State-of-the-art approach to outer planet exploration
Outer planet exploration spacecraft subsystems reliability and ten year flight requirements for planet orbiting and flyby missions
Guttman, C. H.↗
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Guidance and navigation requirements for unmanned flyby and swingby missions to the outer planets. Volume 2: impulsive high thrust missions, phase A
The impulsive, high thrust missions portion of a study on guidance and navigation requirements for unmanned flyby and swingby missions to the outer planet is presented. The proper balance between groundbased navigational capability, using the deep space network (DSN) alone, and an onboard navigational capability with and without supplemental use of DSN tracking, for unmanned missions to the outer planets of the solar system is defined. A general guidance and navigation requirements program is used to survey parametrically the characteristics associated with three types of navigation systems: (1) totally onboard, (2) totally Earth-based, and (3) a combination of these two.
Source record↗
A Summary of the Pioneer 10 Maneuver Strategy
The Pioneer Project placed a number of interesting and precise requirements on the navigation of the Pioneer 10 spacecraft flyby mission to Jupiter during 1972-1973. To satisfy these requirements the Pioneer navigation team employed a number of versatile computer programs to evaluate the strategies and maneuver sequences required to execute midcourse corrections. The Pioneer 10 mission objectives and the midcourse strategies used to satisfy these objectives are summarized.
Frauenholz, R. B.↗
The outer planets - Fly-by prospects
The projected benefits of flyby missions to the outer planets are discussed. Possible changes in existing theories of planetary composition as a result of such missions are also discussed.
Demarcus, W. D.↗
Nonlinear estimation theory applied to the interplanetary orbit determination problem.
Martingale theory and appropriate smoothing properties of Loeve (1953) have been used to develop a modified Gaussian second-order filter. The performance of the filter is evaluated through numerical simulation of a Jupiter flyby mission. The observations used in the simulation are on-board measurements of the angle between Jupiter and a fixed star taken at discrete time intervals. In the numerical study, the influence of each of the second-order terms is evaluated. Five filter algorithms are used in the simulations. Four of the filters are the modified Gaussian second-order filter and three approximations derived by neglecting one or more of the second-order terms in the equations. The fifth filter is the extended Kalman-Bucy filter which is obtained by neglecting all of the second-order terms.
Tapley, B. D.↗
Preliminary Mariner 9 report on the geology of Mars.
Mariner 9 results indicate that Mars is geologically far more heterogeneous than previously suspected from earlier flyby missions; the surface has been shaped by volcanic, tectonic, erosional, and depositional activity. The equatorial region between 30 deg N and 30 deg S latitude is depicted in four geologic sketch maps, and seventeen geologic units are defined on the basis of their textural characteristics. The maps and the brief descriptions of geological units portrayed are followed by a series of more interpretive discussions dealing with topical problems and a summary geologic history. Topics covered include cratering, circular basins, volcanism, canyons, chaotic terrain, channels, and eolian activity.
Mccauley, J. F.↗
Nonlinear estimation theory applied to the interplanetary orbit determination problem.
The performance of a second order filter which is identical to the algorithm developed by Athans et al. (1968) for the scalar case is evaluated through numerical simulation of a Jupiter flyby mission. The observations used in the simulation are on-board measurements of the angle between Jupiter and a fixed star taken at discrete time intervals. In the numerical study, the influence of each of the second order terms is evaluated.
Tapley, B. D.↗
Thruster array thermal control
This paper presents the results of a preliminary investigation of the thermal interactions between elements in the thruster array for a proposed Encke flyby mission. A clustered eight-thruster array was considered as the trial configuration in the current study. Electrically heated dummy thrusters were calibrated to represent the thruster thermal performance. The thermal behavior of the thruster array thermal mockup and the effects of thermal coating applications were investigated. Temperature measurements of the thruster array mockup were performed under various operational modes to substantiate the analytical results. A resultant analytical thermal network model was established to provide pertinent information for thruster array design tradeoff studies.
Wen, L.↗
Use of ballistic arcs for low thrust navigation enhancement in the 1980 Encke slow flyby
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.
Jacobson, R. A.↗
Planetary spacecraft in the U.S. program
In the U.S. program for the exploration of the solar system, the Pioneer spacecraft are used for initial studies of the planets and the planetary and interplanetary environment. The Mariners have been employed for planet-oriented flyby missions followed by more detailed planet investigations with orbiting missions. The Viking lander is designed for surface exploration of the planet Mars. The various planetary missions conducted so far or planned for the next few years are discussed in some detail, giving attention also to the design of the spacecraft employed.
Kraemer, R. S.↗
Statistical analysis of trim maneuvers in low thrust interplanetary navigation
An analytical technique for the statistical analysis of a low thrust trim maneuver in interplanetary navigation has been developed. The maneuver is treated rigorously as a nonlinear function of the trajectory errors to be removed, and the corresponding nongaussian statistics are developed. The method determines the statistical properties of the maneuver direction and duration, as well as the final state dispersion covariance. The analytical technique is applied to the terminal maneuver in a 1980 Encke slow flyby mission and is found to yield accurate statistical results with much less effort than Monte Carlo simulation. The method permits consideration of a shorter terminal maneuver than does linear analysis, with a consequent improvement in delivery accuracy.
Rinker, G. C.↗
Geodetic control net
Computer program, originally developed for Mariner flyby missions, computes planetary control net from measurements of topographical features identified on television pictures. Program solves for areocentric coordinates of 115 surface points and orthogonal camera matrices of 57 far and near encounter pictures.
Davies, M. E.↗
System design impact of guidance and navigation analysis for a SEPS 1979 Encke flyby
Baseline guidance and navigation strategy for an ecliptic projection of the Encke flyby mission consider solar electric propulsion stage parameters in generating optimized and targeted trajectory control. Results show the Encke relative approach error to be dominated by ephemerical uncertainties, particularly the velocity components.
Hong, P.↗
The study of comets, part 2
Flyby missions and systematic observations of comets are projected for studying comet nuclei and cometary dust tail structures.
Donn, B.↗
Limited variance control in statistical low thrust guidance analysis
Difficulties arise in guiding a solar electric propulsion spacecraft due to nongravitational accelerations caused by random fluctuations in the magnitude and direction of the thrust vector. These difficulties may be handled by using a low thrust guidance law based on the linear-quadratic-Gaussian problem of stochastic control theory with a minimum terminal miss performance criterion. Explicit constraints are imposed on the variances of the control parameters, and an algorithm based on the Hilbert space extension of a parameter optimization method is presented for calculation of gains in the guidance law. The terminal navigation of a 1980 flyby mission to the comet Encke is used as an example.
Jacobson, R. A.↗
On the calculation of low-thrust fail-safe trajectories
A guidance algorithm is developed for a low-thrust spacecraft such that target intercept is possible in spite of premature thrust termination along the trajectory. Such a trajectory is called a 'fail-safe' trajectory and the spacecraft thrust is utilized to minimize the relative target-spacecraft approach speed. The fail-safe guidance algorithm is solved using the concept of a critical thrust plane and a non-critical thrust direction. Several examples of fail-safe guidance are presented for a solar-electric propulsion flyby mission to the comet Encke.
Sauer, C. G., Jr.↗
Inflight calibration technique for onboard high-gain antenna pointing
The X-band radio frequency communication system was used for the first time in deep space planetary exploration by the Mariner 10 Venus and Mercury flyby mission. This paper presents the technique utilized for and the results of inflight calibration of high-gain antenna (HGA) pointing. Also discussed is pointing accuracy to maintain a high data transmission rate throughout the mission, including the performance of HGA pointing during the critical period of Mercury encounter.
Ohtakay, H.↗
The geologic development of Mars - A review
The overall view of Mars has changed from earthlike in the prespacecraft era to moonlike following the flyby missions and finally to a planet with intermediate characteristics. There are many impact craters as on the moon, but tectonic and volcanic features resembling structures on earth are also present. However, there is a lack of evidence for the compressional deformation associated with terrestrial plate tectonics and continental drift. Current analyses indicate that Mars has a differentiated interior with a crust and mantle and perhaps a core. Whenever the nature of interior processes, whether overall mantle expansion, plumes, or full-scale convection, the effects at the surface have been predominantly vertical with formation of broad regions of uplift and depression. One of the results is hemispheric asymmetry with cratered terrain in the south and younger uncratered plains in the north.
Mutch, T. A.↗