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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Simulation of Mariner Mars 1971 spacecraft

Preparation for the Mariner Mars 1971 mission is reported, including an extensive training program for operations personnel during which the primary source of spacecraft data was a computer program simulating the spacecraft. The objectives of a simulation model for training purposes differed from objectives appropriate to a design or analysis model. Model subsystems were designed to provide realistic telemetry data reflecting changes due both to commands and environmental parameters affecting the spacecraft at various times during the mission. The spacecraft is modeled along two separate functional lines. Boolean operations are concentrated in the spacecraft logic model, which determines the spacecraft state or mode, while mathematical operations or algorithms are executed in computational subsystem models. Although logic parameters are interrogated as a part of each computational pass, actual logic model processing occurs only when a change-of-state input is generated by the operations organization. The program design, some of the special characteristics of each of the modeled subsystems, and how the model was used in support of mission operations training are presented.

Ausman, N. E., Jr.↗
NASA NTRS1993

Magellan attitude control mission operations

From the Martin Marietta Astronautics Group base in Denver, Colorado, spacecraft engineers have been operating the Magellan spacecraft for the past three and one half years, along with the Jet Propulsion Laboratory, for NASA. The spacecraft team in Denver is responsible for the health of the vehicle, from command generation to evaluation of engineering telemetry. Operation of the spacecraft's Attitude and Articulation Control Subsystem (AACS) has specifically posed several in-flight challenges. This system must provide accurate pointing of the spacecraft throughout each 3.2 hour orbit which typically consists of 5 - 9 discrete maneuvers. Preparation of bi-weekly command sequences, monitoring execution, and trending of subsystem performance is of paramount importance, but in-flight anomalies have also demanded the attention of AACS engineers. Anomalies are often very interesting and challenging aspects of a project, and the Magellan mission was no exception. From the first unsuccessful attempts to perform a starscan, to spacecraft safing events, much has been experienced to add to the `lessons learned' from this mission. Many of Magellan's in-flight experiences, anomalies, and their resolutions are highlighted in this paper.

Dukes, Eileen M.↗
NASA NTRS1977

Real-time dynamic spacecraft simulation

This paper presents experience in designing and implementing a fully interactive real-time dynamic spacecraft simulation software system for the International Ultraviolet Explorer (IUE) satellite to be launched by NASA. The primary objective for this simulator, called SIMIUE, is to help train the IUE Operations Control Center personnel in the dynamic commanding and operations of the IUE spacecraft. It is felt that the approach taken in developing SIMIUE will prove to be largely valid for spacecraft training simulators to be developed for future satellites. For this reason discussion of those aspects of SIMIUE which relate specifically to the IUE satellite has been kept to a minimum.

Macker, A. J.↗
NASA NTRS1974

Apollo experience report: Thermal protection subsystem

The Apollo command module was the first manned spacecraft to be designed to enter the atmosphere of the earth at lunar-return velocity, and the design of the thermal protection subsystem for the resulting entry environment presented a major technological challenge. Brief descriptions of the Apollo command module thermal design requirements and thermal protection configuration, and some highlights of the ground and flight testing used for design verification of the system are presented. Some of the significant events that occurred and decisions that were made during the program concerning the thermal protection subsystem are discussed.

Pavlosky, J. E.↗
NASA NTRS1990

Using input command pre-shaping to suppress multiple mode vibration

Spacecraft, space-borne robotic systems, and manufacturing equipment often utilize lightweight materials and configurations that give rise to vibration problems. Prior research has led to the development of input command pre-shapers that can significantly reduce residual vibration. These shapers exhibit marked insensitivity to errors in natural frequency estimates and can be combined to minimize vibration at more than one frequency. This paper presents a method for the development of multiple mode input shapers which are simpler to implement than previous designs and produce smaller system response delays. The new technique involves the solution of a group of simultaneous non-linear impulse constraint equations. The resulting shapers were tested on a model of MACE, an MIT/NASA experimental flexible structure.

Hyde, James M.↗
NASA NTRS2012

Spacecraft Attitude Tracking and Maneuver Using Combined Magnetic Actuators

A paper describes attitude-control algorithms using the combination of magnetic actuators with reaction wheel assemblies (RWAs) or other types of actuators such as thrusters. The combination of magnetic actuators with one or two RWAs aligned with different body axis expands the two-dimensional control torque to three-dimensional. The algorithms can guarantee the spacecraft attitude and rates to track the commanded attitude precisely. A design example is presented for nadir-pointing, pitch, and yaw maneuvers. The results show that precise attitude tracking can be reached and the attitude- control accuracy is comparable with RWA-based attitude control. When there are only one or two workable RWAs due to RWA failures, the attitude-control system can switch to the control algorithms for the combined magnetic actuators with the RWAs without going to the safe mode, and the control accuracy can be maintained. The attitude-control algorithms of the combined actuators are derived, which can guarantee the spacecraft attitude and rates to track the commanded values precisely. Results show that precise attitude tracking can be reached, and the attitude-control accuracy is comparable with 3-axis wheel control.

Zhou, Zhiqiang↗
NASA NTRS1972

Fuel cell powerplant operation in Apollo spacecraft.

Primary electrical power for loads in the Apollo Command and Service Modules is furnished by a system of three fuel cell powerplants. The powerplants convert cryogenic hydrogen and oxygen into direct current. Water formed in the fuel cell reactions is supplied to the spacecraft for crew use. Waste heat is rejected through a coolant loop to a spacecraft radiator. The ability of the fuel cell to meet its voltage-power requirements and to control its own operating temperature under the environmental extremes of launch, ascent, earth orbit, translunar flight, and lunar orbit was demonstrated on successively more difficult missions leading up to the first lunar landing.

Ching, A. C.↗
NASA NTRS2000

The NASA Spacecraft Transponding Modem

A new deep space transponder is being developed by the Jet Propulsion Laboratory for NASA. The Spacecraft Transponding Modem (STM) implements standard transponder functions and some of the command and telemetry channel service functions that have resided in spacecraft Command/Data Subsystems.

Transponder↗
NASA NTRS1995

STS-71/Mir/Spacelab Mission Update

Live footage shows the crewmembers of STS-71 and Mir 18, Commander Robert L. Gibson, Pilot Charles J. Precourt, Mission Specialists Ellen S. Baker, Bonnie J. Dunbar, Gregory J. Harbaugh, MIR-19 crew upload Anatoly Solovyev and Nikolai Budarin, and MIR-18 crew download Norman E. Thagard, Vladimir Dezhurov, and Gennadiy Strekalov, on board the Russian Space Station Mir and the Atlantis spacecraft complex. The ten-member crew is shown participating in an interview. An animation of the undocking and fly-around of the Atlantis spacecraft is presented. Also shown is the commander of the STS-79 mission, discussing the undocking of the Atlantis Spacecraft.

Source record↗
NASA NTRS1994

Increases in Efficiency and Enhancements to the Mars Observer Non-stored Commanding Process

The Mars Observer team was, until the untimely loss of the spacecraft on August 21, 1993, performing flight operations with greater efficiency and speed than any previous JPL mission of its size. This level of through-put was made possible by a Mission Operations System which was composed of skilled personnel using sophisticated sequencing and commanding tools. During cruise flight operations, however, it was realized by the project that this commanding level was not going to be sufficient to support the activities planned for the mapping operations. The project had committed to providing the science instrument principle investigators with a much higher level of commanding during mapping. Thus, the project began taking steps to enhance the capabilities of the flight team. One mechanism used by project management was a tool available from Total Quality Management (TQM). This tool is known as a Process Action Team (PAT). The Mars Observer PAT was tasked to increase the capacity of the flight team's non-stored commanding process by fifty percent with no increase in staffing and a minimal increase in risk. The outcome of this effort was to, in fact, increase the capacity by a factor of 2.5 rather than the desired fifty percent and actually reduce risk. The majority of these improvements came from the automation of the existing command process. The results required very few changes to the existing mission operations system. Rather, the PAT was able to take advantage of automation capabilities inherent in the existing system and make changes to the existing flight team procedures. This paper will describe in detail the enhancements recommended by the PAT for the non-stored command generation process on Mars Observer. This will be contrasted with the process used by the flight team prior to implementation of these improvements. Finally, there will be a discussion of the applicability of the techniques devised by the PAT for enhancement of the non-stored command process to present and future projects.

Process↗
NASA NTRS2011

Mission Planning and Sequencing Investigation of Third Party Software

Mission Planning and Sequencing (MPS) maintains a system called the Automated Sequence Processor(ASP) which is responsible for checking non?interactive commands and preparing them for radiation to spacecraft. In order to streamline the process and increase maintainability MPS is looking to use a third party workflow engine to control the ASP. In addition to increasing productivity, another driver for the workflow paradigm is the new way that the software is going to represent the spacecraft state. The spacecraft state is going to be represented by a timeline data structure.

work flow engine↗
NASA NTRS2016

Extended Bright Bodies - Flight and Ground Software Challenges on the Cassini Mission at Saturn

Extended bright bodies in the Saturn environment such as Saturn's rings, the planet itself, and Saturn's satellites near the Cassini spacecraft may interfere with the star tracker's ability to find stars. These interferences can create faulty spacecraft attitude knowledge, which would decrease the pointing accuracy or even trip a fault protection response on board the spacecraft. The effects of the extended bright body interference were observed in December of 2000 when Cassini flew by Jupiter. Based on this flight experience and expected star tracker behavior at Saturn, the Cassini AACS operations team defined flight rules to suspend the star tracker during predicted interference windows. The flight rules are also implemented in the existing ground software called Kinematic Predictor Tool to create star identification suspend commands to be uplinked to the spacecraft for future predicted interferences. This paper discusses the details of how extended bright bodies impact Cassini's acquisition of attitude knowledge, how the observed data helped the ground engineers in developing flight rules, and how automated methods are used in the flight and ground software to ensure the spacecraft is continuously operated within these flight rules. This paper also discusses how these established procedures will continue to be used to overcome new bright body challenges that Cassini will encounter during its dips inside the rings of Saturn for its final orbits of a remarkable 20-year mission at Saturn.

Sung, Tina S.↗
NASA NTRS1993

Radioastron flight operations

Radioastron is a space-based very-long-baseline interferometry (VLBI) mission to be operational in the mid-90's. The spacecraft and space radio telescope (SRT) will be designed, manufactured, and launched by the Russians. The United States is constructing a DSN subnet to be used in conjunction with a Russian subnet for Radioastron SRT science data acquisition, phase link, and spacecraft and science payload health monitoring. Command and control will be performed from a Russian tracking facility. In addition to the flight element, the network of ground radio telescopes which will be performing co-observations with the space telescope are essential to the mission. Observatories in 39 locations around the world are expected to participate in the mission. Some aspects of the mission that have helped shaped the flight operations concept are: separate radio channels will be provided for spacecraft operations and for phase link and science data acquisition; 80-90 percent of the spacecraft operational time will be spent in an autonomous mode; and, mission scheduling must take into account not only spacecraft and science payload constraints, but tracking station and ground observatory availability as well. This paper will describe the flight operations system design for translating the Radioastron science program into spacecraft executed events. Planning for in-orbit checkout and contingency response will also be discussed.

Altunin, V. I.↗
NASA NTRS1978

The NASA Standard Telemetry and Command Components /STACC/

The Standard Telemetry and Command Components (STACC) were conceived by NASA for use on the Multimission Modular Spacecraft. The components have wider application, however, and already are being considered for many other spacecraft. A programmable Central Unit controls Remote Interface Units via a full duplex data bus, providing data acquisition and command distribution capability throughout the spacecraft. The Central Unit can meet any uplink, time code, and format requirements without hardware changes. Each remote unit can acquire any type of data (serial digital, bi-level, analog, or passive analog) on any channel. A third type of unit is an optional interface providing I/O capability to an on-board computer. The protocols used on the 1Mbps data bus are compatible with MSFC's 'Standard Interfaces for Digital Data, Multiplex Serial Data Acquisition and Distribution Systems (SIDD/MSDADS Standard)'. The bus design saves significant harness weight and simplifies the single point ground and isolation approaches.

Elliott, N. P.↗