Masters of the Vortex by E.E. Smith — Read

THE METHODS of operation of the _Vortex Blaster II_ had long since been worked out in detail. Approaching any planet Captain Ross, through channels, would ask permission of the various governments to fly in atmosphere, permission to use high explosive, permission to land and be serviced, and permission-after standard precautions-to grant planetary leave to his ship's personnel. All this asking was not, of course, strictly necessary in his case, since every world having even one loose atomic vortex had been demanding long and insistently that Neal Cloud visit it next, but it was strictly according to protocol.

Astrogators had long since plotted the course through planetary atmosphere; not by the demands of the governments concerned and not by any ascending or descending order of violence of the vortices to be extinguished, but by the simple criterion of minimum flight-time ending at the pre-selected point of entry to the planet.