Until the twentieth century, rockets used solid propellant, usually a form of black powder or gunpowder.

Once ignited, they cannot be turned off and solid propellant cannot flow, so it cannot be diverted to another engine.

BREAKTHROUGH Rubin said Iran had achieved "a technological and strategic breakthrough" with its Sejjil, a two-stage, solid propellant missile.

Next year, more than a year ahead of schedule, a vastly improved ICBM, the solid propellant MINUTEMAN, is expected to be ready.

In the table on page 202 we compare the specific impulse and thrust of one type of solid propellant with several liquid propellants.

Since it contains a solid propellant I doubt that a few minutes in vacuum will create out-gassing problems and the fast chemical reaction will work.

Solid propellants are the simplest form of rocketry, and they offer great reliability with very little velocity control.

-The Samen is a tactical solid propellant ballistic missile.

In contrast, the Pegasus launcher, from Orbital Sciences, uses as many as four stages, and a combination of liquid and solid propellants.