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NASA NTRS1979

The LACIE crop years: An assessment of the crop conditions experienced in the three years of LACIE

Meteorological data and LANDSAT spectral data from growing regions in the U.S. Great Plains, the U.S.S.R., and Canada were used to assess growing conditions and to document where anomalies such as drought, floods, and freezes were impacting the crop yield and appearance of spring and winter wheat. In the United States, the weekly rainfall and temperature data were used to estimate soil moisture, which was then related to crop needs by a crop moisture index. The transformation of LANDSAT digital data into a green index number provided a procedure whereby data from a LACIE segment could be classified as drought affected or not. The growing seasons encountered in each LACIE country during the three phases are described.

Hill, J. D.↗

NASA NTRS1997

Comparison of registration techniques for GOES visible imagery data

This paper briefly describes and then compares the effectiveness of five image registration approaches for GOES visible band imagery. The techniques compared are (1) NOAA "point" manual landmarking, (2) manual landmarking on extant feature (whole island, lake, etc.), (3) automatic phase correlation, (4) automatic spatial correlation on edge features, and (5) automatic spatial correlation of region boundaries derived from image segmentation.

Tilton, James C.↗

NASA NTRS1999

A mechanical energy analysis of gait initiation

The analysis of gait initiation (the transient state between standing and walking) is an important diagnostic tool to study pathologic gait and to evaluate prosthetic devices. While past studies have quantified mechanical energy of the body during steady-state gait, to date no one has computed the mechanical energy of the body during gait initiation. In this study, gait initiation in seven normal male subjects was studied using a mechanical energy analysis to compute total body energy. The data showed three separate states: quiet standing, gait initiation, and steady-state gait. During gait initiation, the trends in the energy data for the individual segments were similar to those seen during steady-state gait (and in Winter DA, Quanbury AO, Reimer GD. Analysis of instantaneous energy of normal gait. J Biochem 1976;9:253-257), but diminished in amplitude. However, these amplitudes increased to those seen in steady-state during the gait initiation event (GIE), with the greatest increase occurring in the second step due to the push-off of the foundation leg. The baseline level of mechanical energy was due to the potential energy of the individual segments, while the cyclic nature of the data was indicative of the kinetic energy of the particular leg in swing phase during that step. The data presented showed differences in energy trends during gait initiation from those of steady state, thereby demonstrating the importance of this event in the study of locomotion.

Leg/physiology↗

NASA NTRS2006

Spacebased Observations of Oceanic Influence on the Annual Variation of South American Water Balance

The mass change of South America (SA) continent measured by the Gravity Recovery and Climate Experiment (GRACE) imposes a constraint on the uncertainties in estimating the annual variation of rainfall measured by Tropical Rain Measuring Mission (TRMM) and ocean moisture influx derived from QuikSCAT data. The approximate balance of the mass change rate with the moisture influx less climatological river discharge, in agreement with the conservation principle, bolsters not only the credibility of the spacebased measurements, but supports the characterization of ocean's influence on the annual variation of continental water balance. The annual variation of rainfall is found to be in phase with the mass change rate in the Amazon and the La Plata basins, and the moisture advection across relevant segments of the Pacific and Atlantic coasts agrees with the annual cycle of rainfall in the two basins and the Andes mountains.

rainfall annual cycle↗

NASA NTRS2012

The Building Blocks for JWST I and T (Integrations and Test) to Operations - From Simulator to Flight Units

The James Webb Space Telescope (JWST) Project has an extended integration and test (I&T) phase due to long procurement and development times of various components as well as recent launch delays. The JWST Ground Segment and Operations group has developed a roadmap of the various ground and flight elements and their use in the various JWST I&T test programs. The JWST Project s building block approach to the eventual operational systems, while not new, is complex and challenging; a large-scale mission like JWST involves international partners, many vendors across the United States, and competing needs for the same systems. One of the challenges is resource balancing so simulators and flight products for various elements congeal into integrated systems used for I&T and flight operations activities. This building block approach to an incremental buildup provides for early problem identification with simulators and exercises the flight operations systems, products, and interfaces during the JWST I&T test programs. The JWST Project has completed some early I&T with the simulators, engineering models and some components of the operational ground system. The JWST Project is testing the various flight units as they are delivered and will continue to do so for the entire flight and operational system. The JWST Project has already and will continue to reap the value of the building block approach on the road to launch and flight operations.

Fatig, Curtis↗

NASA NTRS2002

Retinoid quantification by HPLC/MS(n)

Retinoic acid (RA) mediates most of the biological effects of vitamin A that are essential for vertebrate survival. It acts through binding to receptors that belong to the nuclear receptor transcription factor superfamily (Mangelsdorf et al. 1994). It is also a highly potent vertebrate teratogen. To determine the function and effects of endogenous and exogenous RA, it is important to have a highly specific, sensitive, accurate, and precise analytical procedure. Current analyses of RA and other retinoids are labor intensive, of poor sensitivity, have limited specificity, or require compatibility with RA reporter cell lines (Chen et al. 1995. BIOCHEM: Pharmacol. 50: 1257-1264; Creech Kraft et al. 1994. BIOCHEM: J. 301: 111-119; Lanvers et al. 1996. J. Chromatogr. B Biomed. Appl. 685: 233-240; Maden et al. 1998. DEVELOPMENT: 125: 4133-4144; Wagner et al. 1992. DEVELOPMENT: 116: 55-66). This paper describes an HPLC/mass spectrometry/mass spectrometry product ion scan (HPLC/MS(n)) procedure for the analysis of retinoids that employs atmospheric pressure chemical ionization MS. The retinoids are separated by normal-phase column chromatography with a linear hexane-isopropanol-dioxane gradient. Each retinoid is detected by a unique series of MS(n) functions set at optimal collision-induced dissociation energy (30% to 32%) for all MS(n) steps. The scan events are divided into three segments, based on HPLC elution order, to maximize the mass spectrometer duty cycle. The all-trans, 9-cis, and 13-cis RA isomers are separated, if desired, by an isocratic hexane-dioxane-isopropanol mobile phase. This paper describes an HPLC/MS(n) procedure possessing high sensitivity and specificity for retinoids.

NASA Discipline Developmental Biology↗

NASA NTRS2009

Model Validation of an RSRM Transporter Through Full-scale Operational and Modal Testing

The Reusable Solid Rocket Motor (RSRM) segments, which are part of the current Space Shuttle system and will provide the first stage of the Ares launch vehicle, must be transported from their manufacturing facility in Promontory, Utah, to a railhead in Corinne, Utah. This approximately 25-mile trip on secondary paved roads is accomplished using a special transporter system which lifts and conveys each individual segment. ATK Launch Systems (ATK) has recently obtained a new set of these transporters from Scheuerle, a company in Germany. The transporter is a 96-wheel, dual tractor vehicle that supports the payload via a hydraulic suspension. Since this system is a different design than was previously used, computer modeling with validation via test is required to ensure that the environment to which the segment is exposed is not too severe for this space-critical hardware. Accurate prediction of the loads imparted to the rocket motor is essential in order to prevent damage to the segment. To develop and validate a finite element model capable of such accurate predictions, ATA Engineering, Inc., teamed with ATK to perform a modal survey of the transport system, including a forward RSRM segment. A set of electrodynamic shakers was placed around the transporter at locations capable of exciting the transporter vehicle dynamics. Forces from the shakers with varying phase combinations were applied using sinusoidal sweep excitation. The relative phase of the shaker forcing functions was adjusted to match the shape characteristics of each of several target modes, thereby customizing each sweep run for exciting a particular mode. The resulting frequency response functions (FRF) from this series of sine sweeps allowed identification of all target modes and other higher-order modes, allowing good comparison to the finite element model. Furthermore, the survey-derived modal frequencies were correlated with peak frequencies observed during road-going operating tests. This correlation enabled verification of the most significant modes contributing to real-world loading of the motor segment under transport. After traditional model updating, dynamic simulation of the transportation environment was compared to the measured operating data to provided further validation of the analysis model. KEYWORDS Validation, correlation, modal test, rocket motor, transporter

Brillhart, Ralph↗

NASA NTRS1989

Active wavefront control challenges of the NASA Large Deployable Reflector (LDR)

The 20-m Large Deployable Reflector will have a segmented primary mirror. Achieving diffraction-limited performance at 50 microns requires correction for the errors of tilt and piston of the primary mirror. This correction can be obtained in two ways, the use of an active primary or a correction at a demagnified pupil of the primary. A critical requirement is the means for measurement of the wavefront error and maintaining phasing during the observation of objects that may be too faint for determining the error. Absolute phasing can only be determined using a cooperative source. Maintenance of phasing can be done with an on-board source. A number of options are being explored as discussed below. The many issues concerning the assessment and control of an active segmented mirror will be addressed with an early construction of the Precision Segmented Reflector testbed.

Meinel, Aden B.↗

NASA NTRS1993

The time keeping system for GPS block IIR

The precision time keeping system (TKS) in the Global Positioning System (GPS), Block IIR satellites is designed to operate under severe natural and man made environmental conditions. The Block IIR TKS provides precise, autonomous time keeping for periods of up to seven months, without the intervention of the GPS Control Segment. The TKS is implemented using both linear and non-linear controls. The resulting TKS architecture uses a hybrid analog/digital phase locked loop (PLL). The paper provides details of the design and analysis of the TKS. The simulation techniques and the test bed activities used in performing the TKS design trade-offs are described. The effects of non-linear controls are analyzed using a TKS computer simulation of the PLL. The results from a hardware test bed are provided that verify desired TKS operation. The design criteria for the TKS computer simulation and the hardware test bed are indicated. The concepts for verification and testing of the TKS computer simulation and hardware test bed are presented.

Rawicz, H. C.↗

NASA NTRS1995

Micron Accuracy Deployment Experiment (MADE), phase A. Volume 1

This report documents a Phase A In-STEP flight experiment development effort. The objective of the experiment is to deploy a portion of a segmented reflector on the Shuttle and study its micron-level mechanics. Ground test data are presented which projects that the on-orbit precision of the test article should be approximately 5 microns. Extensive hardware configuration development information is also provided.

Peterson, Lee D.↗

NASA NTRS1998

Design of Large Lightweight Space Telescope Optical Systems for the Next Generation Space Telescope

The Next Generation Space Telescope (NGST) is currently in a Pre Phase A study effort to prove feasibility of design and to show that the design can be implemented within cost constraint guidelines and meet the requirements of the science community. In an effort to achieve the science communities goals as outlined in "HST and Beyond" the NGST team has developed a government "yardstick" design of an eight meter diameter segmented telescope which would be launched in an Atlas IIAS launch vehicle to a L2 (Lagrange Point) orbit. This paper will discuss the design of the Optical Telescope Assembly (OTA) and the various issues and complications of designing lightweight optics to be placed in the environment that the NGST will encounter both during launch and during its operational mission at L2. The OTA must be lightweight but structurally must withstand the launch environment and transfer to its final L2 orbit. The OTA must be stable at L2 to provide high quality science at the cryogenic temperatures it will experience. The OTA segmented petal concept is to develop lightweight optics which can either be manipulated to achieve and maintain a desired figure or be rigid enough so that change in shape is only necessary for phasing and alignment. The secondary mirror structural mast must also be rigid with frequency responses which are not coupled to spacecraft modes in order to maintain and decenter and despace requirements.

Jacobson, Dave↗

NASA NTRS1976

Lacie phase 1 Classification and Mensuration Subsystem (CAMS) rework experiment

An experiment was designed to test the ability of the Classification and Mensuration Subsystem rework operations to improve wheat proportion estimates for segments that had been processed previously. Sites selected for the experiment included three in Kansas and three in Texas, with the remaining five distributed in Montana and North and South Dakota. The acquisition dates were selected to be representative of imagery available in actual operations. No more than one acquisition per biophase were used, and biophases were determined by actual crop calendars. All sites were worked by each of four Analyst-Interpreter/Data Processing Analyst Teams who reviewed the initial processing of each segment and accepted or reworked it for an estimate of the proportion of small grains in the segment. Classification results, acquisitions and classification errors and performance results between CAMS regular and ITS rework are tabulated.

Chhikara, R. S.↗

NASA NTRS1975

Amplitude-steered, pseudophased antenna array

Beam may be smoothly scanned around ring array without instantaneous phase transitions while maintaining constant radiated power by gradually transferring power from receding element to element next to leading edge of driven segment, and by accomplishing antenna element switching during intervals when no power is being applied to elements being switched.

Johnson, C. C.↗

NASA NTRS1994

Object recognition and pose estimation of planar objects from range data

The Extravehicular Activity Helper/Retriever (EVAHR) is a robotic device currently under development at the NASA Johnson Space Center that is designed to fetch objects or to assist in retrieving an astronaut who may have become inadvertently de-tethered. The EVAHR will be required to exhibit a high degree of intelligent autonomous operation and will base much of its reasoning upon information obtained from one or more three-dimensional sensors that it will carry and control. At the highest level of visual cognition and reasoning, the EVAHR will be required to detect objects, recognize them, and estimate their spatial orientation and location. The recognition phase and estimation of spatial pose will depend on the ability of the vision system to reliably extract geometric features of the objects such as whether the surface topologies observed are planar or curved and the spatial relationships between the component surfaces. In order to achieve these tasks, three-dimensional sensing of the operational environment and objects in the environment will therefore be essential. One of the sensors being considered to provide image data for object recognition and pose estimation is a phase-shift laser scanner. The characteristics of the data provided by this scanner have been studied and algorithms have been developed for segmenting range images into planar surfaces, extracting basic features such as surface area, and recognizing the object based on the characteristics of extracted features. Also, an approach has been developed for estimating the spatial orientation and location of the recognized object based on orientations of extracted planes and their intersection points. This paper presents some of the algorithms that have been developed for the purpose of recognizing and estimating the pose of objects as viewed by the laser scanner, and characterizes the desirability and utility of these algorithms within the context of the scanner itself, considering data quality and noise.

Pendleton, Thomas W.↗

NASA NTRS1995

Aircrew Discourse: Exploring Strategies of Information and Action Management

This paper explores methodology issues encountered in the analysis of flightcrew communications in aviation simulation research. Examples are provided by two recent studies which are compared on three issues: level of analysis, data definition, and interpretation of the results. The data discussed were collected in a study comparing two levels of aircraft automation. The first example is an investigation of how pilots' information transfer strategies differed as a function of automation during low and high-workload flight phases. The second study focuses on how crews managed actions in the two aircraft during a ten minute, high-workload flight segment. Results indicated that crews in the two aircraft differed in their strategies of information and action management. The differences are discussed in terms of their operational and research significance.

Irwin, Cheryl M.↗

NASA NTRS2003

Enhanced Large Solid Rocket Motor Understanding Through Performance Margin Testing: RSRM Five-Segment Engineering Test Motor (ETM-3)

The Five-Segment Engineering Test Motor (ETM-3) is an extended length reusable solid rocket motor (RSRM) intended to increase motor performance and internal environments above the current four-segment RSRM flight motor. The principal purpose of ETM-3 is to provide a test article for RSRM component margin testing. As the RSRM and Space Shuttle in general continue to age, replacing obsolete materials becomes an ever-increasing issue. Having a five-segment motor that provides environments in excess of normal opera- tion allows a mechanism to subject replacement materials to a more severe environment than experienced in flight. Additionally, ETM-3 offers a second design data point from which to develop and/or validate analytical models that currently have some level of empiricism associated with them. These enhanced models have the potential to further the understanding of RSRM motor performance and solid rocket motor (SRM) propulsion in general. Furthermore, these data could be leveraged to support a five-segment booster (FSB) development program should the Space Shuttle program choose to pursue this option for abort mode enhancements during the ascent phase. A tertiary goal of ETM-3 is to challenge both the ATK Thiokol Propulsion and NASA MSFC technical personnel through the design and analysis of a large solid rocket motor without the benefit of a well-established performance database such as the RSRM. The end result of this undertaking will be a more competent and experienced workforce for both organizations. Of particular interest are the motor design characteristics and the systems engineering approach used to conduct a complex yet successful large motor static test. These aspects of ETM-3 and more will be summarized.

Huppi, Hal↗

NASA NTRS2012

Re-Engineering the Mission Operations System (MOS) for the Prime and Extended Mission

One of the most challenging tasks in a space science mission is designing the Mission Operations System (MOS). Whereas the focus of the project is getting the spacecraft built and tested for launch, the mission operations engineers must build a system to carry out the science objectives. The completed MOS design is then formally assessed in the many reviews. Once a mission has completed the reviews, the Mission Operation System (MOS) design has been validated to the Functional Requirements and is ready for operations. The design was built based on heritage processes, new technology, and lessons learned from past experience. Furthermore, our operational concepts must be properly mapped to the mission design and science objectives. However, during the course of implementing the science objective in the operations phase after launch, the MOS experiences an evolutional change to adapt for actual performance characteristics. This drives the re-engineering of the MOS, because the MOS includes the flight and ground segments. Using the Spitzer mission as an example we demonstrate how the MOS design evolved for both the prime and extended mission to enhance the overall efficiency for science return. In our re-engineering process, we ensured that no requirements were violated or mission objectives compromised. In most cases, optimized performance across the MOS, including gains in science return as well as savings in the budget profile was achieved. Finally, we suggest a need to better categorize the Operations Phase (Phase E) in the NASA Life-Cycle Phases of Formulation and Implementation

Extended Mission↗

NASA NTRSDate not supplied

Intracranial Effects of Artificial Gravity: A 3T MRI Study

INTRODUCTION Spaceflight associated neuro-ocular syndrome (SANS) is characterized by the development of optic disc edema, posterior globe flattening, choroidal/retinal folds and hyperopic refractive errors1. SANS is hypothesized to be a result of headward fluid shifts that invariably occurs in the microgravity environment. As a countermeasure, artificial gravity (AG) through centrifugation has been proposed to reduce this headward fluid shift, however there is no current proof of benefit. The goal of this study was to determine if the application of AG can prevent or reduce known changes in brain volumetry, internal carotid artery (ICA) stroke volume and cerebral spinal fluid (CSF) flow velocity that occurs during simulated chronic headward fluid shift using head down tilt bed rest (HDTBR) methodology2 as an indicator of countermeasure efficacy. METHODS Healthy volunteers were recruited for an IRB approved HDTBR study performed at the German Aerospace Center in Cologne, Germany. Strict six-degree HDTBR was used as a spaceflight analog to induce a continuous headward fluid shift. HDTBR was carried out for 60 days for all subjects. Short-arm centrifugation was utilized to generate AG equating to ~0.3g of acceleration at the level of the eye. The subjects were divided equally into three groups: NoAG (control; n=8), daily intermittent AG (6 x 5 min iAG; n=8), and daily continuous 30 min (cAG; n=8). All studies were performed on a single dedicated 3T MRI Scanner. Pulse-gated MRI phase-contrast flow imaging was used to quantify ICA stroke volume and peak-to-peak CSF flow velocity in the mid cerebral aqueduct. 3D-SPGR was acquired for volumetric segmentation of the brain and CSF spaces. MRI acquisitions were obtained at baseline (BDC), 14 days into HDTBR (HDTBR14), 52 days into HDTBR (HDTBR52) and 3-5 days after HDTBR (recovery, R+3/5).The data were analyzed by the mixed model, which included intervention and time (BDC, HDTBR 14, HDTBR 52, R+3/5) as the fixed effects and included subject as the random effect.RESULTS24 healthy subject volunteers (16 men, 8 women, mean age = 33 years ± 9 [standard deviation] and mean BMI = 24.3 kg/m2 ± 2.0) successfully completed all phases of the study. Strict six-degree HDTBR was characterized by progressive and statistically significant (p<.01) increases in mean combined brain and CSF volumes and mean aqueductal CSF peak-to-peak flow velocity, as well as statistically significant (p<.01) progressive decrease in mean ICA stroke volume from baseline to 52 days post intervention (Figs. 1-3). Compared to baseline, only combined brain and CSF volumes did not return to baseline values in the recovery period (p=NS). Neither iAG nor cAG exerted any significant effects on the measured MRI brain parameters as compared to HDTBR alone (p=NS). CONCLUSION Our results indicate that HDTBR at 6-degrees was effective in producing alterations in ICA stroke volume, aqueductal CSF flow velocity, and combined brain and CSF volumetric change that is associated with chronic headward fluid shift. Short duration, 30-min daily exposure to either iAG or cAG appears to be insufficient in preventing or reducing the effects of chronic HDTBR and thus may not be a suitable countermeasure as currently deployed. AG protocol modifications, including increased duration and magnitude of exposure, should be considered for future research.

L A Kramer↗