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To some readers, an introduction to Sir Arthur C. Clarke may be necessary. To others, no introduction will suffice.

Clarke is most famous for his novels, short stories, and screenplays, including Prelude to Space (1951), Childhood's End (1953), Earthlight (1955), The Deep Range (1957), A Fall of Moondust (1961), Glide Path (1963), The Nine Billion Names of God (1967), 2001: A Space Odyssey (1968), and Rendezvous With Rama (1973). His nonfiction books and essays, meanwhile, have influenced science, particularly astronautics. They include Interplanetary Flight: An Introduction to Astronautics (Temple Press, 1950), The Exploration of Space (Harper, 1951), The Making of a Moon: The Story of the Earth Satellite Program (Harper, 1957), Voices from the Sky: Previews of the Coming Space Age (Harper & Row, 1965), The Promise of Space (Harper & Row, 1968), and The Lost Worlds of 2001 (Sidgwick and Jackson, 1972).

Although he is more revered for his role as an author, Clarke has well deserved the title of futurist for his groundbreaking thinking on space exploration. In October 1945, he published a paper in the magazine Wireless World called “Extra-Terrestrial Relays: Can Rocket Stations Give Worldwide Radio Coverage?” In it, he predicted that geostationary satellites would soon become the basis of global communications. And in his 1979 novel, The Fountains of Paradise, he describes a space elevator that would ferry passengers and cargo to a docked space station, a concept that is currently undergoing its first primitive implementations (see IEEE Spectrum's August 2005 cover story,“A Hoist to the Heavens”

Born in 1917 in Minehead, England, Clarke served in the Royal Air Force during World War II as a radar specialist and was involved in the early-warning system that contributed to the RAF's success in the Battle of Britain. After the war, he earned a first-class degree in mathematics and physics at King's College, London. He then got involved with the nascent British Interplanetary Society, serving as its chairman from 1947 to 1950. In 1948, he published his first book of short stories, The Sentinel, which includes a story by that name that eventually became the basis of his most well-known effort, the screenplay to the 1968 Stanley Kubrick movie 2001: A Space Odyssey, which has inspired generations. Since 1956, Clarke has lived in Sri Lanka.

SPECTRUM: You, Frederick Durant, and Ernst Stuhlinger were all in Barcelona at an International Astronautical Federation meeting on 4 October 1957. What was your reaction when you got the news about Sputnik?

CLARKE: Although I had been writing and speaking about space travel for years, I still have vivid memories of exactly when I heard the news. I was in Barcelona for the 8th International Astronautical Congress. We had already retired to our hotel rooms after a busy day of presentations by the time the news broke. I was awakened by reporters seeking an authoritative comment on the Soviet achievement. Our theories and speculations had suddenly become reality!

For the next few days, the Barcelona Congress became the scene of much animated discussion about what the United States could do to regain some of its scientific prestige. While manned spaceflight and Moon landings were widely speculated about, many still harboured doubts about an American lead in space. One delegate, noticing that there were 23 American and five Soviet papers at the Congress, remarked that while the Americans talked a lot about spaceflight, the Russians just went ahead and did it!

SPECTRUM: In the past 50 years, has the Space Age lived up to your expectations?

CLARKE: On the whole, I think we have had remarkable accomplishments during the first 50 years of the Space Age. Some of us might have preferred things to happen in a different style or time frame, but when our dreams and aspirations are adjusted for reality, there is much we can look back on with satisfaction. (For example, in 1959 I took a bet that men would be landing on the Moon by June 1969, and lost only very narrowly.) And in the heady days of Apollo, we seemed to be on the verge of exploring the planets through manned missions. I could be forgiven for failing to anticipate all the distractions of the 1970s that wrecked our optimistic projections—though I did caution that the Solar System could be lost in the paddy fields of Vietnam. (It almost was.)

SPECTRUM: A lot of what was achieved at the beginning of the Space Age—from Sputnik to the first landing on the moon—was spurred on by the rivalry that was the Cold War. Without that competition, do you think the human impetus to reach for space has slowed somewhat?

CLARKE: Launching Sputnik and landing humans on the Moon were all political decisions, not scientific ones, although scientists and engineers played a lead role in implementing those decisions. (I have only recently learned, from his long-time secretary Carol Rosin, that Wernher von Braun used my 1952 book, The Exploration of Space, to convince President Kennedy that it was possible to go to the Moon.) As William Sims Bainbridge pointed out in his 1976 book, The Spaceflight Revolution: A Sociological Study, space travel is a technological mutation that should not really have arrived until the 21st century. But thanks to the ambition and genius of von Braun and Sergei Korolev, and their influence upon individuals as disparate as Kennedy and Khrushchev, the Moon—like the South Pole—was reached half a century ahead of time.

I hope that nations can at last see better reasons for exploring space, and that future decisions would be informed by intelligence and reason, not the macho-nationalism that fuelled the early Space Race.

SPECTRUM: What is your opinion of private efforts to conquer space? Now that private entrepreneurs such as Peter Diamandis, Elon Musk, and Larry Page have become interested in space competitions, do you think they will provide the impetus?

CLARKE: During 2006, I followed with interest the emergence of this new breed of ‘Citizen Astronauts’ and private space enterprise. Before the current decade is out, fee-paying passengers will be experiencing sub-orbital flights aboard privately funded passenger vehicles, built by a new generation of engineer-entrepreneurs with an unstoppable passion for space. (I’m hoping I could still make such a journey myself). And over the next 50 years, thousands of people will gain access to the orbital realm—and then, to the Moon and beyond.

The Ansari X PRIZE changed the future of personal spaceflight when it inspired the creation of SpaceShipOne by Burt Rutan. Now the Google Lunar X PRIZE can encourage a new fleet of private spacecraft to take humanity back to the Moon. I have endorsed and backed both these efforts as excellent ways to catalyze private investment and citizen involvement in space.

The growth of space tourism will see not just quick orbital hops, but facilities for accommodation and recreation. In October 2006, the Arthur Clarke Foundation selected the American budget-hotelier Bob Bigelow for the Arthur C. Clarke Innovator Award for 2006—in recognition of his work in the development of space habitats. With the successful Russian launch of Bigelow Aerospace’s Genesis 1, Bob is leading the way for private sector individuals willing to advance space exploration with minimum reliance on government programmes. Bob firmly believes in bringing space closer to people’s lives, and Genesis 1 represents the first step in expandable habitats suited for industrial, commercial and recreational purposes.

SPECTRUM: You have lived to see one of your key ideas—geosynchronous satellites—come to fruition. Another idea of yours—the Space Elevator—is coming closer to reality. Do you have any further thoughts on the Space Elevator?

CLARKE: I am very encouraged by the widespread acceptance of the Space Elevator, which can make space transport cheap and affordable to ordinary people. This concept, which I popularised in The Fountains of Paradise (1978), is now taken very seriously, with space agencies and entrepreneurs investing money and effort in developing prototypes. A dozen of these parties competed for the NASA-sponsored, US $150 000 X Prize Cup which took place in October 2006 at the Las Cruces International Airport, New Mexico.

What makes the Space Elevator such an attractive idea is its cost-effectiveness. A ticket to orbit now costs tens of millions of dollars (as the millionaire space tourists have paid). But the actual energy required, if you purchased it from your friendly local utility, would only add about hundred dollars to your electricity bill. And a round-trip would cost only about one tenth of that, as most of the energy could be recovered on the way back!

Once it is built, the Space Elevator could be used to lift payloads, passengers, pre-fabricated components of spacecraft, as well as rocket fuel up to Earth orbit. In this way, more than 90 per cent of the energy needed for the exploration of the Solar System could be provided by Earth-based energy sources. When the Space Elevator becomes a reality in the coming decades, the most expensive components of orbital travel will be in-flight movies and catering.

SPECTRUM: About a dozen years ago, you wrote a book on terraforming Mars. Now that the Phoenix missions to Mars have started, and crewed missions are on the far horizon (probably decades away), what are your thoughts on humans settling in Mars? Have your views on terraforming changed or are you even more certain that we should go that route?

CLARKE: During my lifetime, I have been lucky enough to see our knowledge of Mars advance from almost complete ignorance—worse than that, misleading fantasy—to a real understanding of its geography and climate. Certainly we are still ignorant in many areas, and lack knowledge that future generations will take for granted. But now we have fairly accurate maps of the Red Planet, and can imagine how it might be modified—terraformed—to make it nearer to our heart’s desire. Much has been studied about what it will take to carry out this planetary scale engineering exercise. But whether we should embark on such a venture should be decided very carefully, and future Martian inhabitants must be allowed to have their say. I have sometimes wondered if there might a committee to protect the Martian wilderness in the 22nd century!

SPECTRUM: Since 1995, more than 200 extrasolar planets have been discovered. Does this excite you? It seems that planetary systems are common—what some have suspected for long. Does this lead you to think that other life forms exist in the universe as well?

CLARKE: I have always believed in life elsewhere in the universe (though I don’t agree that some are visiting us secretively in flying saucers). Finding extra-solar planets indicates that there are many worlds that can nurture life, and hopefully some of them will also evolve intelligence. The biggest challenge in our search for extra-terrestrial intelligence is to know what to look for: Radio signals? Optical signals? Something else? I have suggested that supernovae are the industrial accidents of advanced civilisations. Or, as I wondered in one of my best known short stories ‘The Star’, they may be inter-stellar beacons or signals of superior beings…

SPECTRUM: At one point, it had seemed that we were dangerously close to annihilating human beings on Earth through a nuclear war. While the specter of a nuclear holocaust has dimmed somewhat, newer nuclear threats (Iran, North Korea) haven’t eliminated it completely. Do you think the human race will survive the nuclear threat? Or are we bound to self-destruct?

CLARKE: I have often described myself as an optimist. I used to believe that the human race had a 51 per cent chance of survival. Since the end of the Cold War, I have revised this estimate to between 60 and 70 per cent. I have great faith in optimism as a philosophy, if only because it offers us the opportunity of self-fulfilling prophecy.

SPECTRUM: And, finally, what do you think are some of the most important technologies humans should concentrate on developing in the next 50 years?

CLARKE: If I had three wishes, I would ask for these:

1. A method to generate limitless quantities of clean energy.

2. Affordable and reliable means of space transport.

3. Eliminating the design faults in the human body

Interviewed by Saswato R. Das for IEEE Spectrum

To see all of Spectrum's special report Remembering Sputnik, 50 Years Later, go to http://spectrum.ieee.org/sputnik.