Meteor Defence System (Ringworld)

In the Ringworld series by Larry Niven, set in Known Space, the Ringworld is a ring 150 million kilometers in radius, 960 million kilometers in circumference, 1.6 million kilometers wide, and 1 kilometer thick, built by the Pak. It is first visited by the team of humans Louis Wu and Teela Brown, Speaker-To-Animals (a Kzin), and the Pierson's Puppeteer Nessus. Throughout the novel Ringworld, the team cannot understand how the species who built the Ringworld expected to defend it against a variety of threats such as meteors ripping it apart to invasion by aliens. The Ringworld Meteor Defence System was built by the Pak to protect the Ringworld against these threats.

The Meteor Defence System is built into the material of the Ringworld. A network of superconducting cables run through the entire ring. This network of cables can be used to create a magnetic field to act upon the sun of the Ringworld, causing it to flare. A superthermal laser effect is created within the solar flare and can be directed using the Ringworld superconductor network to fire in any direction. The laser is powered by the energy in the solar flare, so the possible energy output is unbelievable.

When the Pak built the Ringworld, they built the Meteor Defence to work automatically. It fires on any object whose projected path crosses the surface of the Ringworld and might potentially cause damage. This automatic function is discovered when Louis Wu and his team orbit the sun and are fired on. The laser blasts off the instruments on the wing of their ship and causes the stasis field on board to activate to protect the lives of the occupants.