Space Nuclear Propulsion
nasa.gov
Space Nuclear Propulsion
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Re: Space Nuclear Propulsion
#2This is the only viable future for space travel. In orbit assembled space ships with nuclear thermal propulsion. Travel time to Mars with conventional chemical propulsion takes just way too long.
Re: Space Nuclear Propulsion
#3This is the only viable future for space travel. In orbit assembled space ships with nuclear thermal propulsion. Travel time to Mars with conventional chemical propulsion takes just way too long.
I think nuclear electric propulsion is probably a viable option as well.
Re: Space Nuclear Propulsion
#4This is the only viable future for space travel. In orbit assembled space ships with nuclear thermal propulsion. Travel time to Mars with conventional chemical propulsion takes just way too long.
There are non-nuclear alternatives, particularly inward of the asteroid belt.
PV in space can be made very thin. The absorption length for photons in CdTe, for example, is just 0.1 microns. Without having to be mechanically robust against wind and rain, great gossamer PV arrays could have very high power/mass ratios. These could drive plasma engines with high Isp.
Re: Space Nuclear Propulsion
#5This is the only viable future for space travel. In orbit assembled space ships with nuclear thermal propulsion. Travel time to Mars with conventional chemical propulsion takes just way too long.
There are non-nuclear alternatives, particularly inward of the asteroid belt. PV in space can be made very thin. The absorption length for photons in CdTe, for example, is just 0.1 microns. Without having to be mechanically robust against wind and rain, great gossamer PV arrays could have very high power/mass ratios. These could drive plasma engines with high Isp.
For crewed missions, wouldn't the low trust lead to very large transit times anyway, in a Mars mission scenario?
Re: Space Nuclear Propulsion
#6Earlier quoted context omitted.
There are non-nuclear alternatives, particularly inward of the asteroid belt. PV in space can be made very thin. The absorption length for photons in CdTe, for example, is just 0.1 microns. Without having to be mechanically robust against wind and rain, great gossamer PV arrays could have very high power/mass ratios. These could drive plasma engines with high Isp.
For crewed missions, wouldn't the low trust lead to very large transit times anyway, in a Mars mission scenario?
That depends on the power/mass ratio of the system.
Lower acceleration systems can also be used to preposition chemical fuels for use by crewed vehicles.
Re: Space Nuclear Propulsion
#7This is the only viable future for space travel. In orbit assembled space ships with nuclear thermal propulsion. Travel time to Mars with conventional chemical propulsion takes just way too long.
There are non-nuclear alternatives, particularly inward of the asteroid belt. PV in space can be made very thin. The absorption length for photons in CdTe, for example, is just 0.1 microns. Without having to be mechanically robust against wind and rain, great gossamer PV arrays could have very high power/mass ratios. These could drive plasma engines with high Isp.
None of that has anything to do with reducing travel times to Mars unless your entire payload is on the order of a couple of pounds.
That's like replying to someone saying it takes too long to drive from New York to Seattle, by saying that we could build an efficient 1000 mile per gallon car, that travels at .01 miles per hour. How efficient the vehicle is isn't the slightest bit useful to solve their complaint.
A high thrust to weight ratio when the weight is a couple of pounds isn't useful. What's useful is having a huge amount of thrust that's large enough to shove multiple tons of mass at high accelerations.
Re: Space Nuclear Propulsion
#8Earlier quoted context omitted.
There are non-nuclear alternatives, particularly inward of the asteroid belt. PV in space can be made very thin. The absorption length for photons in CdTe, for example, is just 0.1 microns. Without having to be mechanically robust against wind and rain, great gossamer PV arrays could have very high power/mass ratios. These could drive plasma engines with high Isp.
None of that has anything to do with reducing travel times to Mars unless your entire payload is on the order of a couple of pounds. That's like replying to someone saying it takes too long to drive from New York to Seattle, by saying that we could build an efficient 1000 mile per gallon car, that travels at .01 miles per hour. How efficient the vehicle is isn't the slightest bit useful to solve their complaint. A hi…
Yeah, no, that's nonsense. There's nothing preventing anyone from scaling up such systems. Remember, construction in space was already stipulated.
Re: Space Nuclear Propulsion
#9Earlier quoted context omitted.
None of that has anything to do with reducing travel times to Mars unless your entire payload is on the order of a couple of pounds. That's like replying to someone saying it takes too long to drive from New York to Seattle, by saying that we could build an efficient 1000 mile per gallon car, that travels at .01 miles per hour. How efficient the vehicle is isn't the slightest bit useful to solve their complaint. A hi…
Yeah, no, that's nonsense. There's nothing preventing anyone from scaling up such systems. Remember, construction in space was already stipulated.
How large would such a construction need to be to accelerate 100 tons at 1g? Maybe someone could do the math for us. I assume it's on the order of dozens/hundreds of miles long per dimension and would be completely infeasible compared to just using an engine with high thrust to begin with.
[Edit]
Here's some rough math.
From wiki, assume a typical ion engine can produce 150mN of thrust from 4,000 W of power input.
Using a space station solar panel as an example of solar collection in space, each space station solar panel is 420 square meters in size and produces 31,000 W of power.
One space station solar panel would then provide (31,000 W / 4,000 W) * 150 mN = 1,162 mN, or .001162 N of force.
The force required to accelerate 100 tons at 1g requires 996,402 Newtons of force.
To generate that much force, you would then need 996,402 N / .001162 N = 857,488,812 space station solar panels worth of power.
As one space station solar panel is 420 square meters, then that requires 857,488,812 * 420 square meters = 360,145,301,040 square meters of solar panels.
Assuming square construction, each side would need to be 600,121 meters, or 373 miles long.
I assure you, just using high thrust engines makes infinitely more sense than building a pv-based ship scaled up so far that the ship's dimensions are nearly 400 miles long on each edge. At least for any time soon ..
Re: Space Nuclear Propulsion
#10This is the only viable future for space travel. In orbit assembled space ships with nuclear thermal propulsion. Travel time to Mars with conventional chemical propulsion takes just way too long.
I think nuclear electric propulsion is probably a viable option as well.
Indeed. Probably a combination of both nuclear-thermal and nuclear-electric or ion drive I think it's called otherwise. The nuclear thermal would provide initial boost, then ion drive can do continuous acceleration half way and then deceleration the other half way. That would get a ship to Mars in a fraction of time.