There are plenty of references to methane, but no in-depth story about systems using it. The last part of the book, attempting to predict what fuels would be p

There are plenty of references to methane, but no in-depth story about systems using it. The last part of the book, attempting to predict what fuels would be popular, prescribed methane for deep space probes, for many of the same reasons you give, but failed to foresee reusable boosters or other departures from the status quo. > as methane has a performance only slightly superior to that of gasoline, and is much harder to handle, nobody could see any point... > For the big first-stage space boosters we will continue to use liquid oxygen and RP-1 or the equivalent. They work and they're cheap — and Saturn V uses a lot of propellant! Later, we may shift to hydrogen as a first-stage fuel, but it appears unlikely. The development of a reusable booster won't change the picture, but if a ram-rocket booster is developed all bets are off. > For the upper stages, the hydrogen-oxygen combination of the J-2 is very satisfactory, and will probably be used for a long time. Later, as more energy is needed, there may be a shift, for the final stage, to hydrogen-fluorine or hydrogen-lithium-fluorine... > Deep space probes, working at low temperatures, will probably use methane, ethane, and diborane for fuels, although propane is a possibility. The oxidizers will be OF2, and possibly ONF3 and NO2F...