Going Interstellar (collection)

One final, and particularly interesting, parallel motive is to use the project as an experiment in the efficacy of volunteer researchers collaborating in a purely virtual capacity. In many ways, Project Icarus may represent a new way for scientific research to be conducted. The Icarus team currently consists of twenty-nine team members, located across six different countries. The researchers are not paid for their efforts and are primarily motivated by a passion for the field. Interaction between team members is mostly conducted by email. However, a private internet forum also exists where the team can engage in extended discussions on a variety of topics. Internet telephony is also utilized, on occasion, as the need for (virtual) face-to-face communication arises. This mainly electronic team is, in itself, an interesting experiment in the virtualization of scientific collaboration and, should the outcome be successful, Project Icarus could serve as a prototype for future scientific and engineering endeavors.

Nuclear Fusion—A Propulsion Scheme for the Future

One of the Terms of Reference of Project Icarus is that the propulsion system must be ‘mainly fusion-based,’ which is currently considered TRL 2. This mandate to use fusion was based on the fact that Daedalus was itself fusion-powered. As the successor to Daedalus it seemed appropriate for Icarus to utilize this same energy source so as to maintain continuity with the original project. Alternatives to this form of propulsion do exist, and popular non-fusion options include solar sailing and even antimatter. The fusion decision was made early on and met with no objections from any team members.

A more comprehensive discussion of the physics of thermonuclear fusion may be found in Dr. Gregory Matloff’s companion essay in this book. Briefly summarized, fusion is a process whereby two atoms are provided with sufficient kinetic energy to merge and create a larger atom and some by-products. Energy is created in the form of electromagnetic radiation and the vast amounts of kinetic energy contained in the new products that are formed from the reaction.

To give some perspective, fusion processes liberate approximately one million times more energy than even the most powerful chemical reactions. Imagine, for a moment, a hypothetical car of the future, where just one gram of fusion fuel could, in theory, power the vehicle for its entire lifetime. This is, of course, a huge oversimplification, and probably not feasible based on the mechanical architecture that would be necessary to harness the fusion energy, but it emphasizes the point quite nicely. Indeed, fusion processes are what have powered our own star, the Sun, for about five billion years, and will continue to do so for five billion years more.

Fusion has been understood since the early twentieth century, and efforts to harness the energy have been ongoing for most of the latter half of the twentieth century. To date, the only effective utilization of fusion energy has been in rapid and uncontrollable thermonuclear bombs, generally referred to as H-bombs. However, the controlled release of energy in power stations has not yet reached a sustainable break-even which is a situation where more energy is released than is actually put in to create the reaction in the first place. Despite this contemporary lack of success, many believe it is simply a matter of time until the technology is perfected. Indeed, progress in experimental fusion reactors has been consistent for a number of decades.

Inertial Confinement Fusion (ICF) is considered a promising approach to fusion propulsion. In ICF the charged reaction products themselves are turned directly into thrust via magnetic nozzles. This process leads to far fewer thermodynamic losses and enables much of the fusion energy to be channeled to create thrust for the spacecraft. The Daedalus spacecraft was to be powered by ICF.

The Project Icarus group has identified no less than seventeen unique approaches to nuclear fusion, including plasma jet driven magneto-inertial confinement fusion, z-pinch fusion, antimatter catalyzed fusion and electrostatic inertial confinement fusion. At the current phase in the project, no one method has yet shown to be a favorable fusion technique that would prove ideal for an interstellar mission. However, research continues, and in the future a candidate will be selected.

* * *

Further Reading