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All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Guideline requirements for serviceable spacecraft grasping/berthing/docking interfaces based on simulations and flight experience

The described efforts support a NASA Space Assembly and Servicing Working Group activity to draft guideline interface standards. The general requirements are to provide a simple, reliable, and durable system. Interface requirements developed include lateral position offset, axial and lateral velocities, and angular misalignment. A survey of concepts and simulation studies of spacecraft docking, existing docking/end effector performance criteria, and space proven, qualified docking data was conducted and evaluated, in order to provide recommended mechanical interface guidelines and interface tolerances for manual and autonomous capture operations. The criterion for the selection of the guidelines was maximum capability to handle malfunctions. Originally the guidelines for a zero velocity docking were considered to be covered within the grasping/berthing definition. It is acknowledged that perhaps a separate category needs to be established for this operation. The draft standard was delivered to the AIAA for review, revision, and issuance as the first U.S. national standard guideline on interfaces. The intent is to develop the guidelines into an International Standards Organization standard.

Thompson, Allen B.↗
NASA NTRS1991

Collision avoidance for CTV: Requirements and capabilities

Collision avoidance must be ensured during Cargo Transfer Vehicle (CTV) operations near the space station. The design of the Collision Avoidance Maneuver (CAM) will involve analysis of CTV failure modes during rendezvous and proximity operations as well as analysis of possible problems external to the CTV, but that would require CTV to execute a CAM. In considering the requirements and design of the CAM for the CTV, the CAM design for the Orbital Maneuvering Vehicle (OMV) is a useful reference point from which some lessons can be learned and many CTV design options can be set forth.

Nosek, Thomas↗
NASA NTRS1991

Guideline requirements for serviceable spacecraft grasping/berthing/docking interfaces based on simulations and flight experience (survey paper)

As space vehicles and structures become larger and more complex, the development of systems to assist humans in assembling, operating, maintaining, and performing space rescue or retrieval of these vehicles and structures becomes increasingly important. With the diversity of international spacecraft, both manned and unmanned, planned to be in orbit in the future, a set of guidelines for berthing and docking subsystems is mandatory if servicing, resupply, and retrieval is to become practical on an international level. Successful interaction between these space systems and ground and/or space-based humans requires standardized and effective operational interface designs, particularly with respect to space grasping/berthing/docking interface mechanisms. This paper defines the spacecraft mechanical interfaces necessary to create a standard dynamic envelope for joining two free-flying spacecraft in a 'hard' berth or dock with each other in space. A review was made of past space flights and dynamics simulations dating back to 1962 to obtain necessary parameters and their values for successful manually controlled and autonomous spacecraft docking/berthing. The various spacecraft docking/berthing mechanisms and concepts are illustrated along with their dynamic capture and impact tolerances including maximum contact velocity along the approach axis and in the y-z plane; capture linear misalignment tolerances; and maximum capture roll, pitch, and yaw angles. From this data sets of recommended guidelines parameters were developed for autonomous and manual impact docking tolerances, non-impact grasping/berthing tolerances (end effectors), berthing contact conditions, and alignment tolerances after rigidizing. Also, detailed requirements were developed for mechanical design interface features, as well as latching, unlatching, and separation tolerances. This data was drafted in the form of a proposed ANSI Standard guideline, reviewed, and added to by members of the committee representing several spacecraft manufacturers, NASA, and the USAF, and a consensus was reached.

Thompson, Allen B.↗
NASA NTRS1993

The SE role in establishing, verifying and controlling top-level program requirements

The program objectives and requirements described in the preceding paragraphs emphasize mission demonstrations. Obtaining desired science or applications information is another type of program objective. The program requirements then state the need for specific data, usually specifying a particular instrument or instrument set; the operating conditions under which the data is to be obtained (e.g., orbit altitude, field of view, and pointing accuracy); and the data handling and use. Conversely, a new instrument may be conceived or created with the program objective to establish its use potential. The Multispectral Scanner employed in the Landsat program is an example.

Mathews, Charles W.↗
NASA NTRS1991

Space transfer vehicle concepts and requirements study. Volume 2, book 3: STV system interfaces

This report presents the results of systems analyses and conceptual design of space transfer vehicles (STV). The missions examined included piloted and unpiloted lunar outpost support and spacecraft servicing, and unpiloted payload delivery to various earth and solar orbits. The study goal was to examine the mission requirements and provide a decision data base for future programmatic development plans. The final lunar transfer vehicles provided a wide range of capabilities and interface requirements while maintaining a constant payload mission model. Launch vehicle and space station sensitivity was examined, with the final vehicles as point design covering the range of possible options. Development programs were defined and technology readiness levels for different options were determined. Volume 1 presents the executive summary, volume 2 provides the study results, and volume 3 the cost and WBS data.

Weber, Gary A.↗
NASA NTRS1992

Distributed project scheduling at NASA: Requirements for manual protocols and computer-based support

The increasing complexity of space operations and the inclusion of interorganizational and international groups in the planning and control of space missions lead to requirements for greater communication, coordination, and cooperation among mission schedulers. These schedulers must jointly allocate scarce shared resources among the various operational and mission oriented activities while adhering to all constraints. This scheduling environment is complicated by such factors as the presence of varying perspectives and conflicting objectives among the schedulers, the need for different schedulers to work in parallel, and limited communication among schedulers. Smooth interaction among schedulers requires the use of protocols that govern such issues as resource sharing, authority to update the schedule, and communication of updates. This paper addresses the development and characteristics of such protocols and their use in a distributed scheduling environment that incorporates computer-aided scheduling tools. An example problem is drawn from the domain of Space Shuttle mission planning.

Richards, Stephen F.↗
NASA NTRS1992

Pitch Control Margin at High Angle of Attack - Quantitative Requirements (Flight Test Correlation With Simulation Predictions)

Aircraft designs that employ relaxed static stability (RSS) have the following problem: reduced pitching moments associated with RSS at high angle of attack (AOA) require a minimum pitch recovery moment or margin to guarantee a safe return from high AOA maneuvers at the most aft center of gravity (CG) encountered during a mission. Recent incidents and mishaps on Class IV aircraft have demonstrated a need for establishing quantitative longitudinal high AOA pitch control margin design guidelines for future aircraft. The Naval Air Warfare Center - Aircraft Division (NA WC-AD) is currently supporting an effort in conjunction with NASA Langley Research Center (NASA LaRC) to quantify such requirements. NASA LaRC has conducted a series of extensive simulation evaluations to define these design guidelines. The purpose of flight tests were to validate the overall research test methodology by comparing pilot comments, pilot ratings, and aircraft response characteristics gathered during inflight recoveries from high AOA conditions to those gathered during the fixed-base simulation sessions. Tests were completed on an F/A-18A in six flights for a total of 9.8 flight hours using an AOA and CG buildup sequence. Flight test results have validated the simulation studies in that pilot rating of high AOA nose-down recoveries were based on the short-term response interval in the forms of pitch acceleration and rate. In addition, flight test has demonstrated that high AOA pitch control margin can be evaluated using a stabilized pushover method.

Flight Testing↗
NASA NTRS1992

A risk-based approach to robotic mission requirements

A NASA Risk Team has developed a method for the application of risk management to the definition of robotic mission requirements for the Space Exploration Initiative. These requirements encompass environmental information, infrastructural emplacement in advance, and either technology testing or system/subsystems demonstration. Attention is presently given to a method for step-by-step consideration and analysis of the risk component inherent in mission architecture, followed by a calculation of the subjective risk level. Mitigation strategies are then applied with the same rules, and a comparison is made.

Dias, William C.↗
NASA NTRS1991

Information systems requirements for the Microgravity Science and Applications Program

NASA's Microgravity Science and Applications (MSAD) Program is presented. Additionally, the types of information produced wiithin the program and the anticipated growth in information system requirements as the program transitions to Space Station Freedom utilization are discussed. Plans for payload operations support in the Freedom era are addressed, as well as current activities to define research community requirements for data and sample archives.

Kicza, M. E.↗
NASA NTRS1992

Projected NASA power requirements for space science and exploration missions

NASA's Office of Space Science and Applications has recently completed its long-range strategic plan which describes a number of exciting space science missions into the early 21st century. In parallel, NASA's new Office of Exploration has begun defining in more detail the architectures of the Space Exploration Initiative (SEI) for returning to the Moon and going to Mars. Both the space science missions and the SEI missions are dependent upon power sources and energy storage with strong requirements for reliability, long life, ease of assembly, autonomy, and light weight. This paper reviews the currently planned space science and SEI missions and focuses upon the power requirements with a view toward guiding technology developers and power designers.

Gary L Bennett↗
NASA NTRS1992

Characteristics and requirements of robotic manipulators for space operations

A robotic manipulator, DTF-1, developed as part of the Flight Telerobotic Servicer (FTS) project at Goddard Space Flight Center is discussed focusing on the technical, operational, and safety requirements. The DTF-1 system design, which is based on the manipulator, gripper, cameras, computer, and an operator control station incorporates the fundamental building blocks of the original FTS, the end product of which was to have been a light-weight, dexterous telerobotic device. For the first time in the history of NASA, space technology and robotics were combined to find new and unique solutions to the demanding requirements of flying a sophisticated robotic manipulator in space. DTF-1 is considered to be the prototype for all future development in space robotics.

Andary, James F.↗
NASA NTRS1992

Instrumental and observational requirements for space-based imaging of magnetospheric emissions

Simulated images of extreme ultraviolet (EUV) emissions from energetic outflowing ions have been constructed to study techniques for remotely sensing the dynamic behavior of hot plasmas in the near-Earth environment. These calculations include realistic assumptions about the energetic ion outflow from high latitudes and take into account the effects of cold plasmaspheric and ionospheric ions. The energetic ion outflow is determined from a statistical study based on five years of measurements from the Energetic Ion Composition Spectrometer on Dynamics Explorer 1. The simulated images change significantly with viewing geometry and certain spacecraft locations are clearly favorable for observing emissions from energetic ions. For example, for a near equatorial orbit, viewing locations greater than 9 Earth radii are required to observe outflowing ions above the cold plasmaspheric background. We will discuss other important considerations for magnetospheric imaging including the sensitivity requirements of the detector. In particular, we consider the performance of multi-layer optics for EUV wavelengths.

Robinson, R. M.↗
NASA NTRS1992

Instrument requirements for imaging the magnetosphere in extreme-ultraviolet and energetic neutral atoms derived from computer-simulated images

Scientific requirements for He(+)(304 A) and energetic neutral atom (ENA) magnetospheric imaging, as well as the derived instrumental requirements are presented. Both ENA imaging of the hot plasma and EUV imaging of the cold plasma are highlighted. The question of the accuracy with which physically significant parameters can be extracted from actual images using computerized algorithms is addressed. An example of an ENA image analyzed by means of the Powell minimization algorithm is given. Automated unfolding of global magnetospheric images is also discussed. A Mercator projection of a model INA image is shown.

Roelof, Edmond C.↗
NASA NTRS1993

Performance under dichoptic versus binocular viewing conditions - Effects of attention and task requirements

Three experiments investigated subjects' ability to allocate attention and cope with task requirements under dichoptic versus binocular viewing conditions. Experiments 1 and 2 employed a target detection task in compound and noncompound stimuli, and Experiment 3 employed a relative-proximity judgment task. The tasks were performed in a focused attention condition in which subjects had to attend to the stimulus presented to one eye or field (under dichoptic and binocular viewing conditions, respectively) while ignoring the stimulus presented to the other eye or field, and in a divided attention condition in which subjects had to attend to the stimuli presented to both eyes or fields. Subjects' performance was affected by the interaction of attention conditions with task requirements, but it was generally the same under dichoptic and binocular viewing conditions. The more dependent the task was on finer discrimination, the more performance was impaired by divided attention. These results suggest that at least with discrete tasks and relatively short exposure durations, performance when each eye is presented with a separate stimulus is the same as when the entire field of stimulation is viewed by both eyes.

Kimchi, Ruth↗
NASA NTRS1992

Defining contamination control requirements for non-human research on Space Station Freedom

The use of non-human biological specimens for life sciences research on Space Station Freedom has generated concerns about spacecraft internal contamination, crew safety and hardware utility. Various NASA organizations convened to discuss the concerns and determine how they should be addressed. This paper will present the issues raised at this meeting, the process by which safety concerns were identified, and the means by which contamination control requirements for all biological payloads were recommended for incorporation into Space Station Freedom safety requirements. The microbiological, toxicological and particulate contamination criteria for long-term spaceflight will be based on realistic assessment of risk and hardware will be designed to meet established contamination criteria while facilitating crew operations, thereby meeting the needs of the investigator.

Corbin, Barbara J.↗
NASA NTRS1993

Investigation of high-alpha lateral-directional control power requirements for high-performance aircraft

Designers of the next-generation fighter and attack airplanes are faced with the requirements of good high angle-of-attack maneuverability as well as efficient high speed cruise capability with low radar cross section (RCS) characteristics. As a result, they are challenged with the task of making critical design trades to achieve the desired levels of maneuverability and performance. This task has highlighted the need for comprehensive, flight-validated lateral-directional control power design guidelines for high angles of attack. A joint NASA/U.S. Navy study has been initiated to address this need and to investigate the complex flight dynamics characteristics and controls requirements for high angle-of-attack lateral-directional maneuvering. A multi-year research program is underway which includes groundbased piloted simulation and flight validation. This paper will give a status update of this program that will include a program overview, description of test methodology and preliminary results.

Foster, John V.↗
NASA NTRS1927

Power Output and Air Requirements of a Two-stroke Cycle Engine for Aeronautical Use

This investigation was undertaken to determine the pressure and amount of air necessary for satisfactory high-speed, two-stroke cycle operation and thus permit the power requirements of the air pump or blower to be determined. Based on power output and air requirement here obtained the two-stroke cycle engine would seem to be favorable for aeronautical use. No attempts were made to secure satisfactory operation at idling speeds.

Paton, C R↗