Visionary author Sir Arthur C. Clarke, whose science fiction and non-fiction works ranged from 2001: A Space Odyssey to an early proposal for geostationary communications satellites, has died at age 90. Along with Robert Heinlein and Isaac Asimov, Clarke was considered one of the "Big Three" science-fiction writers.

Clarke had been wheelchair-bound for several years due to complications stemming polio, said Scott Chase, the secretary of the nonprofit Arthur C. Clarke Foundation.

Clarke died early Wednesday at a hospital in Colombo, Sri Lanka, where he had lived since the 1950s.

In a videotaped 90th birthday message to fans, Clarke said he still hoped to see some sign of intelligent life beyond Earth. Some of us are still waiting for signs of intelligent life on earth.

Clarke was a British science fiction author, inventor, and futurist. He was most famous for the novel 2001: A Space Odyssey, written in collaboration with director Stanley Kubrick, a collaboration which also produced the film of the same name; and as a host and commentator in the British television series Mysterious World.

Clarke served in the Royal Air Force as a radar instructor and technician from 1941-1946. His proposal for satellite communication systems in 1945 won him the Franklin Institute Stuart Ballantine Gold Medal in 1963.

Clarke emigrated to Sri Lanka in 1956 largely to pursue his interest in scuba diving, and lived there until his death. He was knighted by Queen Elizabeth II in 1998, and was awarded Sri Lanka's highest civil honour, Sri Lankabhimanya, in 2005.

Clarke was born in Minehead, Somerset, England on December 16, 1917. As a boy he enjoyed stargazing and reading old American science fiction pulp magazines. After secondary school and studying at Huish's Grammar School, Taunton, he was unable to afford a university education and got a job as an auditor in the pensions section of the Board of Education.

During the Second World War he served in the Royal Air Force as a radar specialist and was involved in the early warning radar defence system, which contributed to the RAF's success during the Battle of Britain. Clarke spent most of his wartime service working on Ground Controlled Approach (GCA) radar as documented in the semi-autobiographical Glide Path, his only non-science-fiction novel. Although GCA did not see much practical use in the war, it proved vital to the Berlin Airlift of 1948-1949 after several years of development. Clarke initially served in the ranks, and was a Corporal instructor on radar at No 9 Radio School, RAF Yatesbury. He was commissioned as a Pilot Officer (Technical Branch) on 27 May 1943. He was promoted Flying Officer on 27 November 1943. He was appointed chief training instructor at RAF Honiley and was demobilised with the rank of Flight Lieutenant. After the war he earned a first-class degree in mathematics and physics at King's College London.

In the postwar years, Clarke became the Chairman of the British Interplanetary Society from 1946-1947 and again from 1951-1953. Although he was not the originator of the concept of geostationary satellites, one of his most important contributions may be his idea that they would be ideal telecommunications relays. He advanced this idea in a paper privately circulated among the core technical members of the BIS in 1945. The concept was published in Wireless World in October of that year. Clarke also wrote a number of non-fiction books describing the technical details and societal implications of rocketry and space flight. The most notable of these may be The Exploration of Space (1951) and The Promise of Space (1968). In recognition of these contributions, the geostationary orbit 22,000 miles above the equator is officially recognized by the International Astronomical Union as a Clarke Orbit.

On a trip to Florida in 1953, Clarke met and married Marilyn Mayfield, a 22-year-old American divorcee with a young son. They separated permanently after six months, although the divorce was not finalised until 1964."The marriage was incompatible from the beginning", says Clarke. Journalists who inquired of Clarke whether he was gay were told, "No, merely mildly cheerful."

While Clarke had a few stories published in fanzines, between 1937 and 1945, his first professional sales appeared in Astounding Science Fiction in 1946: "Loophole" was published in April, while "Rescue Party", his first sale, was published in May. Along with his writing Clarke briefly worked as Assistant Editor of Science Abstracts (1949) before devoting himself to writing full-time from 1951 onward. Clarke also contributed to the Dan Dare series published in Eagle, and his first three published novels were written for children.

Clarke corresponded with C. S. Lewis in the 1940s and 1950s and they once met in an Oxford pub, The Eastgate, to discuss science fiction and space travel. Clarke, after Lewis's death, voiced great praise for him, saying the Ransom Trilogy was one of the few works of science fiction that could be considered literature.

In 1948, Clarke wrote "The Sentinel" for a BBC competition. Though the story was rejected it changed the course of Clarke's career. Not only was it the basis for A Space Odyssey, but "The Sentinel" also introduced a more mystical and cosmic element to Clarke's work. Many of Clarke's later works feature a technologically advanced but still-prejudiced mankind being confronted by a superior alien intelligence. In the cases of The City and the Stars (and its original version, Against the Fall of Night), Childhood's End, and the 2001 series, this encounter produces a conceptual breakthrough that accelerates humanity into the next stage of its evolution. In Clarke's authorized biography, Neil McAleer writes that: "many readers and critics still consider [Childhood's End] Arthur C. Clarke's best novel."

Clarke lived in Sri Lanka from 1956 until his death in 2008, having emigrated there when it was still called Ceylon, first in Unawatuna on the south coast, and then in Colombo. Clarke held citizenship of both the UK and Sri Lanka. He was an avid scuba diver and a member of the Underwater Explorers Club. Living in Sri Lanka afforded him the opportunity to visit the ocean year-round. It also inspired the locale for his novel The Fountains of Paradise in which he described a space elevator. This, he believed, ultimately will be his legacy, more so than geostationary satellites, once space elevators make rocket based access to space obsolete.

His many predictions culminated in 1958 when he began a series of essays in various magazines that eventually became Profiles of the Future published in book form in 1962. A timetable up to the year 2100 describes inventions and ideas including such things as a "global library" for 2005.

In the early 1970s Clarke signed a three-book publishing deal, a record for a science-fiction writer at the time. The first of the three was Rendezvous with Rama in 1973, which won him all the main genre awards and has spawned sequels that, along with the 2001 series, formed the backbone of his later career.

In the 1980s Clarke became well known to many for his television programmes Arthur C. Clarke's Mysterious World, Arthur C. Clarke's World of Strange Powers, and Arthur C. Clarke's Mysterious Universe. In 1986 he was named a Grand Master by the Science Fiction Writers of America. In 1988 he was diagnosed with post-polio syndrome, having originally contracted polio in 1959, and needed to use a wheelchair most of the time thereafter.

In the 1989 Queen's Birthday Honours, Clarke was appointed Commander of the Order of the British Empire (CBE) "for services to British cultural interests in Sri Lanka." The same year he became the first Chancellor of the International Space University, serving from 1989 to 2004 and he also served as Chancellor of Moratuwa University in Sri Lanka from 1979 to 2002.

In 1994, Clarke appeared in a science fiction film; he portrayed himself in the telefilm Without Warning, an American production about an apocalyptic alien first contact scenario presented in the form of a faux newscast.

On 26 May 2000, Clarke was made a British Knight Bachelor "for services to literature" at a ceremony in Colombo. The award of a knighthood had been announced in the 1998 New Year Honours.

Although he and his home were unharmed by the 2004 Indian Ocean earthquake tsunami, his "Arthur C. Clarke Diving School" at Hikkaduwa was destroyed. He made humanitarian appeals, and the Arthur C. Clarke Foundation worked towards a better disaster notification systems. The school has since been rebuilt.

In September 2007, he provided a video greeting for NASA's Cassini probe's flyby of Iapetus (which plays an important role in 2001: A Space Odyssey). In December 2007 on his 90th birthday, Clarke recorded a video message to his friends and fans bidding them good-bye.

Clarke died in Sri Lanka on 19 March 2008 after suffering from breathing problems, according to Rohan de Silva, one of his aides.

Only a few days before he died, he reviewed the manuscript of his final work, The Last Theorem, on which he had collaborated by e-mail with his contemporary Frederik Pohl.

-- 19 March 2008