Needed: Materials for 24th Century Starships
1960s. As science consultant to the series Star Trek: Voyager and Star Trek: DeepSpace Nine, I helped producers create plausible representations and descriptions of future sciences that will make the Milky Way galaxy as navigable as the oceans of Earth are today.
Star Trek has depicted a wide array of interstellar hardware—starships, warpdrives, transporters, etc.—that provide our heroes with the means to travel among the stars in search of adventure and new knowledge. In a one-hour television show, however, we simply do not have the time to let our characters delve into the working details of these technologies. In this article, I share a few of my thoughts on some questions raised by the presumed future existence of these technologies. Specifically, what kinds of materials science problems does this fictional universe pose? Are there materials that currently exist, or that we can imagine, that might solve these problems? What is the probability that those materials might be available in the foreseeable future? I will provide examples of present-day and imaginary Star Trek materials to explore these questions.
A Strong Ship
Today, scientists and engineers are developing new materials for the next generation of reusable launch vehicles under the auspices of NASA's X-33 and X-34 programs. A fully reusable, single-stage-to-orbit (SSTO) launch vehicle will require lightweight materials for structural elements as well as a robust thermal protection system for re-entry. Aluminum-lithium composites and various ceramics are being investigated as possible solutions to the various problems inherent in creating a reusable SSTO vehicle.
The problems of engineering a hull for an Enterprise-like starship are in some respects similar, but a thousand times more difficult. The hull of the Enterprise (Figure 1) must be able to withstand extraordinary mechanical stresses over many years of operation. For example, it must be able to withstand thousands of "g"s when it accelerates to warp. It must maintain its configuration as well as its tensile strength through repeated temperature cycles that range from absolute zero to thousands of degrees Kelvin. And it must be able to hold up with nary a crack for at least the duration of a nominal five-year mission. In the original Star Trek (i.e., the series featuring William Shatner and Leonard Nimoy), the term "tritanium" was coined to describe the principal material used in the construction of the hull of the Enterprise. Contemporary alloys and composites are not up to this task. Can we imagine a material that might be?
Probably the most promising class of materials available today are metal-matrix composites. Here, fibers or whiskers of a material such as silicon carbide are embedded in matrices of aluminum and magnesium alloys. The fibers increase the strength and high-temperature stability of the alloys. Metal-matrix composite materials are currently used in missile guidance systems and other applications.
The hardest substance known to materials science is, of course, diamond. It seems likely that someday soon diamond fibers will be synthesized and embedded in metal matrices. Perhaps Star Trek's tritanium could be created by embedding diamond fibers in a titanium-alloy matrix. Such a composite would almost certainly have exceptionally robust mechanical and thermal properties; conceivably, it might even meet the demands of 24th century spacecraft designers. (Just to be safe, the Enterprise and other starships feature a "structural integrity field" to maintain the hull's rigidity under extreme stress. An inertial damping field protects the crew against the extreme accelerations required to reach warp speeds.)
Warping Away
Viewers of the Star Trek television series and motion pictures frequently wonder how the warp drive works. Rick Sternbach and Michael Okuda, senior illustrator and scenic art supervisor, respectively, for the current Star Trek series (Voyager and Deep Space Nine) have developed a novel answer to this question using exotic materials.
Figure 2.
In his special theory of relativity, Albert Einstein demonstrated that nothing can travel faster than the speed of light in a vacuum. The nearest star beyond our solar system, Alpha Centauri, is four-and-a-half light years away. Hence, a journey to Alpha Centauri would require a minimum of four and a half years.* Clearly, a television series about a starship that visits a new star system every week needs a propulsion system that allows it to exceed the cosmic speed limit. The idea of using "warped" space as a loophole to circumvent the laws of special relativity has been a science fiction staple for decades, and physicists acknowledge that space warps could provide short cuts between the stars. But how does one create the space warp? According to the general theory of relativity, the presence of matter is the only thing that warps space. An enormous amount of very dense matter—as is found in a black hole, for example—warps space to an extreme degree. Black holes may also be connected to other points in space though wormholes, short cuts through the curved space-time fabric of the universe.
In the Star Trek universe, starships, in effect, create their own wormholes.In order to provide a consistent logic and nomenclature for the operation ofthe warp drive (the malfunction and subsequent repair of which has figured prominently in many Star Trek episodes!), Sternbach and Okuda have developed the following scenario. A high-energy plasma, created by a matter-antimatter reaction, is pumped through a series of warp coils cast from a material called "verterium cortenide." Electromagnetic interactions between waves of super-hot plasma and the verterium cortenide coils change the geometry of space surrounding the engine nacelles. In the process, a multilayered wave of warped space is born, and the starship cruises off to its next destination at hundreds of times the speed of light relative to normal space. Within the warp field, however, the starship does not exceed the local speed of light and, therefore, does not violate the principal tenet of special relativity. Some of the starship components used in the process are depicted in Figures 2-4.
Verterium cortenide is clearly a magical kind of material. By design, it has the property that when a high-energy plasma circulates through appropriately fashioned verterium cortenide castings, a warp field is generated. It is impossible to say whether or not such a material could ever be fashioned. However, theoretical physicists are busily working on a "theory of everything," a single mathematical formulation that unifies all four fundamental forces in nature: gravitation, electromagnetism, and the strong and weak nuclear forces. The last three forces have already been combined into a single unified theory. Gravity is the only holdout, but physicists are confident that someday gravity will be integrated into a grand unified theory.
If this happens—that is, if it is someday shown that gravity is simply one manifestation of a single general force—it may then be possible to manipulate gravitational forces through the application of electromagnetic forces, which we know how to generate and control precisely. This could give us the capability to control the geometry of space with electromagnetic forces. In the Star Trek universe, we assume that the unification of the forces of nature has been achieved, and the verterium cortenide warp coils are the medium through which electromagnetic forces are used to alter the geometry of space.
The many technologies necessary to drive starships across the Milky Way are almost surely a number of generations in the future. But some of the enabling technologies may already be on the horizon. For example, metal-matrix composites are currently in increasingly large-scale production. The strength and durability of metal-matrix and other composites increases every year. The rapid rate of growth in computer performance promises corresponding improvements in our understanding of solid-state physics. This, in turn, will someday provide materials scientists with the ability to design new materials at the molecular level for specific performance parameters. Scanning tunneling microscopes and other devices are providing engineers with the ability to build materials atom by atom.
Theoretical physicists are closing in on a theory of everything, which may pave the way for manipulating space-time through the application of electromagnetic forces. It is, of course, difficult to predict if and when any of these promising new theories, materials, and techniques will bear fruit in the form of a working starship. But, given the rapid pace of growth in physics and materials science in this century, it seems reasonable to assume that significant progress will be made in all of the areas cited above by the end of the next century. The power of human ingenuity in solving technical problems has been demonstrated again and again.
Jules Verne once said, "What one person can imagine, another can create." It seems to me that we are witnessing the beginnings of a tremendous revolution in materials science. For this reason, I am very optimistic that by the 24th century some form of piloted interstellar spacecraft will be a reality.
The following article appeared in Vol. 48, Issue 6 of JOM, a publication of The Minerals, Metals & Materials Society, in 1996.
In the 24th century, immense starships will travel the Milky Way galaxy in search of strange new worlds. The ships will be designed and built to tolerate enormous stresses and extreme environments; they will travel at extraordinary velocities through warped space while functioning as self-contained ecosystems supporting hundreds of crew members.
This is the future universe envisioned by the four Star Trek series that have aired on television since the mid-
