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NASA NTRSDate not supplied

Revisiting MEDLI with Improved Modeling and Simulation Tools

The thermal protection system (TPS) of the Mars 2020 capsule will carry a suite of sensors called MEDLI2 (Mars Entry, Descent, and Landing Instrument 2). This suite consists of pressure sensors/transducers and thermocouple plugs meant to measure atmospheric properties, vehicle attitude, TPS performance, etc. While the suite is similar to that carried on the successful MSL (Mars Science Laboratory) mission in 2012, it now includes pressure sensors, thermocouple plugs, and radiometers on the backshell as well. An analysis plan is therefore necessary to help with the interpretation of flight measurements.

Atmospheric Entry↗

NASA NTRS1995

Long-term total solar irradiance variability during sunspot cycle 22

Total solar irradiance measurements from the 1984-1993 Earth Radiation Budget Satellite (ERBS) active cavity radiometer and 1978-1993 Nimbus 7 transfer cavity radiometer spacecraft experiments are analyzed to detect the presence of 11-, 22-, and 80-year irradiance variability components. The analyses confirmed the existence of a significant 11-year irradiance variability component, associated with solar magnetic activity and the sunspot cycle. The analyses also suggest the presence of a 22- or 80-year variability component. The earlier Nimbus 7 and Solar Maximum Mission (SMM) spacecraft irradiance measurements decreased approximately 1.2 and 1.3 W/sq m, respectively, between 1980 and 1986. The Nimbus 7 values increased 1.2 W/sq m between 1986 and 1989. The ERBS irradiance measurements increased 1.3 W/sq m during 1986-1989, and then decreased 0.4 W/sq m (at an annual rate of 0.14 W/sq. m/yr) during 1990-1993. Considering the correlations between ERBS, Nimbus 7, and SMM irradiance trends and solar magnetic activity, the total solar irradiance should decrease to minimum levels by 1997 as solar activity decreases to minimum levels, and then increase to maximum levels by the year 2000 as solar activity rises. The ERBS measurements yielded 165.4 +/- 0.7 W/sq m as the mean irradiance value with measurement accuracies and precisions of 0.2% and 0.02%, respectively. The ERBS mean irradiance value is within 0.2% of the 1367.4, 1365.9, and 1366.9 W/sq m mean values for the SMM, Upper Atmosphere Research Satellite (UARS), and Space Shuttle Atmospheric Laboratory for Applications and Science (ATLAS 1) Solar Constant (SOLCON) active cavity radiometer spacecraft experiments, respectively. The Nimbus 7 measurements yielded 1372.1 W/sq m as the mean value with a measurement accuracy of 0.5%. Empirical irradiance model fits, based upon 10.7 -cm solar radio flux (F10) and photometric sunspot index (PSI), were used to assess the quality of the ERBS, Numbus 7, SMM, and the UARS irradiance data sets and to identify irradiance variability trends which may be caused by drifts or shifts in the spacecraft sensor responses. Comparisons among the fits and measured irradiances indicate that the Nimbus 7 radiometer response shifted by a total of 0.8 W/sq m between September 1989 and April 1990 and that the ERBS and UARS radiometers each drifted approximately 0.5 W/sq m during the first 5 months in orbit.

Lee, Robert B., III↗

NASA NTRS2019

Revolutionizing our Understanding of the Solar System via Sample Return from Mercury

Data from Mariner 10, MESSENGER, and ground-based telescopic observations have facilitated great advancements towards understanding the geochemistry, geology, internal structure, exosphere, and magnetosphere of Mercury. However, there are critical science questions that can be only addressed via examination of a sample in Earth-based laboratories, where numerous highly sensitive analytical measurements are possible. Collecting a sample from the surface of Mercury and bringing it to Earth for in-depth analysis would allow for transformative Solar System science to be conducted, examining aspects of our Solar System such as the evolution of the protoplanetary disk, space weathering on airless bodies, the geochemical behavior of elements at extreme conditions, and the origin and distribution of volatiles across the terrestrial planets. Furthermore, our knowledge of Mercury’s differentiation and geochemical processes, chronology and geologic evolution, tectonism and geomechanical properties, and past and ongoing magnetism would be greatly advanced via analysis of a sample from Mercury. Although there are ample challenges and knowledge gaps associated with sample return from Mercury in terms of both spacecraft requirements and material requirements for curatorial facilities, a sample from the planet would be an invaluable scientific resource for generations to come, enabling the most sophisticated measurements to be brought to bear for decades and helping to truly unlock the mysteries of our Solar System.

Vander Kaaden, Kathleen E.↗

NASA NTRS1987

Compositional information for the Moon: Some characteristics of current near-IR spectra (telescopic and laboratory)

For the last decade telescopic near infrared spectra have been obtained for small lunar areas. Such spectra, with the ground truth foundation from lunar samples, have been used extensively to address a multitude of problems in lunar science. Much of the near infrared spectral reflectance data from both laboratory and telescopic measurements have recently been compiled in comparable formats and an initial comparative assessment of the available data using selected spectral parameters has been made. The objective is to develop a framework for the systematics of lunar near-IR spectra in order to better interpret spectra of unknown materials in terms of useful compositional information. Each spectrum was first classified according to its general character then a variety of parameters sensitive to mineralogy and alteration products were measured for each spectrum: band width, band strength, absorption band center near 1 micron, band symmetry, continuum slope, etc. The telescopic and laboratory data sets are briefly described. The comparative analysis shows that a few well known lunar spectral properties are evident in both sets, such as the systematic variation in pyroxene composition between the highlands and the mare. However, an additional gabbroic component can be detected in many highland craters.

Pieters, Carle M.↗

NASA NTRS1983

Metric analysis and data validation across FORTRAN projects

The desire to predict the effort in developing or explaining the quality of software has led to the proposal of several metrics. As a step toward validating these metrics, the Software Engineering Laboratory (SEL) has analyzed the software science metrics, cyclomatic complexity, and various standard program measures for their relation to effort (including design through acceptance testing), development errors (both discrete and weighted according to the amount of time to locate and fix), and one another. The data investigated are collected from a project FORTRAN environment and examined across several projects at once, within individual projects and by reporting accuracy checks demonstrating the need to validate a database. When the data comes from individual programmers or certain validated projects, the metrics' correlations with actual effort seem to be strongest. For modules developed entirely by individual programmers, the validity ratios induce a statistically significant ordering of several of the metrics' correlations. When comparing the strongest correlations, neither software science's E metric cyclomatic complexity not source lines of code appears to relate convincingly better with effort than the others.

Basili, Victor R.↗

NASA NTRS1992

ATMOS: Long term atmospheric measurements for mission to planet Earth

A long-term, space-based measurement program, together with continued balloon and aircraft-borne investigations, is essential to monitor the predicted effects in the atmosphere, to determine to what extent the concentration measurements agree with current models of stratospheric chemistry, and to determine the condition of the ozone layer. The Atmospheric Trace Molecule Spectroscopy (ATMOS) Experiment is currently making comprehensive, global measurements of Earth's atmosphere as part of the Atmospheric Laboratory for Applications and Science (ATLAS) program on the Space Shuttle. Part of NASA's Mission to Planet Earth, ATLAS is a continuing series of missions to study Earth and the Sun and provide a more fundamental understanding of the solar influences on Earth's atmosphere. The ATMOS program, instruments, and science results are presented.

Source record↗

NASA NTRS2003

Laser Remote Sensing and Lidar Measurements for Planetary Bodies

Laser Remote Sensing and lidar have been used for earth remote sensing for a number of years however the inefficiency of laser devices has limited their application to planetary sensing where power is at a premium. The potential availability of a large amount of power for the Jupiter Icy Moons Orbiter (JIMO) opens up the potential to implement laser remote sensing for planetary bodies. Lidars have been and can be used to map terrain, measure atmospheric and surface parameters including velocity and composition. In this paper we will provide an overview of the lidar capabilities at the Jet Propulsion Laboratory and address the types of lidar measurements that could be relevant to JIMO science investigations.

Spiers, G. D.↗

NASA NTRS2012

Detecting Organic Compounds Released from Iron Oxidizing Bacteria using Sample Analysis at Mars (SAM) Like Instrument Protocols

Mars is a planet of great interest for Astrobiology since its past environmental conditions are thought to have been favourable for the emergence life. At present, the Red Planet is extremely cold and dry and the surface is exposed to intense UV and ionizing radiation, conditions generally considered to be incompatible with life as we know it on Earth. It was proposed that the shallow subsurface of Mars, where temperatures can be above freezing and liquid water can exist on rock surfaces, could harbor chemolithoautotrophic bacteria such as the iron oxidizing microorganism Pseudomonas sp. HerB. The Mars Science Laboratory (MSL) mission will provide the next opportunity to carry out in situ measurements for organic compounds of possible biological origin on Mars. One instrument onboard MSL, called the Sample Analysis at Mars (SAM) instrument suite, will carry out a broad and sensitive search for organic compounds in surface samples using either high temperature pyrolysis or chemical extraction followed by gas chromatography mass spectrometry. We present gas chromatograph mass spectrometer (GC/MS) data on crushed olivine rock powders that have been inoculated with Pseudomonas sp. HerB at different concentrations ranging from approx 10(exp 2) to 10(exp 7) cells per gram. The inoculated olivine samples were heated under helium carrier gas flow at 500 C and the pyrolysis products concentrated using a SAM-like hydrocarbon trap set at -20 C followed by trap heating and analysis by GC/Ms. In addition, the samples were also extracted using a low temperature "one-pot" chemical extraction technique using N-methyl, N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) as the silylating agent prior to GC/MS analysis. We identified several aldehydes, thiols, and alkene nitriles after pyrolysis GC/MS analysis of the bacteria that were not found in the olivine control samples that had not been inoculated with bacteria. The distribution of pyrolysis products extracted from the bacteria was clearly distinct from similar GC/MS analyses of the carbonaceous meteorite Murchison that was dominated by sulfur containing aromatic compounds. A similar comparison, if organic compounds are detected by SAM on Mars, could be useful to help discriminate between meteoritic or biological origins.

Glavin, D. P.↗

NASA NTRS1996

On the Assessment and Uncertainty of Atmospheric Trace Gas Burden Measurements with High Resolution Infrared Solar Occultation Spectra from Space by the ATMOS Experiment

The Atmospheric Trace Molecule Spectroscopy (ATMOS) instrument is a high resolution Fourier transform spectrometer that measures atmospheric composition from low Earth orbit with infrared solar occultation sounding in the limb geometry. Following an initial flight in 1985, ATMOS participated in the Atmospheric Laboratory for Applications and Science (ATLAS) 1, 2, and 3 Space Shuttle missions in 1992, 1993, and 1994 yielding a total of 440 occultation measurements over a nine year period. The suite of more than thirty atmospheric trace gases profiled includes CO2, O3, N2O, CH4, H2O, NO, NO2, HNO3, HCl, HF, ClONO2, CCl3F, CCl2F2, CHF2Cl, and N2O5. The analysis method has been revised throughout the mission years culminating in the 'version 2' data set. The spectroscopic error analysis is described in the context of supporting the precision estimates reported with the profiles; in addition, systematic uncertainties assessed from the quality of the spectroscopic database are described and tabulated for comparisons with other experiments.

Abrams, M. C.↗

NASA NTRS2016

Overview of the Radiation Dosimetry Experiment (RaD-X) Flight Mission

The NASA Radiation Dosimetry Experiment (RaD-X) stratospheric balloon flight mission addresses the need to reduce the uncertainty in predicting human exposure to cosmic radiation in the aircraft environment. Measurements were taken that characterize the dosimetric properties of cosmic ray primaries, the ultimate source of aviation radiation exposure, and the cosmic ray secondary radiations that are produced and transported to aviation altitudes. In addition, radiation detectors were flown to assess their potential application to long-term, continuous monitoring of the aircraft radiation environment. RaD-X was successfully launched from Fort Sumner, New Mexico (34.5 N, 104.2 W), on 25 September 2015. Over 18 h of science data were obtained from a total of four different type dosimeters at altitudes above 20 km. The RaD-X flight mission was supported by laboratory radiation exposure testing of the balloon flight dosimeters and also by coordinated radiation measurements taken on ER-2 and commercial aircraft. This paper provides the science background and motivation for the RaD-X flight mission, a brief description of the balloon flight profile and the supporting aircraft flights, and a summary of the articles included in the RaD-X special collection and their contributions to the science goals of the RaD-X mission.

Mertens, Christopher J.↗

NASA NTRS1989

Establishing a measurement based maintenance improvement program - Lessons learned in the SEL

The Software Engineering Laboratory (SEL) is a joint venture between NASA's Goddard Space Flight Center, the University of Maryland, and Computer Sciences Corporation. The use of a goal-oriented approach to measurement to establish a maintenance improvement program within the SEL is discussed. Differences are found to exist between the initial phase of the program and its routine application. This approach is demonstrated through concrete examples, and lessons learned in the establishment of a measurement based, maintenance improvement program are summarized.

Rombach, H. Dieter↗

NASA NTRS2020

NISAR flight feed passive antenna measurements

NISAR (NASA ISRO SAR, National Aeronautics and Space Administration, Indian Space Research Organization, Synthetic Aperture Radar) is an Earth science project currently in its final development phase at NASA Jet Propulsion Laboratory (JPL) and at ISRO. Due for launch in 2022 it will assess how our planet changes over time by measuring differences in the Earth’s solid surface due to factors like climate change, movement and melting of glaciers, earthquakes, land-slides, deforestation, agriculture and others. The enabling instrument for this mission is a dual band radar (L-band and S-band) that feeds a 12m deployable mesh reflector. This paper describes the measurement campaign of the L-band flight feed in its passive configuration. Further measurements will be done using the antenna with the active radar components but they are not part of this paper.

Harrell, Jefferson A.↗

NASA NTRS2022

NISAR Flight Feed Passive Antenna Measurements

Harrell, Jefferson A.↗

NASA NTRS2019

NISAR flight feed assembly measurement campaign

NISAR (NASA ISRO SAR, National Aeronautics and Space Administration, Indian Space Research Organization, Synthetic Aperture Radar) is an Earth science project currently in its final development phase at NASA Jet Propulsion Laboratory (JPL) and at ISRO. Due for launch in 2022, it will assess how our planet changes overtime by measuring differences in the Earth’s solid surface due to factors like climate change, movement and melting of glaciers, earthquakes, land-slides, deforestation, agriculture and others. The enabling instrument for this mission is a dual band radar (L-Band and S-Band) that feeds a 12m deployable mesh reflector. This paper describes the antenna measurement campaign of the L-Band feed array developed at JPL. The SBand feed array is developed by ISRO and is not part of this paper. While Measurements of the Engineering Model have been published before, this paper focuses on the first measurements done with the Flight Model.

Harrell, Jefferson A.↗

NASA NTRS1998

The Physics of Hard Spheres Experiment on MSL-1: Required Measurements and Instrument Performance

The Physics of HArd Spheres Experiment (PHaSE), one of NASA Lewis Research Center's first major light scattering experiments for microgravity research on complex fluids, flew on board the Space Shuttle's Microgravity Science Laboratory (MSL-1) in 1997. Using colloidal systems of various concentrations of micron-sized plastic spheres in a refractive index-matching fluid as test samples, illuminated by laser light during and after crystallization, investigations were conducted to measure the nucleation and growth rate of colloidal crystals as well as the structure, rheology, and dynamics of the equilibrium crystal. Together, these measurements support an enhanced understanding of the nature of the liquid-to-solid transition. Achievement of the science objectives required an accurate experimental determination of eight fundamental properties for the hard sphere colloidal samples. The instrument design met almost all of the original measurement requirements, but with compromise on the number of samples on which data were taken. The instrument performs 2-D Bragg and low angle scattering from 0.4 deg. to 60 deg., dynamic and single-channel static scattering from 10 deg. to 170 deg., rheology using fiber optics, and white light imaging of the sample. As a result, PHaSE provided a timely microgravity demonstration of critical light scattering measurement techniques and hardware concepts, while generating data already showing promise of interesting new scientific findings in the field of condensed matter physics.

Doherty, Michael P.↗

NASA NTRS2019

Vertical and Horizontal Heterogeneity of Atmospheric Dust Loading in Northern Gale Crater, Mars

This paper updates the record of atmospheric dust loading within northern Gale Crater, Mars, by providing line-of-sight extinction (LOS-Ext) measurements of the intervening dust between the rover and the crater rim. These measurements are derived from images taken with the Navigation Cameras (Navcam) onboard the Mars Science Laboratory (MSL) rover, Curiosity. The observations span 2.44 Mars years, from Mars Year (MY) 31 at a solar longitude (L(sub s)) of 208° to t L(sub s) = 7° of MY34, sols 100–1701 of the MSL surface mission. This work examines the dataset for seasonal trends of the LOS-Ext in addition to horizontal variations and the vertical structure of LOS-Ext. The LOS-Ext has a repetitive pattern with a single peak in the latter half of the Mars year. The atmosphere in the crater is well mixed horizontally but not vertically as larger LOS-Ext is seen nearer the crater floor than at higher altitudes within the crater. The results allow a discussion on whether or not Gale Crater is a sink for atmospheric dust or a source of atmospheric dust in the current era.

Casey A. Moore↗

NASA NTRS2021

CME Magnetic Structure and IMF Preconditioning Affecting SEP Transport

Coronal mass ejections (CMEs) and solar energetic particles (SEPs) are two manifestations of the various solar phenomena that are known to cause severe space weather effects throughout the heliosphere. The evolution of CMEs after eruption, especially in terms of their magnetic structure, and the configuration of the interplanetary magnetic field (IMF) that influences the transport of SEPs are currently areas of active research. These two aspects are not necessarily independent of each other, especially during solar maximum when multiple eruptive events can occur close in time. Accordingly, we present in this work theanalysis of a CME that erupted from the Sun on 2012 May 11 (SOL2012-05-11) and an SEP event following an eruption that took place on 2012 May 17 (SOL2012-05-17),∼20◦in both latitude and longitude away from the May 11 CME source region. After observing in detailthe eruption and early evolution of the May 11 CME using remote-sensing data from three viewpoints, we evaluate its propagation through interplanetary space using several models.Then, we analyse in-situ measurements from five predicted impact locations (Venus, Earth, the Spitzer Space Telescope, the Mars Science Laboratory en route to Mars, and Mars) in the inner heliosphere in order to search for CME signatures. We find that all five in-situlocations detect signatures of an impulsive SEP event, which we trace back to the May 17 eruption. These findings suggest that the May 11 CME, which was crossing the various locations around the time of the May 17 eruption, provided a direct magnetic connectivityfor the efficient transport of SEPs with an impulsive profile. We discuss the space weather implications of CME evolution, regarding in particular its magnetic structure, and CME-driven IMF preconditioning that facilitates SEP transport from a later event. Finally, this work remarks the importance of the availability of data from multiple spacecraft, even those that do not include space weather research as their primary objective.

Erika Palmerio↗

NASA NTRS1998

Atmos/Atlas 3 Infrared Profile Measurements of Trace Gases in The November 1994 Tropical and Subtropical Upper Troposphere

Vertical mixing ratio profiles of four relatively long-lives gases, HCN, C2H2, CO, and C2H6, have been retrieved from 0.01/cm resolution infrared solar occultation spectra recorded between latitudes of 5.3degN and 31.4degN. The observations were obtained by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the Atmospheric Laboratory for Applications and Science (ATLAS) 3 shuttle flight, 3-12 November 1994. Elevated mixing ratios below the tropopause were measured for these gases during several of the occultations. The positive correlations obtained between the simultaneously measured mixing ratios suggest that the enhancements are likely the result of surface emissions, most likely biomass burning and/or urban industrial activities, followed by common injection via deep convective transport of the gases to the upper troposphere. The elevated levels of HCN may account for at least part of the "missing NO," in the upper troposphere. Comparisons of the observations with values measured during a recent aircraft campaign are presented.

Rinsland, C. P.↗