"Into the Comet" is a science fiction short story by British writer Arthur C. Clarke.
It is one of several stories by many science fiction authors in which problems are solved by reverting to 'primitive' technology.
The plot concerns a journey by a spaceship to enter through the layers of gas surrounding a comet and observe the nucleus at close range.
Once convinced, the astronomer creates a production line of the crew, using abaci to carry out the calculations that the computer would normally do.
The procedure is successful and an orbit is calculated to bring the ship within radio range of Earth.