An astrogation plotter was a basic tool of hyperspace navigation. Normally kept in a strongbox under the main engineering console with a galactic chart of pulsars and other variable stars, it was employed in circumstances when the navigation computer systems of a starship had suffered a catastrophic failure. By manually plotting the position of at least two such stars, a spacer could plot a rudimentary course for the hyperdrive and avoid being stranded in the depths of space.