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The proceedings of the symposium are reported. Technological areas covered include actuators, aerospace mechanism applications for ground support equipment, lubricants, latches, connectors, and other mechanisms for large space structures.
The results of a test program designed to verify the operational and thermal performance of the Cryogenic Limb Array Etalon Spectrometer (CLAES) S/N001 Ne/CO2 cryostat, as monitored and serviced by the Data Acquisition System and Ground Support Equipment, are presented. The S/N001 model test assembly consists of the S/N001 configuration coupled with an instrument thermal mass simulator (ITMS) for simulating the thermal behavior of the instrument package. The test data for the cryostat include the rate of temperature decrease of the various parts of the cryostat/ITMS and the final equilibrium temperatures of the shields, thermal links, and tank. The test results showed that system heat rates, operating temperatures, and expected end-of-life temperature predictions all agree with predictions within estimated margins.
This paper describes the results of the first lifetest of a high power ring-cusp ion thruster. A 30-cm laboratory model thruster was operated steady-state at a nominal beam power of 5kW on xenon propellant for approximately 900 hours. This test was conducted to identify life-limiting erosion mechanisms and thruster design modifications, and to demonstrate operation using simplified power processing. The results from this test are described including the conclusions derived from extensive post-test analyses of the thruster. Modifications to the thruster and ground support equipment, which have been incorporated to solve problems identified by the lifetest, are also described.
A basic understanding is provided of the National Space Transportation System payload processing operations performed at NASA-Kennedy. The payload facilities, support services, and ground support equipment used to support that process are described.
The results of the first life test of a high power ring-cusp ion thruster are presented. A 30-cm laboratory model thruster was operated steady-state at a nominal beam power of 5 kW on xenon propellant for approximately 900 hours. This test was conducted to identify life-timing erosion modifications, and to demonstrate operation using simplified power processing. The results from this test are described including the conclusions derived from extensive post-test analyses of the thruster. Modifications to the thruster and ground support equipment, which were incorporated to solve problems identified by the lifetest, are also described.
Progress in assessing the feasibility, benefits, and risks associated with AI expert systems applied to low cost expendable launch vehicle systems is described. Part one identified potential application areas in vehicle operations and on-board functions, assessed measures of cost benefit, and identified key technologies to aid in the implementation of decision support systems in this environment. Part two of the program began the development of prototypes to demonstrate real-time vehicle checkout with controller and diagnostic/analysis intelligent systems and to gather true measures of cost savings vs. conventional software, verification and validation requirements, and maintainability improvement. The main objective of the expert advanced development projects was to provide a robust intelligent system for control/analysis that must be performed within a specified real-time window in order to meet the demands of the given application. The efforts to develop the two prototypes are described. Prime emphasis was on a controller expert system to show real-time performance in a cryogenic propellant loading application and safety validation implementation of this system experimentally, using commercial-off-the-shelf software tools and object oriented programming techniques. This smart ground support equipment prototype is based in C with imbedded expert system rules written in the CLIPS protocol. The relational database, ORACLE, provides non-real-time data support. The second demonstration develops the vehicle/ground intelligent automation concept, from phase one, to show cooperation between multiple expert systems. This automated test conductor (ATC) prototype utilizes a knowledge-bus approach for intelligent information processing by use of virtual sensors and blackboards to solve complex problems. It incorporates distributed processing of real-time data and object-oriented techniques for command, configuration control, and auto-code generation.
The work flow assistant (WFA) is an advanced technology project under the shuttle processing data management system (SPDMS) at Kennedy Space Center (KSC). It will be utilized for short range scheduling, controlling work flow on the floor, and providing near real-time status for all major space transportation systems (STS) work centers at KSC. It will increase personnel and STS safety and improve productivity through deeper active scheduling that includes tracking and correlation of STS and ground support equipment (GSE) configuration and work. It will also provide greater accessibility to this data. WFA defines a standards concept for scheduling data which permits both commercial off-the-shelf (COTS) scheduling tools and WFA developed applications to be reused. WFA will utilize industry standard languages and workstations to achieve a scalable, adaptable, and portable architecture which may be used at other sites.
The facility Hazardous Gas Detection System (HGDS) at Kennedy Space Center (KSC) is a mass spectrometer based gas analyzer. Two instruments make up the HGDS, which is installed in a prime/backup arrangement, with the option of using both analyzers on the same sample line, or on two different lines simultaneously. It is used for monitoring the Shuttle during fuel loading, countdown, and drainback, if necessary. The use of complex instruments, operated over many shifts, has caused problems in tracking the status of the ground support equipment (GSE) and the vehicle. A requirement for overall system reliability has been a major force in the development of Shuttle GSE, and is the ultimate driver in the choice to pursue artificial intelligence (AI) techniques for Shuttle and Advanced Launch System (ALS) mass spectrometer systems. Shuttle applications of AI are detailed.
Twenty-two papers are documented regarding aeronautical and spacecraft hardware. Technological areas include actuators, latches, cryogenic mechanisms, vacuum tribology, bearings, robotics, ground support equipment for aerospace applications, and other mechanisms.
A stand alone pressure transducer (SAPT) is a credit-card-sized smart pressure sensor inserted between the tile and the aluminum skin of a space shuttle. Reliably initiating the SAPT units via RF signals in a prelaunch environment is a challenging problem. Multiple-source interference may exist if more than one GSE (ground support equipment) antenna is turned on at the same time to meet the simultaneity requirement of 10 ms. A polygon model for orbiter, external tank, solid rocket booster, and tail service masts is used to simulate the prelaunch environment. Geometric optics is then applied to identify the coverage areas and the areas which are vulnerable to multipath and/or multiple-source interference. Simulation results show that the underside areas of an orbiter have incidence angles exceeding 80 deg. For multipath interference, both sides of the cargo bay areas are found to be vulnerable to a worst-case multipath loss exceeding 20 dB. Multiple-source interference areas are also identified. Mitigation methods for the coverage and interference problem are described. It is shown that multiple-source interference can be eliminated (or controlled) using the time-division-multiplexing method or the time-stamp approach.
ANPS computer program assists programmers attempting to model prelaunch countdown sequence. Designed to write simulation programs for problems concerning prelaunch activities of space vehicles and operation of ground support equipment and has potential for use in developing network-reliability models for systems and subsystems of equipment. Aids user in defining problem and then automatically writes appropriate simulation program in GPSS/PC code. Written in Turbo Prolog Version 2.0.
The objectives of NASA product assurance in the 1990s are identified. They are to provide for personnel safety, and safe and reliable operation of hardware and software during the lifetime of a program or mission. The NASA product assurance program, a multi-discipline effort that focuses on safety, reliability, maintainability, and quality assurance expertise to meet NASA operational requirements is described. This program supports NASA 's unmanned launch vehicles such as satellites and planetary probes, manned spacecraft (such as the Space Shuttle and Space Station Freedom), and ground support equipment.
Chlorofluorocarbons (CFC's) in the atmosphere are believed to present a major environmental problem because they are able to interact with and deplete the ozone layer. NASA has been mandated to replace chlorinated solvents in precision cleaning, cleanliness verification, and degreasing of aerospace fluid systems hardware and ground support equipment. KSC has a CFC phase-out plan which provides for the elimination of over 90 percent of the CFC and halon use by 1995. The Materials Science Laboratory and KSC is evaluating four analytical methods for the determination of nonvolatile residues removal by water: (1) infrared analyses using an attenuated total reflectance; (2) surface tension analyses, (3) total organic content analyses, and (4) turbidity analyses. This research project examined the ultrasonic-turbidity responses for 22 hydrocarbons in an effect to determine: (1) if ultrasonics in heated water (70 C) will clean hydrocarbons (oils, greases, gels, and fluids) from aerospace hardware; (2) if the cleaning process by ultrasonics will simultaneously emulsify the removed hydrocarbons in the water; and (3) if a turbidimeter can be used successfully as an analytical instrument for quantifying the removal of hydrocarbons. Sixteen of the 22 hydrocarbons tested showed that ultrasonics would remove it at least 90 percent of the contaminated hydrocarbon from the hardware in 10 minutes or less giving a good ultrasonic-turbidity response. Six hydrocarbons had a lower percentage removal, a slower removal rate, and a marginal ultrasonic-turbidity response.
This study was initiated to identify operations problems and cost drivers for current propulsion systems and to identify technology and design approaches to increase the operational efficiency and reduce operations costs for future propulsion systems. To provide readily usable data for the Advanced Launch System (ALS) program, the results of the OEPSS study have been organized into a series of OEPSS Data Books. This volume describes three propulsion concepts that will simplify the propulsion system design and significantly reduce operational requirements. The concepts include: (1) a fully integrated, booster propulsion module concept for the ALS that avoids the complex system created by using autonomous engines with numerous artificial interfaces; (2) an LOX tank aft concept which avoids potentially dangerous geysering in long LOX propellant lines; and (3) an air augmented, rocket engine nozzle afterburning propulsion concept that will significantly reduce LOX propellant requirements, reduce vehicle size and simplify ground operations and ground support equipment and facilities.
The Pegasus air launched space booster, which successfully flew its maiden flight on 5 Apr. 1990, provides the international satellite community with a flexible cost effective means for delivering small payloads into low Earth orbit. The vehicle's simple, robust design and horizontal integration methods ensure maximum reliability and significantly reduce launch base infrastructure requirements. The vehicle's air launched approach and ability to launch over open ocean regions provide unmatched flexibility in launch location and approach used to ensure range safety. The PegaStar integrated spacecraft bus, which complements the Pegasus launch system, can provide a turnkey means for delivering instrument and sensor packages into low Earth orbit and providing extended (5 to 10 year) on orbit operational support. Pegasus and PegaStar are described, including payload interfaces, delivery capability; integration methods, facility and ground support equipment requirements; and typical launch operations.
The purpose of the symposium was to provide a forum for the interchange of information among those active in the field of mechanisms technology. To that end, 25 papers were presented on aeronautics and space flight, with special emphasis on actuators, aerospace mechanism applications for ground-support equipment, lubricants, latches, connectors, and other mechanisms for large space structures. The papers were prepared by authors from a broad aerospace background, including the U.S. aerospace industry, NASA, and European participants.
The LITE electronics system consists of the following seven subsystems: Laser Transmitter Module (LTM), Boresight Assembly (BA), Aft-Optics Electronics (AOE), Digital Data Handling Unit (DDHU), Engineering Data System (EDS), Instrument Controller (IC), and the Ground Support Equipment (GSE). Each of these subsystems is discussed.
Cryogenic components and techniques for the superfluid helium on-orbit transfer (SHOOT) flight demonstration are described. Instrumentation for measuring liquid quantity, position, flow rate, temperature, and pressure has been developed using the data obtained from the IRAS, Cosmic Background Explorer, and Spacelab 2 helium dewars. Topics discussed include valves and burst disks, fluid management devices, structural/thermal components, instrumentation, and ground support equipment and performance test apparatus.