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All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

HALOE Algorithm Improvements for Upper Tropospheric Soundings

This report details the ongoing efforts by GATS, Inc., in conjunction with Hampton University and University of Wyoming, in NASA's Mission to Planet Earth UARS Science Investigator Program entitled "HALOE Algorithm Improvements for Upper Tropospheric Sounding." The goal of this effort is to develop and implement major inversion and processing improvements that will extend HALOE measurements further into the troposphere. In particular, O3, H2O, and CH4 retrievals may be extended into the middle troposphere, and NO, HCl and possibly HF into the upper troposphere. Key areas of research being carried out to accomplish this include: pointing/tracking analysis; cloud identification and modeling; simultaneous multichannel retrieval capability; forward model improvements; high vertical-resolution gas filter channel retrievals; a refined temperature retrieval; robust error analyses; long-term trend reliability studies; and data validation. The current (first year) effort concentrates on the pointer/tracker correction algorithms, cloud filtering and validation, and multichannel retrieval development. However, these areas are all highly coupled, so progress in one area benefits from and sometimes depends on work in others.

Thompson, Robert E.↗
NASA NTRS2001

HALOE Algorithm Improvements for Upper Tropospheric Sounding

This report details the ongoing efforts by GATS, Inc., in conjunction with Hampton University and University of Wyoming, in NASA's Mission to Planet Earth UARS Science Investigator Program entitled "HALOE Algorithm Improvements for Upper Tropospheric Sounding." The goal of this effort is to develop and implement major inversion and processing improvements that will extend HALOE measurements further into the troposphere. In particular, O3, H2O, and CH4 retrievals may be extended into the middle troposphere, and NO, HCl and possibly HF into the upper troposphere. Key areas of research being carried out to accomplish this include: pointing/tracking analysis; cloud identification and modeling; simultaneous multichannel retrieval capability; forward model improvements; high vertical-resolution gas filter channel retrievals; a refined temperature retrieval; robust error analyses; long-term trend reliability studies; and data validation. The current (first year) effort concentrates on the pointer/tracker correction algorithms, cloud filtering and validation, and multichannel retrieval development. However, these areas are all highly coupled, so progress in one area benefits from and sometimes depends on work in others.

Thompson, Robert E.↗
NASA NTRS2001

HALOE Algorithm Improvements for Upper Tropospheric Sounding

This report details the ongoing efforts by GATS, Inc., in conjunction with Hampton University and University of Wyoming, in NASA's Mission to Planet Earth Upper Atmospheric Research Satellite (UARS) Science Investigator Program entitled 'HALOE Algorithm Improvements for Upper Tropospheric Sounding.' The goal of this effort is to develop and implement major inversion and processing improvements that will extend Halogen Occultation Experiment (HALOE) measurements further into the troposphere. In particular, O3, H2O, and CH4 retrievals may be extended into the middle troposphere, and NO, HCl and possibly HF into the upper troposphere. Key areas of research being carried out to accomplish this include: pointing/tracking analysis; cloud identification and modeling; simultaneous multichannel retrieval capability; forward model improvements; high vertical-resolution gas filter channel retrievals; a refined temperature retrieval; robust error analyses; long-term trend reliability studies; and data validation. The current (first year) effort concentrates on the pointer/tracker correction algorithms, cloud filtering and validation, and multichannel retrieval development. However, these areas are all highly coupled, so progress in one area benefits from and sometimes depends on work in others.

Thompson, Robert Earl↗
NASA NTRS2001

HALOE Temperature Data Comparison with Rocket-Borne Falling Sphere Temperatures

Recent comparison of upper stratospheric and mesospheric temperatures measured with the HALOE instrument on UARS and the rocket-borne passive inflatable falling sphere launched from Wallops Island reveals a temperature bias of up to 10 K between about 66 and 72 km. Falling sphere measurements analyzed between 1991 and 1995 were used in the comparison, however, these measurements were processed with an earlier version of the reduction software that included temperature bias in the region of 70 km. The bias arose from a discontinuity in the falling sphere drag table. This discontinuity occurs when the sphere's fall velocity changes from the supersonic to the subsonic flow regime and has been called the MACH 1 problem. Improvement to the software employed and the availability of a new atmospheric model is now used to initiate reduction of the radar tracking data. It is possible new reduction of the existing data will reduce the bias currently observed. We plan to show changes, if any, in the size of the bias between HALOE and the falling sphere temperatures after reprocessing of the sphere measurements.

Schmidlin, F. J.↗
NASA NTRS2001

Exploring the Hot Galactic Halo Using Shadows of High Latitude Clouds

The objective of this proposal was to measure variations in the 1/4 keV emission from the galactic halo, using ROSAT (x-ray astronomy satellite) Position Sensitive Proportional Counters (PSPC) observations toward known enhancements in the absorbing column density along the line-of-sight out of the Galaxy. Target directions were selected to have a low total hydrogen column density but to also show significant gradients in the amount of absorbing material, as traced by Infrared Astronomical Satellite (IRAS) 100 micron emission, on angular scales that would be contained within the PSPC field of view. In addition, we restricted the galactic latitude of the target directions to be greater than 60 degrees or less than -60 degrees in order to enable a cleaner separation of Galactic halo emission from that of the Galactic disk. The observations would also provide a measurement of the brightness of the emission from the Local Bubble.

Juda, M.↗
NASA NTRS2002

Tindallia Californiensis sp. nov.: A New Halo-Alkaliphilic Primary Anaerobe, Isolated from Meromictic soda Mono Lake in California and the Correction of Diagnosis for Genus Tindallia

A novel extremely halo-alkaliphilic, bacterium strain APO (sup T) was isolated from sediments of the athalassic, meromictic, soda Mono Lake in California. Gram positive, spore-forming, slightly curved rods with sizes 0.6-0.7x 2.5-4.0 micrometers which occur singly, in pairs or short curved chains. Cells, are motile by singular subcentral flagellum. Strain APO (sup T) is mesophilic: growth was observed over the temperature range of +10 C to +48 C (optimum +37 C), NaCl concentration range 1-20 %, wt/vol (optimum 3-5%, wt/vol) and pH range 8.0-11.0 (optimum pH 9.5). The novel isolate is strictly halo-alkaliphilic, requires sodium chloride in medium, obligately anaerobic and catalase-negative. Strain APO (sup T) is organo-heterotroph with fermentative type of metabolism, and uses as substrates: peptone, badotryptone, casamino acids, yeast extract, L-serine, L-lysine, L-histidine, L-arginine, and pyruvate. The main end products of growth on peptone medium were: lactate, acetate, propionate, and ethanol. Strain APO (sup T) is resistant to kanamycin, but sensitive to chloramphenicol, tetracycline, and gentamycin. The sum of G+C in DNA is 44.4 mol% (by HPLC method). On the bait of physiological and molecular properties, the isolate was considered as novel species of genus Tindallia; and the name Tindallia californiensis sp. nov., is proposed for new isolate (type strain APO (sup T) - ATCC BAA_393(sup T) = DSMZ 14871 (sup T)).

Pikuta, Elena↗
NASA NTRS2002

HALOE Observations of Perturbations in High Northern Latitude NO and O3 During the April 2002 Solar Storm Episode

The April 2002 solar storm event provides a unique opportunity to study the resulting effects on upper atmospheric constituents such as NO and O3. Two sources may perturb these constituents. For a magnetic-storm-source, energetic particles collide with and dissociate N2 in the lower thermosphere to produce excited nitrogen atoms which then combine with O to produce NO. The NO subsequently is transported down to lower altitudes where it reacts with and thus destroys mesospheric and possibly stratospheric ozone. For a solar-particle-event-source, high energy particles penetrate directly into the mesosphere, break apart N2 and water vapor, creating NOx and HOx to destroy ozone in the middle atmosphere. We present perturbations in high northern latitude NO and O3 as measured by the Halogen Occultation Experiment (HALOE) aboard the Upper Atmosphere Research Satellite between April 20-27. HALOE observations show an order of magnitude increase in mesospheric NO and a factor of approximately 2 decrease in mesospheric O3. We will also compare these observations with NASA GSFC 2D model computations.

Anderson, John↗
NASA NTRS2003

Studies of the Hot Gas in the Galactic halo and Local Bubble

This paper presents a report on the progress made on Studies of the Hot Gas in the Galactic halo and Local Bubble at Johns Hopkins University. The broad goals of this project are to determine the physical conditions and history of the hot phase of the Galaxy's interstellar medium. Such gas resides in the Galactic halo, the Local Bubble surrounding the solar neighborhood, other bubbles, and supernova remnants. A better understanding of the hot gas and the processes occurring within it requires several types of work, including ultraviolet and X-ray data analyses and computer modeling.

Shelton, Robin L.↗
NASA NTRS2003

Interannual and Long-Term Changes in Middle Atmosphere Temperature from Haloe

Radiative models of the middle atmosphere indicate that the largest temperature response due to steadily increasing amounts of atmospheric CO2 should occur at pressure altitudes between 1 and 0.1 hPa (about 48 to 64 km) and be of the order of 0.5 to 0.6 K/decade on a pressure surface . Such a rate assumes that there is no trend in ozone or in the dissipation of wave activity for that region of the middle atmosphere. This rate of cooling is only of the order of 0.20 to 0.25% per decade, which is a small trend to discern from observations. We have analyzed the 11-year, Version 19 (or V19) temperature versus pressure profile (or T(p)) time series from the UARS Halogen Occultation Experiment (HALOE) for such trends at selected pressure levels. The HALOE T(p) time series are being obtained using CO2 transmission data centered at 2.8 micrometers and from a single instrument that uses the limb solar occultation measurement geometry, which provides significant advantages for the calibration of its single profiles.

Remsbwerg, Ellis↗
NASA NTRS2007

Intercomparisons of Aura MLS, ACE, and HALOE Observations of Long-Lived Trace Species Using the Langley Lagrangian Chemistry and Transport Model

We use the LaRC Lagrangian Chemistry and Transport Model (LCTM) [Considine et al., 2007; Pierce et al., 2003] to intercompare ACE, Aura, and HALOE observations of long-lived trace species. The LCTM calculates the transport, mixing, and photochemical evolution of an ensemble of parcels that have been initialized from ACE-FTS measurements. Here we focus on late November, 2004 comparisons, due to the previous 3-week period of continuous HALOE observations and MLS v2.2 data on November 29, 2004.

Considine, David B.↗
NASA NTRS2008

On the Response of Halogen Occultation Experiment (HALOE) Stratospheric Oxone and Temperature to the 11-yr Solar Cycle Forcing

Results are presented on responses in 14-yr time series of stratospheric ozone and temperature from the Halogen Occultation Experiment (HALOE) of the Upper Atmosphere Research Satellite (UARS) to a solar cycle (SC-like) variation. The ozone time series are for ten, 20-degree wide, latitude bins from 45S to 45N and for thirteen "half-Umkehr" layers of about 2.5 km thickness and extending from 63 hPa to 0.7 hPa. The temperature time series analyses were restricted to pressure levels in the range of 2 hPa to 0.7 hPa. Multiple linear regression (MLR) techniques were applied to each of the 130 time series of zonally-averaged, sunrise plus sunset ozone points over that latitude/pressure domain. A simple, 11-yr periodic term and a linear trend term were added to the final MLR models after their seasonal and interannual terms had been determined. Where the amplitudes of the 11-yr terms were significant, they were in-phase with those of the more standard proxies for the solar uv-flux. The max minus min response for ozone is of order 2 to 3% from about 2 to 5 hPa and for the latitudes of 45S to 45N. There is also a significant max minus min response of order 1 K for temperature between 15S and 15N and from 2 to 0.7 hPa. The associated linear trends for ozone are near zero in the upper stratosphere. Negative ozone trends of 4 to 6%/decade were found at 10 to 20 hPa across the low to middle latitudes of both hemispheres. It is concluded that the analyzed responses from the HALOE data are of good quality and can be used to evaluate the responses of climate/chemistry models to a solar cycle forcing.

Remsberg, E. E.↗
NASA NTRS2011

Solar Wind Strahl Observations and Their Implication to the Core-Halo Formation due to Scattering

A study of the kinetic properties of the strahl electron velocity distribution functions (VDF?s) in the solar wind is presented. This study focuses on the mechanisms that control and regulate the electron VDF?s and the stability of the strahl electrons in the solar wind; mechanisms that are not yet well understood. Various parameters are investigated such as the strahl-electron density, temperature anisotropy, and electron heat-flux. These parameters are used to investigate the stability of the strahl population. The analysis check for whether the strahl electrons are constrained by some instability (e.g., the whistler or KAW instabilities), or are maintained by other types of processes. The electron heat-flux and temperature anisotropy are determined by modeling of the 3D-VDF?s from which the moments properties of the various populations are obtained. The results of this study have profound implication on the current hypothesis about the probable formation of the solar wind halo electrons produced from the scattering of the strahl population. This hypothesis is strengthened by direct observations of the strahl electrons being scattered into the core-halo in an isolated event. The observation implies that the scattering of the strahl is not a continuous process but occurs in bursts in regions where conditions for wave growth providing the scattering are optimum. Sometimes, observations indicate that the strahl component is anisotropic (Tper/Tpal approx. 2). This provides a possible free energy source for the excitation of whistler waves as a possible scattering mechanism, however this condition is not always observed. The study is based on high time resolution data from the Cluster/PEACE electron spectrometer.

Vinas, Adolfo F.↗
NASA NTRS2011

Suzaku Observations of 4U 1957+11: Potentially the Most Rapidly Spinning Black Hole in (the Halo of) the Galaxy

We present three Suzaku observations of the black hole candidate 4U 1957+11 (V 1408 Aql) - a source that exhibits some of. the simplest and cleanest examples of soft, disk-dominated spectra. 4U 1957+ II also presents among the. highest peak temperatures found from disk-dominated spectra. Such temperatures may be associated with rapid black hole spin. The 4U 1957+11 spectra also require a very low normalization, which can be explained by a combination of small inner disk radius and a large distance (> 10 kpc) which places 4U 1957+ 11 well into the Galactic halo. We perform Joint fits to the Suzaku spectra with both relativistic and Comptonized disk models. Assuming a low mass black hole and the nearest distance (3 Stellar Mass, 10 kpc), the dimensionless spin parameter a* = Jc/GM(sup 2)> or approx. 0.9. Higher masses and farther distances yield a* approx. = 1. Similar conclusions are reached with Comptonization models; they imply a combination of small inner disk radii (or, equivalently, rapid spin) and large distance. Low spin cannot be recovered unless 4U 1957+11 is a low mass black hole that is at the unusually large distance of > or approx.40 kpc. We speculate whether the suggested maximal spin is related to how the system came to reside in the halo.

Nowak, Michael A.↗
NASA NTRS2016

Low-Thrust Transfers from Distant Retrograde Orbits to L2 Halo Orbits in the Earth-Moon System

This paper presents a study of transfers between distant retrograde orbits (DROs) and L2 halo orbits in the Earth-Moon system that could be flown by a spacecraft with solar electric propulsion (SEP). Two collocation-based optimal control methods are used to optimize these highly-nonlinear transfers: Legendre pseudospectral and Hermite-Simpson. Transfers between DROs and halo orbits using low-thrust propulsion have not been studied previously. This paper offers a study of several families of trajectories, parameterized by the number of orbital revolutions in a synodic frame. Even with a poor initial guess, a method is described to reliably generate families of solutions. The circular restricted 3-body problem (CRTBP) is used throughout the paper so that the results are autonomous and simpler to understand.

trajectory design↗
NASA NTRS2017

Orbit Maintenance and Navigation of Human Spacecraft at Cislunar Near Rectilinear Halo Orbits

Multiple studies have concluded that Earth-Moon libration point orbits are attractive candidates for staging operations. The Near Rectilinear Halo Orbit (NRHO), a member of the Earth-Moon halo orbit family, has been singularly demonstrated to meet multi-mission architectural constraints. In this paper, the challenges associated with operating human spacecraft in the NRHO are evaluated. Navigation accuracies and human vehicle process noise effects are applied to various station keeping strategies in order to obtain a reliable orbit maintenance algorithm. Additionally, the ability to absorb missed burns, construct phasing maneuvers to avoid eclipses and conduct rendezvous and proximity operations are examined.

Davis, Diane↗
NASA NTRS2017

Targeting Cislunar Near Rectilinear Halo Orbits for Human Space Exploration

Part of the challenge of charting a human exploration space architecture is finding locations to stage missions to multiple destinations. To that end, a specific subset of Earth-Moon halo orbits, known as Near Rectilinear Halo Orbits (NRHOs) are evaluated. In this paper, a systematic process for generating full ephemeris based ballistic NRHOs is outlined, different size NRHOs are examined for their favorability to avoid eclipses, the performance requirements for missions to and from NRHOs are calculated, and disposal options are evaluated. Combined, these studies confirm the feasibility of cislunar NRHOs to enable human exploration in the cislunar proving ground.

Williams, Jacob↗
NASA NTRS2018

Analysis of Cislunar Transfers from a Near Rectilinear Halo Orbit with High Power Solar Electric Propulsion

As government and commercial interest in the exploration of the Moon and cislu- nar space has grown, Near Rectilinear Halo Orbits (NRHOs) have shown to be of particular interest as staging orbits for human exploration of the Moon. Once in such staging orbits, low thrust solar electric propulsion (SEP) can enable efficient transfer to other orbits in cislunar space. This paper captures ongoing analysis to design efficient transfers of a massive spacecraft from a L2 Southern NRHO to a Distant Retrograde Orbit, L1 Northern NRHO, and Flat L2 Halo Orbit using low thrust SEP. For each transfer type, reference transfer is designed for an assumed 39 t spacecraft with 26.6 kW SEP system. For each reference transfer, analysis is completed to understand the sensitivity of the transfer to changes in initial mass and SEP power and identify the optimal number of thrusters to use for a given combination of mass and power.

SEP↗
NASA NTRS2021

Atacama Cosmology Telescope: Combined kinematic and thermal Sunyaev-Zel’dovich measurements from BOSS CMASS and LOWZ halos

The scattering of cosmic microwave background (CMB) photons off the free-electron gas in galaxies and clusters leaves detectable imprints on high resolution CMB maps: the thermal and kinematic Sunyaev-Zel’dovich effects (tSZ and kSZ respectively). We use combined microwave maps from the Atacama Cosmology Telescope DR5 and Planck in combination with the CMASS (mean redshifthzi¼0.55and host halo masshMviri¼3×1013M⊙) and LOWZ (hzi¼0.31,hMviri¼5×1013M⊙) galaxy catalogs from the Baryon Oscillation Spectroscopic Survey (BOSS DR10 and DR12), to study the gas associated with these galaxy groups. Using individual reconstructed velocities, we perform a stacking analysis and reject the no-kSZ hypothes is at 6.5σ, the highest significance to date. This directly translates into a measurement of the electron number density profile, and thus of the gas density profile. Despite the limited signal to noise, the measurement shows at high significance that the gas density profile is more extended than the dark matter density profile, for any reasonable baryon abundance (formally>90σfor the cosmic baryon abundance). We simultaneously measure the tSZ signal, i.e., the electron thermal pressure profile of the same CMASS objects, and reject theno-tSZ hypothesis at10σ. We combine tSZ and kSZ measurements to estimate the electron temperature to20% precision in several aperture bins, and find it comparable to the virial temperature. In a companion paper, we analyze these measurements to constrain the gas thermodynamics and the properties of feedback inside galaxy groups. We present the corresponding LOWZ measurements in this paper, ruling out a null kSZ (tSZ)signal at 2.9ð13.9Þσ, and leave their interpretation to future work. This paper and the companion paper demonstrate that current CMB experiments can detect and resolve gas profiles in low mass halos and at high redshifts, which are the most sensitive to feedback in galaxy formation and the most difficult to measure any other way. They will be a crucial input to cosmological hydrodynamical simulations, thus improving our understanding of galaxy formation. These precise gas profiles are already sufficient to reduce the main limiting theoretical systematic in galaxy-galaxy lensing: baryonic uncertainties. Future such measurements will thus unleash the statistical power of weak lensing from the Rubin, Euclid and Roman observatories. Our stacking software Thumb Stack is publicly available and directly applicable to future Simons Observatory andCMB-S4 data.

Emmanuel Schaan↗