Artist's depiction of a hypothetical Wormhole Induction Propelled Spacecraft, based loosely on the 1994 "warp drive" paper of Miguel Alcubierre. Credit: NASA CD-98-76634 by Les Bossinas.
The term breakthrough propulsion refers to concepts like space drives and faster-than-light travel, the kind of breakthroughs that would make interstellar travel practical.
For a general explanation of the challenges and approaches of interstellar flight, please visit the companion website:Warp Drive: When? The Warp-When site is written for the general public and uses icons of science fiction to help convey such notions. This website, on the other hand, is intended for scientists and engineers.
This research falls within the realm of physics instead of technology, with the distinction being that physics is about uncovering the laws of nature while technology is about applying that physics to build useful devices. Since existing technology is inadequate for traversing astronomical distances between neighboring stars (even if advanced to the limit of its underlying physics), the only way to circumvent these limits is to discover new propulsion physics. The discovery of new force-production and energy-exchange principles would lead to a whole new class of technologies. This is the motivation of breakthrough propulsion physics research.
Objectively, the desired breakthroughs might turn out to be impossible, but progress is not made by conceding defeat. Reciprocally, breakthroughs have a habit of taking pessimists by surprise, but can equally remain elusive. By proceeding in small, incremental steps that focus on the immediate questions and by emphasizing the reliability of the findings rather than their long-range implications, relevant and dependable knowledge will result. Regardless of whether the breakthroughs are found, this inquiry provides an additional perspective with which to seek answers to the lingering unknowns of our universe.
All NASA support to sustain cognizance on these possibilities has been withdrawn as of October 1, 2008. The final NASA contribution was to assist in the compilation of a graduate-level technical book, Frontiers of Propulsion Science, which is due out in early 2009. This book (750 pages, hardback) will be volume 227 of the series, Progress in Astronautics and Aeronautics Series, which will be published by American Institute for Aeronautics and Astronautics (AIAA).
Prior to this point, the project's leader, Marc G. Millis, continued to monitor and assess a variety of ongoing research with the assistance of an informal network of volunteers scattered across academia, industry, various NASA Centers, and other Federal labs. During that time, several publications were completed to document the progress made. When funding for active research was available, which ran from 1996 to 2002, the project oversaw research into 8 different approaches, produced 16 peer-reviewed journal articles, and an award-winning website (Warp-When), all for a total investment of less than $1.6M. Also during that funded time, the BPP Project coordinated with related research funded at the NASA Marshall Space Flight Center. With the implementation of the 2003 Federal Budget (p.325), all advanced propulsion research was deferred, including these research efforts.Accordingly, this web site will no longer be updated.
No breakthroughs appear imminent. This is a nascent field where a variety of concepts and issues are being explored in the scientific literature, beginning since about the early 1990s. The collective status is still at step 1 and 2 of the scientific method, "defining the problem" and "collecting data," but a small number of approaches are already at step 4, "testing hypotheses;" with experiments underway.
Cautionary note: On a topic this visionary and whose implications are profound, there is a risk of encountering, premature conclusions in the literature, driven by overzealous enthusiasts as well as pedantic pessimists. The most productive path is to seek out and build upon publications that focus on the critical make-break issues and lingering unknowns, both from the innovators' perspective and their skeptical challengers. Avoid works with broad-sweeping and unsubstantiated claims, either supportive or dismissive.
The references below can serve as starting points for deeper inquires. Citations within these reports will take you to other relevant works. An interim survey is also provided on a separate web page for your convenience.
Millis, M. G. (2005) "Assessing
Trends in Astrodynamics and Applications,
New York Academy of Sciences,
[Note: Although this is published through a non-NASA venue, the contents of this government-sponsored work are available without copyright restrictions in the US.]
+Web Page +Download PDF (0.1 MB).
Millis, M. G. (2004) Breakthrough Propulsion Physics Project: Project Management Methods , NASA/TM–2004-213406.