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NASA NTRSDate not supplied

Lunar Explorer Instrument for space biology Applications (LEIA): An overview of planned science concept of operations

Radiation and reduced gravity pose biological risks to crewed deep space exploration. To better understand deep space radiation biology, the LEIA mission will measure charged particles and fast neutrons as well as yeast growth, metabolic rate, and bioengineered production of carotenoids at the lunar surface. LEIA will be delivered to the south polar region of the Moon by the Commercial Lunar Payload Services (CLPS) program. The LEIA science concept of operations was developed to isolate radiation and partial gravity from other environmental conditions experienced by the payload. Due to CLPS integration requirements, there will be at least eight months from loading yeast into the payload until activation on the lunar surface. Replicate yeast strains will be loaded in a randomized complete block design to minimize batch differences in desiccation tolerance and positional effects in the microfluidics culture system. Temperature and relative humidity will be controlled throughout integration and flight to maintain yeast viability and to enable measurement of yeast growth parameters within the lunar surface operations timeframe, with the ground control matching environmental conditions where possible. LEIA is co-manifested with the European Space Agency’s PROSPECT mission, which will be operating a drill during yeast growth. Vibration translated through the lunar lander will be mitigated and quantified to account for potential impacts on LEIA optical measurements and yeast growth rate. Total space radiation dose, including the transit exposure from Earth to the Moon, will be measured to obtain more accurate charged particle and fast neutron dose rates on the lunar surface. These radiation data will also yield ground truth radiation dose experienced by the yeast during the mission. Quantifying these environmental factors impacting the LEIA payload will allow more accurate ground control experiments to better isolate the biological responses to radiation and reduced gravity at the lunar surface.

Lunar Surface Mission↗
NASA NTRS1990

Simulated ion thruster operation without beam extraction

The development of high power (100's of kilowatts) ion engines may be greatly facilitated through the use of a technique which enables optimization of the discharge chamber to be performed without beam extraction. Ion thruster operation without beam extraction results in an experimentally determined decrease in the accelerator system transparency to ions from approximately 0.8 down to 0.22 for the standard J-Series thruster ion optics. This decreased ion transparency translates into a decreased propellant flow rate requirement for operation without beam extraction, enabling testing to be performed in smaller vacuum chambers with lower pumping speeds. Performance curves simulated without beam extraction are shown to agree well with actual performance curves obtained with beam extraction. Screen grid temperatures, however, are shown to be significantly higher without beam extraction due to the decrease in the accelerator system transparency to ions.

Brophy, John R.↗
NASA NTRS2017

Medical Systems Engineering to Support Mars Mission Crew Autonomy

Human spaceflight missions to Mars face exceptionally challenging resource limitations that far exceed those faced before. Increasing transit times, decreasing opportunity for resupply, communications challenges, and extended time to evacuate a crew to definitive medical care dictate a level of crew autonomy in medical care that is beyond the current medical model. To approach this challenge, a medical systems engineering approach is proposed that relies on a clearly articulated Concept of Operations and risk analysis tools that are in development at NASA. This paper proposes an operational clinical model with key terminology and concepts translated to a controls theory paradigm to frame a common language between clinical and engineering teams. This common language will be used for design and validation of an exploration medical system that is fully integrated into a Mars transit vehicle. This approach merges medical simulation, human factors evaluation techniques, and human-in-the-loop testing in ground based analogs to tie medical hardware and software subsystem performance and overall medical system functionality to metrics of operational medical autonomy. Merging increases in operational clinical autonomy with a more restricted vehicle system resource scenario in interplanetary spaceflight will require an unprecedented level of medical and engineering integration. Full integration of medical capabilities into a Mars vehicle system may require a new approach to integrating medical system design and operations into the vehicle Program structure. Prior to the standing-up of a Mars Mission Program, proof of concept is proposed through the Human Research Program.

Antonsen, Erik↗
NASA NTRS1988

Life-span knowledge engineering for space operations

Ordinarily, knowledge engineering is thought of as the process of translating the knowledge and problem solving strategies of a human expert into rules and procedures incorporated into a machine based expert system which can, given adequate input, solve the same sorts of problems as the expert. One appeal of these knowledge based systems is their ability to take care of problems without having a human expert present. For work in space, being independent of humans is especially important both for situations where devices will be in remote or dangerous locales and for situations such as space stations where human resources are limited and schedules are tight. In qualification of the above ideas, it is argued herein that the notion of knowledge engineering and the expectations for its application should be extended beyond the period of construction of unit expert systems to the entire knowledge system management associated with one or another real systems, whether it is a piece of hardware or an entire human-machine operation such as a lunar factory.

Hays, Dan↗
NASA NTRS2018

Testing and Maturing a Mass Translating Mechanism for a Deep Space CubeSat

Near Earth Asteroid (NEA) Scout is a deep space satellite set to launch aboard NASA’s Exploration Mission 1. The spacecraft fits within a CubeSat standard 6U (about 300 x 200 x 100 mm) and is designed to travel 1 AU over a 2.5 year mission to observe NEA VG 1991. The spacecraft will use an 86 square meter solar sail to maneuver from lunar orbit to the NEA. One of the critical mechanisms aboard NEA Scout, the Active Mass Translator (AMT), has gone through rigorous design and test cycles since its conception in July of 2015. The AMT is a two-axis translation table required to balance the spacecraft’s center of mass (CM) and solar sail center of pressure (CP) while also trimming disturbance torque created by off-nominal sail conditions. The AMT has very limited mass and volume requirements, but is still required to deliver a large translation range—about 160 x 68 mm—at sub mm accuracy and precision. The system must accommodate and protect a shielded wire harness and coax cables during translation. Lastly, the system has been constrained to operate in complete exposure to space with limited power and data budgets for mechanical and thermal needs. The NEA Scout team has developed and carried out a rigorous test suite for the prototype and engineering development unit (EDU). These tests uncovered numerous design failures and led to many failure investigations and iteration cycles. This paper will site each discovery and discuss at length the most surprising and difficult failures to date as the NEA Scout AMT moved through functional, random vibration, thermal vacuum, harnessing, and design life verification testing. A paper was previously presented at the 43rd Aerospace Mechanisms Symposia entitled, “Development of a High Performance, Low Profile Translation Table with Wire Feedthrough for a Deep Space CubeSat”. This paper will make note of specific lessons learned from the test activities: testing ideologies for high-risk missions, thermal mitigation design for small mechanisms, non-flight qualified stepper motor accommodation, harnessing volume allocation/design, and ground testing of mechanisms developed for zero-g environments.

Few, Alex↗
NASA NTRS1972

Five-centimeter diameter ion thruster development

All system components were tested for endurance and steady state and cyclic operation. The following results were obtained: acceleration system (electrostatic type), 3100 hours continuous running; acceleration system (translation type), 2026 hours continuous running; cathode-isolator-vaporizer assembly, 5000 hours continuous operation and 190 restart cycles with 1750 hours operation; mercury expulsion system, 5000 hours continuous running; and neutralizer, 5100 hours continuous operation. The results of component optimization studies such as neutralizer position, neutralizer keeper hole, and screen grid geometry are included. Extensive mapping of the magnet field within and immediately outside the thruster are shown. A technique of electroplating the molybdenum accelerator grid with copper to study erosion patterns is described. Results of tests being conducted to more fully understand the operation of the hollow cathode are also given. This type of 5-cm thruster will be space tested on the Communication Technology Satellite in 1975.

Weigand, A. J.↗
NASA NTRS2015

Experimental Design for Pre-Clinical Animal Model Study in Microgravity

The Rodent Research program at NASAs Ames Research Center (ARC) has pioneered a new research capability on the International Space Station in less than four years and has progressed toward translating research to the ISS utilizing commercial rockets, collaborating with academia and science industry, and training crew for research purposes on-orbit. Animal models are the foundation of pre-clinical research to understand human diseases and evaluate new therapeutics. Advancement in alleviating ground diseases such as muscle atrophy and osteoporosis can come from the study of similar conditions that are known to occur as a result of exposure to the spaceflight environment. During the completion of the flight phase of two missions, our practices, hardware and operations evolved from tested to developed standards, which successfully translated the studies from ground to space. Results from these studies contribute to the science community via both the primary investigation and banked samples that are shared in publicly available data repository such as GeneLab. Every completed mission sets a foundation to build and design greater complexity into future research and answer questions about common human diseases on ground and in space. Here, we present methods developed for the translation of a rodent experiment to the ISS including a description of hardware and kits available for investigators and a discussion of operational constraints.

Rodent Research↗
NASA NTRS1994

Dexterous end effector flight demonstration

The Dexterous End Effector Flight Experiment is a flight demonstration of newly developed equipment and methods which make for more dexterous manipulation of robotic arms. The following concepts are to be demonstrated: The Force Torque Sensor is a six axis load cell located at the end of the RMS which displays load data to the operator on the orbiter CCTV monitor. TRAC is a target system which provides six axis positional information to the operator. It has the characteristic of having high sensitivity to attitude misalignment while being flat. AUTO-TRAC is a variation of TRAC in which a computer analyzes a target, displays translational and attitude misalignment information, and provides cues to the operator for corrective inputs. The Magnetic End Effector is a fault tolerant end effector which grapples payloads using magnetic attraction. The Carrier Latch Assembly is a fault tolerant payload carrier, which uses mechanical latches and/or magnetic attraction to hold small payloads during launch/landing and to release payloads as desired. The flight experiment goals and objectives are explained. The experiment equipment is described, and the tasks to be performed during the demonstration are discussed.

Carter, Edward L.↗
NASA NTRS1993

Generalized seismic analysis

There is a constant need to be able to solve for enforced motion of structures. Spacecraft need to be qualified for acceleration inputs. Truck cargoes need to be safeguarded from road mishaps. Office buildings need to withstand earthquake shocks. Marine machinery needs to be able to withstand hull shocks. All of these kinds of enforced motions are being grouped together under the heading of seismic inputs. Attempts have been made to cope with this problem over the years and they usually have ended up with some limiting or compromise conditions. The crudest approach was to limit the problem to acceleration occurring only at a base of a structure, constrained to be rigid. The analyst would assign arbitrarily outsized masses to base points. He would then calculate the magnitude of force to apply to the base mass (or masses) in order to produce the specified acceleration. He would of necessity have to sacrifice the determination of stresses in the vicinity of the base, because of the artificial nature of the input forces. The author followed the lead of John M. Biggs by using relative coordinates for a rigid base in a 1975 paper, and again in a 1981 paper . This method of relative coordinates was extended and made operational as DMAP ALTER packets to rigid formats 9, 10, 11, and 12 under contract N60921-82-C-0128. This method was presented at the twelfth NASTRAN Colloquium. Another analyst in the field developed a method that computed the forces from enforced motion then applied them as a forcing to the remaining unknowns after the knowns were partitioned off. The method was translated into DMAP ALTER's but was never made operational. All of this activity jelled into the current effort. Much thought was invested in working out ways to unshakle the analysis of enforced motions from the limitations that persisted.

Butler, Thomas G.↗
NASA NTRS2018

System and Method for Executing Operations Specified in a Procedure Language

A system for executing a procedure includes a procedure execution engine. The procedure execution engine is configured to translate a procedure defined via a procedure language to natural language statements corresponding to the operations specified by the procedure language. The procedure execution engine is also configured to generate a user interface for controlling execution of the procedure, and to display the natural language statements via the user interface. The procedure execution engine is further configured to indicate progress of execution of the procedure, via the user interface, based on the displayed natural language statements.

Kortenkamp, David Michael↗
NASA NTRS1990

Active control of bearing preload using piezoelectric translators

In many spacecraft applications, mechanisms are required to perform precision pointing operations or to sometimes dither about or track a moving object. These mechanisms perform in a predictable and repeatable manner in benign temperature environments. Severe thermal gradients experienced in actual space applications however, cause assemblies to expand and contract around their bearings. This results in unpredictable changes in bearing preload, and hence bearing friction. This becomes a limitation for servos controlling pointing accuracy. Likewise, uncontrollable vibrations may couple into fixed preload (hence, fixed stiffness) mechanisms and limit pointing accuracy. Consequently, a complex problem faced today is how to design mechanisms that remain insensitive to changing thermal and vibrational spacecraft environments. Research presented involves the simplified modeling and test results of an actuator module that used piezoelectrically preload controlled bearings. The feasibility of actively controlling bearing preload was demonstrated. Because bearing friction is related to preload, a thermally active system designed with aluminum components and a 440 C bearing, was friction tested at temperatures ranging from 0 to 70 C (32 to 158 F). Effectiveness of the translators were demonstrated by mapping a controllable friction range throughout tested temperatures. It was learned that constant preload for this system could be maintained over an approximate 44 C (79 F) temperature span. From testing, it was also discovered that at the more deviate temperatures, expansions were so large that radial clearances were taken up and the duplex bearing became radially preloaded. Thus, active control of bearing preload is feasible but may be limited by inherent geometry constraints and materials used in the system.

Nye, Ted W.↗
NASA NTRS1982

Magnetically suspended Stirling cryogenic space refrigerator Status report

At the 1979 Cryogenic Engineering Conference, attention was given to conceptual designs of spaceborne cryogenic refrigeration systems which can provide long-term, unattended operation. Since that time, efforts have continued to translate one of those concepts into an engineering model. The present investigation is concerned with a refrigerator which was designed to generate 5 W of cooling power at a temperature of 65 K. The compression heat of the refrigerator is dissipated at a temperature of 300 K, and the output of the system is to be maintained reliably for a period of five years or longer. The refrigerator design is based on the Stirling cycle, which has an ideal efficiency equal to that of the Carnot cycle. Attention is given to some background information concerning a cryogenic refrigerator, the design of the refrigerator components, and the development status. The magnetic bearings and the linear motors have been tested at the component level.

Daniels, A.↗
NASA NTRS1989

Precision engineering and optomechanics; Proceedings of the Meeting, San Diego, CA, Aug. 10, 11, 1989

Various papers on precision engineering and optomechanics are presented. Individual topics addressed include: performance optimization of an IR sensor optical system, design and development of a rugged airborne scanning optical assembly for a calibrated IR imaging radiometer, numerical method for Cassegrain telescope baffle design, precision alignment of an IR imaging system, optical alignment of a pupil imaging spectrometer, optical alignment equipment and methods for visible and IR imaging meteorological radiometer. Also addressed are: vibration-design aspects of an IR-scanning earth sensor, chopping secondary mirror for the Kuiper Airborne Observatory, advanced flexure suspension systems, subminiature IR detector translation stage, thermal/optical test setup for the Geostationary Operational Environmental Satellite Telescope, design of the GOES telescope secondary mirror mounting.

Vukobratovich, Daniel↗
NASA NTRS2001

Predictive Compensator Optimization for Head Tracking Lag in Virtual Environments

We examined the perceptual impact of plant noise parameterization for Kalman Filter predictive compensation of time delays intrinsic to head tracked virtual environments (VEs). Subjects were tested in their ability to discriminate between the VE system's minimum latency and conditions in which artificially added latency was then predictively compensated back to the system minimum. Two head tracking predictors were parameterized off-line according to cost functions that minimized prediction errors in (1) rotation, and (2) rotation projected into translational displacement with emphasis on higher frequency human operator noise. These predictors were compared with a parameterization obtained from the VE literature for cost function (1). Results from 12 subjects showed that both parameterization type and amount of compensated latency affected discrimination. Analysis of the head motion used in the parameterizations and the subsequent discriminability results suggest that higher frequency predictor artifacts are contributory cues for discriminating the presence of predictive compensation.

Adelstein, Barnard D.↗
NASA NTRS2009

Apollo Guidance, Navigation, and Control (GNC) Hardware Overview

This viewgraph presentation reviews basic guidance, navigation and control (GNC) concepts, examines the Command and Service Module (CSM) and Lunar Module (LM) GNC organization and discusses the primary GNC and the CSM Stabilization and Control System (SCS), as well as other CSM-specific hardware. The LM Abort Guidance System (AGS), Control Electronics System (CES) and other LM-specific hardware are also addressed. Three subsystems exist on each vehicle: the computer subsystem (CSS), the inertial subsystem (ISS) and the optical subsystem (OSS). The CSS and ISS are almost identical between CSM and LM and each is designed to operate independently. CSM SCS hardware are highlighted, including translation control, rotation controls, gyro assemblies, a gyro display coupler and flight director attitude indicators. The LM AGS hardware are also highlighted and include the abort electronics assembly and the abort sensor assembly; while the LM CES hardware includes the attitude controller assembly, thrust/translation controller assemblies and the ascent engine arming assemble. Other common hardware including the Orbital Rate Display - Earth and Lunar (ORDEAL) and the Crewman Optical Alignment Sight (COAS), a docking aid, are also highlighted.

Interbartolo, Michael↗
NASA NTRS2009

Modification of Otolith-Ocular Reflexes, Motion Perception and Manual Control During Variable Radius Centrifugation Following Space Flight

Two joint ESA-NASA studies are examining changes in otolith-ocular reflexes and motion perception following short duration space flights, and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. Data is currently being collected on astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation is utilized to elicit otolith reflexes in the lateral plane without concordant roll canal cues. Unilateral centrifugation (400 deg/s, 3.5 cm radius) stimulates one otolith positioned off-axis while the opposite side is centered over the axis of rotation. During this paradigm, roll-tilt perception is measured using a subjective visual vertical task and ocular counter-rolling is obtained using binocular video-oculography. During a second paradigm (216 deg/s, less than 20 cm radius), the effects of stimulus frequency (0.15 - 0.6 Hz) are examined on eye movements and motion perception. A closed-loop nulling task is also performed with and without vibrotactile display feedback of chair radial position. Data collection is currently ongoing. Results to date suggest there is a trend for perceived tilt and translation amplitudes to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. One result of this study will be to characterize the variability (gain, asymmetry) in both otolith-ocular responses and motion perception during variable radius centrifugation, and measure the time course of post-flight recovery. This study will also address how adaptive changes in otolith-mediated reflexes correspond to one's ability to perform closed-loop nulling tasks following G-transitions, and whether manual control performance can be improved with vibrotactile feedback of orientation.

Wood, Scott J.↗
NASA NTRS2009

ZAG-Otolith: Modification of Otolith-Ocular Reflexes, Motion Perception and Manual Control during Variable Radius Centrifugation Following Space Flight

Two joint ESA-NASA studies are examining changes in otolith-ocular reflexes and motion perception following short duration space flights, and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. METHODS. Data is currently being collected on astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation is utilized to elicit otolith reflexes in the lateral plane without concordant roll canal cues. Unilateral centrifugation (400 deg/s, 3.5 cm radius) stimulates one otolith positioned off-axis while the opposite side is centered over the axis of rotation. During this paradigm, roll-tilt perception is measured using a subjective visual vertical task and ocular counter-rolling is obtained using binocular video-oculography. During a second paradigm (216 deg/s, <20 cm radius), the effects of stimulus frequency (0.15 - 0.6 Hz) are examined on eye movements and motion perception. A closed-loop nulling task is also performed with and without vibrotactile display feedback of chair radial position. PRELIMINARY RESULTS. Data collection is currently ongoing. Results to date suggest there is a trend for perceived tilt and translation amplitudes to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. DISCUSSION. One result of this study will be to characterize the variability (gain, asymmetry) in both otolithocular responses and motion perception during variable radius centrifugation, and measure the time course of postflight recovery. This study will also address how adaptive changes in otolith-mediated reflexes correspond to one's ability to perform closed-loop nulling tasks following G-transitions, and whether manual control performance can be improved with vibrotactile feedback of orientation.

Wood, S. J.↗
NASA NTRS2013

A Model of Manual Control with Perspective Scene Viewing

A model of manual control during perspective scene viewing is presented, which combines the Crossover Model with a simpli ed model of perspective-scene viewing and visual- cue selection. The model is developed for a particular example task: an idealized constant- altitude task in which the operator controls longitudinal position in the presence of both longitudinal and pitch disturbances. An experiment is performed to develop and vali- date the model. The model corresponds closely with the experimental measurements, and identi ed model parameters are highly consistent with the visual cues available in the perspective scene. The modeling results indicate that operators used one visual cue for position control, and another visual cue for velocity control (lead generation). Additionally, operators responded more quickly to rotation (pitch) than translation (longitudinal).

pilot modeling↗