Star Wars' Darth Vader, Star Trek's Borg, and the Cybermen of Dr. Who are variations on this theme — and it's no coincidence they're all "bad guys." Cyborgs symbolize one of our greatest fears: that over time, we will become so enmeshed in our technology that we lose our humanity.

Transhumanists believe that the development of such technology will lead one day to "Human version 2.0" — an upgrade of the human body that not only eliminates many of the problems that plague us, but improves upon the basic human design. For instance, sometranshumanists envision a day when the human brain will be re-wired with computer chips, allowing us to think, learn and communicate with unprecedented speed and accuracy.

There's an ethical leap between using technology to help people overcome disabilities, and using it to "improve" healthy humans. The 1972 science fiction novel, Cyborg by Martin Caidin, which was turned into the popular TV show The Six-Million-Dollar Man, bridges the gap by creating a cyborg superman as a life-saving measure. The title character was a NASA test pilot who suffered traumatic injuries when his plane crashed. His legs, left arm, and an eye were replaced with bionic parts, giving him superior speed, strength and vision.

Martin Caidin's novel may have been inspired by discussions taking place within the space community around that time. NASA had considered the possibility of engineering humans, not to create super heroes, but to help us travel to the other planets and the stars beyond.

Building a Better Astronaut

Without a spacesuit, a person could only survive for about 90 seconds in the vacuum of space. Not only does space lack breathable oxygen, but the vacuum pressure would cause the blood in your veins to bubble and expand. Space is so cold — minus 270 C (minus 454 F) — you would be frozen solid in short order. Radiation is another mode of destruction — space contains high energy gamma and X-rays, as well as the lower energy but still harmful UV light.

In 1960, Manfred Clynes and Nathan Kline published an essay inAstronautics titled "Cyborgs in Space." Comparing man in space to a fish out of water, they noted that even if you could bring everything you need on your space explorations, "the bubble all too easily bursts."

However, if the human body were altered to adapt to the conditions of space, astronauts would be free to explore the universe without limitation.

"Solving the many technical problems involved in manned space flight by adapting man to his environment, rather than vice versa, will not only mark a significant step forward in man's scientific progress, but may well provide a new and larger dimension for man's spirit as well," the authors write.

The Clynes & Kline paper coined the term "cyborg," and NASA followed up on their suggestions, commissioning a study on the topic. "The Cyborg Study: Engineering Man for Space" was released in 1963, and it reviewed the possibility of organ replacement, as well as how drugs and hibernation could be used to make space travel less stressful. The report concluded that replacing the heart, lungs and kidneys — the organs most stressed by space travel — was not feasible with the technology available at the time.

In considering how hibernation and drugs could be used to deal with physical and psychological stress, the study's scope included master control over an astronaut's brain and body. The current academic discussion of cyborg studies embraces an even broader view of "cyborg" to mean the general impact of technology on our lives.

"You could say that cyborgization started with furs and fire, and certainly with glasses and dentures," says James Hughes, medical ethicist at Trinity College in Hartford, Connecticut.

Hughes is the author of the book, Citizen Cyborg: Why Democratic Societies Must Respond to the Redesigned Human of the Future. Hughes says we should acknowledge that we are already living in the Age of the Cyborg. This process has been gradual but steady, and as medical technology advances, more people will opt for the advantages of the latest innovations — so long as they're convinced the benefits outweigh the risks. Hughes points to LASIK eye surgery as one example.

"I continue to wear glasses, and one of the reasons is that I want to see more evidence that LASIK really works in ways it's supposed to," says Hughes. "I haven't been convinced yet. I think many people will have that reaction to sticking hardware in their brain. Your laptop is obsolescent almost the day you buy it, so why would you want to stick something in your brain when you'd need surgery in order to replace it?"

Today a surgical brain implant such as the one to treat Parkinson's disease is a remedy of last resort. But if the technology was more benign, with an easier way for people to download the latest upgrade, such implants might become more common.

"You might imagine that you could swallow a nanotech pill, and nanobots would unfold in your gut and migrate their way past the blood-brain barrier and find where they're supposed to go," says Hughes. "You could theoretically give them instructions, and say, 'It's time for you guys to flush out because I want the next upgrade.' They all die and go out in your urine, and then you take another pill."

Kevin Warwick, of the Cybernetic Intelligence Research Group at the University of Reading in England, isn't waiting for the invention of medical nanobots. He had a computer device surgically implanted in his arm in two separate experiments.