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NASA NTRS2004

Graupel and Snow Determination in Convection Using Dual-Wavelength Radar

Convective storms contain significant amounts of snow and graupel that each have different scattering properties for radar and radiometer remote sensing. TRMM TMI algorithms have relied heavily on radiative transfer calculations based on cloud model predicted microphysics information. In general, without in situ aircraft measurements, it is very difficult to separate snow and graupel using remote measurements. At the 94 GHZ frequency, snow is weakly attenuating while graupel is strongly attenuating. With a non-attenuating frequency such as X-band, one can distinguish Mie scattering from larger hydrometeors as well as attenuation from graupel. The presence of supercooled water will also cause attenuation of the 94 GHz radar signal, but this is mainly in convective updrafts. We will present preliminary results aimed at distinguishing snow from graupel using dual-wavelength (9.6 GHz, 94 GHz) measurements from aircraft overflights of convective storms in Florida. Measurements were made with the 9.6 GHz ER-2 Doppler Radar (EDOP) and the 94 GHz Cloud Radar System (CRS) over a number of different precipitation systems. Analysis of the vertical profiles at the two wavelengths provides information on snow and graupel regions, as well as supercooled water. The presentation will include examples from different cases and discussion of the results.

Heymsfield, Gerald↗
NASA NTRS2005

Global, Multi-Year Analysis of Clouds and Earth's Radiant Energy System Terra Observations and Radiative Transfer Calculations

An extended record of the Terra Surface and Atmosphere Radiation Budget (SARB) computed by CERES (Clouds and Earth s Radiant Energy System) is produced in gridded form, facilitating an investigation of global scale direct aerosol forcing. The new gridded version (dubbed FSW) has a spacing of 1 at the Equator. A companion document (Rutan et al. 2005) focuses on advances to (and validation of) the ungridded, footprint scale calculations (dubbed CRS), primarily in clear-sky conditions. While mainly intended to provide observations of fluxes at the top of atmosphere (TOA), CERES (Wielicki et al. 1996) includes a program to also compute the fluxes at TOA, within the atmosphere and at the surface, and also to validate the results with independent ground based measurements (Charlock and Alberta 1996). ARM surface data has been a focus for this component of CERES. To permit the user to infer cloud forcing and direct aerosol forcing with the computed SARB, CERES includes surface and TOA fluxes that have been computed for cloud-free (clear) and aerosol free (pristine) footprints; this accounts for aerosol effects (SW scattering and absorption, and LW scattering, absorption and emission) to both clear and cloudy skies.

Charlock, T. P.↗
NASA NTRS2007

Cosmic Ray Flux in the Presence of a Neutral Background

The study of cosmic rays (CRs) is a very mature subject developed around the concept of radiative particle flux phi as a mono-variant function of energy E, that is phi = phi(E). This is based on the notion of the cosmos as being filled with cosmic radiation in the form of a collisionless exosphere of plasma. Neutrals, however, are likewise ubiquitous in space and planetary trapped-radiation belts. It will be shown that in the presence of a neutral background of density rho, flux phi is actually bivariant in energy E and rho, creating a surface phi(E,rho). This is an intrinsic property of charged-particle flux, that flux is not merely a function of E but is dependent upon density rho when a background of neutrals is present. The effect is produced by multiple scattering of charged particles off neutral and ionized atoms along with ionization loss where charged and neutral populations interact. For the harder portion of CR spectra, flux is mono-variant but at nonrelativistic energies (below approx, 350 MeV) it becomes sensitive to the presence of neutral backgrounds. The dependence of phi(E,rho) upon background neutrals is helpful in discussing the anomalous CR (ACR) flux made up of ionized components of the heliospheric neutral atmosphere.

Wilson, Thomas L.↗
NASA NTRS2008

The Spectrum of Ultrahigh Energy Cosmic Rays and Constraints on Lorentz Invariance Violation

There has been much interest in possible violations of Lorentz invariance, particularly motivated by quantum gravity theories. It has been suggested that a small amount of Lorentz invariance violation (LIV) could turn off photomeson interactions of ultrahigh energy cosmic rays (UHECRs) with photons of the cosmic background radiation and thereby eliminate the resulting sharp steepening in the spectrum of the highest energy CRs predicted by Greisen Zatsepin and Kuzmin (GZK). Recent measurements of the UHECR spectrum reported by the HiRes and Auger collaborations, however, indicate the presence of the GZK effect. We present the results of a detailed calculation of the modification of the UHECR spectrum caused by LIV using the formalism of Coleman and Glashow. We then use a chi-squared analysis to compare our results with the experimental UHECR data and thereby place limits on the amount of LIV. We also discuss how a small amount of LIV that is consistent with the experimental data can still lead to a recovery of the cosmic ray flux at higher energies than presently observed.

Stecker, F. W.↗
NASA NTRS2009

Lorentz Invariance Violation and the Observed Spectrum of Ultrahigh Energy Cosmic Rays

There has been much interest in possible violations of Lorentz invariance, particularly motivated by quantum gravity theories. It has been suggested that a small amount of Lorentz invariance violation (LIV) could turn of photomeson interactions of ultrahigh energy cosmic rays (UHECRs) with photons of the cosmic background radiation and thereby eliminate the resulting sharp steepening in the spectrum of the highest energy CRs predicted by Greisen Zatsepin and Kuzmin (GZK). Recent measurements of the UHECR spectrum reported by the HiRes and Auger collaborations, however, indicate the presence of the GZK effect. We present the results of a detailed calculation of the modification of the UHECR spectrum caused by LIV using the formalism of Coleman and Glashow. We then compare these results with the experimental UHECR data from Auger and HiRes. Based on these data, we find a best fit amount of LIV of 4.5+1:5 ..4:5 x 10(exp -23),consistent with an upper limit of 6 x 10(exp -23). This possible amount of LIV can lead to a recovery of the cosmic ray spectrum at higher energies than presently observed. Such an LIV recovery effect can be tested observationally using future detectors.

Scully, S. T.↗
NASA NTRS2009

Vertical Cloud Climatology During TC4 Derived from High-Altitude Aircraft Merged Lidar and Radar Profiles

Aircraft lidar works by shooting laser pulses toward the earth and recording the return time and intensity of any of the light returning to the aircraft after scattering off atmospheric particles and/or the Earth s surface. The scattered light signatures can be analyzed to tell the exact location of cloud and aerosol layers and, with the aid of a few optical assumptions, can be analyzed to retrieve estimates of optical properties such as atmospheric transparency. Radar works in a similar fashion except it sends pulses toward earth at a much larger wavelength than lidar. Radar records the return time and intensity of cloud or rain reflection returning to the aircraft. Lidar can measure scatter from optically thin cirrus and aerosol layers whose particles are too small for the radar to detect. Radar can provide reflection profiles through thick cloud layers of larger particles that lidar cannot penetrate. Only after merging the two instrument products can accurate measurements of the locations of all layers in the full atmospheric column be achieved. Accurate knowledge of the vertical distribution of clouds is important information for understanding the Earth/atmosphere radiative balance and for improving weather/climate forecast models. This paper describes one such merged data set developed from the Tropical Composition, Cloud and Climate Coupling (TC4) experiment based in Costa Rica in July-August 2007 using the nadir viewing Cloud Physics Lidar (CPL) and the Cloud Radar System (CRS) on board the NASA ER-2 aircraft. Statistics were developed concerning cloud probability through the atmospheric column and frequency of the number of cloud layers. These statistics were calculated for the full study area, four sub-regions, and over land compared to over ocean across all available flights. The results are valid for the TC4 experiment only, as preferred cloud patterns took priority during mission planning. The TC4 Study Area was a very cloudy region, with cloudy profiles occurring 94 percent of the time during the ER-2 flights. One to three cloud layers were common, with the average calculated at 2.03 layers per profile. The upper troposphere had a cloud frequency generally over 30%, reaching 42 percent near 13 km during the study. There were regional differences. The Caribbean was much clearer than the Pacific regions. Land had a much higher frequency of high clouds than ocean areas. One region just south and west of Panama had a high probability of clouds below 15 km altitude with the frequency never dropping below 25% and reaching a maximum of 60% at 11-13 km altitude. These cloud statistics will help characterize the cloud volume for TC4 scientists as they try to understand the complexities of the tropical atmosphere.

Hlavka, Dennis↗
NASA NTRS2010

Modelling Cosmic-Ray Effects in the Protosolar Disk

The role that Galactic cosmic rays (GCRs) and solar energetic particles (SEPs) play in the dynamic evolution of protosolar disks and the origin of our Solar System is a fundamental one. The GCRs are an important component of the interstellar medium (ISM), and even play a role in correcting the age determinations of some irons versus CAIs (calcium-aluminum inclusions) in meteoroids . Because CRs also are one of the energy transport mechanisms in a planetary nebula, the question of modelling their effect upon this broad subject is a serious topic for planetary science. The problem is addressed here.

Wilson, Thomas L.↗
NASA NTRS2010

Risk Mitigation Approach to Commercial Resupply to the International Space Station

In August 2006, NASA awarded Space Act Agreements (SAAs) for Commercial Orbital Transportation Services (COTS) under the Commercial Crew and Cargo Project Office at Johnson Space Center. One of the goals of the SAAs is to facilitate U.S. private industry demonstration of cargo transportation capabilities, ultimately achieving reliable, cost effective access to low-Earth orbit (LEO). Each COTS provider is required to complete International Space Stations (ISS) Integration activities, which includes meeting the physical and functional interfaces and interface requirements between the ISS and COTS vehicles. These requirements focus on the areas of risk to the ISS during rendezvous and proximity operations, as well as the integration operations while the COTS vehicle is berthed to the ISS. On December 23, 2008, NASA awarded Commercial Resupply Service (CRS) contracts to provide resupply services to the ISS, following the Shuttle retirement. In addition to performing any ISS Integration activities, NASA will be performing independent assessments of the launch vehicle and orbital vehicle to evaluate the readiness of the contractor to deliver NASA cargo safely to the ISS. This paper will address the activities NASA Centers, both JSC and KSC, in the oversight and insight function over commercial visiting vehicles to the ISS.

Koons, Diane S.↗
NASA NTRS2010

Measurements and Simulations of Nadir-Viewing Radar Returns from the Melting Layer at X- and W-Bands

Simulated radar signatures within the melting layer in stratiform rain, namely the radar bright band, are checked by means of comparisons with simultaneous measurements of the bright band made by the EDOP (X-band) and CRS (W-band) airborne Doppler radars during the CRYSTAL-FACE campaign in 2002. A stratified-sphere model, allowing the fractional water content to vary along the radius of the particle, is used to compute the scattering properties of individual melting snowflakes. Using the effective dielectric constants computed by the conjugate gradient-fast Fourier transform (CGFFT) numerical method for X and W bands, and expressing the fractional water content of melting particle as an exponential function in particle radius, it is found that at X band the simulated radar bright-band profiles are in an excellent agreement with the measured profiles. It is also found that the simulated W-band profiles usually resemble the shapes of the measured bright-band profiles even though persistent offsets between them are present. These offsets, however, can be explained by the attenuation caused by cloud water and water vapor at W band. This is confirmed by the comparisons of the radar profiles made in the rain regions where the un-attenuated W-band reflectivity profiles can be estimated through the X- and W band Doppler velocity measurements. The bright-band model described in this paper has the potential to be used effectively for both radar and radiometer algorithms relevant to the TRMM and GPM satellite missions.

Liao, Liang↗
NASA NTRS2010

COTS/CRS: KSC Evolving Host Initiatives with Commercial Space Partners

NASA's Commercial Crew and Cargo Program Office (C3PO) leads the agency's commercial efforts to stimulate United States private companies as the shuttle program comes to a close. Through the Commercial Orbital Transportation Services (COTS) program, two companies, SpaceX and Orbital, were selected to demonstrate their ability to perform flights to the International Space Station. The Commercial Resupply Services (CRS) Project leverages off the COTS experience, and awarded these two private companies contracts to resupply the International Space Station after shuttle fly out. As a 2010 summer intern, I supported the COTS/CRS team in their team meetings, attended and contributed to project discussions and planning, and assisted in developing visual representations for the variety of processes and organizational endeavors required for the program to run smoothly. One aspect of the COTS/CRS program gives the involved private companies the opportunity to request available services from Kennedy Space Center (KSC); one of my projects included assisting in the development of a related Task Order Request (TOR) process. In addition, an integral part of the project was to maintain and enhance the team database for processing the variety of TORS. My experience in the project gave me great insight into the growing field of commercial space activities. The development of the TOR process involved coordinating representatives from a variety of backgrounds at KSC. A clear and concise visual representation of the TOR process in the form of a flow chart was necessary to successfully implement a task order request from one of NASA's commercial partners. The goals of the process charts were to communicate the team's ideas and foster a common thought process while at the same time allow the process to grow and evolve. It was critical that the requests from the private companies were addressed quickly and thoroughly as the process developed this summer is expected to have extensive future use.

Yohpe, Megan↗
NASA NTRS2011

Life Science on the International Space Station Using the Next Generation of Cargo Vehicles

With the retirement of the Space Shuttle and the transition of the International Space Station (ISS) from assembly to full laboratory capabilities, the opportunity to perform life science research in space has increased dramatically, while the operational considerations associated with transportation of the experiments has changed dramatically. US researchers have allocations on the European Automated Transfer Vehicle (ATV) and Japanese H-II Transfer Vehicle (HTV). In addition, the International Space Station (ISS) Cargo Resupply Services (CRS) contract will provide consumables and payloads to and from the ISS via the unmanned SpaceX (offers launch and return capabilities) and Orbital (offers only launch capabilities) resupply vehicles. Early requirements drove the capabilities of the vehicle providers; however, many other engineering considerations affect the actual design and operations plans. To better enable the use of the International Space Station as a National Laboratory, ground and on-orbit facility development can augment the vehicle capabilities to better support needs for cell biology, animal research, and conditioned sample return. NASA Life scientists with experience launching research on the space shuttle can find the trades between the capabilities of the many different vehicles to be confusing. In this presentation we will summarize vehicle and associated ground processing capabilities as well as key concepts of operations for different types of life sciences research being launched in the cargo vehicles. We will provide the latest status of vehicle capabilities and support hardware and facilities development being made to enable the broadest implementation of life sciences research on the ISS.

Robinson, J. A.↗
NASA NTRS2011

Updates on HRF Payloads Operations in Columbus ATCS

The NASA developed Human Research Facility 1 (HRF1) and Human Research Facility (HRF2) experiment racks have been operating in the European Space Agency (ESA) Columbus module of the International Space Station (ISS) since Summer 2008. The two racks are of the same design. Since the start of operations, unexpected pressure spikes were observed in the Columbus module's thermal-hydraulic system during the racks activation sequence. The root cause of these spikes was identified in the activation command sequence in the Rack Interface Controller (RIC), which controls the flow of thermal-hydraulic system fluid through the rack. A new Common RIC Software (CRS) release fixed the bug and was uploaded on both racks in late 2009. This paper gives a short introduction to the topic, describes the Columbus module countermeasures to mitigate the spikes, describes the ground validation test of the new software, and describes the flight checks performed before and after the final upload. Finally, the new on-orbit test designed to further simplify the racks hydraulic management is presented.

DePalo, Savino↗
NASA NTRS2012

Constraints on Cosmic Rays, Magnetic Fields, and Dark Matter from Gamma-ray Observations of the Coma Cluster of Galaxies with VERITAS and FERMI

Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated and, on account of weak energy losses, can accumulate, suggesting that clusters may also be sources of very high energy (VHE; E greater than100 GeV) gamma-ray emission. We report here on VHE gamma-ray observations of the Coma galaxy cluster with the VERITAS array of imaging Cerenkov telescopes, with complementing Fermi Large Area Telescope observations at GeV energies. No significant gamma-ray emission from the Coma Cluster was detected. Integral flux upper limits at the 99 confidence level were measured to be on the order of (2-5) x 10(sup -8) photons m(sup -2) s(sup -1) (VERITAS,greater than 220 GeV) and approximately 2 x 10(sup -6) photons m(sup -2) s(sup -1) (Fermi, 1-3 GeV), respectively. We use the gamma-ray upper limits to constrain cosmic rays (CRs) and magnetic fields in Coma. Using an analytical approach, the CR-to-thermal pressure ratio is constrained to be less than 16% from VERITAS data and less than 1.7% from Fermi data (averaged within the virial radius). These upper limits are starting to constrain the CR physics in self-consistent cosmological cluster simulations and cap the maximum CR acceleration efficiency at structure formation shocks to be 50. Alternatively, this may argue for non-negligible CR transport processes such as CR streaming and diffusion into the outer cluster regions. Assuming that the radio-emitting electrons of the Coma halo result from hadronic CR interactions, the observations imply a lower limit on the central magnetic field in Coma of approximately (2-5.5)microG, depending on the radial magnetic field profile and on the gamma-ray spectral index. Since these values are below those inferred by Faraday rotation measurements in Coma (for most of the parameter space), this renders the hadronic model a very plausible explanation of the Coma radio halo. Finally, since galaxy clusters are dark matter (DM) dominated, the VERITAS upper limits have been used to place constraints on the thermally averaged product of the total self-annihilation cross section and the relative velocity of the DM particles, (sigma upsilon)

cosmic↗
NASA NTRS2012

FERMI Observations of Gamma -Ray Emission From the Moon

We report on the detection of high-energy γ -ray emission from the Moon during the first 24 months of observations by the Fermi Large Area Telescope (LAT). This emission comes from particle cascades produced by cosmicray (CR) nuclei and electrons interacting with the lunar surface. The differential spectrum of the Moon is soft and can be described as a log-parabolic function with an effective cutoff at 2-3 GeV, while the average integral flux measured with the LAT from the beginning of observations in 2008 August to the end of 2010 August is F(greater than100 MeV) = (1.04 plus or minus 0.01 [statistical error] plus or minus 0.1 [systematic error]) × 10(sup −6) cm(sup −2) s(sup −1). This flux is about a factor 2-3 higher than that observed between 1991 and 1994 by the EGRET experiment on board the Compton Gamma Ray Observatory, F(greater than100 MeV)≈5×10(sup −7) cm(sup −2) s(sup −1), when solar activity was relatively high. The higher gamma -ray flux measured by Fermi is consistent with the deep solar minimum conditions during the first 24 months of the mission, which reduced effects of heliospheric modulation, and thus increased the heliospheric flux of Galactic CRs. A detailed comparison of the light curve with McMurdo Neutron Monitor rates suggests a correlation of the trends. The Moon and the Sun are so far the only known bright emitters of gamma-rays with fast celestial motion. Their paths across the sky are projected onto the Galactic center and high Galactic latitudes as well as onto other areas crowded with high-energy gamma-ray sources. Analysis of the lunar and solar emission may thus be important for studies of weak and transient sources near the ecliptic.

fermi↗
NASA NTRS2014

High-Energy X-Ray Detection of G359.89-0.08 (SGR A-E): Magnetic Flux Tube Emission Powered by Cosmic Rays?

We report the first detection of high-energy X-ray (E (is) greater than 10 keV) emission from the Galactic center non-thermal filament G359.89−0.08 (Sgr A−E) using data acquired with the Nuclear Spectroscopic Telescope Array (NuSTAR). The bright filament was detected up to approximately 50 keV during a NuSTAR Galactic center monitoring campaign. The featureless power-law spectrum with a photon index gamma approximately equals 2.3 confirms a non-thermal emission mechanism. The observed flux in the 3-79 keV band is F(sub X) = (2.0 +/- 0.1) × 10(exp -12)erg cm(-2) s(-1) , corresponding to an unabsorbed X-ray luminosity L(sub X) = (2.6+/-0.8)×10(exp 34) erg s(-1) assuming a distance of 8.0 kpc. Based on theoretical predictions and observations, we conclude that Sgr A−E is unlikely to be a pulsar wind nebula (PWN) or supernova remnant-molecular cloud (SNR-MC) interaction, as previously hypothesized. Instead, the emission could be due to a magnetic flux tube which traps TeV electrons. We propose two possible TeV electron sources: old PWNe (up to (is) approximately 100 kyr) with low surface brightness and radii up to (is) approximately 30 pc or MCs illuminated by cosmic rays (CRs) from CR accelerators such as SNRs or Sgr A*.

X-rays: individual↗
NASA NTRS2015

Center Planning and Development: Multi-User Spaceport Initiatives

The Vehicle Assembly building at NASAs Kennedy Space Center has been used since 1966 to vertically assemble every launch vehicle, since the Apollo Program, launched from Launch Complex 39 (LC-39). After the cancellation of the Constellation Program in 2010 and the retirement of the Space Shuttle Program in 2011, the VAB faced an uncertain future. As the Space Launch System (SLS) gained a foothold as the future of American spaceflight to deep space, NASA was only using a portion of the VABs initial potential. With three high bays connected to the Crawler Way transportation system, the potential exists for up to three rockets to be simultaneously processed for launch. The Kennedy Space Center (KSC) Master plan, supported by the Center Planning and Development (CPD) Directorate, is guiding Kennedy toward a 21st century multi-user spaceport. This concept will maintain Kennedy as the United States premier gateway to space and provide multi-user operations through partnerships with the commercial aerospace industry. Commercial aerospace companies, now tasked with transporting cargo and, in the future, astronauts to the International Space Station (ISS) via the Commercial Resupply Service (CRS) and Commercial Crew Program (CCP), are a rapidly growing industry with increasing capabilities to make launch operations more economical for both private companies and the government. Commercial operations to Low Earth Orbit allow the government to focus on travel to farther destinations through the SLS Program. With LC-39B designated as a multi-use launch pad, companies seeking to use it will require an integration facility to assemble, integrate, and test their launch vehicle. An Announcement for Proposals (AFP) was released in June, beginning the process of finding a non-NASA user for High Bay 2 (HB2) and the Mobile Launcher Platforms (MLPs). An Industry Day, a business meeting and tour for interested companies and organizations, was also arranged to identify and answer any additional questions posed by potential proposers. After amending the AFP and posting additional material for potential users to consider, proposals are being accepted until July 31, at which point they will be evaluated to determine the proposer which best meets the objectives of the government. By identifying VAB HB2 as available and seeking proposals from the commercial sector for VAB HB2 and MLP use, Center Planning and Development is ensuring Kennedy Space Centers relevance in the evolving launch industry of the 21st century.

AFP↗
NASA NTRS2015

Self-Cleaning Boudouard Reactor for Full Oxygen Recovery from CO2 Project

Oxygen recovery from respiratory CO2 is an important aspect of human spaceflight. Methods exist to sequester the CO2, but production of oxygen needs further development. The current ISS Carbon Dioxide Reduction System (CRS) uses the Sabatier reaction to produce water (and ultimately breathing air). Oxygen recovery is limited to 50% because half of the hydrogen used in the Sabatier reactor is lost as methane, which is vented overboard. The Bosch reaction is the only real alternative to the Sabatier reaction, but in the last reaction in the cycle (Boudouard) the resulting carbon buildup will eventually foul the nickel or iron catalyst, reducing reactor life and increasing consumables. To minimize this fouling, find a use for this waste product, and increase efficiency, we propose testing various self-cleaning catalyst designs in an existing MSFC Boudouard reaction test bed and to determine which one is the most reliable in conversion and lack of fouling. Challenges include mechanical reliability of the cleaning method and maintaining high conversion efficiency with lower catalyst surface area. The above chemical reactions are well understood, but planned implementations are novel (TRL 2) and haven't been investigated at any level.

Technology Portfolio System↗
NASA NTRS2014

Inferred Cosmic-Ray Spectrum from Fermi-LAT Gamma-Ray Observations of the Earths Limb

Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly-discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the -ray emission from the Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range approx. 90 GeV-6 TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68 +/- 0.04 and 2.61 +/- 0.08 above approx. 200 GeV, respectively.

fermi↗