I'm on mobile so this'll be pretty in-a-nutshell: Aerospikes are rocket nozzles that are very efficient across a wide range of altitudes because at different a

I'm on mobile so this'll be pretty in-a-nutshell: Aerospikes are rocket nozzles that are very efficient across a wide range of altitudes because at different altitudes you have different pressures and temperatures. Normal rocket engines usually compensate for this with variable geometry nozzles.