The Challenge of Interstellar Spaceflight

An artist’s conception of traveling through a wormhole.

The prospects for any interstellar flight by humans or their machines seem exceedingly remote. Nonetheless, the inclination to contemplate interstellar travel remains strong. In fact, interest is likely to grow, as a consequence of current research of the nature of the galaxy and the revised view of its cosmic neighborhood that will certainly follow.

While there is growing interest in interstellar flight, the practical difficulties of achieving it have caused some people to abandon the challenge and ask whether any stellar travel may be possible. The results of such detachment, to say the least, are fascinating. Once one removes the requirement that the travelers be human or under human control, interesting possibilities emerge. If creatures from Earth venture into the galaxy, they may do so in ways that depart considerably from conventional views of rocket travel.

There are basically only four methods for humans to travel beyond the solar system:

• Faster than the speed of light (warp drive or wormholes).
• Multigenerational spaceships.
• Suspended animation.
• Extremely long-lived species.

Science fiction writers achieve faster-than-light speeds effortlessly, but in reality nearly insurmountable barriers exist. The fictional versions of spacecraft powered by matter/anti-matter drive at “warp” speed require the suspension of at least five laws of physics. Anti-matter exists, but faster-than-light travel appears highly unlikely. In the novel Contact, Carl Sagan resolved this difficulty by dispatching a human crew through a wormhole created on the basis of information supplied by a SETI message. Might breakthroughs in physics allow the creation of wormholes that evade the conventional limits of space and time? Perhaps, but at present scientists doubt that wormholes could be constructed that would provide sufficiently secure tunnels.

Some form of multi-generational spaceship might also be conceived. Given the distances involved between even relatively close stars, it appears that any trip would take longer than a human lifetime. Such migration would require spaceships with 8-10 generations living and dying and knowing nothing but life in an enclosed and entirely artificial environment. Serious proposals exist for such ships, but so far no one has demonstrated that it would be possible to create a self-contained “terrarium” that could support humans on Earth, much less moving through the near-vacuum of space. In the late 1980s, in an experiment funded at $150 million by Texas oil magnate Edward Bass, humans at Biosphere 2 in Arizona’s Santa Catalina Mountains sought to test technologies that might be useful for sustaining life on the Moon or Mars. Unfortunately, their terrarium leaked. The experiment ended badly and after 1994 further experiments in human habitation ceased. The goal of keeping people alive in an enclosed, self-contained environment speeding through interstellar space may be beyond human capabilities for many more centuries.

Suspended animation as depicted in the film, “Alien.”

There also is the possibility of suspended animation. This has long been a staple of science fiction, and makes it possible for astronauts to undertake a state of deep hibernation for long-duration space flight. In films such as 2001: A Space Odyssey, Alien, and Avatar it serves well as a plot device. But there is some basis for it in the real world. In the 1960s and 1970s NASA investigated “depressed metabolism” but abandoned it when they found that it was technically unfeasible. But whether techniques such as cryonics, which attempt to freeze individuals for later revival, will ever be useful in space travel is unknown.

Then there is the intriguing possibility that independent human and robotic exploration, or even joint human and robotic exploration, may be soon outmoded by an even more radical concept—the merger of humans and robots into a single entity. The dichotomy between humans and robots is really a product of industrial age thinking and the accompanying emphasis on machines that serve humankind. In a post-industrial age we might rethink this issue and reach a new consensus.

A provocative possibility appears in the futuristic literature, predicting an abrupt change in robotic technologies. Studies in artificial intelligence are leading some to question whether computers that drive technologically sophisticated robots might become so intelligent in the twenty-first century as to acquire sentient qualities. Intellectuals, for example Ray Kurzweil, note that we are on the verge of creating a new silicon-based life form. It might even include, as Kurzweil suggests, downloading human memory into computers, and creating new and virtual forms of life.

Unpiloted Daedalus star probe design was the output from a British Interplanetary Society study completed in the late 1970s. CREDIT: © David A. Hardy at http://www.astroart.org

Furthermore, the rapid rise of biotechnology suggests that the human body may be enormously enhanced through the application of machinery. Under the auspices of the Defense Advanced Research Projects Agency, researchers have demonstrated the feasibility—mostly theoretical to date—of attaching machine parts to biological entities. In one experiment, scientists used tissue from the antennae of moths to seek out explosives. If this tissue were attached to tiny flying robots in a battlefield setting, this merger of biological and robotic entities might prove useful. In contrast, humans might be equipped with mechanical parts that would add robotic features. One possibility involves donning an exoskeleton that provides combatants with a combination of bodily armor, enhanced mobility, and sensory extension devices. While these ideas, as well as others that are even more extreme, may be a generation or more in the future they suggest great possibilities in the context of space flight.

How might we remake the human body to more effectively meet the rigors of space exploration through the adaptation of technology? The term “cyborg” was coined in 1960 by Nathan Kline and Manfred Clynes in a study for NASA. In particular, Kline and Clynes thought that through the use of electronic implants they could modify humans to survive in space without a spacesuit.

Skeptics may question these ideas, but space exploration was fiction in the truest sense of the word less than seventy-five years ago. Buck Rogers might have been entertaining on the Saturday matinee in the 1930s and 1940s, but few believed they would see space flight in their lifetimes. Advances in biotechnology, propelled by national security considerations to create more advanced robots, might permit the development of entities that are part biological and part machine. After all, science fiction stories frequently feature cyborgs that merge biological and mechanical capabilities.

Given sufficient time, a new space exploration paradigm may emerge. Over the years advocates of robotic and human cooperation have envisioned the two exploring space together, but even in this vision, the two remained separate entities—master and servant, owner and slave, flesh and machine. New technological developments might permit a true merger—humans equipped with robotic parts or machines possessing sentient qualities.