4 ms·

Without the 1G of acceleration, you're limiting how far you can go in a single generation. At 0.1g, that 1000 light year trip would take 90 years (to those on t

Without the 1G of acceleration, you're limiting how far you can go in a single generation. At 0.1g, that 1000 light year trip would take 90 years (to those on the ship). The beauty of 1G is that it provides normal gravity and you can go great distances in a human lifespan. Of course a 2G trip will get you there in half the time, but it's harder for humans to live at 2G. Though maybe the time to the destination is not a problem if you don't mind a generational ship where generations of humans live (and die) on the journey. It doesn't matter to those on earth, since the trip will still take over 1000 years in their timeframe, so whether it's 1015 years, 1100 years or 2000 years probably doesn't really matter to them.

ClumsyPilot 5y ago
"The beauty of 1G is that it provides normal gravity and you can go great distances in a human lifespan." It like unicorns - beatifull and entirely fancifull. Fusion or fission cant do it, even a ship with pure antimatter drive cannot accelerate like that for decades We will have hibernation before we have practical antimatter, and lets you travel intersteller without wasting enegy
- AnimalMuppet 5y ago
  > even a ship with pure antimatter drive cannot accelerate like that for decades Sure it can. You just need a decently-sized asteroid and an equally-sized antimatter asteroid for fuel, and you can do it for decades, even with the price you pay early to accelerate the fuel you will use later.
  - ClumsyPilot 5y ago
    What are you trying to do with an asteroid, and why does it need to be decently sized? Neither is relevant. You calculate mass fraction, i.e. for a ship to get to orbit using kerosene, the ship must be 97% made of fuel my mass. If you have an antimatter ship, if you can produce, store, and 100% efficiently use antimatter and carry nothing else as your reaction mass and don't have issues with waste heat or radiation, your ship will need to be over 90% fuel by mass to maintain 1G acceleration for years.
    - AnimalMuppet 5y ago
      > What are you trying to do with an asteroid, and why does it need to be decently sized? Neither is relevant. I'm using the asteroid for mass, to react with the antimatter. So, yeah, it's relevant. > If you have an antimatter ship, if you can produce, store, and 100% efficiently use antimatter and carry nothing else as your reaction mass and don't have issues with waste heat or radiation, your ship will need to be over 90% fuel by mass to maintain 1G acceleration for years. Yup. And it's exponential - if the non-fuel mass is 10% to be able to do 10 years, then to do 20 years, the non-fuel mass can only be 1%, and for 30 years it can only be 0.1%. That's why you need the asteroid.
      - ClumsyPilot 5y ago
        Taking antimatter fuel out of your carefully designed, failsafe magnetic containment tanks and putting it into a highly-volatile asteroid of doom (attached with what? Antimatter-immune rope that can pull a billion tonns at 1G?) does not mean the rocket equasion gives you a free pass. Its still the same formula, nothing has changed. Its combined weight of your ship and it's asteroids. All you are saying is "you need a big fuel tank"
        AnimalMuppet 5y ago
        I'm saying approximately how big a fuel tank you need to refute your "you can't do it for decades" statement.
        ClumsyPilot 5y ago
        So how big is it? Is a "decently sized asteroid" 50 meters across? 5,000? 500,000? Thats 4 orders of magnitude range. Like I know what's a decently sized car, or a house, or a mountain
iso1210 5y ago
If you could somehow accelerate at 1G indefinitely you can get anywhere in the universe in a human lifespan. Of course to accelerate a 1000 ton spaceship you'd need about 4 quadrillion tons of fuel.

ClumsyPilot 5y ago

"The beauty of 1G is that it provides normal gravity and you can go great distances in a human lifespan." It like unicorns - beatifull and entirely fancifull. Fusion or fission cant do it, even a ship with pure antimatter drive cannot accelerate like that for decades We will have hibernation before we have practical antimatter, and lets you travel intersteller without wasting enegy

AnimalMuppet 5y ago
> even a ship with pure antimatter drive cannot accelerate like that for decades Sure it can. You just need a decently-sized asteroid and an equally-sized antimatter asteroid for fuel, and you can do it for decades, even with the price you pay early to accelerate the fuel you will use later.
- ClumsyPilot 5y ago
  What are you trying to do with an asteroid, and why does it need to be decently sized? Neither is relevant. You calculate mass fraction, i.e. for a ship to get to orbit using kerosene, the ship must be 97% made of fuel my mass. If you have an antimatter ship, if you can produce, store, and 100% efficiently use antimatter and carry nothing else as your reaction mass and don't have issues with waste heat or radiation, your ship will need to be over 90% fuel by mass to maintain 1G acceleration for years.
  - AnimalMuppet 5y ago
    > What are you trying to do with an asteroid, and why does it need to be decently sized? Neither is relevant. I'm using the asteroid for mass, to react with the antimatter. So, yeah, it's relevant. > If you have an antimatter ship, if you can produce, store, and 100% efficiently use antimatter and carry nothing else as your reaction mass and don't have issues with waste heat or radiation, your ship will need to be over 90% fuel by mass to maintain 1G acceleration for years. Yup. And it's exponential - if the non-fuel mass is 10% to be able to do 10 years, then to do 20 years, the non-fuel mass can only be 1%, and for 30 years it can only be 0.1%. That's why you need the asteroid.
    - ClumsyPilot 5y ago
      Taking antimatter fuel out of your carefully designed, failsafe magnetic containment tanks and putting it into a highly-volatile asteroid of doom (attached with what? Antimatter-immune rope that can pull a billion tonns at 1G?) does not mean the rocket equasion gives you a free pass. Its still the same formula, nothing has changed. Its combined weight of your ship and it's asteroids. All you are saying is "you need a big fuel tank"
      - AnimalMuppet 5y ago
        I'm saying approximately how big a fuel tank you need to refute your "you can't do it for decades" statement.
        ClumsyPilot 5y ago
        So how big is it? Is a "decently sized asteroid" 50 meters across? 5,000? 500,000? Thats 4 orders of magnitude range. Like I know what's a decently sized car, or a house, or a mountain

iso1210 5y ago

If you could somehow accelerate at 1G indefinitely you can get anywhere in the universe in a human lifespan. Of course to accelerate a 1000 ton spaceship you'd need about 4 quadrillion tons of fuel.