Space pioneer and visionary, Robert Lull Forward, has died of brain cancer. Forward leaves behind a legacy of inventive research on solar sails, space tethers, antimatter propulsion, and other advanced space propulsion technologies.

At age 70, Forward passed away at home early in the morning on Sept. 21.

The innovative thinker of space and time, Forward was a persistent voice in opening the space frontier. Through countless talks to professional as well as space advocacy groups -- always wearing an unforgettable bright and lively vest that was his trademark -- Forward was a stalwart believer in a grand vision of humanity's space future.

During his career, Forward worked for 31 years at the Hughes Aircraft Company Corporate Research Laboratories in Malibu, California. While at Hughes, he received 18 patents and published numerous papers on experimental gravity instruments and measurements.

In the first paper on using the normal modes of the Earth to set an upper limit on interstellar millicycle gravitational radiation, Forward detailed the wideband "chirp" signal to be expected from the gravitational collapse of a binary neutron star pair. In his research work, he also outlined a method for "flattening" spacetime over a hatbox-sized region in an orbiting microgravity space lab to the picogravity level.

Forward took early retirement in 1987 to spend more time writing novels and working in his aerospace consulting company business, Forward Unlimited.

In addition to over 200 papers and articles, Forward published 11 "hard" science fiction novels, where the science is as accurate as possible, consistent with telling a good story. It was the stated objective of Forward to teach science through his novels. For example, his first book, Dragon's Egg, expanded upon the idea of SETI expert Frank Drake regarding tiny fast-living creatures living on the surface of a neutron star. Forward later described Dragon's Egg as a textbook on neutron star physics disguised as a novel.

While struggling with his cancer, Forward prepared several obituaries for various professional organizations to which he belonged. One of those self-authored obituaries began: "The intelligent pattern of protoplasm that had been Robert L. Forward ceased coherent operation."

Robert Hoyt, friend and an associate with Forward on developing space tethers, said: "Hopefully, Bob's spirit, now unburdened by that nuisance called inertia, has reached lightspeed. I hope you all will join me in wishing him: Ad Astra, Bob!"