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 3 added 47 characters in body edited Jan 20 '16 at 12:08 Brian Lynch 4,1201818 silver badges3232 bronze badges There are simply two options: either you provide 1 g of acceleration on the spacecraft the entire flight (from thrust) or you use a rotating habitat to provide centrifugal acceleration. Applying 1 g of acceleration is probably not possible given the fact your trajectory will have to be planned to accommodate that (i.e., you will be expending a ridiculous amount of propellant to achieve this), so a rotating habitat would be the most feasible option. In that case, the energy required is minimal -- either just enough to overcome friction between the rotating and non-rotating components of the spacecraft, or essentially zero if the entire spacecraft itself rotates. But... Let's consider some ballpark estimates if you still insist on trying to achieve a 1 g continuous acceleration from thrust... If you want to do this with chemical rocket motors, you'll be looking at a manoeuvre that needs so much fuel my calculator simply says "error" (basically you'll need a $$\Delta v$$ of over 2500 km/s, assuming a 3 day flight). If you want to use ion thrusters then you'll still need to achieve the same $$\Delta v$$ but your specific impulse will be much higher (say 6,000 s instead of 350 s). This leads to a mass ratio of about 6E18, or rather 6 billion billion (so you will need over 6,000,000,000,000,000,000 kg of propellant for every 1 kg of empty mass). Not to mention the assumptions made here in terms of how you will power this and provide the thrust on that huge mass to get 1 g of acceleration. Note that I'm approaching this question in terms of accessible technology. You could look into what kind of specific thrust would make this achievable for a more acceptable mass ratio, or some kind of external source of propulsion, but at that point you are making up propulsion technology that does not exist! There are simply two options: either you provide 1 g of acceleration on the spacecraft the entire flight (from thrust) or you use a rotating habitat to provide centrifugal acceleration. Applying 1 g of acceleration is probably not possible given the fact your trajectory will have to be planned to accommodate that (i.e., you will be expending a ridiculous amount of propellant to achieve this), so a rotating habitat would be the most feasible option. In that case, the energy required is minimal -- either just enough to overcome friction between the rotating and non-rotating components of the spacecraft, or essentially zero if the entire spacecraft itself rotates. But... Let's consider some ballpark estimates if you still insist on trying to achieve a 1 g continuous acceleration from thrust... If you want to do this with chemical rocket motors, you'll be looking at a manoeuvre that needs so much fuel my calculator simply says "error" (basically you'll need a $$\Delta v$$ of over 2500 km/s, assuming a 3 day flight). If you want to use ion thrusters then you'll still need to achieve the same $$\Delta v$$ but your specific impulse will be much higher (say 6,000 s instead of 350 s). This leads to a mass ratio of about 6E18, or rather 6 billion billion (so you will need over 6,000,000,000,000,000,000 kg of propellant for every 1 kg of empty mass). Not to mention the assumptions made here in terms of how you will power this and provide the thrust on that huge mass to get 1 g of acceleration. Note that I'm approaching this question in terms of accessible technology. You could look into what kind of specific thrust would make this achievable for a more acceptable mass ratio, but at that point you are making up propulsion technology that does not exist! There are simply two options: either you provide 1 g of acceleration on the spacecraft the entire flight (from thrust) or you use a rotating habitat to provide centrifugal acceleration. Applying 1 g of acceleration is probably not possible given the fact your trajectory will have to be planned to accommodate that (i.e., you will be expending a ridiculous amount of propellant to achieve this), so a rotating habitat would be the most feasible option. In that case, the energy required is minimal -- either just enough to overcome friction between the rotating and non-rotating components of the spacecraft, or essentially zero if the entire spacecraft itself rotates. But... Let's consider some ballpark estimates if you still insist on trying to achieve a 1 g continuous acceleration from thrust... If you want to do this with chemical rocket motors, you'll be looking at a manoeuvre that needs so much fuel my calculator simply says "error" (basically you'll need a $$\Delta v$$ of over 2500 km/s, assuming a 3 day flight). If you want to use ion thrusters then you'll still need to achieve the same $$\Delta v$$ but your specific impulse will be much higher (say 6,000 s instead of 350 s). This leads to a mass ratio of about 6E18, or rather 6 billion billion (so you will need over 6,000,000,000,000,000,000 kg of propellant for every 1 kg of empty mass). Not to mention the assumptions made here in terms of how you will power this and provide the thrust on that huge mass to get 1 g of acceleration. Note that I'm approaching this question in terms of accessible technology. You could look into what kind of specific thrust would make this achievable for a more acceptable mass ratio, or some kind of external source of propulsion, but at that point you are making up propulsion technology that does not exist! 2 added 1182 characters in body; added 2 characters in body; deleted 2 characters in body; added 2 characters in body edited Jan 20 '16 at 10:53 Brian Lynch 4,1201818 silver badges3232 bronze badges There are simply two options: either you provide 1 g of acceleration on the spacecraft the entire flight (from thrust) or you use a rotating habitat to provide centrifugal acceleration. Applying 1 g of acceleration is probably not possible given the fact your trajectory will have to be planned to accommodate that (i.e., you will be expending a ridiculous amount of propellant to achieve this), so a rotating habitat would be the most feasible option. In that case, the energy required is minimal -- either just enough to overcome friction between the rotating and non-rotating components of the spacecraft, or essentially zero if the entire spacecraft itself rotates. But... Let's consider some ballpark estimates if you still insist on trying to achieve a 1 g continuous acceleration from thrust... If you want to do this with chemical rocket motors, you'll be looking at a manoeuvre that needs so much fuel my calculator simply says "error" (basically you'll need a $$\Delta v$$ of over 2500 km/s, assuming a 3 day flight). If you want to use ion thrusters then you'll still need to achieve the same $$\Delta v$$ but your specific impulse will be much higher (say 6,000 s instead of 350 s). This leads to a mass ratio of about 6E18, or rather 6 billion billion (so you will need over 6,000,000,000,000,000,000 kg of propellant for every 1 kg of empty mass). Not to mention the assumptions made here in terms of how you will power this and provide the thrust on that huge mass to get 1 g of acceleration. Note that I'm approaching this question in terms of accessible technology. You could look into what kind of specific thrust would make this achievable for a more acceptable mass ratio, but at that point you are making up propulsion technology that does not exist! There are simply two options: either you provide 1 g of acceleration on the spacecraft the entire flight (from thrust) or you use a rotating habitat to provide centrifugal acceleration. Applying 1 g of acceleration is probably not possible given the fact your trajectory will have to be planned to accommodate that, so a rotating habitat would be the most feasible option. In that case, the energy required is minimal -- either just enough to overcome friction between the rotating and non-rotating components of the spacecraft, or essentially zero if the entire spacecraft itself rotates. There are simply two options: either you provide 1 g of acceleration on the spacecraft the entire flight (from thrust) or you use a rotating habitat to provide centrifugal acceleration. Applying 1 g of acceleration is probably not possible given the fact your trajectory will have to be planned to accommodate that (i.e., you will be expending a ridiculous amount of propellant to achieve this), so a rotating habitat would be the most feasible option. In that case, the energy required is minimal -- either just enough to overcome friction between the rotating and non-rotating components of the spacecraft, or essentially zero if the entire spacecraft itself rotates. But... Let's consider some ballpark estimates if you still insist on trying to achieve a 1 g continuous acceleration from thrust... If you want to do this with chemical rocket motors, you'll be looking at a manoeuvre that needs so much fuel my calculator simply says "error" (basically you'll need a $$\Delta v$$ of over 2500 km/s, assuming a 3 day flight). If you want to use ion thrusters then you'll still need to achieve the same $$\Delta v$$ but your specific impulse will be much higher (say 6,000 s instead of 350 s). This leads to a mass ratio of about 6E18, or rather 6 billion billion (so you will need over 6,000,000,000,000,000,000 kg of propellant for every 1 kg of empty mass). Not to mention the assumptions made here in terms of how you will power this and provide the thrust on that huge mass to get 1 g of acceleration. Note that I'm approaching this question in terms of accessible technology. You could look into what kind of specific thrust would make this achievable for a more acceptable mass ratio, but at that point you are making up propulsion technology that does not exist! 1 answered Jan 19 '16 at 19:01 Brian Lynch 4,1201818 silver badges3232 bronze badges There are simply two options: either you provide 1 g of acceleration on the spacecraft the entire flight (from thrust) or you use a rotating habitat to provide centrifugal acceleration. Applying 1 g of acceleration is probably not possible given the fact your trajectory will have to be planned to accommodate that, so a rotating habitat would be the most feasible option. In that case, the energy required is minimal -- either just enough to overcome friction between the rotating and non-rotating components of the spacecraft, or essentially zero if the entire spacecraft itself rotates.