Systems Considerations (Valving, tanks, etc) Characteristics of some monopropellants (Reprinted from H. Koelle, Handbook of Astronautical Engineering, McGraw-Hill, 1961.) Flame Chemical Density temp
Suppose we want to move a satellite in a circular orbit to a position ∆ϑ apart in the same orbit, in a time ∆t (assumed to be several orbital times at least). The general approach is to transfer to a lower (for positive ∆ϑ ) or higher (for ∆ϑ < 0 ) nearby
The only practical way to accelerate something in free space is by reaction. The idea is the same as in air breathing propulsion (to push something backwards) but in rockets the “something” must be inside and is lost. Here is a revealing derivation of the thrust equation for vacuum:
The result appears to be trivial, but it is not. Notice that the “velocity increment” ∆V is actually equal to the decrease in orbital velocity. The rocket is pushing forward, but the velocity is decreasing. This is because in a r-2 force field, the kinetic energy is equal in magnitude but of the opposite sign
1. Constant Power and Thrust: Prescribed Mission Time Starting with a mass M0 , and operating for a time t an electric thruster of jet speed c, such as to accomplish an equivalent (force-free) velocity change of ∆V , the final
Collaborate Document Management Plan and design up front Create a short model section for information content and order Create a layout template Create a document control system for revisions Accept individual responsibility and deadlines
Uniqueness of Satellite Manufacture Small production runs Extreme operational environments Limited repair/replace options after launch High product cost and importance High cost test environment Highly coupled designs minimize weight and maximize performance but yield high complexity
Objective To introduce and discuss the fundamentals of earned value project management Work Breakdown Structures Program plans and schedules Earned value management systems Cost and schedule variances Estimates at completion
