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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Lessons learned from evaluating launch-site processing problems of Space Shuttle payloads

The authors discuss a trend analysis program that is being conducted on the problem reports written during the processing of Space Shuttle payloads at Kennedy Space Center. The program is aimed at developing lessons learned that can both improve the effectiveness of the current payload processing cycles as well as help to guide the processing strategies for Space Station Freedom. The payload processing reports from STS 26R and STS 41 are used. A two-tier evaluation activity is described, and some typical results from the tier one analyses are presented.

Flores, Carlos A.↗
NASA NTRS1992

Payload training for the Space Station ERA

Training astronaut and ground controllers for payload operations onboard Space Station Freedom presents challenges not found in precursor programs such as Skylab and Spacelab. The evolution from current Spacelab payload training concepts is discussed, and the proposed SSF payload training approach is presented along with development strategies and recommendations.

Griner, Carolyn S.↗
NASA NTRS1993

Simulating flight boundary conditions for orbiter payload modal survey

An approach to simulate the characteristics of the payload/orbiter interfaces for the payload modal survey was developed. The flexure designed for this approach is required to provide adequate stiffness separation in the free and constrained interface degrees of freedom to closely resemble the flight boundary condition. Payloads will behave linearly and demonstrate similar modal effective mass distribution and load path as the flight if the flexure fixture is used for the payload modal survey. The potential non-linearities caused by the trunnion slippage during the conventional fixed base modal survey may be eliminated. Consequently, the effort to correlate the test and analysis models can be significantly reduced. An example is given to illustrate the selection and the sensitivity of the flexure stiffness. The advantages of using flexure fixtures for the modal survey and for the analytical model verification are also demonstrated.

Chung, Y. T.↗
NASA NTRS1988

Fracture control requirements for payloads using the National Space Transportation System (NSTS)

The purpose of this document is to establish the fracture control requirements for all payload hardware to be launched or retrieved using the National Space Transportation System (NSTS). Meeting these requirements implements the minimum fracture control requirements of NHB 1700.7, 'Safety Policy and Requirements for Payloads Using the Space Transportation System (STS).' All NSTS payload fracture control shall be in accordance with the requirements stated herein.

George A Rodney↗
NASA NTRS1993

The 1993 Shuttle Small Payloads Symposium

The 1993 Shuttle Small Payloads Symposium is a combined symposia of the Get Away Special (GAS), Hitchhiker, and Complex Autonomous Payloads (CAP) programs, and is proposed to continue as an annual conference. The focus of this conference is to educate potential Space Shuttle Payload Bay users as to the types of carrier systems provided and for current users to share experiment concepts.

Thomas, Lawrence R.↗
NASA NTRS1993

Geostationary payload concepts for personal satellite communications

This paper reviews candidate satellite payload architectures for systems providing world-wide communication services to mobile users equipped with hand-held terminals based on large geostationary satellites. There are a number of problems related to the payload architecture, on-board routing and beamforming, and the design of the S-band Tx and L-band Rx antenna and front ends. A number of solutions are outlined, based on trade-offs with respect to the most significant performance parameters such as capacity, G/T, flexibility of routing traffic to beams and re-configuration of the spot-beam coverage, and payload mass and power. Candidate antenna and front-end configurations were studied, in particular direct radiating arrays, arrays magnified by a reflector and active focused reflectors with overlapping feed clusters for both transmit (multimax) and receive (beam synthesis). Regarding the on-board routing and beamforming sub-systems, analog techniques based on banks of SAW filters, FET or CMOS switches and cross-bar fixed and variable beamforming are compared with a hybrid analog/digital approach based on Chirp Fourier Transform (CFT) demultiplexer combined with digital beamforming or a fully digital processor implementation, also based on CFT demultiplexing.

Benedicto, J.↗
NASA NTRS1994

Results of a laboratory experiment that tests rotating unbalanced-mass devices for scanning gimbaled payloads and free-flying spacecraft

Rotating unbalanced-mass (RUM) devices are a new way to scan space-based, balloon-borne, and ground-based gimbaled payloads, like x-ray and gamma-ray telescopes. They can also be used to scan free-flying spacecraft. Circular scans, linear scans, and raster scans can be generated. A pair of RUM devices generates the basic scan motion and an auxiliary control system using torque motors, control moment gyros, or reaction wheels keeps the scan centered on the target and produces some complementary motion for raster scanning. Previous analyses and simulation results show that this approach offers significant power savings compared to scanning only with the auxiliary control system, especially with large payloads and high scan frequencies. However, these claims have never been proven until now. This paper describes a laboratory experiment which tests the concept of scanning a gimbaled payload with RUM devices. A description of the experiment is given and test results that prove the concept are presented. The test results are compared with those from a computer simulation model of the experiment and the differences are discussed.

Alhorn, D. C.↗
NASA NTRS1993

Integrating payload design, planning, and control in the Dutch Utilisation Centre

Spacecraft payload design, experiment planning and scheduling, and payload control are traditionally separate areas of activity. This paper describes the development of a prototype software tool--the Activity Scheduling System (ASS)--which integrates these activity areas. ASS is part of a larger project to build a Dutch Utilisation Centre (DUC), intended eventually to support all space utilization activities in The Netherlands. ASS has been tested on the High Performance Capillary Electrophoresis payload. The paper outlines the integrated preparation and operations concept embodied in ASS. It describes the ASS prototype, including a typical session. The results of testing are summarized. Possible enhancement of ASS, including integration into DUC, is sketched.

Grant, T. J.↗
NASA NTRS1994

Automated path planning of the Payload Inspection and Processing System

The Payload Changeout Room Inspection and Processing System (PIPS) is a highly redundant manipulator intended for performing tasks in the crowded and sensitive environment of the Space Shuttle Orbiter payload bay. Its dexterity will be exploited to maneuver the end effector in a workspace populated with obstacles. A method is described by which the end effector of a highly redundant manipulator is directed toward a target via a Lyapunov stability function. A cost function is constructed which represents the distance from the manipulator links to obstacles. Obstacles are avoided by causing the vector of joint parameters to move orthogonally to the gradient of the workspace cost function. A C language program implements the algorithm to generate a joint history. The resulting motion is graphically displayed using the Interactive Graphical Robot Instruction Program (IGRIP) produced by Deneb Robotics. The graphical simulation has the potential to be a useful tool in path planning for the PIPS in the Shuttle Payload Bay environment.

Byers, Robert M.↗
NASA NTRS1995

Advanced Payload Transfer Measurement System (APT-MS) Mechanical Features

During the last two feet or so of transfer, for a large or heavy payload to its restraining fixture, the consequences of unplanned contact (or impact) between payload and support structure can range from merely annoying to something approaching disaster. Current transfer methods employ technicians with meter sticks stationed at the various hold-down locations to estimate the distances to contact. This information is communicated orally to the crane operator. It is understandable that this work proceeds carefully and therefore slowly. The objectives of this study are (1) to explore mechanical sources of measurement error; and (2) to develop an improved prototype design that is compact, inexpensive, and addresses the measurement error issues. APT is a relatively inexpensive electro-mechanical device that reduces both time and manpower required to make shuttle payload transfers. APT measurement system would provide a GUI for the 'move-conductor' (crane operator) so he could see the displacements of all hold-down interfaces as they move together and thus have a more accurate, comprehensive and 'real-time' picture of the engagement activity. An error model attempts to include all estimatable sources of mechanical error and design features were introduced to reduce or eliminate major sources of error.

Brewer, William V.↗
NASA NTRS1995

The Extreme Ultraviolet Spectrograph Sounding Rocket Payload: Recent Modifications for Planetary Observations in the EUV/FUV

We report on the status of modifications to an existing extreme ultraviolet (EUV) telescope/spectrograph sounding rocket payload for planetary observations in the 800 - 1200 A wavelength band. The instrument is composed of an existing Wolter Type 2 grazing incidence telescope, a newly built 0.4-m normal incidence Rowland Circle spectrograph, and an open-structure resistive-anode microchannel plate detector. The modified payload has successfully completed three NASA sounding rocket flights within 1994-1995. Future flights are anticipated for additional studies of planetary and cometary atmospheres and interstellar absorption. A detailed description of the payload, along with the performance characteristics of the integrated instrument are presented. In addition, some preliminary flight results from the above three missions are also presented.

Slater, David C.↗
NASA NTRS1995

Architecture for Payload Planning System (PPS) Software Distribution

The complex and diverse nature of the pay load operations to be performed on the Space Station requires a robust and flexible planning approach, and the proper software tools which tools to support that approach. To date, the planning software for most manned operations in space has been utilized in a centralized planning environment. Centralized planning is characterized by the following: performed by a small team of people, performed at a single location, and performed using single-user planning systems. This approach, while valid for short duration flights, is not conducive to the long duration and highly distributed payload operations environment of the Space Station. The Payload Planning System (PPS) is being designed specifically to support the planning needs of the large number of geographically distributed users of the Space Station. This paper problem provides a general description of the distributed planning architecture that PPS must support and describes the concepts proposed for making PPS available to the Space Station payload user community.

Howell, Eric↗
NASA NTRS1996

Thermal Control Subsystem Design for the Avionics of a Space Station Payload

A case study of the thermal control subsystem development for a space based payload is presented from the concept stage through preliminary design. This payload, the Space Acceleration Measurement System 2 (SAMS-2), will measure the acceleration environment at select locations within the International Space Station. Its thermal control subsystem must maintain component temperatures within an acceptable range over a 10 year life span, while restricting accessible surfaces to touch temperature limits and insuring fail safe conditions in the event of loss of cooling. In addition to these primary design objectives, system level requirements and constraints are imposed on the payload, many of which are driven by multidisciplinary issues. Blending these issues into the overall system design required concurrent design sessions with the project team, iterative conceptual design layouts, thermal analysis and modeling, and hardware testing. Multiple tradeoff studies were also performed to investigate the many options which surfaced during the development cycle.

Moran, Matthew E.↗
NASA NTRS1995

Effect of Payload on Risk of Vehicle Loss Due to Engine Failure

A family of optimal-control problems for an NLS-type vehicle involving single engine failures has been solved. The solutions to these problems indicate that loading a vehicle under the assumption of a core engine out at launch may not be ideal. This study has partially quantified the added risk of additional payload by showing the maximum payload for various engine failure times. The ability to reoptimize trajectories midcourse in response to an engine loss coupled with a willingness to accept a degraded orbit, as an emergency measure, can result in much larger payloads for a given vehicle.

Queen, Eric↗
NASA NTRS1997

An Acceleration Measurement Capability on International Space Station Supporting Microgravity Science Payloads

The conditions present in low-earth-orbit have enabled various scientific investigations to be conducted. A fundamental reason that space is a useful environment for science is the presence of a decreased effect of gravity while in orbital free-fall. Science investigations are conducted to study phenomena occurring as a result of reductions in buoyancy forces and phenomena enabled as a result of the apparent lack of gravity. The science community requires knowledge of the environment in which their experiments are being conducted. A general purpose measurement system was developed in the 1980's to supply scientific investigators with data of the residual acceleration environment. The Space Acceleration Measurement System, or SAMS, has flown aboard the NASA shuttle fleet over fourteen times, successfully acquiring acceleration measurement data in support of microgravity science experiments. As NASA continues its development of the International Space Station and its associated research payloads, it once again becomes necessary to address the requirement to measure the residual acceleration in support of the planned scientific investigations. As a follow-on to the SAMS project, SAMS-2 was initiated to investigate the requirements and develop the measurement system to support the microgravity science payloads aboard the International Space Station. The characteristics of the payload complement to be supported by SAMS-2 and the different capabilities provided by the station requires a fresh look at the design implementation of a general purpose measurement system. Not only is there a requirement for measurements in support of numerous, potentially simultaneous experiments, but this support is required to be provided for at least ten years of on-orbit operation as compared to a ten to fourteen day mission on shuttle. These differences in fundamental requirements result in the design configuration of the space station-based SAMS-2 being significantly different than that of the shuttle-based SAMS. This paper describes these differences in requirements and the planned features to be provided to the science user community. Some of the unique challenges faced in developing a general purpose measurement system are also discussed.

Sutliff, Thomas J.↗
NASA NTRS1997

Lightning Effects in the Payload Changeout Room

Analytical and empirical studies have been performed to provide better understanding of the electromagnetic environment inside the Payload Changeout Room and Orbiter payload bay resulting from lightning strikes to the launch pad lightning protection system. The analytical studies consisted of physical and mathematical modeling of the pad structure and the Payload Changeout Room. Empirical testing was performed using a lightning simulator to simulate controlled (8 kA) lightning strikes to the catenary wire lightning protection system. In addition to the analyses and testing listed above, an analysis of the configuration with the vehicle present was conducted, in lieu of testing, by the Finite Difference, Time Domain method.

Thomas, Garland L.↗
NASA NTRS1998

A Station Tethered Express Payload System (STEPS)

Most capsules designed to return payloads from earth orbit use rockets for deorbit. They have modest payload mass & volume fractions. Active attitude control raises costs, and the deorbit rocket imposes risks which increase development and operational costs. This note describes an alternative concept now being developed under NASA funding. It uses a tether to both deorbit and orient the capsule. This allows simultaneous reduction of capsule complexity, cost, loads, hazards, and reentry errors. The flight of SEDS-1 in 1993 proved out the basic concepts. A 20 km tether slung a 26 kg payload back to earth from a 74O x 19O km orbit, accurately enough for a pre-positioned observer to videotape the reentry. As air drag built up just before reentry, the tether was blown back and became a kite-tail, with tension increasing as predicted before flight. The tether was still attached at approx. 110 km, when telemetry was lost.

Carroll, Joseph A.↗
NASA NTRS1961

Effects of Flight Conditions at Booster Separation on Payload Weight in Orbit

A study of the principal flight parameters at booster separation was conducted to find the effect of each on the weight of the payload boosted into an earth orbit along a zero drag gravity turn trajectory. The parameters considered include Mach number (3 to 9), flight-path angle (10 deg to 55 deg), altitude (90,000 and 350,000 ft), inert weight ratio (0.05 to 0.15), and thrust-weight ratio (1.5 to 2.5), with a specific impulse of 289 seconds. Both transfer ellipse and direct orbit trajectories were considered. With either trajectory method, payload weight was highest for low initial flight-path angles and high initial Mach numbers. Of course, high initial Mach numbers require greater energy expenditures from the booster. Changes in initial altitude had little effect on payload weight, and only small gains were evident when thrust-weight ratio was increased.

Nelson, Richard D.↗