He was the director of Germany's Max Planck Institute for Solar System Research for 16 years from 1974, overseeing the successful Giotto space mission to Halley's Comet in 1986.

He was a foreign associate of the United States National Academy of Sciences and worked with US space agency NASA on several space probes.

Axford conducted ground-breaking research in planetary science, comets and solar physics over 50 years and made significant contributions to the fields of plasma and space physics, the New Zealand Press Association reported.

He died Saturday at his home after a long illness and is survived by his wife, Joy, and four children.