Various reaction drives in M-Space and their fuel

[Pentallion]

On 9/25/2019 at 5:19 AM, Joerg said:

And yes, I wing a lot of it all the time, much like I wing e.g. horse stats.

That's called a pegasus.

[Thot]

8 hours ago, Joerg said:

Sure. Once you have decided to use humans like ablative armor, there is nothing to stop you from crewing expandable missiles with them.

That was the norm throughout most of human history, especially in warfare. And see Battlestar Galactica for reasons why this might be the only option.

 

8 hours ago, Joerg said:

Why? A micrometeorite creates a puncture and might require you to repair a number of vital systems or shut off certain systems (and activate the redundancy plans).

You have to make a choice here: Either micrometeorites are bad, or you can easily patch  holes. Which is it?

 

8 hours ago, Joerg said:

So basically, you FTLed to your planetary destination and then used maneuver jets for the final docking or landing?

 

Chemical rockets to lift off and maneuver to a certain distance from the planetary body (100,000 km), then FTL into the orbit of another planetary body within range, then land with aerobreaking (which does make sense because it's cheap to take off again with rented rockets) or just dock with a space station at the destination..

 

8 hours ago, Joerg said:

If this is a genetic advantage, then you will witness the birth of a hereditary class of oligarchs.

Or just gene therapy for anyone willing to go into space.

 

8 hours ago, Joerg said:

Since you are declaring these characters so, what is to stop you from declaring each and any of them to be a member of one of the spacefaring castes?

Because that implies they have a lot of resources, which again changes the tone of the campaign completely.

 

8 hours ago, Joerg said:

"Exotic" reaction mass like metal ions evaporated from an anode, as I regularly do in my AAS lamps in the lab. I can name a couple of ion sources used in mass spectroscopy, where the ion source and subsequent accelerator is essentially an ion drive(r). The technology of the ion source is about as "complicated" as a vacuum tube TV screen.

And what is the exhaust velocity of those "ion drives"?

8 hours ago, Joerg said:

Getting every aspect of technology right is impossible.

But the fundamentals of the fundamentals, like fuel consumption, the number one limiting factor in space travel, should somewhat relate to reality in a hard SF setting.

[Thot]

4 hours ago, g33k said:

Accelerate your reaction mass to near-c velocities -- even small amounts of it -- and let God and Einstein give you more reaction-mass.

The only way to do that is to convert it into photons. Lamps aren't putting out a lot of pressure, though.

[Thot]

1 hour ago, Lloyd Dupont said:

If space travel is such a difficult matter, why bother? even today there is hardly anyone in Antarctica, and it's much easier!

I guess, it's a "realistic option" only if it's "relatively easy" (to go there, with the setting's technology) and "somewhat attractive"..

Let's see....

- science station
- biggest gravity well in the asteroid belt (gravity might help some industrial / chemical reaction, and be welcome by "local workers")
- hideout for pirate? although might be a worst hideout that some lonesome forgotten asteroid or just plan deep space...
- trade station, halfway between inner planet and outer planet, rest stop, refuel stop, etc...

mmmm.... it's all I can think of for now....

Science station? Why bother? Send a probe and do the data anlysis from Earth?

Industrial? What would you produce out there, and for who?

Pirates? Who would they be pirating on out there?

Trade station? Who would trade what there?

 

[Lloyd Dupont]

12 minutes ago, Thot said:

Industrial? What would you produce out there, and for who?

It seems to me that the asteroid belt would be an ideal "location" (a few billion miles across ) to do mining and manufacturing, since all those raw material with 0 gravity well. But one might need some "local" mining facility. Might be easier to bring asteroid to Ceres and extract mineral there than to ferry them whole to Earth (as some people are talking about today in the real world)...

 

Anyway, if you want scifi adventure on Ceres you don't really need to explain it an overthink it much. If you really start to think and justify it, maybe you should start with: there is no such thing as space adventure...

Edited September 30, 2019 by Lloyd Dupont

[Thot]

Oh, but there can be, just not that far out. Earth orbit, solar orbit at 1 AU, maybe more of the inner system, that offers so much space (literally) that you can spend millennia there.

[Joerg]

3 hours ago, Thot said:

You have to make a choice here: Either micrometeorites are bad, or you can easily patch  holes. Which is it?

Micrometeorites punch holes. If you catch them front to back, the likelihood to have vital systems or organs punctured increases significantly. As a secondary effect, their delta V at impact is propagated as hard radiation.

It is similar to the slugs fired in The Expanse.

 

3 hours ago, Thot said:

Chemical rockets to lift off and maneuver to a certain distance from the planetary body (100,000 km), then FTL into the orbit of another planetary body within range, then land with aerobreaking (which does make sense because it's cheap to take off again with rented rockets) or just dock with a space station at the destination..

FTL but no sky hooks?

At least you have orbital infrastructure. Lack of that irks me considerably in too many planetary romances marketed as SF.

 

3 hours ago, Thot said:

Or just gene therapy for anyone willing to go into space.

Crispr in the living organism? Ok, Red/Green/Blue Mars had retroviral re-writing (also as rejuvenation).

 

3 hours ago, Thot said:

Because that implies they have a lot of resources, which again changes the tone of the campaign completely.

They have lots of resources as soon as they pick them up.

 

3 hours ago, Thot said:

And what is the exhaust velocity of those "ion drives"?

Depends only on the length and power of the acceleration unit. Same as a railgun.

 

3 hours ago, Thot said:

But the fundamentals of the fundamentals, like fuel consumption, the number one limiting factor in space travel, should somewhat relate to reality in a hard SF setting.

If that is your dealbreaker, go ahead and fix it. Fusion plants on board of space ships are a new peeve of mine - apart from the problem to get a fusion reaction up and running producing more energy than it takes to keep it going (and cooling the equipment), the only energy output that we are planning to use is heat, so it will be unobtainium thermocouples or unobtainium heat sinks to get them do any good on anything smaller than Rocketship Solaris. Vastly improved PV cells using the solar energy from that artificial sun are another form of unobtainium.

Electricity appears to be the most versatile form of energy you might want, and unobtained-yet "high temperature" supra-conductors would limit waste heat considerably, but the internal energy source for high powered output, like weaponry, magnetic shields, or similar, requires a high throughput that fuel cells with capacitors have a hard time to satisfy for a short term, let alone sustain.

Peter F. Hamiltons crystalline super-capacitors are a form of reasonable unobtainium for energy storage, and photovoltaics are an available if hopelessly underused source of electrical energy in space. While only using a fraction of the energy impacting the collector produced by that fusion reaction 8 light minutes away from us, that reactor is working 24/7, with an expected life-time of a few hundred million years before forcing us to find ways to move our planet (or whatever we value of it) further away from its current orbit.

 

2 hours ago, Thot said:

Oh, but there can be, just not that far out. Earth orbit, solar orbit at 1 AU, maybe more of the inner system, that offers so much space (literally) that you can spend millennia there.

Space - yes. Matter for all the platforms you might want to build for populating the Goldilocks-zone with habitats - not really. You'll have to sling that in from further outward in the system if you don't start taking Mercury apart (and Mercury only provides planetary core matter good for structures, but not for the habitats). If you want water, you syphon off some methane from Jupiter and react it with regolith from further in-system as source of oxygen, and then add some cyanobacteria to make good use of solar energy.

But even if you disperse humanity all around the Goldilocks zone, this still means all eggs in the same basket in case of solar flares, nearby supernovae or similar events. Having some underground habitats further out might at least allow some reclamation after such genocidal events.

My own setting has a kind of polynesian colonisation of the Goldilocks Zone, with one of my unobtainiums being vacuum-inhabiting life forms. Their means of propulsion remains a design challenge, though, although I am playing with media that slow down speed of light to walking speeds, thereby making relativistic accumulation of virtual mass in ring-shaped media possible, and possibly warping space-time in a way that allows warp drives. (Not necessarily FTL.)

[rsanford]

This is the MOST interesting discussion. I am planning a sci-fi game (alas minimal space travel) but I can guarantee that it won’t be nearly as well thought out as what y’all have put together.

[ThornPlutonius]

15 hours ago, Lloyd Dupont said:

It's a question I sometimes ask myself...
If space travel is such a difficult matter, why bother? even today there is hardly anyone in Antarctica, and it's much easier!

I guess, it's a "realistic option" only if it's "relatively easy" (to go there, with the setting's technology) and "somewhat attractive"..

Let's see....

- science station
- biggest gravity well in the asteroid belt (gravity might help some industrial / chemical reaction, and be welcome by "local workers")
- hideout for pirate? although might be a worst hideout that some lonesome forgotten asteroid or just plan deep space...
- trade station, halfway between inner planet and outer planet, rest stop, refuel stop, etc...

mmmm.... it's all I can think of for now....

To avoid extinction.  All of our human "eggs" are currently "in one basket".  We are becoming increasingly aware of the fragility of our "basket".

[g33k]

On 9/29/2019 at 8:12 PM, Thot said:

The only way to do that is to convert it into photons. Lamps aren't putting out a lot of pressure, though.

If you accelerate your reaction mass to 0.999999c, the mass is about 1000fold greater.  It makes your tankfull of reaction-mass (effectvely) much bigger.

It just takes a LOT of energy... and some handwavium applied to the actual engineering technologies!

(n.b. if you can build a big-ish one of these into an engine & little ones into guns, in a little 1-or-2-person ship, you have a "starfighter" type ship.)

[NickMiddleton]

On 9/30/2019 at 2:42 AM, Lloyd Dupont said:

It's a question I sometimes ask myself...
If space travel is such a difficult matter, why bother?

"Ask ten different scientists about the environment, population control, genetics, and you'll get ten different answers. But there's one thing every scientist on the planet agrees on. Whether it happens in a hundred years or a thousand years or a million years, eventually our Sun will grow cold and go out. When that happens, it won't just take us. It'll take Marilyn Monroe, and Lao-Tzu, and Einstein, and Morobuto, and Buddy Holly, and Aristophanes, and all of this…all of this…was for nothing. Unless we go to the stars."

Nick

[Thot]

3 hours ago, g33k said:

If you accelerate your reaction mass to 0.999999c, the mass is about 1000fold greater. 

If you can accelerate something to that speed, you don't need to accelerate anything to that speed.

[Thot]

2 hours ago, NickMiddleton said:

 Unless we go to the stars."

But then, you don't really need a spaceship, what you need is a self-sufficient habitat moving away from the sun early enough... So IF fusion is possible on a human-useable scale, that is what we'll see. Otherwise, we'll use some leftover uranium and hope it lasts long enough to somehow get to some other star.

[Joerg]

2 hours ago, NickMiddleton said:

"Ask ten different scientists about the environment, population control, genetics, and you'll get ten different answers. But there's one thing every scientist on the planet agrees on. Whether it happens in a hundred years or a thousand years or a million years, eventually our Sun will grow cold and go out.

Eventually. In the mean time (and much sooner), it will get hotter and hotter. Then, it will expand into a Red Giant, which will probably extend outward to our current orbit, before collapsing into a White Dwarf (not the magazine...).

 

2 hours ago, NickMiddleton said:

When that happens, it won't just take us. It'll take Marilyn Monroe, and Lao-Tzu, and Einstein, and Morobuto, and Buddy Holly, and Aristophanes, and all of this…all of this…was for nothing. Unless we go to the stars."

Our TV has gone to the stars for some decades (before we started digital encoding), and might be reconstructed.

For documentation of our culture to persist, all we need are time capsules. With written instructions about our DNA etc., a curious squid or snail alien might even be able to re-create the monsters which produced this amusing antiques.

[Thot]

On 9/30/2019 at 2:12 PM, Joerg said:

FTL but no sky hooks?

Skyhooks fail for the same reason that other would-be solutions would: Too complicated. AND they also have this issue that they'll wreck the whole planet if something goes wrong. Which it will.

Quote

Vastly improved PV cells using the solar energy from that artificial sun are another form of unobtainium.

You can use present-day technology there.

Quote

Electricity appears to be the most versatile form of energy you might want, and unobtained-yet "high temperature" supra-conductors would limit waste heat considerably, but the internal energy source for high powered output, like weaponry, magnetic shields, or similar, requires a high throughput that fuel cells with capacitors have a hard time to satisfy for a short term, let alone sustain.

 

Quote

Space - yes. Matter for all the platforms you might want to build for populating the Goldilocks-zone with habitats - not really.

 

Quote

My own setting has a kind of polynesian colonisation of the Goldilocks Zone, with one of my unobtainiums being vacuum-inhabiting life forms. Their means of propulsion remains a design challenge, though, although I am playing with media that slow down speed of light to walking speeds, thereby making relativistic accumulation of virtual mass in ring-shaped media possible, and possibly warping space-time in a way that allows warp drives. (Not necessarily FTL.)

How about just making them live for a million and then some years, and have them just use old-fashioned "poop a little gas out of the rear" drives? They'll probably lie dormant until they reach another star drifting, but they'll arrive. IF you can reach a velocity that is needed to escape the origin solar system.

Edited October 1, 2019 by Thot

[Joerg]

10 minutes ago, Thot said:

If you can accelerate something to that speed, you don't need to accelerate anything to that speed.

If you can provide a medium which has a signficantly lower value for C, relativistic speeds might be achievable. Chains of Bose Einstein condensates apparently have already succeeded to slow down light by several magnitudes.

This trickery might enable you to produce a singularity - a volume where normal physics don't apply.

[Thot]

10 minutes ago, Joerg said:

If you can provide a medium which has a signficantly lower value for C, relativistic speeds might be achievable. Chains of Bose Einstein condensates apparently have already succeeded to slow down light by several magnitudes.

I think  the speed of light is an application of a rule , not the rule itself. In other words: Speed of light in a vacuum is the maximum speed this universe will alow, but slowing down light will not decrease the maximum speed the universe allows.

Or at least that is what special relativity assumes.

 

[Joerg]

3 minutes ago, Thot said:

Skyhooks fail for the same reason that other would-be solutions would: Too complicated. AND they also have this issue that they'll wreck the whole planet if something goes wrong. Which it will.

Rockets fail because we cannot afford to upset our atmosphere any more than we already have. Without a fuel-saving method, we're grounded.

Atmospheric friction will do quite a good job reducing a falling skyhook to atmospheric pollution. The rest falling into the water will of course create a bigger splash than anybody could like, but over a quite long period of time.

But things that go wrong don't necessarily mean that the skyhook comes down.

 

And "too complicated" was what everybody said about booster rockets making a vertical landing after having done their job. Too complicated is just an engineering challenge, not impossible.

 

Your proposal for relying solely on chemical rockets for a space setting reminds me strongly of Frank Miller taking the PDP 10 as the pinnacle of computer miniaturisation for his Traveller technology. A Raspberry PI has almost the same calculation power, and speed.

Space 1999 is hilarious to watch nowadays...

 

3 minutes ago, Thot said:

You can use present-day technology there.

Present day technology for nuclear power plants are steam turbines and dumping heat into nearby bodies of water. Deuterium fusion produces high temperatures first and foremost, which means more steam and more heat, but no direct conversion of radiation into electricity. I haven't seen any plans for a tokamak involving photo-voltaics. (But then, keeping the prototypes running for long enough to break even in terms of energy expended to start it up is the current goal of the technology.)

 

 

3 minutes ago, Thot said:

Yes. Possibly enough mass to create a 50km asteroid if all of that would be collected in the Earth Moon L5. Optimistically, you could maybe create a hundred collector areas the diameter of earth with that - practically nothing. The Belt and the Jovian Trojans have many times that mass, and they have the volatiles required to create habitats.

(Although water should be the smallest problem... in The Expanse, the rise of the sea levels could have been ferried over to Mars, solving two problems in one go. The salt could have been separated out and deposited on the moon or elsewhere.)

 

3 minutes ago, Thot said:

How about just making them live for a million and then some years, and have them just use old-fashioned "poop a little gas out of the rear" drives? They'll probably lie dormant until they reach another star drifting, but they'll arrive. IF you can reach a velocity that is needed to escape the origin solar system.

They need to use that thrust to gather more gas to poop out than the thrust cost them. After all, they probably have the imperative to procreate.

Solar sails and bioelectrics are probably easier on their mass. They might also be useful for harvesting the matter portion of the solar wind.

[Joerg]

7 minutes ago, Thot said:

I think  the speed of light is an application of a rule , not the rule itself. In other words: Speed of light in a vacuum is the maximum speed this universe will alow, but slowing down light will not decrease the maximum speed the universe allows.

Or at least that is what special relativity assumes.

Being able to create a state where the rules of physics are re-written might enable us to do some things we deem impossible right now. My hard-to-obtainium exotic matter for my warp drives is a tunnel of such near-singularities in ring-shape Bose Einstein condensates (Rb in carbon nanotubes) around a vessel with a certain velocity to separate the vessel from lateral space, creating a warp tunnel.

This probably doesn't work in theoretical physics, and the physics I learned as a chemist don't even begin to enable me to do calculations on this idea. But they don't allow me to refute the possibility, either.

 

And no, slowing the speed of light doesn't take the hard limit up. It only allows relativistic effects at much lower energies. Might slow down shipboard time, for instance.

[Lloyd Dupont]

9 hours ago, NickMiddleton said:

"Ask ten different scientists about the environment, population control, genetics, and you'll get ten different answers. But there's one thing every scientist on the planet agrees on. Whether it happens in a hundred years or a thousand years or a million years, eventually our Sun will grow cold and go out. When that happens, it won't just take us. It'll take Marilyn Monroe, and Lao-Tzu, and Einstein, and Morobuto, and Buddy Holly, and Aristophanes, and all of this…all of this…was for nothing. Unless we go to the stars."

Nick

Just to be super clear..

You know we have a few hundred million years ahead of us before it get problematic.... and a few billion before the star dies?

Just to clarify since a setting in a few million of years would look very different, I assume, from a setting in a few thousands of years...

[Joerg]

2 hours ago, Lloyd Dupont said:

Just to be super clear..

You know we have a few hundred million years ahead of us before it get problematic.... and a few billion before the star dies?

The death of our star and the merger with Andromeda might come roughly at the same time, and it is extremely unlikely that there will be creatures resembling us witnessing either event.

The gradual increase of heat output of our primary is orders of magnitude slower than the runaway greenhouse effect that we appear willing to provoke.

 

2 hours ago, Lloyd Dupont said:

Just to clarify since a setting in a few million of years would look very different, I assume, from a setting in a few thousands of years...

We are at the (apparently quite rare) cusp of spreading into our solar system and establish a presence away from our home planet. This appears to be one of the big filters that create the Fermi Paradox.

[ThornPlutonius]

16 hours ago, Joerg said:

[snip]

Your proposal for relying solely on chemical rockets for a space setting reminds me strongly of Frank Miller taking the PDP 10 as the pinnacle of computer miniaturisation for his Traveller technology. A Raspberry PI has almost the same calculation power, and speed.

[snip]

Marc Miller

[pachristian]

I’m fond of Traveller 2300’s stutterwarp drive. The drive propels a ship by making quantum electron jumps of a few centimeters at a time, but cycling the drive millions or billions of times a second. The drive has a variable speed, depending on ambient gravity. Once gravity exceeds 0.1 m/sec2, the stutterwarp ceases to work. Within a star system it moves the ship at sub-light speed, and once you get a certain distance out, FTL speeds. Net effect is that you need rockets to get on and off a planet, but the stutterwarp drive for interplanetary and interstellar travel. One of the smarter things they did is have a relatively low power consumption: As the stutterwarp handwavium’s you past Einsteinian physics, the starship does not need an antimatter reactor or singularity for power. Well worth checking out for hard science fiction fans.

[Thot]

On 10/2/2019 at 5:54 PM, pachristian said:

I’m fond of Traveller 2300’s stutterwarp drive. The drive propels a ship by making quantum electron jumps of a few centimeters at a time, but cycling the drive millions or billions of times a second. The drive has a variable speed, depending on ambient gravity. Once gravity exceeds 0.1 m/sec2, the stutterwarp ceases to work. Within a star system it moves the ship at sub-light speed, and once you get a certain distance out, FTL speeds. Net effect is that you need rockets to get on and off a planet, but the stutterwarp drive for interplanetary and interstellar travel. One of the smarter things they did is have a relatively low power consumption: As the stutterwarp handwavium’s you past Einsteinian physics, the starship does not need an antimatter reactor or singularity for power. Well worth checking out for hard science fiction fans.

The problem with that is that it utterly changes space combat based on a completely arbitrarily chosen form of space magic. This again doesn't ring very futuristic to me, more like fantasy.

[Pentallion]

Just watch Another Life on Netflix.  Their drive is reactionless.  It's what NASA is trying to make.  And it's FTL.  It's also the same kind of drive I used in Junkyard Blues, which will hopefully be released as an M-Space campaign in 2020.