Engineering topics
Publications and source records attributed to Beckman, J. C..
An overview is presented of deep space missions being planned for launch on the Space Shuttle, one element of the Space Transportation System (STS). A comparison is made between mission requirements and the planned capabilities of the STS. Finally, a potential evolution of the STS in order to accomodate these missions with adequate mass margins is discussed.
The paper addresses the dynamical problem and question of technical feasibility associated with delivering a simple, semi-hard lander to one of the Galilean satellites, Ganymede. Emphasis is placed on the identification of a viable, not necessarily optimal, baseline trajectory and maneuver sequence. Simplicity is stressed in the lander's use of two fixed-impulse solid rockets for landing maneuvers. It is shown through an error analysis that navigation and maneuver execution errors can be compensated on the baseline descent trajectory by controlling just the thrust direction. Finally, specific subsystem capabilities needed on the lander to achieve a successful touchdown within a specific performance envelope are also identified.
The formational and evolutionary history of natural satellites, their mineralogical composition and other phenomena of scientific interest are discussed. Key scientific questions about IO, Ganymede, Callisto, and Europa are posed and the measurements and instruments required for a Galilean satellite lander in the 1980's are described.
This paper presents a mission strategy for exploring the outer planets in the 1980s. The strategy is based on the anticipated findings of the 1977 Voyager Jupiter/Saturn Mission, and the 1982 Jupiter Orbiter Probe (JOP) Mission, recently approved as a new project start, beginning in October 1977. The JOP Mission then becomes a principal element in the strategy presented here. Characteristics (launch energy, trajectory parameters, etc.) of other mission opportunities to the outer planets in the 1980s are developed and presented. The need for and benefits from advanced propulsion systems, which can enable the more difficult missions to the outer planets, also are cited. The overall mission strategy, including a description of the options, is evolved in consideration of scientific rationale and return, and technical and programmatic coupling factors.
The Jupiter Orbiter Probe (JOP), scheduled to be launched by the Shuttle IUS in 1981, is described in terms of its scientific mission objectives. These include: analysis of the chemical composition and physical state of Jupiter's atmosphere, the chemical composition and physical state of Ganymede and Callisto, and the topology and behavior of the magnetic field and energetic particle fluxes. Attention is given to an atmospheric probe which will be launched from the main probe, and to the navigation requirements necessary to 'bounce' the JOP around the Jovian moons.
Science goals for missions to Jupiter in the early 1980's are reviewed and a case is made for the science community to play the key role in assigning relative priorities for these goals. A reference set of measurement requirements and their priorities is established and those high priority goals that are most demanding on spacecraft and mission design are used to develop a reference mission concept. An orbiter mission is required to satisfy a majority of the measurements, and a spacecraft data handling capability as least equivalent to the Mariner Jupiter/Saturn spacecraft is the major system design driver. This reference Mission Concept is called Mariner Jupiter Orbiter. The remaining measurement requirements are reviewed in light of the potential science return of this mission, and certain options are developed to augment this science return. Two attractive options fulfill high priority objectives not achieved by the reference Mariner Jupiter Orbiter mission alone: an atmospheric entry probe, released prior to orbit insertion; and a daughter satellite dedicated to particle and fields measurements, ejected into an independent orbit about Jupiter.
Review of the initial studies that define a challenging Mariner Jupiter Orbiter mission. Elegant and precise astrodynamics are shown to make possible a bravura examination of the entire Jovian system with two Mariner-class spacecraft to be launched in 1981. This mission is expected to advance considerably our understanding of the origin and evolution of the solar system.
Consideration of the problem of exploring the Jupiter-Galilean satellite system by a spacecraft in orbit about the planet. A simple patched conic algorithm is developed which identifies Jupiter orbiter trajectories that utilize gravity assist flybys of the Galilean satellites. A detailed reference mission is designed against specific science criteria for satellite exploration to demonstrate the possible science return of utilizing close satellite encounters. A navigation strategy is developed, including both planet and satellite relative orbit determination and a maneuver analysis; spacecraft delivery statistics are determined in the barycentric Jupiter-Galilean satellite coordinate system and mapped to the satellite target planes to determine feasibility. A simple maneuver sequence is employed which yields acceptable velocity requirements.