Engineering topics
Publications and source records attributed to Mcdanell, J. P..
The potential application of the dual spacecraft tracking technique to the Voyager mission is discussed. The concept and technology status is reviewed and results pertaining to the JSX-Uranus option Saturn encounter, where potential navigation benefits are greatest, are presented. Results for a Jupiter encounter demonstration also are given and, finally, software modifications and tracking requirements are examined.
The paper presents the results of the prelaunch navigation studies conducted for the Mariner spacecraft launched toward encounters with the giant planets. The navigation system and the strategy for using this system are described. The requirements on the navigation system demanded by the goals of the project are mentioned, and the predicted navigational capability relative to each of the requirements is discussed. Baseline navigation results for three possible trajectories are analyzed.
A technique is presented for improving navigation accuracy in the Solar Electric Encke Slow Flyby Mission proposed to encounter the comet Encke during its 1980 apparition. The effect of the dominant navigation error source, the high level thruster noise, is reduced through the introduction of a ballistic coast arc for the purpose of orbit determination enhancement. The placement and duration of the arc is investigated with respect to its impact on final delivery error and on control effort required for trajectory correction. Also examined are the changes in delivery accuracy and control effort as a result of the time lag between the state estimation process and the thrust control program update.
The initial results of a terminal navigation analysis for the proposed 1980 solar electric slow flyby mission to the comet Encke are presented. The navigation technique employs onboard optical measurements with the scientific television camera, groundbased observations of the spacecraft and comet, and groundbased orbit determination and thrust vector update computation. The knowledge and delivery accuracies of the spacecraft are evaluated as a function of the important parameters affecting the terminal navigation. These include optical measurement accuracy, thruster noise level, duration of the planned terminal coast period, comet ephemeris uncertainty, guidance initiation time, guidance update frequency, and optical data rate.
Earth-based orbit determination capability for SEP spacecraft in multistation tracking and in thrust subsystem error modeling is described. Five different tracking strategies are applied to a 15 day segment of an Encke rendezvous mission. Both optimal and suboptimal orbit determination performance are determined for a wide range of process noise parameter values. The multi-station tracking techniques are found to be extremely effective, reducing orbit determination errors by orders of magnitude over that obtained with conventional single-station tracking. Explicitly differenced multistation data (QVLBI) is found to be least sensitive to gross modeling errors, but if a reasonably good process noise model is available, explicit differencing is not required.
Explore the source record for details and available documents.
Continuity and smoothness properties of piecewise optimal control at junction between singular and nonsingular subarcs, developing necessary conditions
Saturn 5 suboptimal continuous guidance design, eliminating discontinuous control encountered in SA-502 flight
Jacobi-type conditions for singular optimization problems obtained by transformation to nonsingular form adaptable to linear quadratic optimal control theory
Jacobi conditions for singular optimization problems by transforming singular accessory minimum problem into nonclassical nonsingular form, considering optimal control theory applicability