starship-design: Millis's hypothetical "Space Drives"

["L. Parker" <lparker@cacaphony.net>]

Millis’s hypothetical "Space Drives"

A "space drive" can be defined as an idealized form of propulsion where the
fundamental properties of matter and spacetime are used to create propulsive
forces anywhere in space without having to carry and expel a reaction mass.
Such an achievement would revolutionize space travel as it would circumvent
the need for propellant. A variety of hypothetical space drives were created
and analyzed by Millis to identify the specific problems that have to be
solved to make such schemes plausible. These hypothetical drives are just
briefly introduced here. Please note that these concepts are purely
hypothetical constructs aimed to illustrate the remaining challenges. Before
any of these space drives can become reality, a method must be discovered
where a vehicle can create and control an external asymmetric force on
itself without expelling a reaction mass and the method must satisfy
conservation laws in the process.

[Note: This section is excerpted from Millis' "Challenge to Create the Space
Drive," in the AIAA Journal of Propulsion and Power, Vol.13, No.5, pp.
577-582, Sept.-Oct. 1997. This 6 page report uses 7 hypothetical space drive
concepts to highlight the unsolved physics and candidate next steps toward
creating a propellantless space drive. It also contains figures for each
concept which are not currently available electronically.]

Lee