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NASA NTRS2008

Relationship between Mean Winds and Large 10-day Precipitation Anomalies over the Continental U.S.

To better understand the role of surface boundary forcing upon interannual and decadal variability of droughts and precipitation excesses over the continental U. S., an observational study has been carried out to better investigate the dynamical linkages between surface boundary forcing and droughts/floods. This study examines the relationship during the warm season between observed mean wind patterns on the 10-15 day time scale and anomalies in precipitation on that same time scale over the U. S. Each of the 7 cases of significant 10-day, warm-season drought over the U, S. since 1948 that has been investigated was accompanied by significant continental-scale ridging of the mean 10-day 250 mb wind pattern over the continental U.S. and a mid-Pacific relative maximum of 250 mb wind speed of at least 30 m/sec within 20 degrees of the international Date Line. This perhaps suggests the presence of a wave-guide phenomenon over the Pacific. The drought signal for each of these cases was still quite evident when averaged over the monthly time scale. While peak magnitudes of the precipitation anomalies were much larger for the 7 chosen cases of significant of precipitation excess were than for the drought cases none of the patterns of precipitation excess were as unambiguous or wide-spread as the drought cases. In only 2 to 3 cases was there evidence of a continental trough in the 250 mb winds. In fact, one case showed slight ridging over Canada and the extreme northern U.S. Strong southerly low-level jets, however, were evident in the 925 mb winds over south-central Texas or the nearby Gulf of Mexico in virtually all of the excessive precipitation cases, while the Great Plains LLJ was weak or displaced to the north of Texas in most of the drought cases. We will further investigate the asymmetry between droughts and precipitation excesses in their horizontal homogeneity and extent, in their temporal evolution, and in how the are forced by the combined effects of the mean 250 mb westerlies and the mean 925 mb southerly winds.

Helfand, H. Mark↗

NASA NTRS2011

Spitzer IRS Spectroscopy of the 10 Myr-Old EF Cha Debris Disk: Evidence for Phyllosilicate-Rich Dust in the Terrestrial Zone

We describe Spitzer IRS spectroscopic observations of the approx. 10 Myr-old star, EF Chao Compositional modeling of the spectra from 5 micron to 35 micron confirms that it is surrounded by a luminous debris disk with L(sub D)/L(sub *) approx. 10(exp -3), containing dust with temperatures between 225 K and 430 K characteristic of the terrestrial zone. The EF Cha spectrum shows evidence for many solid-state features, unlike most cold, low-luminosity debris disks but like some other 10-20 Myr-old luminous, warm debris disks (e.g. HD 113766A). The EF Cha debris disk is unusually rich in a species or combination of species whose emissivities resemble that of finely-powdered, laboratory-measured phyllosilicate species (talc, saponite, and smectite), which are likely produced by aqueous alteration of primordial anhydrous rocky materials. The dust and, by inference, the parent bodies of the debris also contain abundant amorphous silicates and metal sulfides, and possibly water ice. The dust's total olivine to pyroxene ratio of approx. 2 also provides evidence of aqueous alteration. The large mass volume of grains with sizes comparable to or below the radiation blow-out limit implies that planetesimals may be colliding at a rate high enough to yield the emitting dust but not so high as to devolatize the planetesimals via impact processing. Because phyllosilicates are produced by the interactions between anhydrous rock and warm, reactive water, EF Cha's disk is a likely signpost for water delivery to the terrestrial zone of a young planetary system.

Currie, Thayne↗

NASA NTRS2016

Design of a Two-Stage Light Gas Gun for Muzzle Velocities of 10 - 11 kms

Space debris poses a major risk to spacecraft. In low earth orbit, impact velocities can be 10 11 kms and as high as 15 kms. For debris shield design, it would be desirable to be able to launch controlled shape projectiles to these velocities. The design of the proposed 10 11 kmsec gun uses, as a starting point, the Ames 1.280.22 two stage gun, which has achieved muzzle velocities of 10 11.3 kmsec. That gun is scaled up to a 0.3125 launch tube diameter. The gun is then optimized with respect to maximum pressures by varying the pump tube length to diameter ratio (LD), the piston mass and the hydrogen pressure. A pump tube LD of 36.4 is selected giving the best overall performance. Piezometric ratios for the optimized guns are found to be 2.3, much more favorable than for more traditional two stage light gas guns, which range from 4 to 6. The maximum powder chamber pressures are 20 to 30 ksi. To reduce maximum pressures, the desirable range of the included angle of the cone of the high pressure coupling is found to be 7.3 to 14.6 degrees. Lowering the break valve rupture pressure is found to lower the maximum projectile base pressure, but to raise the maximum gun pressure. For the optimized gun with a pump tube LD of 36.4, increasing the muzzle velocity by decreasing the projectile mass and increasing the powder loads is studied. It appears that saboted spheres could be launched to 10.25 and possibly as high as 10.7 10.8 kmsec, and that disc-like plastic models could be launched to 11.05 kms. The use of a tantalum liner to greatly reduce bore erosion and increase muzzle velocity is discussed. With a tantalum liner, CFD code calculations predict muzzle velocities as high as 12 to 13 kms.

Gun Design↗

NASA NTRS2016

Flash Spectroscopy: Emission Lines From the Ionized Circumstellar Material Around 10-Day-Old Type II Supernovae

Supernovae (SNe) embedded in dense circumstellar material (CSM) may show prominent emission lines in their early-time spectra (< or =10 days after the explosion), owing to recombination of the CSM ionized by the shock-breakout flash. From such spectra ("flash spectroscopy"), we can measure various physical properties of the CSM, as well as the mass-loss rate of the progenitor during the year prior to its explosion. Searching through the Palomar Transient Factory (PTF and iPTF) SN spectroscopy databases from 2009 through 2014, we found 12 SNe II showing flash-ionized (FI) signatures in their first spectra. All are younger than 10 days. These events constitute 14% of all 84 SNe in our sample having a spectrum within 10 days from explosion, and 18% of SNe II observed at ages <5 days, thereby setting lower limits on the fraction of FI events. We classified as "blue/featureless" (BF) those events having a first spectrum that is similar to that of a blackbody, without any emission or absorption signatures. It is possible that some BF events had FI signatures at an earlier phase than observed, or that they lack dense CSM around the progenitor. Within 2 days after explosion, 8 out of 11 SNe in our sample are either BF events or show FI signatures. Interestingly, we found that 19 out of 21 SNe brighter than an absolute magnitude M(sub R) = −18.2 belong to the FI or BF groups, and that all FI events peaked above M(sub R) = −17.6 mag, significantly brighter than average SNe II.

supernovae: general↗

NASA NTRS2018

Development of a 50 mK - 10 K Flight-Worthy Vibration-Free Continuous Adiabatic Demagnetization Refrigerator

The cryogenics and fluids branch at NASA Goddard Space Flight Center is currently developing a flight-worthy vibration-free 50 mK to 10 K Continous Adiabatic Demagnetization Refrigerator (CADR) that will potentially serve as the cooling scheme for future space flight missions such as OST, LUVOIR, and other flagship missions. This 7 stage CADR will lift 6 microW of heat at its lowest stage and reject heat to a temperature platform at 10 K. A single stage 4 - 10 K flight-worthy ADR unit was recently demonstrated with an optimized cycle time of 132 seconds and a heat lift of ~13 mW at 4 K. We discuss the development progress and details of its desing in this presentation.

ADR↗

NASA NTRS2014

10 meter Sub-Orbital Large Balloon Reflector (LBR)

The realization of a large, space-based 10 meter class telescope for far-infrared/THz studies has long been a goal of NASA. Such a telescope could study the origins of stars, planets, molecular clouds, and galaxies; providing a much needed means of following-up on tantalizing results from recent successful missions such as Spitzer, Herschel, and SOFIA. Indeed, Herschel began its life in the US space program as the Large Deployable Reflector (LDR) to be assembled in low Earth orbit by shuttle astronauts. Escalating costs and smaller federal budget allocations resulted in a downsizing of the mission. However, by combining successful suborbital balloon and ground-based telescope technologies, the dream of a 10 meter class telescope free of ~99% of the Earth's atmospheric absorption in the far-infrared can be realized. The same telescope can also be used to perform sensitive, high spectral and spatial resolution limb sounding studies of the Earth's atmosphere in greenhouse gases such as CO, ClO, O3, and water, as well as serve as a high flying hub for any number of telecommunications and surveillance activities. Flight times of 100+ days will be possible, with instruments having mass and power requirements in excess of ~500 kg and ~1 kW.Here we present the results of our NIAC Step 1, Phase B design study where each key aspect of the LBR concept is discussed and recommendations made for further study in Phase II.These aspects include realization of a large spherical reflecting surface, spherical corrector, pointing system, instrument module, and service module/gondola. Once each hardware component is introduced, a typical LBR Mission profile is described that enables the realization of a stratospheric 10 meter THz observatory and limb sounder. Verification of the design approach was achieved by using a combination of analytical modelling, lab testing of materials and techniques, and building a 3 meter rooftop LBR prototype.

Telescope↗

NASA NTRS2016

Design of a Two-Stage Light Gas Gun for Muzzle Velocities of 10 - 11 km/s

Space debris poses a major risk to spacecraft. In low earth orbit, impact velocities can be 10 - 11 km/s and as high as 15 km/s. For debris shield design, it would be desirable to be able to launch projectiles of known shape and mass to these velocities. The design of the proposed 10 - 11 km/sec gun uses, as a starting point, the Ames 1.28”/0.22” two stage gun, which has achieved muzzle velocities of 10 - 11.3 km/sec. That gun is scaled up to a 0.3125” launch tube diameter. The gun is then optimized with respect to maximum pressures by varying the pump tube length to diameter ratio (L/D), the piston mass and the hydrogen pressure. A pump tube L/D of 36.4 is selected giving the best overall performance. Piezometric ratios for the optimized guns are found to be ~2.3, much more favorable than for more traditional two stage light gas guns, which range from 4 to 6. (The piezometric ratio for a gun is defined as the maximum projectile base pressure divided by the constant projectile base pressure which, acting over the entire barrel length, would produce the same muzzle velocity.) The maximum powder chamber pressures are 20 to 30 ksi. To reduce maximum pressures, the desirable range of the included angle of the cone of the high pressure coupling is found to be 7.3 to 14.6 degrees. Lowering the break valve rupture pressure is found to lower the maximum projectile base pressure, but to raise the maximum gun pressure. For the optimized gun with a pump tube L/D of 36.4, increasing the muzzle velocity by decreasing the projectile mass and increasing the powder loads is studied. It appears that saboted spheres could be launched to 10.25 and possibly as high as 10.8 km/sec, and that disc-like plastic models could be launched to 11.05 km/s. The use of a tantalum liner to greatly reduce bore erosion and increase muzzle velocity is discussed. With a tantalum liner, CFD code calculations predict muzzle velocities as high as 12 to 13 km/s.

Bogdanoff, David W.↗

NASA NTRS2021

Daily Rainfall Estimate by Emissivity Temporal Variation from 10 Satellites

Rainfall retrieval algorithms for passive microwave radiometers often exploit the brightness temperature depression due to ice scattering at high-frequency channels (≥85 GHz) over land. This study presents an alternate method to estimate the daily rainfall amount using the emissivity temporal variation (i.e., Δe) under rain-free conditions at low-frequency channels (19, 24, and 37 GHz). Emissivity is derived from 10 passive microwave radiometers, including the Global Precipitation Measurement (GPM) Microwave Imager (GMI), the Advanced Microwave Scanning Radiometer 2 (AMSR2), three Special Sensor Microwave Imager/Sounders (SSMIS), the Advanced Technology Microwave Sounder (ATMS), and four Advanced Microwave Sounding Units-A (AMSU-A). Four different satellite combination schemes are used to derive the Δe for daily rainfall estimates. They are all 10 satellites, 5 imagers, 6 satellites with very different equator crossing times, and GMI only. Results show that Δe from all 10 satellites has the best performance with a correlation of 0.60 and RMSE of 6.52 mm, compared with the Integrated Multisatellite Retrievals for GPM (IMERG) Final run product. The 6-satellites scheme has comparable performance with the all-10-satellites scheme. The 5-imagers scheme performs noticeably worse with a correlation of 0.49 and RMSE of 7.28 mm, while the GMI-only scheme performs the worst with a correlation of 0.25 and RMSE of 11.36 mm. The inferior performance from the 5-imagers and GMI-only schemes can be explained by the much longer revisit time, which cannot accurately capture the emissivity temporal variation.

Yalei You↗

NASA NTRSDate not supplied

Preparations for Tomographic Background-Oriented Schlieren at the 31-Inch Mach 10 Wind Tunnel

This paper details effort by researchers at NASA Langley Research Center to prepare for an upcoming high-speed tomographic background-oriented schlieren test entry in the 31-Inch Mach 10 wind tunnel. In order to troubleshoot potential problems that will arise when setting up the experiment in the actual test facility, a full-scale mock-up of the 31-Inch Mach 10 wind tunnel test section was constructed in the laboratory to provide equivalent characteristic optical access and mounting options. A 3D-printed model that replicates the scale of the forebody of a supersonic retropropulsion (SRP) model that will be used in the final test entry has been fabricated with a central nozzle that can be connected to a high-pressure gas supply to approximate the nozzle flow that will occur. Six high-speed imaging systems consisting of a high-speed camera with a fiber illuminator module have been assembled and mounted on the test section mock-up to provide six unique perspective views of the nozzle flow from the model. Tests with one of the imaging systems using a pulsed laser light source showed that sufficient signal intensity and illumination uniformity was achieved, as demonstrated by the 2D BOS data obtained with the system. Additional work to show that retroreflective material would survive inside of the test section of the 31-Inch Mach 10 tunnel was also performed. Finally, a remotely-controlled tomographic BOS calibration system is discussed.

Brett F Bathel↗

NASA NTRSDate not supplied

Geophysical Retrievals and Cloud Analyses from Merged Airborne Radiometer Datasets Covering 10–684 GHz

Airborne microwave radiometers provide insight about numerous aspects of Earth’s atmosphere and yield critical validation datasets for spaceborne radiometers. Three radiometers that are important to NASA’s airborne remote-sensing arsenal include: the Advanced Microwave Precipitation Radiometer (AMPR), covering 10–85 GHz; the Conical Scanning Millimeter-wave Imaging Radiometer (CoSMIR), covering 50–183 GHz; and the Compact Scanning Submillimeter-wave Imaging Radiometer (CoSSIR), covering 170–684 GHz. The NASA field campaigns of interest to this study include: the Integrated Precipitation and Hydrology Experiment (IPHEx) in 2014, the Olympic Mountains Experiment and Radar Definition Experiment (OLYMPEX/RADEX) in 2015–2016, the Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) in 2020–2023, and the Airborne Lightning Observatory for FEGS and TGFs (ALOFT) in 2023. To provide a more comprehensive perspective on clouds and precipitation observed during these airborne field campaigns, AMPR data were merged spatiotemporally with CoSMIR data for IPHEx, OLYMPEX/RADEX, and IMPACTS (2020 and 2022), while considering differences in instrument characteristics and operations, providing brightness temperature (Tb) values from 10–183 GHz in a common background grid throughout each flight. AMPR and CoSSIR data were similarly merged for IMPACTS (2023) and ALOFT, providing a common background grid with Tb values covering 10–684 GHz throughout each flight. These merged Tb data were employed in geophysical retrievals using the Community Radiative Transfer Model (CRTM), an Eddington radiative transfer model, and a one-dimensional variational (1DVAR) inversion method. Retrievals of cloud liquid water path were of primary interest. This presentation will include an overview of the methods for the radiometer data mergers, the radiative transfer methods, the geophysical retrievals, and detailed results from examining trends in Tb and cloud liquid water path in clouds, precipitation, and cloud-to-precipitation transition zones.

Corey G Amiot↗

NASA NTRS2023

Kmt-2022-Blg-0440lb: A New q < 10 −4 Microlensing Planet With the Central-Resonant Caustic Degeneracy Broken

We present the observations and analysis of a high-magnification microlensing planetary event, KMT-2022-BLG-0440, for which the weak and short-lived planetary signal was covered by both the KMTNet survey and follow-up observations. The binary-lens models with a central caustic provide the best fits, with a planet/host mass ratio, q = 0.75–1.00 ×10 −4 at 1 σ. The binary-lens models with a resonant caustic and a brown-dwarf mass ratio are both excluded by ∆χ 2 > 70. The binary-source model can fit the anomaly well but is rejected by the ‘colour argument’ on the second source. From Bayesian analyses, it is estimated that the host star is likely a K or M dwarf located in the Galactic disc, the planet probably has a Neptune-mass, and the projected planet-host separation is 1.9 +0.6 −0.7 or 4.6 +1.4 −1.7 au, subject to the close/wide de generac y. This is the third q < 10 −4 planet from a high-magnification planetary signal ( A ≳ 65). Together with another such planet, KMT-2021-BLG-0171Lb, the ongoing follow-up program for the KMTNet high-magnification events has demonstrated its ability to detect high-magnification planetary signals for q < 10 −4 planets, which are challenging for the current microlensing surveys.

planets and satellites: detection↗

NASA NTRSDate not supplied

The AEDC 10-Deg Cone Wind Tunnel/Flight Laminar-Turbulent Correlation Program

The AEDC 10-Deg Cone Program stands as a historical tunnel/flight correlation program in which a simple standard calibration body (a sharp, smooth, slender 10-deg included-angle cone) was used for correlation of wind tunnel flow quality and Reynolds number effects in 23 major wind tunnels. The investigation, initiated by the USAF at AEDC, was conducted in the 1970’s and included participation by NASA, the Navy, the United Kingdom, France, the Netherlands, and Industry. The flight test was performed at NASA/DFRC (now AFRC) at Edwards AFB on a NASA F-15 A aircraft to Mach 2.0. Testing in the wind tunnels was from Mach 0.2 to 5.5. This program produced an extensive database.

AEDC 10-Deg Cone↗

NASA NTRSDate not supplied

Wake Velocimetry of a Sphere-Cone Model in a Mach 10 Air Freestream using FLEET

Velocity measurements in the wake behind a sphere-cone-shaped vehicle wind tunnel model in a Mach 10 hypersonic air flow using femtosecond laser electronic excitation tagging (FLEET) are reported in this work. The FLEET measurements were performed at 1 kHz using a femtosecond laser centered at 800 nm and an ultrahigh-speed intensified camera system. The results reported here are for a single freestream condition corresponding to approximately Re ∞ /L = 3.6∙10 6 m -1 . The performance of the velocimetry instrument was evaluated in the quiescent test section at conditions relevant to the wake measurements. For velocity measurements in the wake, the FLEET measurement volume was translated to several radial locations from the model centerline in the vertical direction and at a streamwise location corresponding to approximately 12 mm from the payload. Reverse flow with mean velocities ranging from -12 m/s to -48 m/s were observed in the recirculating region of the wake, whereas hypersonic velocities in the range of 1079 m/s to 1183 m/s were observed in the free shear layer. A velocity uncertainty methodology is also outlined and applied for the reported measurements. The velocity data reported in this work is expected to play a significant role in the validation of computational codes modeling the hard-to-predict separated hypersonic wake.

FLEET↗

NASA NTRSDate not supplied

Wake Velocimetry of a Sphere-Cone Model in a Mach 10 Air Freestream using FLEET

FLEET↗

NASA NTRS1971

Sounding rocket flight report, MUMP 9 and MUMP 10

The results of the launching of two-Marshall-University of Michigan Probes (MUMP 9 and MUMP 10), Nike-Tomahawk sounding rocket payloads, are summarized. The MUMP is similar to the thermosphere probe, an ejectable instrument package for studying the variability of the earth's atmospheric parameters. The MUMP 9 payload included an omegatron mass analyzer, a molecular fluorescence densitometer, a mini-tilty filter, and a lunar position sensor. This complement of instruments permitted the determination of the molecular nitrogen density and temperature in the altitude range from approximately 143 to 297 km over Wallops Island, Virginia, during January 1971. The MUMP 10 payload included an omegatron mass analyzer, an electron temperature probe, a cryogenic densitometer, and a solar position sensor. These instruments permitted the determination of the molecular nitrogen density and temperature and the charged particle density and temperature in the altitude range from approximately 145 to 290 km over Wallops Island during the afternoon preceding the MUMP 9 launch.

Grassl, H. J.↗

NASA NTRS1971

Sounding rocket flight report: MUMP 9 and MUMP 10

The results of the launching of two Marshall-University of Michigan Probes (MUMP 9 and MUMP 10), Nike-Tomahawk sounding rocket payloads, are summarized. The MUMP 9 paylaod included an omegatron mass analyzer, a molecular fluorescence densitometer, a mini-tilty filter, and a lunar position sensor. This complement of instruments permitted the determination of the molecular nitrogen density and temperature in the altitude range from approximately 143 to 297 km over Wallops Island, Virginia, during January 1971. The MUMP 10 payload included an omegatron mass analyzer, an electron temperature probe (Spencer, Brace, and Carignan, 1962), a cryogenic densitometer, and a solar position sensor. This complement of instruments permitted the determination of the molecular nitrogen density and temperature and the charged particle density and temperature in the altitude range from approximately 145 to 290 km over Wallops Island, Virginia, during the afternoon preceding the MUMP 9 launch in January 1971. A general description of the payload kinematics, orientation analysis, and the technique for the reduction and analysis of the data is given.

Grassl, H. J.↗

NASA NTRS1972

Interstellar propagation of galactic cosmic-ray nuclei 2 less than or equal to Z less than or equal to 8 in the energy range 10 to 1000 MeV per nucleon.

Analysis of the differential kinetic energy per nucleon spectra of galactic cosmic-ray He, Li, Be, B, C, N, and O with the University of Chicago cosmic-ray telescope on board the IMP-5 satellite in 1969-1970. The ratios He/(C + N + O) and (Li + Be + B)/(C + N + O) obtained from these spectra are found, within errors of about 20%, to be energy-independent over the energy range 10-1000 MeV per nucleon, and equal to about 15 and about 0.25, respectively. These results are compared with discrepancies existing among other measurements of these ratios, and with predictions of a class of steady-state models of cosmic-ray propagation which assume that Li, Be, and B are absent in cosmic-ray sources. The best fits for the present measurements are obtained for models with a source spectrum in the form of a power law in total energy per nucleon, but even these fits are outside the error limits at energies below 100 MeV per nucleon. In the context of the propagation models examined, it is concluded that the observed behavior of these ratios requires an additional mechanism operative at low energies. This mechanism may be adiabatic deceleration of cosmic rays in the solar wind. In order for this mechanism to be adiabatic deceleration, the deceleration in 1969 must have been such that particles observed at 10 to 20 MeV per nucleon had energies greater than 100 to 150 MeV per nucleon in the local interstellar space.

Mason, G. M.↗

NASA NTRS1972

A Summary of the Pioneer 10 Maneuver Strategy

The Pioneer Project placed a number of interesting and precise requirements on the navigation of the Pioneer 10 spacecraft flyby mission to Jupiter during 1972-1973. To satisfy these requirements the Pioneer navigation team employed a number of versatile computer programs to evaluate the strategies and maneuver sequences required to execute midcourse corrections. The Pioneer 10 mission objectives and the midcourse strategies used to satisfy these objectives are summarized.

Frauenholz, R. B.↗