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Command and telemetry in autonomous spacecraft design

Some major steps are summarized in the evolution of autonomous design features for planetary exploration spacecraft. The control and data architectures for the Viking, Voyager, and Galileo spacecraft are considered. Telemetry and command capabilities are fundamental features of spacecraft design that have been successfully used for autonomous control. Also discussed is the Autonomous Redundancy and Maintenance Management Subsystem (ARMMS) concept. The software approach to autonomous control provides for modifications to the control process or the addition of new operating features during flight operations.

Turner, P. R.

Proximity operations considerations affecting spacecraft design

Experience from several recent spacecraft development programs, such as Space Station Freedom (SSF) and the Orbital Maneuvering Vehicle (OMV) has shown the need for factoring proximity operations considerations into the vehicle design process. Proximity operations, those orbital maneuvers and procedures which involve operation of two or more spacecraft at ranges of less than one nautical mile, are essential to the construction, servicing, and operation of complex spacecraft. Typical proximity operations considerations which drive spacecraft design may be broken into two broad categories; flight profile characteristics and concerns, and use of various spacecraft systems during proximity operations. Proximity operations flight profile concerns include the following: (1) relative approach/separation line; (2) relative orientation of the vehicles; (3) relative translational and rotational rates; (4) vehicle interaction, in the form of thruster plume impingement, mating or demating operations, or uncontrolled contact/collision; and (5) active vehicle piloting. Spacecraft systems used during proximity operations include the following: (1) sensors, such as radar, laser ranging devices, or optical ranging systems; (2) effector hardware, such as thrusters; (3) flight control software; and (4) mating hardware, needed for docking or berthing operations. A discussion of how these factors affect vehicle design follows, addressing both active and passive/cooperative vehicles.

Staas, Steven K.

Pioneer Venus spacecraft design and operation

The Pioneer Venus Orbiter and Multiprobe spacecraft design and operation enabled both remote and in-situ measurements of the Venusian environment from the outermost fringes of the atmosphere all the way to the surface. Both spacecraft were spin-stabilized and solar-cell powered from launch to Venus. Since orbit insertion, the Orbiter has been transmitting measurements from a highly elliptical 24-h orbit with periapsis altitudes down to about 150 km. Data rates up to 2048 bits/s have been utilized through a despun high-gain antenna transmitting at S-band frequency. Spacecraft attitudes, orbit periods, and periapsis altitudes are being maintained as required with a hydrazine propulsion system. The Multiprobe spacecraft (Bus with all four Probes attached) performed the necessary Probe checkouts and deployed the Probes to achieve the desired Probe and Bus targeting. Silver-zinc batteries provided the necessary power on each of the four Probes from separation from the Bus through the entry/descent sequence. Data rates of 256 and 128 bits/s on the Large Probe were maintained with 40-W radiated power, and 64 and 16 bits/s on the Small Probes were maintained with 10-W radiated power, through omni antennas directly to Earth-based stations. Each Probe's entry/descent sequence was controlled with a hardwired entry sequence programmer to achieve the desired scientific and spacecraft operations.

Nothwang, G. J.

Spacecraft Design Considerations for Piloted Reentry and Landing

With the end of the Space Shuttle era anticipated in this decade and the requirements for the Crew Exploration Vehicle (CEV) now being defined, an opportune window exists for incorporating 'lessons learned' from relevant aircraft and space flight experience into the early stages of designing the next generation of human spacecraft. This includes addressing not only the technological and overall mission challenges, but also taking into account the comprehensive effects that space flight has on the pilot, all of which must be balanced to ensure the safety of the crew. This manuscript presents a unique and timely overview of a multitude of competing, often unrelated, requirements and constraints governing spacecraft design that must be collectively considered in order to ensure the success of future space exploration missions.

Stroud, Kenneth J.

Interplanetary spacecraft design using solar electric propulsion

Emphasis of the electric propulsion technology program is now on the application of solar electric propulsion to scientific missions. Candidate planetary, cometary, and geosynchronous missions are being studied. The object of this paper is to describe a basic spacecraft design proposed as the means to accomplish (1) a comet Encke slow flyby, (2) a comet Encke rendezvous, and (3) an out-of-the-ecliptic mission. The discussion includes design differences foreseen for the various missions and indicates those areas where spacecraft design commonality is possible. Particular emphasis is placed on a solar electric propulsion module design which permits an attractive degree of design inheritance from mission to mission.

Duxbury, J. H.

Reengineering the JPL Spacecraft Design Process

This presentation describes the factors that have emerged in the evolved process of reengineering the unmanned spacecraft design process at the Jet Propulsion Laboratory in Pasadena, California. Topics discussed include: New facilities, new design factors, new system-level tools, complex performance objectives, changing behaviors, design integration, leadership styles, and optimization.

Spacecraft Design Reengineering JPL

Spacecraft design project multipurpose satellite bus MPS

The thrust of this project was to design not a single spacecraft, but to design a multimission bus capable of supporting several current payloads and unnamed, unspecified future payloads. Spiraling costs of spacecraft and shrinking defense budgets necessitated a fresh look at the feasibility of a multimission spacecraft bus. The design team chose two very diverse and different payloads, and along with them two vastly different orbits, to show that multimission spacecraft buses are an area where indeed more research and effort needs to be made. Tradeoffs, of course, were made throughout the design, but optimization of subsystem components limited weight and volume penalties, performance degradation, and reliability concerns. Simplicity was chosen over more complex, sophisticated and usually more efficient designs. Cost of individual subsystem components was not a primary concern in the design phase, but every effort was made to chose flight tested and flight proven hardware. Significant cost savings could be realized if a standard spacecraft bus was indeed designed and purchased in finite quantities.

Kellman, Lyle

Making Human Spaceflight Practical and Affordable: Spacecraft Designs and their Degree of Operability

As we push toward new and diverse space transportation capabilities, reduction in operations cost becomes increasingly important. Achieving affordable and safe human spaceflight capabilities will be the mark of success for new programs and new providers. The ability to perceive the operational implications of design decisions is crucial in developing safe yet cost competitive space transportation systems. Any human spaceflight program - government or commercial - must make countless decisions either to implement spacecraft system capabilities or adopt operational constraints or workarounds to account for the lack of such spacecraft capabilities. These decisions can benefit from the collective experience that NASA has accumulated in building and operating crewed spacecraft over the last five decades. This paper reviews NASA s history in developing and operating human rated spacecraft, reviewing the key aspects of spacecraft design and their resultant impacts on operations phase complexity and cost. Specific examples from current and past programs - including the Space Shuttle and International Space Station - are provided to illustrate design traits that either increase or increase cost and complexity associated with spacecraft operations. These examples address factors such as overall design performance margins, levels of redundancy, degree of automated failure response, type and quantity of command and telemetry interfaces, and the definition of reference scenarios for analysis and test. Each example - from early program requirements, design implementation and resulting real-time operations experience - to tell the end-to-end "story" Based on these experiences, specific techniques are recommended to enable earlier and more effective assessment of operations concerns during the design process. A formal method for the assessment of spacecraft operability is defined and results of such operability assessments for recent spacecraft designs are provided. Recent experience in applying these techniques to Orion spacecraft development is reviewed to highlight the direct benefits of early operational assessment and collaborative development efforts.

Crocker, Alan R.

Human factors in spacecraft design

This paper describes some of the salient implications of evolving mission parameters for spacecraft design. Among the requirements for future spacecraft are new, higher standards of living, increased support of human productivity, and greater accommodation of physical and cultural variability. Design issues include volumetric allowances, architecture and layouts, closed life support systems, health maintenance systems, recreational facilities, automation, privacy, and decor. An understanding of behavioral responses to design elements is a precondition for critical design decisions. Human factors research results must be taken into account early in the course of the design process.

Harrison, Albert A.

Influence of Natural Environments in Spacecraft Design, Development, and Operation

Spacecraft are growing in complexity and sensitivity to environmental effects. The spacecraft engineer must understand and take these effects into account in building reliable, survivable, and affordable spacecraft. Too much protections, however, means unnecessary expense while too little will potentially lead to early mission loss. The ability to balance cost and risk necessitates an understanding of how the environment impacts the spacecraft and is a critical factor in its design. This presentation is intended to address both the space environment and its effects with the intent of introducing the influence of the environment on spacecraft performance.

Edwards, Dave

Influence of Natural Environments in Spacecraft Design, Development, and Operation

Spacecraft are growing in complexity and sensitivity to environmental effects. The spacecraft engineer must understand and take these effects into account in building reliable, survivable, and affordable spacecraft. Too much protections, however, means unnecessary expense while too little will potentially lead to early mission loss. The ability to balance cost and risk necessitates an understanding of how the environment impacts the spacecraft and is a critical factor in its design. This presentation is intended to address both the space environment and its effects with the intent of introducing the influence of the environment on spacecraft performance.

Edwards, Dave

Models for Galactic Cosmic Ray and Solar Energetic Particles and their Application to Spacecraft Design

The effects of radiation environment in interplanetary space must be taken into account for spacecraft design. This is done by modeling this environment and propagating it to the electronic parts of interest within the spacecraft then calculating the effects of this radiation on these parts. This talk will present a survey of the existing models for the interplanetary radiation environment and the results of comparing them with measurements. It will also include a survey of radiation transport methods and methods for estimating the effects of this radiation on spacecraft.

Adams, James H., Jr.