Soviet Mission to Halley's Comet

In 1986, two Soviet space probes intercepted Halley's Comet during its first visit to Earth since 1910. But the mission had some covert American help. Hear from the man in charge, Russian physicist Roald Sagdeev.(Photo: Halley's Comet during its 1986 visit to the centre of the solar system. Credit: Science Photo Library)