At the beginning of the 20th Century, there was a burst of scientific investigation into interplanetary travel, largely driven by the inspiration of fiction by writers such as Jules Verne and H.G.Wells. Scientists seized on the rocket as a technology that was able to achieve this in real life.
At the cutting edge? Who else?
But even though, when the knock on the door finally comes (probably later on this week) and I open the door and sign, print and date the delivery note for the package that clearly contains my Nobel prize for rocket surgery (judging by the sound when I shake it), I don't think I'll ever be able to say it quite as well as Tsiolkovsky when he (or someone very like him) said,
"If the reaction mass would have to be accelerated from zero speed to the exhaust speed all energy produced would go into the reaction mass and nothing would be left for kinetic energy gain by the rocket and payload. However, if the rocket already moves and accelerates (the reaction mass is expelled in the direction opposite to the direction in which the rocket moves) less kinetic energy is added to the reaction mass. To see this, if, for example, ve=10 km/s and the speed of the rocket is 3 km/s, then the speed of a small amount of expended reaction mass changes from 3 forwards to 7 km/s rearwards. Thus, while the energy required is 50 MJ per kg reaction mass, only 20 MJ is used for the increase in speed of the reaction mass. The remaining 30 MJ is the increase of the kinetic energy of the rocket and payload."