Engineering topics

Stanford, R. H.

Publications and source records attributed to Stanford, R. H..

7 records

NASA NTRS1986

Precision maneuver determination for trajectory corrections

The interplanetary navigation of a spacecraft requires precise calculation of trajectory correction maneuver parameters. Velocity increments must be found which make the required corrections, minimize propellant consumption, and do not violate hardware design constraints or scientific objectives. This process is illustrated by its application to the Galileo Mission. The paper describes inflight analysis techniques, mathematical modeling, and computational algorithms used in the precision maneuver calculation scenario.

Hintz, G. R.↗

NASA NTRS1986

Application of Taylor's series to trajectory propagation

This paper describes the propagation of trajectories by the application of the preprocessor ATOMCC which uses Taylor's series to solve initial value problems in ordinary differential equations. Comparison of the results obtained with those from other methods are presented. The current studies indicate that the ATOMCC preprocessor is an easy, yet fast and accurate method for generating trajectories.

Stanford, R. H.↗

NASA NTRS1984

Constrained maneuver strategies for Project Galileo

The design of maneuvers for Project Galileo is constrained by thruster configuration, modes of thruster usage and limitations required for the safety of the spacecraft and its instruments. The methods used to analyze maneuvers with respect to these constraints is described. The velocity changes necessary for the implementation of a candidate trajectory have been studied and some general conclusions are described.

Stanford, R. H.↗

NASA NTRS1983

Planning Transport and Manufacturing for Lowest Cost

A method applicable to transportation and manufacturing. New algorithm alleviates some mathematical difficulties of planning segmented trajectories for lowest cost. Algorithm involves modified Newtonian iterative method in which periapse times, closest approach distances, and orientations of approach hyperbolas serves as independent variables.

Damario, L. A.↗

NASA NTRS1981

Interplanetary trajectory optimization

A procedure for minimizing total impulsive Delta-V for constrained multiple-flyby trajectories, which was originally developed for application to satellite tours, has been modified for application to interplanetary trajectories. The modification includes adding to the cost function the Delta-V required to escape from a parking orbit about the launch planet and the Delta-V required for insertion into orbit about the arrival planet. The hyperbolic excess velocity vector with respect to the launch planet and the launch date have been added to the set of independent variables for the optimization. Each trajectory originates at departure from the parking orbit rather than at a fixed position in space, as is the case for the satellite tour application. The multi-conic trajectory propagation techniques and the Newton optimization algorithm of the original method have been retained. Examples of the application of this new method are given for several types of Galileo interplanetary trajectory options, including Mars powered flyby, broken plane, VEGA, and Delta VEGA trajectories.

Damario, L. A.↗

NASA NTRS1980

A new method for optimizing multiple flyby trajectories

A new procedure has been developed which minimizes total impulsive Delta V for multiple flyby trajectories with constraints on flyby parameters and maneuver times. The method involves solving a bounds-constrained parameter optimization problem with a Newton algorithm utilizing analytic first and second derivatives. Each trajectory segment connecting consecutive maneuver points is found by first targeting from the preceding maneuver point to the parameters of the upcoming flyby and then propagating the resulting trajectory to the next maneuver point. Multi-conic techniques are used for trajectory propagation and for computation of the state transition matrix. This procedure has successfully optimized Galileo satellite tours containing up to 11 flybys.

Damario, L. A.↗

NASA NTRS1979

Optimization of multiple flyby trajectories

A procedure has been developed which minimizes total delta-V (instantaneous velocity change) for a multiple flyby trajectory with constraints on flyby altitude and orientation. The solution is found by varying the locations of maneuver points between each flyby to minimize the delta-Vs at the maneuver points. Each trajectory segment connecting consecutive maneuver points is found by solving an N-body analog to Lambert's problem. Multiconic techniques are used for trajectory propagation and for computation of the state transition matrix. The constrained parameter optimization problem is converted to an unconstrained problem by means of penalty functions and then solved with a quasi-Newton algorithm utilizing analytic first derivatives. This procedure has been successfully applied to Galileo satellite tour trajectories.

Damario, L. A.↗