Rudolph Steiner was a scientist who devised and orchestrated the Gemini Plan, a scheme to bring Venus into Earth's orbit and allow the planet's mineral resources to be economically available.
Funded by a consortium of industrialists, he was based in a hi-tech complex in Australia, from which he planned to launch a missile armed with a fusion explosive to Venus, thus altering its trajectory.
His assistant, Murray Stevens, calculated that Steiner's plan would lead to the destruction of Earth, but he refused to listen. The plan was defeated by Stevens and the Third Doctor, who reprogrammed the missile to collide with the sun, and Steiner was arrested. (COMIC: Gemini Plan)