New trajectory options for ballistic Mercury Orbiter Mission
This paper reports on recent advances made in obtaining low delta V trajectories to conduct Mercury orbiter missions.
Mercury↗
Engineering topics
Yen, C. L.
Publications and source records attributed to Yen, C. L..
Interplanetary missions for the late twentieth century
A set of missions that is feasible during the remainder of this century and which will significantly contribute to our understanding of the solar system is presented. Targets include comets, asteroids, the outer planets and their satellites, and Mars. Mission opportunities for these targets are described in terms of launch vehicle, propulsion, and flight-time requirements, as well as other mission constraints such as launch payload margin and launch period objectives. Examples of encounter designs are also given.
Wallace, R. A.↗
The Mariner Mark II Comet Rendezvous/Asteroid Flyby Mission
The Comet Rendezvous/Asteroid Flyby will be the first mission in the Mariner Mark II program. The July 1990 launch will result in a fast flyby of the asteroid Tanete in May 1991 and a rendezvous with comet Kopff in February 1994, 879 days before comet perihelion. The spacecraft will return detailed data on the comet nucleus and its environment for nearly 1000 days. Several important comet characteristics will not be precisely known until the spacecraft performs its first measurements, which means that operations strategies must be adaptable to a range of conditions. In addition, the operation of a spacecraft in a dusty environment near a low-mass body imposes unique constraints on trajectory and orbit design.
Stetson, D. S.↗
Mission design for the low-cost Mariner Mark II missions
Mariner Mark II is a program of missions, now under study at JPL, which will maximize scientific return at substantially reduced cost. There will be 3 to 5 missions in the program investigating comets, asteroids, the outer planets and their satellites, and Mars in the 1990s. Mission opportunities for these targets in this time period are described in terms of launch vehicle, propulsion, and flight time requirements, as well as other mission constraints such as margin and launch period objectives. Example encounter designs as well as mission launch scenarios are also described.
Wallace, R. A.↗
Ion drive performance and trajectories
The use of Solar Electric Propulsion (SEP) for the Solar Probe Mission is addressed. The dependence of the payload mass on the site of the SEP and the flight time are described on the basis of preliminary data. The range of hardware expected to be available in the 1980's is summarized. There are several classes of optimal low-thrust trajectories for the Solar Probe Mission. These are trajectory types A, B, C corresponding to one, two, or three orbital revolutions, respectively. Plots of transfer trajectories corresponding to type-A, type-A with a Venus Swingby, type-B, and type-C with ab Icarus Rendezvous are shown. A summary of the SEP performance is given.
Yen, C. L.↗
SPAR demonstration problems
A series of examples are presented to indicate some of the principal functions of the SPAR system and to illustrate SPAR's control card-data card structure. Information in the following categories is given: (1) a description of the problem and, in most cases, comparisons with analytical solutions; (2) a list of the input cards; (3) a printout of the table of contents of the direct access library into which all SPAR output was directed; and (4) a few representative plots.
Yen, C. L.↗
A preliminary design and implementation of the low-thrust simulation and trajectory search program (LOWTRAJ)
The results are presented of one phase of research conducted for the JPL Solar Electric Propulsion (SEP) Navigation Software System development program. It deals only with the problem of designing the flight quality trajectory program, which is a major subset of the entire navigation software system. In this phase of research (breadboard development phase), attempts were made to assess the SEP trajectory software functional requirements, to investigate the program design method satisfying these requirements, to identify the primary anticipated problem areas, and to provide solutions to these problem areas. These efforts culminated in the development of a compact breadboard program. A functional description and the mathematical formulation of the program are presented.
Yen, C. L.↗
Low-thrust mission risk analysis, with application to a 1980 rendezvous with the comet Encke
A computerized failure process simulation procedure is used to evaluate the risk in a solar electric space mission. The procedure uses currently available thrust-subsystem reliability data and performs approximate simulations of the thrust sybsystem burn operation, the system failure processes, and the retargeting operations. The method is applied to assess the risks in carrying out a 1980 rendezvous mission to the comet Encke. Analysis of the results and evaluation of the effects of various risk factors on the mission show that system component failure rates are the limiting factors in attaining a high mission relability. It is also shown that a well-designed trajectory and system operation mode can be used effectively to partially compensate for unreliable thruster performance.
Yen, C. L.↗
Low-thrust mission risk analysis.
A computerized multi-stage failure process simulation procedure is used to evaluate the risk in a solar electric space mission. The procedure uses currently available thrust-subsystem reliability data and performs approximate simulations of the thrust subsystem burn operation, the system failure processes, and the retargetting operations. The application of the method is used to assess the risks in carrying out a 1980 rendezvous mission to Comet Encke. Analysis of the results and evaluation of the effects of various risk factors on the mission show that system component failure rates is the limiting factor in attaining a high mission reliability. But it is also shown that a well-designed trajectory and system operation mode can be used effectively to partially compensate for unreliable thruster performance.
Yen, C. L.↗