>>12093353>AerospikesBad technology everywhere in the solar system except for Titan and Venus, in fact anything other than vacuum optimized is bad for any vehicles operating in greater-than-Mars-atmospheric density.
The actual future breakthrough in propulsion will be microfission rockets; think Orion drive but instead of kiloton yield nukes you're using a superconducting magnet to crush a fuel pellet the size of a pea enough to cause it to go supercritical and release the energy equivalent of a few hundred kilos of chemical propellants. Even at a pessimistic Isp of 50,000 and a dry mass fraction of 80% you'd have a vehicle capable of doing 100,000 m/s of delta V easily. A slightly more optimistic Isp of 80,000 and a mass fraction of 50% gets you over 500,000 m/s of delta V, easily unlocking everything this side of the Kuiper belt for human exploration and eventually colonization.
To put it another way, a microfission tug vehicle that had a mass fraction of 50%, Isp of 50,000 and a total wet mass of 30 tons would be able to throw 970 tons onto a Mars intercept starting from LEO. Alternatively, it could push 570 tons of payload from a circular low Earth orbit all the way to a circular Mars orbit, in one stage. If 400 kilograms of that 570,000 kilograms of payload were reserved for fuel pellets, the 15 ton tug would have enough delta V to get all the way BACK to a circular low Earth orbit again.
