Trajectory correction maneuver design based on B-plane targeting for low-thruster
For the interplanetary mission, the spacecraft must require the trajectory correction maneuver (TCM) to reduce the trajectory error due to the influence of unexpected external perturbation forces. There are many kinds of researches focused on these TCM techniques for the impulsive thrust. Among them, the B-plane targeting method is mainly applied to the interplanetary mission as TCM method. However, there are brilliant developments in the propulsion systems; especially the electrical propulsion system is adopted in some spacecraft. Thus, it is necessary to design the TCM algorithm for such low-thruster for future interplanetary missions. Therefore, in this paper, the TCM algorithm for the low thrust such like electrical propulsion system is suggested to correct the target B-vector and target time to closest approach (TCA). To design the low thrust guidance scheme, the Lyapunov feedback control is used in this paper.
DERIVATION OF THE B-PLANE (BODY PLANE) AND ITS ASSOCIATED PARAMETERS
When sending a spacecraft to some extraterrestrial body, one navigation and mission design metric used is B-plane (Body Plane) targeting. The spacecraft’s target body miss distance (with its associated covariance) and the target body’s impact radius, can be readily mapped onto this B-plane. Things such as the performance of trajectory correction maneuvers (TCMs) and the effects of dynamic model errors (as well as perturbative effects of angular momentum desaturations {AMDs}) upon the trajectory, can be characterized and optimized in terms of B-plane parameters. It is herein that the advantage of it use is sought and found.
Enumeration of total coliforms, fecal coliforms, and Escherichia coli in foods by hydrophobic grid membrane filter: supplementary report.
Raw, comminuted poultry meat was used to determine the specificity of the media and incubation conditions used in the hydrophobic grid membrane filter method. Confirmation rates for target colonies were 100% for total coliforms, 98% for fecal coliforms, and 97-99% for Escherichia coli. The results of total coliform enumeration in 30 pasteurized milk samples by both the hydrophobic grid membrane filter method and AOAC method 46.013-46.016 are also reported.