Breakthrough Propulsion Physics Program

The Breakthrough Propulsion Physics Project (BPP) was a research project funded by NASA from 1996-2002 to study various proposals for revolutionary methods of spacecraft propulsion that would require breakthroughs in physics before they could be realized . During its six years of operational funding, this program received a total investment of $1.2 million.

The Breakthrough Propulsion Physics project addressed a selection of “incremental and affordable” research questions towards the overall goal of propellantless propulsion, hyperfast travel, and breakthrough propulsion methods. By the end of the project, sixteen of these investigations were completed. The results found “about a third were found not to be viable, a quarter have clear opportunities for sequels, and the rest remain unresolved.”

Disjunction

The disjuction drive is a hypothetical drive based on the separation of the source of a field from the matter with which it would otherwise interact. According to a summary of speculative propulsion ideas:

This concept entertains the possibility that the source of a field and that which reacts to a field can be separated. By displacing them in space, the reactant is shifted to a point where the field has a slope, thus producing reaction forces between the source and the reactant. Although existing evidence strongly suggests that the source, reactant, and inertial mass properties are inseparable, any future evidence to the contrary would have revolutionary implication to this propulsion application.

The concept is expressed mathematically as:

$V={\frac {-Gm_{S}}{\sqrt {(x-d)^{2}+y^{2}}}}$

Pitch and bias

One proposed method of achieving a diametric drive, or possibly a disjunction drive, which was studied in the BPP was called the pitch drive. This has been described as involving a hypothetical disjoint field which would eliminate the need for the field to be generated on the spacecraft itself.

One specific proposal for such a pitch drive was called the bias drive. According to this proposal, if it were possible to locally alter the value of the gravitational constant G in front of and behind the craft, one could create a bias drive. While the gravitational constant is a fundamental physical constant in general relativity, the Brans–Dicke theory of gravitation does in a sense allow for a locally varying gravitational constant, so the notion of a locally varying gravitational constant has been seriously discussed in mainstream physics. It has been claimed that one problem with the concept of a bias drive was that it might create a singularity in the field's gradient located inside the vehicle.

The bias drive and pitch drive is expressed qualitatively in mathematics as:

$V=(xBe^{..r^{2}}+1)[-G(m/r)]$

and

$V=[(-Gm)/r]+(-xAe^{..r^{2}})$

respectively.

where:

$e^{..r^{2}}$ is the Gaussian distribution over $r\!$ dimensionless

$A\!$ is the magnitude of hypothetical pitch drive effect

$B\!$ is the magnitude of hypothetical bias drive effect

Alcubierre drive

Main article: Alcubierre drive

The Alcubierre drive, also called the warp drive, is a proposal, originally due to the physicist Miguel Alcubierre, who proved mathematically that movement at speeds greater than the speed of light was possible without locally exceeding the speed of light. NASA has an experiment which consists of White–Juday warp-field interferometer utilizing a 633 nm HeNe laser beam which is split in two. One beam passes through an electromagnetic field which attempts to distort space enough to see a phase difference between the two beams when they are brought back together. NASA scientist Harold White indicates that a difference of only one part in ten million would be enough to prove the feasibility of the concept. To many people, this concept is reminiscent of the fictional "warp drive" from the science fiction series Star Trek.

Differential sail

The differential sail was another speculative proposal, which appealed to the zero-point energy field. As the Heisenberg uncertainty principle implies that there is no such thing as an exact amount of energy in an exact location, vacuum fluctuations are known to lead to discernible effects such as the Casimir effect. The differential sail was a speculation that it might be possible to induce differences in the pressure of vacuum fluctuations on either side of a sail-like structure—with the pressure being somehow reduced on the forward surface of the sail, but pushing as normal on the raft surface—and thus propel a vehicle forward.

A quantum vacuum plasma thruster is an example of this type of propulsion source.

Tau Zero Foundation

After funding ended, program manager Marc G. Millis was supported by NASA to complete documentation of results. Frontiers of Propulsion Science was published by the AIAA in February 2009, providing a deeper explanation of several propulsion methods.

Following program cancellation in 2002, Millis and others founded the Tau Zero Foundation to continue pioneering the research.

See also

• Hyperdrive
• Tau Zero Foundation
• Time travel
• Wormhole

External links

• "Breakthroughs" commonly submitted to NASA These are ideas that do not work, often submitted to NASA anyway
• Tau Zero
• ShwayComs BPP Participant
• Project Greenglow and the battle with gravity BBC