Physics, Astronomy & Cosmology / Re: Could plutonium-238 dioxide fuel be used for interstellar travel?« on: Today at 01:16:48 »
Quote from: OP
Could plutonium-238 dioxide fuel be used for interstellar travel?No.
Pu-238 is better considered a "battery" than a fuel
- A battery that lasts 30 years or so
- And can put out 10 to a few hundred Watts of electricity
- It is used in radioisotope thermoelectric generators, which aren't very efficient (typically 3-7%), and don't produce any usable thrust
- although the Perseverance Mars rover uses this inefficiency as a way to keep the electronics warm at night (combined heat and power)
If you want more power (kilowatts), solar cells are more useful in the inner solar system - although the Juno mission to Jupiter also uses a very large array of solar cells.
If you want propulsion, the most efficient is probably an ion drive - but for interstellar use, these would MegaWatts of power (current ground-based models have been demonstrated up to 70kW).
- You will probably want a uranium nuclear reactor to power it
- You will quickly run out of reaction mass (typically Xenon)
- You will quickly run out of fuel (typically Uranium)
- And it is hard to find sources of Xenon and Uranium out in interstellar space
To really do interstellar travel, you can't afford to carry all the fuel and power with you - they are too heavy.
- One suggestion is to use magnetic fields to gather hydrogen from space, and fuse it to produce power (perhaps that is what Eternal Student was alluding to?)