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NASA NTRSDate not supplied

Operational Modal Analysis of the Artemis I Dynamic Rollout Test and Wet Dress Rehearsal

NASA has developed an expendable heavy lift launch vehicle capability, the Space Launch System (SLS), to support lunar and deep space exploration. The uncrewed Artemis I was the first flight of this new launch vehicle and tested critical systems for the upcoming crewed Artemis II flight to the moon. Accelerations were recorded at a multitude of locations on Artemis, the Mobile Launcher (ML), and the Crawler Transporter (CT)during the rollout of Artemis I from the Vehicle Assembly Building (VAB) to Launch Pad 39B March 2022 and is referred to as the Artemis I Dynamic Rollout Test (DRT). While Artemis I was at Launch Pad 39B, the Wet Dress Rehearsal (WDR) was performed to demonstrate launch readiness and acceleration measurements were also recorded. Finally, Artemis I rolled back from Launch Pad 39B to the VAB in April 2022, where acceleration measurements were also recorded and is referred to as the rollback portion of DRT. Because the forces during rollout and at the launch pad acting on Artemis I, the ML, and the CT are not directly measurable, Operational Modal Analysis (OMA) techniques, instead of traditional Experimental Modal Analysis (EMA) techniques, were used to identify modal characteristics. The OMA analysis of DRT and WDR directly builds upon the lessons learned from the OMA analysis of an earlier rollout of the ML from the VAB. DRT and WDR dynamic characteristics will be used to support SLS Integrated Modal Test finite element model correlation efforts and Exploration Ground System ML and CT finite element model verification and validation, which are part of the Building Block approach the Space Launch System program has implemented. The dynamic characteristics extracted from DRT as well as the rollout acceleration time histories themselves will be used in the development of generic rollout forcing functions that will provide refined estimates of the Artemis IV rollout forces, which will have the heavier and larger SLS Block 1B launch vehicle and Mobile Launcher 2 (ML-2). This paper briefly describes Artemis I, the ML, and the CT physical characteristics, DRT rollout/rollback and WDR data collection, the challenges in implementing OMA techniques due in part to the CT harmonics, and how these challenges were overcome to obtain the Artemis I DRT configuration and WDR configuration modal characteristics.

Apollo↗
NASA NTRSDate not supplied

Operational Modal Analysis of the Artemis I Dynamic Rollout Test and Wet Dress Rehearsal

NASA has developed an expendable heavy lift launch vehicle capability, the Space Launch System (SLS), to support lunar and deep space exploration. The uncrewed Artemis I was the first flight of this new launch vehicle and tested critical systems for the upcoming crewed Artemis II flight to the moon. Accelerations were recorded at a multitude of locations on Artemis, the Mobile Launcher (ML), and the Crawler Transporter (CT)during the rollout of Artemis I from the Vehicle Assembly Building (VAB) to Launch Pad 39B March 2022 and is referred to as the Artemis I Dynamic Rollout Test (DRT). While Artemis I was at Launch Pad 39B, the Wet Dress Rehearsal (WDR) was performed to demonstrate launch readiness and acceleration measurements were also recorded. Finally, Artemis I rolled back from Launch Pad 39B to the VAB in April 2022, where acceleration measurements were also recorded and is referred to as the rollback portion of DRT. Because the forces during rollout and at the launch pad acting on Artemis I, the ML, and the CT are not directly measurable, Operational Modal Analysis (OMA) techniques, instead of traditional Experimental Modal Analysis (EMA) techniques, were used to identify modal characteristics. The OMA analysis of DRT and WDR directly builds upon the lessons learned from the OMA analysis of an earlier rollout of the ML from the VAB. DRT and WDR dynamic characteristics will be used to support SLS Integrated Modal Test finite element model correlation efforts and Exploration Ground System ML and CT finite element model verification and validation, which are part of the Building Block approach the Space Launch System program has implemented. The dynamic characteristics extracted from DRT as well as the rollout acceleration time histories themselves will be used in the development of generic rollout forcing functions that will provide refined estimates of the Artemis IV rollout forces, which will have the heavier and larger SLS Block 1B launch vehicle and Mobile Launcher 2 (ML-2). This paper briefly describes Artemis I, the ML, and the CT physical characteristics, DRT rollout/rollback and WDR data collection, the challenges in implementing OMA techniques due in part to the CT harmonics, and how these challenges were overcome to obtain the Artemis I DRT configuration and WDR configuration modal characteristics.

Apollo↗
NASA NTRS2017

Impact-Facilitated Hydrothermal Alteration in the Rim of Endeavour Crater, Mars

Endeavour crater, a Noachian-aged, 22 km diameter impact structure on Meridiani Planum, Mars, has been investigated by the Mars Exploration Rover Opportunuity for over 2000 sols (Mars days). The rocks of the western rim region (oldest to youngest) are: (i) the pre-impact Matijevic fm.; (ii) rim-forming Shoemaker fm. polymict impact breccias; (iii) Grasberg fm., fine-grained sediments draping the lower slopes; and (iv) Burns fm., sulfate-rich sandstones that onlap the Grasberg fm. The rim is segmented and transected by radial fracture zones. Evidence for fluid-mediated alteration includes m-scale detections of phyllosilicates from orbit, and cm-scale variations in rock/soil composition/mineralogy documented by the Opportunity instrument suite. The m-scale phyllosilicate detections include Fe(3+)-Mg and aluminous smectites that occur in patches in the Matijevic and Shoemaker fms. Rock compositions do not reveal substantial differences for smectite-bearing compared to smectite-free rocks. Interpretation: large-scale hydrothermal alteration powered by impact-deposited heat acting on limited water supplies engendered mineralogic transfomations under low water/rock, near-isochemical conditions. The cm-scale alterations, localized in fracture zones, occurred at higher water/rock as evidenced by enhanced Si and Al contents through leaching of more soluble elements, and deposition of Mg, Ni and Mn sulphates and halogen salts in soils. Visible/near infrared reflectance of narrow curvilinear red zones indicate higher nanophase ferric oxide contents and possibly hydration compared to surrounding outcrops. Broad fracture zones on the rim have reflectance features consistent with development of ferric oxide minerals. Interpretation: water fluxing through the fractures in a hydrothermal system resulting from the impact engendered alteration and leaching under high water/rock conditions. Late, localized alteration is documented by Ca-sulfate-rich veins that are not confined to fracture zones; some cross-cut the Grasberg fm. Interpretation: late fluid mobilization of soluble elements, likely in a later alteration event.

Mittlefehldt, D. W.↗
NASA NTRS2018

Pulsed Fission-Fusion (PuFF)

In September 2013 the NASA Innovative Advanced Concept (NIAC) organization awarded a phase I contract to the PuFF team. Our phase 1 proposal discussed a pulsed fission-fusion propulsion system that injected gaseous deuterium (D) and tritium (T) as a mixture in a column, surrounded concentrically by gaseous uranium fluoride (UF6) and then an outer shell of liquid lithium. A high power current would flow down the liquid lithium and the resulting Lorentz force would compress the column by roughly a factor of 10. The compressed column would reach criticality and a combination of fission and fusion reactions would occur. The fission reactions would further energize the fusion center, and the fusion reactions would generate neutrons that promote more complete burnup of the fission fuel. The lithium liner provides some help as a neutron reflector but also acts as a propulsive medium, being converted to plasma which is then expanded against a magnetic nozzle for thrust. The expansion of the (primarily) lithium plasma against the nozzle's magnetic field inducts a current that is used to charge the system for the next pulse. Our concept also included secondary injection of a Field Reversed Configuration (FRC) plasmoid that would provide a secondary compression direction, axially against the column, and push the column away from the injection manifold, increasing the manifold's survivability.Our phase 1 proposal included modeling the above process first under steady state assumptions and second under a time variant integration. We proposed including these results into a Mars concept vehicle and finally proposing promising conditions to be evaluated experimentally in Phase II. In phase I we quickly realized that we needed to modify our approach. Our steady state work was completed as proposed, and the results indicated that one, a two stage compression system was not needed and two, that we wanted to move away from UF6. The steady state model shows much more margin than expected, to the point that we may well reach breakeven with the Charger – 1 facility, a 572 kJ Marx bank currently under refurbishment at UAH. Additionally we found that using gaseous D-T and UF6, provided a relatively simple prospect of using a pulsed injector, made reaching criticality more difficult. The introduction of large amounts of fluorine meant a radiative sink, sapping power from the fusion plasma and was harder to handle. Therefore we moved to a solid uranium target that held D-T under pressure. In so doing we could move our target closer to criticality and remove any material that did not sustain the reaction.

Fusion↗
NASA NTRS1981

Lattice defects in semiconducting Hg/1-x/Cd/x/Te alloys. I - Defect structure of undoped and copper doped Hg/0.8/Cd/0.2/Te. II - Defect structure of indium-doped Hg/0.8/Cd/0.2/Te

Hall effect and mobility measurements were conducted on undoped Hg(0.8)Cd(0.2)Te crystals which were quenched to room temperature after being subjected to equilibration at temperatures ranging from 400 to 655 C in various Hg atmospheres. The variation of the hole concentration in the cooled crystals at 77 K as a function of Hg's partial pressure at the equilibration temperature, together with a comparison of the hole mobility in the undoped samples with that in copper-doped ones, yields a defect model for the undoped crystals according to which they are intrinsic at the equilibration temperatures and the native acceptor defects are doubly ionized. In the second part of this paper, the effects of indium doping are considered. The concentration of electrons obtained in the cooled crystals was found to be lower than the intrinsic carrier concentration at the equilibration temperatures. A defect model is proposed according to which most of the indium is incorporated as In2Te3(s) dissolved in the crystal, with only a small fraction of indium acting as single donors occupying Hg lattice sites.

Vydyanath, H. R.↗
NASA NTRS1977

Forced baroclinic ocean motions. II - The linear equatorial bounded case

Results obtained in the first part of this paper (1976), which studied forced baroclinic ocean motions in the linear equatorial unbounded case, are extended to the case of an ocean bounded by two meridians. A complete solution for the linear spin-up in response to a switched-on, x-dependent wind stress is obtained in terms of five components: the unbounded nonoscillatory response to the wind stress forcing; the inertia-gravity waves generated when the forcing switches on, together with their reflections; the quasi-geostrophic Rossby modes forming the eastern boundary response and a western boundary layer; and the equatorial Kelvin wave component of the western boundary response. Kelvin waves are generated if the forcings include a zonal wind component that is symmetric about the equator or an antisymmetric meridional wind stress. For non-Kelvin symmetries, spin-up occurs entirely by the effects of Rossby waves emanating from the eastern boundary. The state approaches the steady solution as increasing numbers of these reach an interior point. In Kelvin symmetries, the Rossby waves act to bring the sea surface tilt to the steady value and the spin-up of the tilt proceeds as in non-Kelvin cases.

Cane, M. A.↗
NASA NTRS2021

Spectroscopic Signatures of the Vanishing Natural Coronagraph of eta Carinae

Eta Carinae is a massive interacting binary system shrouded in a complex circumstellar environment whose evolution is the source of the long-term brightening observed during the last 80 years. An occulter, acting as a natural coronagraph, impacts observations from our perspective, but not from most other directions. Other sight-lines are visible to us through studies of the Homunculus reflection nebula. The coronagraph appears to be vanishing, decreasing the extinction towards the central star, and causing the star's secular brightening. In contrast, the Homunculus remains at an almost constant brightness. The coronagraph primarily suppresses the stellar continuum, to a lesser extent the wind lines, and not the circumstellar emission lines. This explains why the absolute values of equivalent widths (EWs) of the emission lines in our direct view are larger than those seen in reflected by the Homunculus, why the direct view absolute EWs are decreasing with time, and why lower-excitation spectral wind lines formed at larger radii (e.g Fe ii 4585A) decrease in intensity at a faster pace than higher excitation lines that form closer to the star (e.g. Hdelta). Our main result is that the star, despite its 10-fold brightening over two decades, is relatively stable. A vanishing coronagraph that can explain both the large flux evolution and the much weaker spectral evolution. This is contrary to suggestions that the long-term variability is intrinsic to the primary star that is still recovering from the Great Eruption with a decreasing mass-loss rate and a polar wind that is evolving at a slower pace than at the equator.

A. Damineli↗
NASA NTRS2005

Acquisition of Autonomous Behaviors by Robotic Assistants

Our research achievements under the NASA-JSC grant contributed significantly in the following areas. Multi-agent based robot control architecture called the Intelligent Machine Architecture (IMA) : The Vanderbilt team received a Space Act Award for this research from NASA JSC in October 2004. Cognitive Control and the Self Agent : Cognitive control in human is the ability to consciously manipulate thoughts and behaviors using attention to deal with conflicting goals and demands. We have been updating the IMA Self Agent towards this goal. If opportunity arises, we would like to work with NASA to empower Robonaut to do cognitive control. Applications 1. SES for Robonaut, 2. Robonaut Fault Diagnostic System, 3. ISAC Behavior Generation and Learning, 4. Segway Research.

Peters, R. A., II↗
NASA NTRSDate not supplied

A Human-in-the-Loop Evaluation of ACAS Xu

As part of the Phase 2 UAS DAA MOPS, a Class 3 DAA system has been under development with the potential to resolve many of the limitations of Class 1 and 2 systems. A Class 3 system would combine the DAA and CA functions into a single, unified system, and would also extend the CA capabilities relative to TCAS II. Class 3 is enabled by the Airborne Collision Avoidance System (ACAS) XU, a next generation CA system developed specifically for UAS operations. Unlike Class 2 systems, ACAS XU provides CA protection against both cooperative and non-cooperative traffic. Class 3 systems also expand the CA logic to allow horizontal RAs in addition to vertical RAs. The purpose of the current study was to evaluate ACAS XU in a real-time, HITL simulation. The latest version of ACAS XU was implemented and pilots were tasked with responding to scripted traffic conflicts over the course of four experimental trials. Variables included the location of the ACAS XU guidance information (standalone vs. integrated) and traffic conflict type (DAA or CA threat). Sixteen active UAS pilots participated in the study, with ATC and ‘pseudo’ pilots acting as airspace confederates. Results showed that pilots were able to maintain DWC with ACAS XU at a rate comparable to previous research (~5%). Compliance rates to initial RAs were high (~90%) but dropped significantly when the target heading value issued during horizontal RAs were updated over the course of an encounter (30-70%). The implications of these findings on the display, alerting, and guidance requirements for Class 3 systems will be discussed.

unmanned aircraft systems↗
NASA NTRSDate not supplied

A Human-in-the-Loop Evaluation of ACAS Xu

As part of the Phase 2 UAS DAA MOPS, a Class 3 DAA system has been under development with the potential to resolve many of the limitations of Class 1 and 2 systems. A Class 3 system would combine the DAA and CA functions into a single, unified system, and would also extend the CA capabilities relative to TCAS II. Class 3 is enabled by the Airborne Collision Avoidance System (ACAS) XU, a next generation CA system developed specifically for UAS operations. Unlike Class 2 systems, ACAS XU provides CA protection against both cooperative and non-cooperative traffic. Class 3 systems also expand the CA logic to allow horizontal RAs in addition to vertical RAs. The purpose of the current study was to evaluate ACAS XU in a real-time, HITL simulation. The latest version of ACAS XU was implemented and pilots were tasked with responding to scripted traffic conflicts over the course of four experimental trials. Variables included the location of the ACAS XU guidance information (standalone vs. integrated) and traffic conflict type (DAA or CA threat). Sixteen active UAS pilots participated in the study, with ATC and ‘pseudo’ pilots acting as airspace confederates. Results showed that pilots were able to maintain DWC with ACAS XU at a rate comparable to previous research (~5%). Compliance rates to initial RAs were high (~90%) but dropped significantly when the target heading value issued during horizontal RAs were updated over the course of an encounter (30-70%). The implications of these findings on the display, alerting, and guidance requirements for Class 3 systems will be discussed.

unmanned aircraft systems↗
NASA NTRS2020

A Human-in-theLoop Evaluation of ACAS Xu

As part of the Phase 2 UAS DAA MOPS, a Class 3 DAA system has been under development with the potential to resolve many of the limitations of Class 1 and 2 systems. A Class 3 system would combine the DAA and CA functions into a single, unified system, and would also extend the CA capabilities relative to TCAS II. Class 3 is enabled by the Airborne Collision Avoidance System (ACAS) XU, a next generation CA system developed specifically for UAS operations. Unlike Class 2 systems, ACAS XU provides CA protection against both cooperative and non-cooperative traffic. Class 3 systems also expand the CA logic to allow horizontal RAs in addition to vertical RAs. The purpose of the current study was to evaluate ACAS XU in a real-time, HITL simulation. The latest version of ACAS XU was implemented and pilots were tasked with responding to scripted traffic conflicts over the course of four experimental trials. Variables included the location of the ACAS XU guidance information (standalone vs. integrated) and traffic conflict type (DAA or CA threat). Sixteen active UAS pilots participated in the study, with ATC and ‘pseudo’ pilots acting as airspace confederates. Results showed that pilots were able to maintain DWC with ACAS XU at a rate comparable to previous research (~5%). Compliance rates to initial RAs were high (~90%) but dropped significantly when the target heading value issued during horizontal RAs were updated over the course of an encounter (30-70%). The implications of these findings on the display, alerting, and guidance requirements for Class 3 systems will be discussed.

unmanned aircraft systems↗
NASA NTRS2009

Sensitivity of a Cloud-Resolving Model to Bulk and Explicit Bin Microphysical Schemes: Cloud Microphysics and Storm Dynamics Interactions - Part 2

Part I of this paper compares two simulations, one using a bulk and the other a detailed bin microphysical scheme, of a long-lasting, continental mesoscale convective system with leading convection and trailing stratiform region. Diagnostic studies and sensitivity tests are carried out in Part II to explain the simulated contrasts in the spatial and temporal variations by the two microphysical schemes and to understand the interactions between cloud microphysics and storm dynamics. It is found that the fixed raindrop size distribution in the bulk scheme artificially enhances rain evaporation rate and produces a stronger near surface cool pool compared with the bin simulation. In the bulk simulation, cool pool circulation dominates the near-surface environmental wind shear in contrast to the near-balance between cool pool and wind shear in the bin simulation. This is the main reason for the contrasting quasi-steady states simulated in Part I. Sensitivity tests also show that large amounts of fast-falling hail produced in the original bulk scheme not only result in a narrow trailing stratiform region but also act to further exacerbate the strong cool pool simulated in the bulk parameterization. An empirical formula for a correction factor, r(q(sub r)) = 0.11q(sub r)(exp -1.27) + 0.98, is developed to correct the overestimation of rain evaporation in the bulk model, where r is the ratio of the rain evaporation rate between the bulk and bin simulations and q(sub r)(g per kilogram) is the rain mixing ratio. This formula offers a practical fix for the simple bulk scheme in rain evaporation parameterization.

Li, Xiaowen↗
NASA NTRS2003

Sensory Motor Coordination in Robonaut

As a participant of the year 2000 NASA Summer Faculty Fellowship Program, I worked with the engineers of the Dexterous Robotics Laboratory at NASA Johnson Space Center on the Robonaut project. The Robonaut is an articulated torso with two dexterous arms, left and right five-fingered hands, and a head with cameras mounted on an articulated neck. This advanced space robot, now driven only teleoperatively using VR gloves, sensors and helmets, is to be upgraded to a thinking system that can find, interact with and assist humans autonomously, allowing the Crew to work with Robonaut as a (junior) member of their team. Thus, the work performed this summer was toward the goal of enabling Robonaut to operate autonomously as an intelligent assistant to astronauts. Our underlying hypothesis is that a robot can develop intelligence if it learns a set of basic behaviors (i.e., reflexes - actions tightly coupled to sensing) and through experience learns how to sequence these to solve problems or to accomplish higher-level tasks. We describe our approach to the automatic acquisition of basic behaviors as learning sensory-motor coordination (SMC). Although research in the ontogenesis of animals development from the time of conception) supports the approach of learning SMC as the foundation for intelligent, autonomous behavior, we do not know whether it will prove viable for the development of autonomy in robots. The first step in testing the hypothesis is to determine if SMC can be learned by the robot. To do this, we have taken advantage of Robonaut's teleoperated control system. When a person teleoperates Robonaut, the person's own SMC causes the robot to act purposefully. If the sensory signals that the robot detects during teleoperation are recorded over several repetitions of the same task, it should be possible through signal analysis to identify the sensory-motor couplings that accompany purposeful motion. In this report, reasons for suspecting SMC as the basis for intelligent behavior will be reviewed. A robot control system for autonomous behavior that uses learned SMC will be proposed. Techniques for the extraction of salient parameters from sensory and motor data will be discussed. Experiments with Robonaut will be discussed and preliminary data presented.

Peters, Richard Alan, II↗
NASA NTRS2020

Design and Test of an Electromechanical Rover Tether for the Exploration of Vertical Lunar Pit

Moon Diver is a proposed mission to land and deploy an extreme-terrain, tethered rover for the exploration of Tranquillitatis Pit, a large vertical cave entrance into the subsurface of Earth’s Moon. By leveraging a supportive tether, the Axel rover, developed by NASA’s Jet Propulsion Laboratory, would perform a controlled descent into the pit and deploy instruments along the pit wall. The purpose of this mission concept is to study a volcanic secondary crust as a function of depth in order to determine formation processes and chemical makeup. The lifeline of the mission would be the tether, which provides power from, and communication to the top-side lander. Critically, the tether also serves as mechanical support between the suspended rover and the lander, which acts as an anchor. While space tethers have been deployed both in orbit and terrestrially, the use of the proposed tether is unlike any known in the literature; the tether must come into contact with the terrain while under load. With respect to the environment, the tether must also survive abrasion from glassy regolith and volcanic rocks, bending around sharp edges, thermal extremes, and exposure to full spectrum ultra-violet (UV) radiation, all while reliably transferring up to 100 W of power and 1 Mbps of data. Furthermore, since the Axel rover pays out tether from an internal spool, the tether’s diameter must be minimized to increase spool capacity, allowing for up to a 300-m traverse while also meeting static and dynamic strength requirements. This paper covers several phases of the tether’s initial development, including i) a trade study of structure and materials with consideration for space heritage, ii) selected design justification, and iii) results from tests on prototype tethers looking into mechanical, electrical, and environmental properties, including exposure to rock regolith abrasion, load profiles at temperature, and degradation due to UV exposure while exposed to vacuum. Finally, we provide insights and lessons learned from lab and field tests, which inform our continued effort to design a tether capable of surviving rugged, lunar conditions.

Nensas, Issa↗
NASA NTRS1994

Force-velocity and power characteristics of rat soleus muscle fibers after hindlimb suspension

The effects of 1, 2, and 3 wk of hindlimb suspension (HS) on force-velocity and power characteristics of single rat soleus fibers were determined. After 1, 2, or 3 wk of HA, small fiber bundles were isolated, placed in skinning solution, and stored at -20 C until studied. Single fibers were isolated and placed between a motor arm and force transducer, functional properties were studied, and fiber protein content was subsequently analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Additional fibers were isolated from soleus of control after 1 and 3 wk of HS, and fiber type distribution and myosin light chain stoichiometry were determined from SDS-PAGE analysis. After 1 wk of HS, percent type I fibers declined from 82 to 74%, whereas hybrid fibers increased from 10 to 18%. Percent fast type II fibers increased from 8% in control and 1 wk of HS to 26% by 3 wk of HS. Most fibers showed an increased unloaded maximal shortening velocity (V sub O)), but myosin heavy chain remained entirely slow type I. The mechanism for increased V(sub O) is unknown. There was a progressive decrease in fiber diameter and peak force after 1, 2, and 3 wk of HS, respectively. One week of HS resulted in a shift of the force-velocity curve, and between 2 and 3 wk of HS the curve shifted further such that V(sub O) was higher than control at all relative loads less than 45% peak isometric force. Peak absolute power output of soleus fibers progressively decreased through 2 wk of HS but showed no further change at 3 wk. The results suggest that between 2 and 3 wk the HS-induced alterations in the force-velocity relationship act to maintain the power output of single soleus fibers despite a continued reduction in fiber force.

Mcdonald, K. S.↗
NASA NTRS1983

On the Mechanism of Serotonin-Induced Dipsogenesis in the Rat

Subcutaneous administration of 1-5-hydroxytryptophan (5-HTP), the precursor of serotonin, to female rats induces copious drinking accompanied by activation of the renin-angiotensin system. Neither a reduction in blood pressure nor body temperature accompanied administration of 5-HTP. The objective of the present study was to determine whether serotonin-induced dipsogenesis, like that of 5-HTP, is mediated via the renin-angiotensin system. Serotonin (2 mg/kg, SC)-induced drinking was inhibited by the dopaminergic antagonist, haloperidol (150 /micro g/kg, IP), which also inhibits angiotensin II-induced drinking, Both captopril (35 mg/kg, IP), an angiotensin converting enzyme inhibitor, and propranolol (6 micro g/kg, IP), a beta-adrenergic antagonist, blocked serotonin-induced dipsogenesis. The alpha(sub a),-adrenergic agonist, clonidine (6.25 micro g/kg, SC), which suppresses renin release from the kidney, attenuated serotonin-induced water intake. The dipsogenic responses to submaximal concentrations of both serotonin (1 mg/kg, SC) and isoproterenol (8 micro g/kg, SC) were additive rather than interactive suggesting that similar pathways mediate both responses. The serotonergic receptor antagonist, methysergide (3 mg/kg, IP), inhibited serotonin-induced drinking but had no effect on isoproterenol (25micro g/kg, SC)-induced dipsogenesis. However, neither serotonin (2 mg/kg, SC) nor isoproterenol (25 micro g/kg, SC)-induced drinking was inhibited by cinansefin (25 micro g/kg, IP). These data indicate that serotonin induces drinking in rats via the renin-angiotensin system. However, the results of the studies using methysergide suggest that scrotonin appears to act at a point prior to activation of beta-adrenoceptors in the pathway leading to release of renin from the kidneys.

Kikta, Dianne C.↗
NASA NTRS1995

Simulating the dynamic interaction of a robotic arm and the Space Shuttle remote manipulator system

Industrial robots are usually attached to a rigid base. Placing the robot on a compliant base introduces dynamic coupling between the two systems. The Vehicle Emulation System (VES) is a six DOF platform that is capable of modeling this interaction. The VES employs a force-torque sensor as the interface between robot and base. A computer simulation of the VES is presented. Each of the hardware and software components is described and Simulink is used as the programming environment. The simulation performance is compared with experimental results to validate accuracy. A second simulation which models the dynamic interaction of a robot and a flexible base acts as a comparison to the simulated motion of the VES. Results are presented that compare the simulated VES motion with the motion of the VES hardware using the same admittance model. The two computer simulations are compared to determine how well the VES is expected to emulate the desired motion. Simulation results are given for robots mounted to the end effector of the Space Shuttle Remote Manipulator System (SRMS). It is shown that for fast motions of the two robots studied, the SRMS experiences disturbances on the order of centimeters. Larger disturbances are possible if different manipulators are used.

Garrahan, Steven L.↗
NASA NTRSDate not supplied

CLINICAL DECISION SUPPORT: PATH TO FUNCTIONAL REQUIREMENTS

Long-duration, deep-space exploration missions present significant challenges to crew health and performance. These challenges include the individual and combined effects of microgravity, radiation exposure, isolation, limited resources (mass, volume, power, data and crew time), limited options for evacuation and those associated with delayed or constrained communications, all of which demand greater crew autonomy. Specifically, as the communication delays intensify the further we explore space, the unqualified need for Earth-independent medical operations focused on autonomous diagnosis, treatment and prevention will be key to mission continuation and success. To augment the requisite knowledge, skills and abilities (KSAs) of a time-constrained crew operating under stressful conditions, combatting fatigue, and facing a potential medical crisis, a robust clinical decision support system (CDSS) is a probable solution that would facilitate, guide and inform Earth-independent medical operations, while assisting crewmembers through various clinical presentations. The Exploration Medical Capability (ExMC) Element of the Human Research Program (HRP) is expanding the boundaries of space medical systems to advance the care of astronauts on future exploration missions beyond low Earth orbit. ExMC is actively identifying and testing next-generation medical care and crew health maintenance technologies. The Clinical Decision Support (CDS) project addresses gap Medical-701 within the Inflight Medical Conditions risk: “Enhance medical capabilities within an exploration medical system.” Though mass, volume, and power will face increasing constraints, the projected computational capabilities of spacecraft systems will increase exponentially as information technology continues to advance this decade and beyond. Hence, data, software and computational resources will play an essential and synergistic role in maintaining crew health, wellness and performance in deep space missions. The focus of the CDS project is to develop recommended requirements for an in-vehicle CDSS that acts as a ‘virtual assistant’ for delivering optimal health, performance and medical care during exploration missions. The CDSS is envisioned as an integrated, software-based tool deployed on a laptop computer or handheld device. The CDSS will assist the crew and ground support when interacting with knowledge/databases (e.g. records, pharmacy, schedule), instrumentation (e.g. imaging, physiological monitoring devices), and habitat (e.g. wellness system, task performance system) and vehicle systems (e.g. environmental system, communication system). In addition, the human interface will employ a context-based approach that accounts for the crew’s situation. Thus, extraneous and clinically/operationally non-relevant information are reduced to avoid an increase in cognitive load. The framework of an ideal spaceflight CDSS is to include core and advanced analytical features that incorporate work from collaborators yet maintain a flexible platform for integrating new technology in the future. In fiscal year 2021 (FY21), the CDS project identified requirements through two primary mechanisms: (i) the development of software implementation prototypes and (ii) the application of systems engineering processes. The CDS project developed and tested a series of increasingly complex system prototypes that were based on use cases derived from the CDSS concept of operations (ConOps). These software implementations yielded insights on CDSS functionality as well as lessons learned that provided the initial requirements for CDSS capability. By applying a systems engineering (SE) approach, medical scenarios provided in the ConOps and the use cases for software implementation underwent functional decomposition to identify CDSS functionality. Also, systems-based modeling language (SysML) tools such as activity diagrams were developed from the same ConOps and use cases to identify CDSS functionality. The lessons learned from software implementation defined both specific requirements and broad areas of requirements. Within these defined broad requirement areas, further analysis of the SE products identified specific capability that resulted in the final functional requirements. In summary, the software prototypes, functional decomposition of the ConOps and use cases, and SysML diagrams provided the basis for the CDSS requirements developed in FY21. In the upcoming year, these requirements will be refined for their final ExMC baseline review in latter FY22.

clinical decision support↗