Best Raw Propellant Sources For A Scifi Spaceship

  • Thread starter Bab5space
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  • #1
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Rocketry is not good enough for the standard scifi spaceship that can take off and land like it pleases with high payloads.

Yet I still like rocketry because I like the fiery exhaust plumes. So I am considering linking the spaceship's rocket engine to a portal linked to to a planetary propellant depot. Feed the ship up to 7 light seconds out max.


What does this do for storyverse?

1. SSTO spaceships are now easy to make, just be willing to foot the propellant bill.

2. The moon can be used as a base once propellant depots are set up and portals attached. Extending range from the home planet even further (14 light seconds of propellant out). The only difference is that 7 light seconds out you could only be portal fed moon made propellant.

Now I know processing can be made a lot easier on the moon since we have portals to transport water from Earth to make some nice moon propellant combos.


But if I add warp and hyperdrives into the equation and they go to unexplored places what do they do?

Find a moon to set up propelant depots and then fly to the local planet with it.

Assuming they were in a hurry and did'nt want to process the propellant to get better efficiency, how efficient would moon regolith (moon dirt) be? Provided it was thermally propelled with nuclear power?

If it is inefficient, then the moon propellant depot will need either a lot of dirt stashed on a conveyor belt headed for a portal, or a lot of heavy duty tractors dumping the raw regolith into portals.

If efficient, it will take less propellant mass per unit of thrust (unlikely since we are not even procesding the propellant).


What are othet sources in the solat system that offer efficient proppellant sources youcan good efficiency out if without procssing it?
 

Answers and Replies

  • #2
anorlunda
Staff Emeritus
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Why so complicated? If you have a portal to beam stuff around, who needs spaceships?
 
  • #3
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Excellent question! I am delighted to answer it and there is a logic to it.

As much as I like scifi ships that can take off and accelerate ad they please, if the scifi universe is not a complete utopia then it breaks the setting.

No one in right mind will allow constant acceleration craft to be so common as depicted in scifi, since anyone of them could cause great WMD damage. Consider every civillian with a starship being given a nuke... same thing more or less. That is how much damage a relativistic collision can cause. And constant acceleration is good at that.

My method here at least puts the acceleration on a long leash.

Also I like fiery rocket plumes and cannot realistically use them for long burns without antimatter... which again would not be given to civilllians due to WMD.


EDIT: To an extent you do not have to ride in a spaceship. You just wait for it to reach the planet and enter the portal.

I limited portal range so space rockets and gathering propellant would still be relevant. Nothing for free.
 
  • #4
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Every time we increase the energy density of our fuels, along with it comes risks. When we were all riding horses, you could get hit by a horse at maximum horse speed. Then came the car, now we have increased impact velocities, and everyone is driving around with many liters of flammable liquid in a tank. We seem to have survived (so far at least) the fact that we are all constantly surrounded by people barreling around in heavy and fast moving petrol bombs...
 
  • #5
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Every time we increase the energy density of our fuels, along with it comes risks. When we were all riding horses, you could get hit by a horse at maximum horse speed. Then came the car, now we have increased impact velocities, and everyone is driving around with many liters of flammable liquid in a tank. We seem to have survived (so far at least) the fact that we are all constantly surrounded by people barreling around in heavy and fast moving petrol bombs...


True. But antimatter is on a whole nother level.

Even the exhaust is radioactive unless you just heat the propellant with a reaction rather than dumping antimatter out in the exhaust.

That does limit the temp you can burn propellant, and thus overall thrust.

Hotter is always better... it's just our engines cannot survove that without melting.


Fusion has the same issues, it's just not as much of WMD.
 
  • #6
member 656954
I limited portal range so space rockets and gathering propellant would still be relevant

Sure, so then I just link portals together, no rockets needed apart from placing the portals.
 
  • #7
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Fusion has the same issues, it's just not as much of WMD.

The largest weapon we've detonated was a 3 stage fusion device (Tsar Bomba). Most modern nukes are thermonuclear, ie fusion weapons with a fission primary.
 
  • #8
member 656954
The largest weapon we've detonated was a 3 stage fusion device (Tsar Bomba). Most modern nukes are thermonuclear, ie fusion weapons with a fission primary.

Very true, plus, if your space drive is plasma, there needs to be quite the volume of it to generate thrust, so the many stories of a 'plasma torch' being used to incinerate cities and other ships probably isn't too far off the truth. A giant, mobile, flying cutting torch of many thousands of degrees that's a mile or so long sounds like an effective WMD to me :eek:
 
  • #9
stefan r
Science Advisor
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Put one portal at high altitude. Maybe in a water tower. Place the second portal on the ground or lower. Connect a pipe from the top portal through a generator and release the water through the lower portal. That gives you an unlimited energy supply.

Any mass works as propellant in a mass driver. Medieval catapult or trebuchet works well. Compressed oxygen should work well.

Within "7 light seconds " of an atmosphere you can just open the portal. Near Earth you would drop one portal down the marrianes trench. Reverse the flow with a u shaped pipe(s) so you get thrust. You get around 1atmosphere pressure for every 10 m depth.
 
  • #10
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I am considering linking the spaceship's rocket engine to a portal linked to to a planetary propellant depot.
If you are OK with asymmetrical portals then just open one into the Sun.
 
  • #11
stefan r
Science Advisor
908
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If you are OK with asymmetrical portals then just open one into the Sun.
Each end of the portal might be some sort of device. So, for example approaching from one direction it is like a bagel where you can pass material through the center but approaching from the opposite would be more like a muffin. You could carefully pass a hose through a bagel but would cause problems if you submerge it in water or burn it.

If the portal are tough enough we could drop one into a volcano or a bore hole. Then we could build artificial islands like Palmira or build ski resorts in Kansas.
 

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