001: A Space Odyssey. I think we actually have most of the technology needed to construct and launch it (as a global community). I'm assuming that by best theoretical ship, the thread is discussing the most realistic...

But that's just my opinion.

[Nuke]

i assume theoretical as something that we can actually build as our current scientific understanding is developed into viable technology.

im going to have to go with a boring fusion drive. fusion does not even need to be break even and probably wont be in this case. a second reactor would be needed for electrical power, and that can be fission or fusion. its probably not going to a torch. just a notch above a high power mpd drive. 

[K^2]

52 minutes ago, Spacescifi said:

Black hole spaceship?

Sounds like an orbiter maybe landing on low g moons.

1g Earth?

It's a bit like having a discussion on what's the best car to get to the next town over, and you're insisting it's definitely a bicycle, because you can get it up to your apartment and store it on the balcony. I mean, that has utility, but if we're talking about going a bit further than your neighborhood, a car's definitely more practical. And the fact that you have to keep it in a garage, even if you have to take a lift down, is hardly an inconvenience worth discussing.

The exploding bit is a bigger problem, I admit, but given that all you have to do to prevent it is feed it a few hundred metric tons of garbage a year, it doesn't seem like that hard of a thing to avoid.

[Spacescifi]

55 minutes ago, K^2 said:

It's a bit like having a discussion on what's the best car to get to the next town over, and you're insisting it's definitely a bicycle, because you can get it up to your apartment and store it on the balcony. I mean, that has utility, but if we're talking about going a bit further than your neighborhood, a car's definitely more practical. And the fact that you have to keep it in a garage, even if you have to take a lift down, is hardly an inconvenience worth discussing.

The exploding bit is a bigger problem, I admit, but given that all you have to do to prevent it is feed it a few hundred metric tons of garbage a year, it doesn't seem like that hard of a thing to avoid.

 

The challenge is getting the few metric tons.

Like asteroids are an easy option, but the challenge lies in location.

For the most part, unless my knowledge is incomplete, the big rocks are farther out, and the ones that stray closer to the inner planets are smaller I think.

Correct me if you know otherwise.

I know big asteroids cross Earth's path on occasion, and a BH ship could hunt those down.

Really I wonder what the mileage is like?

Are you going to have to do low acceleration to last a year or can you truly fly at 1g for months, getting to pluto in a matter of weeks or less?

Because it seems to me that mass and thrust still matters... or does it?

Are you telling me that BH shoot out reaction mass at lighthugger speed so THAT is why it can have great thrust and endurance?

Meaning it will quite literally particle beam of doom anything behind it within a few kilometers.

Again... radiation is also a huge concen, but at least it's not landing on a planet so...

 

Edited June 19, 2020 by Spacescifi

[SOXBLOX]

I'll say either fusion or an NSWR. With highly concentrated Uranium salts, of course, because when moar boosters fails, moar nukes has got ur back!

[K^2]

42 minutes ago, Spacescifi said:

The challenge is getting the few metric tons.

We're talking about a ship that can be moving thousands of tons of cargo at a time, completing a round trip between Earth and Mars on average in about a week. The fuel requirement seems absolutely trivial when you're dealing with that level of industry, but if you have to have a simple, practical solution a magrail on the Moon solves the problem entirely. Launching cargo from the Moon is practically free once you have the infrastructure, so just load up boxes of moon rock and deliver them to high Lunar orbit, where they can be used to refuel your black hole powered cargo haulers and passenger liners.

[Spacescifi]

24 minutes ago, SOXBLOX said:

I'll say either fusion or an NSWR. With highly concentrated Uranium salts, of course, because when moar boosters fails, moar nukes has got ur back!

 

Hmmm... I wonder how well an AM catalyzed NSWR would do?

Make it easier I suppose, but it still needs water propellant, so you will run out just like with SRBs. And I don't know where you are going to get more water from easily in space.

NSWR is paradoxically great for an SSTO, if no one minds the cancer.

14 minutes ago, K^2 said:

We're talking about a ship that can be moving thousands of tons of cargo at a time, completing a round trip between Earth and Mars on average in about a week. The fuel requirement seems absolutely trivial when you're dealing with that level of industry, but if you have to have a simple, practical solution a magrail on the Moon solves the problem entirely. Launching cargo from the Moon is practically free once you have the infrastructure, so just load up boxes of moon rock and deliver them to high Lunar orbit, where they can be used to refuel your black hole powered cargo haulers and passenger liners.

 

Good point.

Sounds like it is better for a solar system economy.

If I combined this with any fictional form of warp or FTL I wished, it would be okayish I suppose.

Just not as convinient as space opera aficanados like.

[kerbiloid]

5 hours ago, cubinator said:

The best theoretical spaceship is one where I just fly wherever I want, as fast as I want. No fuel, no heat, no rules!

A ship that explains you that you don't need to get anywhere.

[KSK]

12 hours ago, Spacescifi said:

Make it easier I suppose, but it still needs water propellant, so you will run out just like with SRBs. And I don't know where you are going to get more water from easily in space.

In our solar system there is water ice on Mercury (permanently shadowed craters), Mars, Ceres, and several of the moons of Jupiter and Saturn. There is evidence of water on the moon, although its unclear how much of it is ice (useful) or, for example, hydrated minerals (not so useful). 

And that's with a relatively hot yellow star. Red dwarf stars are cooler and so the frost line of any planetary system around them might be expected to be closer in to the star, hence most or all of those planets are likely to comprise ice and other volatiles. Red dwarfs are also the most common star type in the Milky Way galaxy. I know you've commented on Elite Dangerous in other threads - I'm not sure if you've got it or played it but if you have, the procedural generation system that Frontier used to create their multitudinous star systems is apparently quite scientifically accurate in that it takes our current understanding of planetary formation into account. And you really don't have to play E: D for long to figure out that red dwarf systems with orbiting icy bodies are pretty much ten to the credit.

I don't think that finding a source of water in space is going to be particularly difficult. Put another way, if your fictional setting relies on icy bodies for refueling then having lots of them conveniently available isn't so unrealistic that your reader's suspension of disbelief will be broken. Harvesting that water of course is another matter but, as you're fond of saying, that's an engineering problem. But it's an engineering problem that would be solvable right now in the 21st century, so I don't see it being any big deal for any  sci-fi setting, whether it uses next-to-present, NASA 2.0 level tech or space opera rule-of-cool tech.

On a more meta level, any inhabited star systems in your fictional setting (especially if 'inhabited' means space stations or other artificial environments) will plausibly have at least one or two suitable icy bodies for propellant harvesting, simply because that availability of propellant would have been enormously useful and possibly essential to the original colonisation effort.

If you're out exploring new systems then, at a pinch, you could have your exploration vessel make use of Kuiper Belt or even Oort cloud bodies for refuelling, although that's likely to be something of an emergency measure since they're necessarily pretty far out from the star and finding them is probably going to be more difficult (smaller bodies, big volume of space to search in). More plausibly, the first thing your exploration vessel does when arriving in-system is to scan for icy bodies and, if it can't find any (unlikely but possible), flag up that system as unsuitable for development and jump out again.

 

 

[Bill Phil]

18 minutes ago, KSK said:

In our solar system there is water ice on Mercury (permanently shadowed craters), Mars, Ceres, and several of the moons of Jupiter and Saturn. There is evidence of water on the moon, although its unclear how much of it is ice (useful) or, for example, hydrated minerals (not so useful). 

And that's with a relatively hot yellow star. Red dwarf stars are cooler and so the frost line of any planetary system around them might be expected to be closer in to the star, hence most or all of those planets are likely to comprise ice and other volatiles. Red dwarfs are also the most common star type in the Milky Way galaxy. I know you've commented on Elite Dangerous in other threads - I'm not sure if you've got it or played it but if you have, the procedural generation system that Frontier used to create their multitudinous star systems is apparently quite scientifically accurate in that it takes our current understanding of planetary formation into account. And you really don't have to play E: D for long to figure out that red dwarf systems with orbiting icy bodies are pretty much ten to the credit.

I don't think that finding a source of water in space is going to be particularly difficult. Put another way, if your fictional setting relies on icy bodies for refueling then having lots of them conveniently available isn't so unrealistic that your reader's suspension of disbelief will be broken. Harvesting that water of course is another matter but, as you're fond of saying, that's an engineering problem. But it's an engineering problem that would be solvable right now in the 21st century, so I don't see it being any big deal for any  sci-fi setting, whether it uses next-to-present, NASA 2.0 level tech or space opera rule-of-cool tech.

On a more meta level, any inhabited star systems in your fictional setting (especially if 'inhabited' means space stations or other artificial environments) will plausibly have at least one or two suitable icy bodies for propellant harvesting, simply because that availability of propellant would have been enormously useful and possibly essential to the original colonisation effort.

If you're out exploring new systems then, at a pinch, you could have your exploration vessel make use of Kuiper Belt or even Oort cloud bodies for refuelling, although that's likely to be something of an emergency measure since they're necessarily pretty far out from the star and finding them is probably going to be more difficult (smaller bodies, big volume of space to search in). More plausibly, the first thing your exploration vessel does when arriving in-system is to scan for icy bodies and, if it can't find any (unlikely but possible), flag up that system as unsuitable for development and jump out again.

 

 

Keep in mind that oxygen is one of the most abundant elements on rocky planet surfaces. It also makes up 89% of the mass of water. So for a suitably energy rich civilization that has managed to run low on water you could take hydrogen from a gas giant and bond it with oxygen from a rocky planet. Indeed one plan for lunar resources was to extract oxygen from the surface and being hydrogen from Earth.

Now for a twist on the Elite aspect - fuel scooping a star could be a way to get some hydrogen while the nearest planet could be a source of oxygen. Easy.

[wumpus]

20 hours ago, Spacescifi said:

Barring a way to do warp/FTL, nothing tops antimatter catalyzed nuclear pulse.

This assumes you have anti-matter, but can't afford to use pure antimatter drives.  It also ignores other possible ways to ignite a fusion explosion (laser ignition being the obvious one).  But any way to reduce the pulse of a pulse drive should allow a decrease in the mass and complexity of the pusher plate, and that is a good thing.

KSP doesn't have much in the way of specific fuels.  We have fuel, oxidizer,  monopropellant, and solid.  RSS/RO has a bunch of real fuels, but I think limits them to proven examples.  My old take on the fuels (what we thought each one was):

On 4/6/2018 at 12:32 PM, wumpus said:

Basically it is whatever fuel is convenient.  I *think* there was a normalization based on a rocket engine that used hypergolic fuels, but they've moved a bit beyond that.

NTR uses only fuel: which pretty much has to be hydrogen (I suspect "oxidizer" would be better than any other fuel).
Terrier screams RT-10 type hydrox [expander cycle] engine
most of the bigger engines appear to be kerolox engines

Monoprop could reasonably work as HTP, it doesn't appear to have multiple uses.  Solid is presumably aluminum perchlorate.

This being KSP, I'm going to go with an "essense of snacks [US edition]":  fuel is partially hydrogenated soybean oil, oxidizer is high fructose corn syrup, monoprop is carbon dioxide (think fizzy drinks), and solid is solidified powdered cheese (preferably artificial).  No comments that HFCS won't reduce PHSO (you can reverse them, but I don't think the problem will go away).

[Spacescifi]

2 hours ago, Bill Phil said:

Keep in mind that oxygen is one of the most abundant elements on rocky planet surfaces. It also makes up 89% of the mass of water. So for a suitably energy rich civilization that has managed to run low on water you could take hydrogen from a gas giant and bond it with oxygen from a rocky planet. Indeed one plan for lunar resources was to extract oxygen from the surface and being hydrogen from Earth.

Now for a twist on the Elite aspect - fuel scooping a star could be a way to get some hydrogen while the nearest planet could be a source of oxygen. Easy.

 

Fuel scooping a star?

At what range without burning up?

I have played oolite, a modern remake of the original elite.

In it you literally can fly just over the surface of the sun for several minutes scooping up extra fuel for canisters to sell.

Is that realisic? Not as far as what we know.

Spaceships die long before they even reach the surface of the sun.

Now presuming we could scoop hydrogen gas from several lightseconds out... heat would still present an issue, as well as the time it takes to gather sufficient hydogen gas mass for fuel without the star cooking you.

[Bill Phil]

34 minutes ago, Spacescifi said:

 

Fuel scooping a star?

At what range without burning up?

I have played oolite, a modern remake of the original elite.

In it you literally can fly just over the surface of the sun for several minutes scooping up extra fuel for canisters to sell.

Is that realisic? Not as far as what we know.

Spaceships die long before they even reach the surface of the sun.

Now presuming we could scoop hydrogen gas from several lightseconds out... heat would still present an issue, as well as the time it takes to gather sufficient hydogen gas mass for fuel without the star cooking you.

Remember Bussard Ramjets? Well, it turns out the corona is billions of times denser than the interstellar medium, especially the Local Bubble. A magnetic scoop could potentially collect significant amounts of hydrogen. Of course there are still issues with this. But considering that we want to just stay in orbit and the velocities are smaller, the drag issue may be possible to overcome. 

With a 1km collector diameter more than 5 tonnes per second of hydrogen could be possible. 

The main challenge will likely be keeping the superconductors cold. Might be possible however.

[Nuke]

i think you are better off scooping gas giants. 

[Nuke]

On 6/18/2020 at 8:55 PM, K^2 said:

We're talking about a ship that can be moving thousands of tons of cargo at a time, completing a round trip between Earth and Mars on average in about a week. The fuel requirement seems absolutely trivial when you're dealing with that level of industry, but if you have to have a simple, practical solution a magrail on the Moon solves the problem entirely. Launching cargo from the Moon is practically free once you have the infrastructure, so just load up boxes of moon rock and deliver them to high Lunar orbit, where they can be used to refuel your black hole powered cargo haulers and passenger liners.

i presume there are limits to how much "fuel" you can put into the thing. otherwise you can just put as much in as you need for the entire life of the ship or at least till the next servicing. but i guess you get to a point where the whole thing is too massive to be an effective space transport. 

Edited June 20, 2020 by Nuke

[Spacescifi]

27 minutes ago, Nuke said:

i presume there are limits to how much "fuel" you can put into the thing. otherwise you can just put as much in as you need for the entire life of the ship or at least till the next servicing. but i guess you get to a point where the whole thing is too massive to be an effective space transport. 

 

The more mass a space vessel has the more diminishing returns thrust provides.

By the time a vessel has enough mass to generate it's own gravity field (which I presume a BH does) the thrust will need to be really good.

Not only that, acceleration will have to be at a resonable rate.

For example, if the BH made a .0.50 gravity field (half of 1g), that means if you accelerated at 1g your gravity for crew would be 1.5 g.

We would have to keep acceleration at 1g levels or lower.

[KSK]

1 hour ago, Spacescifi said:

 

The more mass a space vessel has the more diminishing returns thrust provides.

By the time a vessel has enough mass to generate it's own gravity field (which I presume a BH does) the thrust will need to be really good.

Not only that, acceleration will have to be at a resonable rate.

For example, if the BH made a .0.50 gravity field (half of 1g), that means if you accelerated at 1g your gravity for crew would be 1.5 g.

We would have to keep acceleration at 1g levels or lower.

Why would you presume that? 

https://en.wikipedia.org/wiki/Black_hole_starship

The smaller a black hole is, the faster it evaporates by Hawking radiation. As it evaporates it loses mass, therefore getting smaller and evaporating faster, leading to a runaway effect that eventually results in it exploding as per @K^2's post. To avoid that explosion, you keep shovelling material in to replace the lost mass.

Using a black hole to drive a starship relies on somehow converting that Hawking radiation to energy and thrust. Which is clearly a Non-Trivial Engineering Problem but in theory it may be possible and this thread is concerned with theoretical spacecraft.

As per the linked article, there's a sweet spot where the black hole is big enough to have a useful lifetime but small enough to produce enough power and also small enough to be feasibly (for generous values of feasible) manufactured. Apparently that sweet spot is around 600 thousand tons. For comparison, the mass of the earth is around 13 billion trillion tons, so it's immediately clear that the gravity field produced by a black hole starship is going to be insignificant compared to Earth's gravity.

It's also clear that, again as per @K^2's post, a black hole starship is easily capable of moving thousands of tons of cargo because those thousands of tons are a rounding error compared to the mass of the ship's drive.

A black hole massive enough to create a 0.5g gravity field would be useless as a propulsion system because it wouldn't evaporate fast enough to produce the required thrust.

Edit:  This is my highly simplified understanding based on a ten minute internet search. Corrections by @K^2 are welcome!

 

Edited June 20, 2020 by KSK

[natsirt721]

GUT generator attached to a photon drive. Infinite fuel, and a free petawatt laser in case the locals get frisky. May lead to minor vacuum decay.