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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on USn by Materials Project

USn crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. U is bonded to six equivalent U and six equivalent Sn atoms to form UU6Sn6 cuboctahedra that share corners with eighteen equivalent UU6Sn6 cuboctahedra, edges with six equivalent UU6Sn6 cuboctahedra, edges with twelve equivalent SnU6Sn6 cuboctahedra, faces with eight equivalent UU6Sn6 cuboctahedra, and faces with twelve equivalent SnU6Sn6 cuboctahedra. All U–U bond lengths are 3.11 Å. All U–Sn bond lengths are 3.28 Å. Sn is bonded to six equivalent U and six equivalent Sn atoms to form SnU6Sn6 cuboctahedra that share corners with eighteen equivalent SnU6Sn6 cuboctahedra, edges with six equivalent SnU6Sn6 cuboctahedra, edges with twelve equivalent UU6Sn6 cuboctahedra, faces with eight equivalent SnU6Sn6 cuboctahedra, and faces with twelve equivalent UU6Sn6 cuboctahedra. All Sn–Sn bond lengths are 3.11 Å.

36 MATERIALS SCIENCE↗
NASA NTRS1974

The real-time acquisition and tracking program for the USNS Vanguard

The computer program for the real-time acquisition and tracking program uses a variety of filtering algorithms including an extended Kalman filter to derive real-time orbit determination (position-velocity state vectors) from shipboard tracking and navigation data. Results from Apollo missions are given to show that orbital parameters can be estimated quickly and accurately using these methods.

Brammer, R. F.↗
NASA NTRS1984

Fuel property effects on USN gas turbine combustors

For several years the Department of Defense has been sponsoring fuel accommodation investigations with gas turbine engine manufacturers and supporting organizations to quantify the effect of changes in fuel properties and characteristics on the operation and performance of military engine components and systems. Inasmuch as there are many differences in hardware between the operational engines in the military inventories, due to differences in design philosophy and requirements, efforts were initially expended to acquire fuel effects data from rigs simulating the hot sections of these different engines. Correlations were then sought using the data acquired to produce more general, generic relationships that could be applied to all military gas turbine engines regardless of their origin. Finally, models could be developed from these correlations that could predict the effect of fuel property changes on current and future engines. This presentation describes some of the work performed by Pratt and Whitney Aircraft, under Naval Air Propulsion Center sponsorship, to determine the effect of fuel properties on the hot section and fuel system of the Navy's TF30-P-414 gas turbine engine.

Masters, A. I.↗
NASA NTRS2002

STS 107 Shuttle Press Kit: Providing 24/7 Space Science Research

Space shuttle mission STS-107, the 28th flight of the space shuttle Columbia and the 113th shuttle mission to date, will give more than 70 international scientists access to both the microgravity environment of space and a set of seven human researchers for 16 uninterrupted days. Columbia's 16-day mission is dedicated to a mixed complement of competitively selected and commercially sponsored research in the space, life and physical sciences. An international crew of seven, including the first Israeli astronaut, will work 24 hours a day in two alternating shifts to carry out experiments in the areas of astronaut health and safety; advanced technology development; and Earth and space sciences. When Columbia is launched from Kennedy Space Center's Launch Pad 39A it will carry a SPACEHAB Research Double Module (RDM) in its payload bay. The RDM is a pressurized environment that is accessible to the crew while in orbit via a tunnel from the shuttle's middeck. Together, the RDM and the middeck will accommodate the majority of the mission's payloads/experiments. STS-107 marks the first flight of the RDM, though SPACEHAB Modules and Cargo Carriers have flown on 17 previous space shuttle missions. Astronaut Rick Husband (Colonel, USAF) will command STS-107 and will be joined on Columbia's flight deck by pilot William 'Willie' McCool (Commander, USN). Columbia will be crewed by Mission Specialist 2 (Flight Engineer) Kalpana Chawla (Ph.D.), Mission Specialist 3 (Payload Commander) Michael Anderson (Lieutenant Colonel, USAF), Mission Specialist 1 David Brown (Captain, USN), Mission Specialist 4 Laurel Clark (Commander, USN) and Payload Specialist 1 Ilan Ramon (Colonel, Israeli Air Force), the first Israeli astronaut. STS-107 marks Husband's second flight into space - he served as pilot during STS-96, a 10-day mission that saw the first shuttle docking with the International Space Station. Husband served as Chief of Safety for the Astronaut Office until his selection to command the STS-107 crew. Anderson and Chawla will also be making their second spaceflights. Anderson first flew on STS-89 in January 1998 (the eighth Shuttle-Mir docking mission) while Chawla flew on STS-87 in November 1997 (the fourth U.S. Microgravity Payload flight). McCool, Brown, Clark and Ramon will be making their first flights into space.

Source record↗
NASA NTRS2003

Orbit Determination Error Analysis Results for the Triana Sun-Earth L2 Libration Point Mission

Using the NASA Goddard Space Flight Center's Orbit Determination Error Analysis System (ODEAS), orbit determination error analysis results are presented for all phases of the Triana Sun-Earth L1 libration point mission and for the science data collection phase of a future Sun-Earth L2 libration point mission. The Triana spacecraft was nominally to be released by the Space Shuttle in a low Earth orbit, and this analysis focuses on that scenario. From the release orbit a transfer trajectory insertion (TTI) maneuver performed using a solid stage would increase the velocity be approximately 3.1 km/sec sending Triana on a direct trajectory to its mission orbit. The Triana mission orbit is a Sun-Earth L1 Lissajous orbit with a Sun-Earth-vehicle (SEV) angle between 4.0 and 15.0 degrees, which would be achieved after a Lissajous orbit insertion (LOI) maneuver at approximately launch plus 6 months. Because Triana was to be launched by the Space Shuttle, TTI could potentially occur over a 16 orbit range from low Earth orbit. This analysis was performed assuming TTI was performed from a low Earth orbit with an inclination of 28.5 degrees and assuming support from a combination of three Deep Space Network (DSN) stations, Goldstone, Canberra, and Madrid and four commercial Universal Space Network (USN) stations, Alaska, Hawaii, Perth, and Santiago. These ground stations would provide coherent two-way range and range rate tracking data usable for orbit determination. Larger range and range rate errors were assumed for the USN stations. Nominally, DSN support would end at TTI+144 hours assuming there were no USN problems. Post-TTI coverage for a range of TTI longitudes for a given nominal trajectory case were analyzed. The orbit determination error analysis after the first correction maneuver would be generally applicable to any libration point mission utilizing a direct trajectory.

Marr, G.↗
NASA NTRS1972

GEOS-2 C-band radar system project. Marine study using C-band radars

One of the secondary objectives of the GEOS-2 C-band Systems Project is to study the feasibility of using geodetic satellites to both evaluate shipborne instrumentation and to determine ship positions in broad ocean areas. The purpose of this task is to determine whether shipborne C-band radar tracking, in conjunction with ground based tracking, is sufficiently accurate to provide instrumentation evaluation and ship position estimates. Data from several Apollo tracking ships, in particular the USNS Vanguard, was made available for this effort. A series of tests, using the USNS Vanguard, were carried out in the Port Canaveral and Bahama Acoustic Transponder Array Areas. The major portion of the analyses reported are the result of preliminary investigations using the data from these tests.

Source record↗
NASA NTRS1995

TRISTAR 1: Evaluation methods for testing head-up display (HUD) flight symbology

The first in a series of piloted head-up display (HUD) flight symbology studies (TRISTAR) measuring pilot task performance was conducted at the NASA Ames Research Center by the Tri-Service Flight Symbology Working Group (FSWG). Sponsored by the U.S. Army Aeroflightdynamics Directorate, this study served as a focal point for the FSWG to examine HUD test methodology and flight symbology presentations. HUD climb-dive marker dynamics and climb-dive ladder presentations were examined as pilots performed air-to-air (A/A), air-to-ground (A/G), instrument landing system (ILS), and unusual attitude (UA) recover tasks. Symbolic presentations resembled pitch ladder variations used by the U.S. Air Force (USAF), U.S. Navy (USN), and Royal Air Force (RAF). The study was initiated by the FSWG to address HUD flight symbology deficiencies, standardization, issue identification, and test methodologies. It provided the mechanism by which the USAF, USN, RAF, and USA could integrate organizational ideas and reduce differences for comparisons. Specifically it examined flight symbology issues collectively identified by each organization and the use of objective and subjective text methodology and flight tasking proposed by the FSWG.

Newman, R. L.↗
NASA NTRS2002

Initial Results on the Meteoritic Component of new Sediment Cores Containing Deposits of the Eltanin Impact Event

The late Pliocene impact of the Eltanin asteroid is the only known asteroid impact in a deep- ocean (-5 km) basin . This was first discovered in 1981 as an Ir anomaly in sediment cores collected by the USNS Eltanin in 1965. In 1995, Polarstern expedition ANT XII/4 made the first geological survey of the suspected impact region. Three sediment cores sampled around the San Martin seamounts (approx. 57.5 S, 91 W) contained well-preserved impact deposits that include disturbed ocean sediments and meteoritic impact ejecta. The latter is composed of shock-melted asteroidal materials and unmelted meteorites. In 2001, the FS Polarstern returned to the impact area during expedition ANT XVIIU5a. At least 16 cores were recovered that contain ejecta deposits. These cores and geophysical data from the expedition can be used to map the effects of the impact over a region of about 80,000 square km. To date we have measured Ir concentrations in sediments from seven of the new cores and preliminary data should be available for a few more by the time of the meeting. Our initial interpretation of these data is that there is a region in the vicinity of the San Martin Seamounts comprising at least 20,000 square km in which the average amount of meteoritic material deposited was more than 1 g per square cm. This alone is enough material to support a 500 m asteroid. Beyond this is a region of about 60,000 square km, mostly to the north and west, where the amount of ejecta probably averages about 0.2 g per square cm. Another 400 km to the east, USNS Eltanin core E10-2 has about 0.05 g per square cm, so we know that ejecta probably occurs across more than a million square km of ocean floor. A key to future exploration of this impact is to find evidence of the ejecta at more sites distant from the seamounts. We currently have almost no data from regions to the west or south of the San Martin seamounts.

Kyte, Frank T.↗
NASA NTRS2006

Understanding Cataract Risk in Aerospace Flight Crew And Review of Mechanisms of Cataract Formation

Induction of cataracts by occupational exposure in flight crew has been an important topic of interest in aerospace medicine in the past five years, in association with numerous reports of flight-associated disease incidences. Due to numerous confounding variables, it has been difficult to determine if there is increased cataract risk directly caused by interaction with the flight environment, specifically associated with added radiation exposure during flight. Military aviator records from the United States Air Force (USAF) and Navy (USN) and US astronauts at the National Aeronautics and Space Administration (NASA)/Lyndon B. Johnson Space Center (JSC) were evaluated for the presence, location and age of diagnosis of cataracts. Military aviators were found to have a statistically significant younger average age of onset of their cataracts compared with astronauts, however the incidence density of cataracts was found to be statistically higher in astronauts than in military aviators. USAF and USN aviator s cataracts were most commonly located in the posterior subcapsular region of the lens while astronauts cataracts were most likely to originate generally in the cortical zone. A prospective clinical trial which controls for confounding variables in examination technique, cataract classification, diet, exposure, and pharmacological intervention is needed to determine what percentage of the risk for cataracts are due to radiation, and how to best develop countermeasures to protect flight crews from radiation bioeffects in the future.

Jones, Jeffrey A.↗
NASA NTRS2007

Potential Fifty Percent Reduction in Saturation Diving Decompression Time Using a Combination of Intermittent Recompression and Exercise

Conventional saturation decompression protocols use linear decompression rates that become progressively slower at shallower depths, consistent with free gas phase control vs. dissolved gas elimination kinetics. If decompression is limited by control of free gas phase, linear decompression is an inefficient strategy. The NASA prebreathe reduction program demonstrated that exercise during O2 prebreathe resulted in a 50% reduction (2 h vs. 4 h) in the saturation decompression time from 14.7 to 4.3 psi and a significant reduction in decompression sickness (DCS: 0 vs. 23.7%). Combining exercise with intermittent recompression, which controls gas phase growth and eliminates supersaturation before exercising, may enable more efficient saturation decompression schedules. A tissue bubble dynamics model (TBDM) was used in conjunction with a NASA exercise prebreathe model (NEPM) that relates tissue inert gas exchange rate constants to exercise (ml O2/kg-min), to develop a schedule for decompression from helium saturation at 400 fsw. The models provide significant prediction (p < 0.001) and goodness of fit with 430 cases of DCS in 6437 laboratory dives for TBDM (p = 0.77) and with 22 cases of DCS in 159 altitude exposures for NEPM (p = 0.70). The models have also been used operationally in over 25,000 dives (TBDM) and 40 spacewalks (NEPM). The standard U.S. Navy (USN) linear saturation decompression schedule from saturation at 400 fsw required 114.5 h with a maximum Bubble Growth Index (BGI(sub max)) of 17.5. Decompression using intermittent recompression combined with two 10 min exercise periods (75% VO2 (sub peak)) per day required 54.25 h (BGI(sub max): 14.7). Combined intermittent recompression and exercise resulted in a theoretical 53% (2.5 day) reduction in decompression time and theoretically lower DCS risk compared to the standard USN decompression schedule. These results warrant future decompression trials to evaluate the efficacy of this approach.

Gernhardt, Michael I.↗
NASA NTRS2010

Secure Autonomous Automated Scheduling (SAAS)

This report describes network-centric operations, where a virtual mission operations center autonomously receives sensor triggers, and schedules space and ground assets using Internet-based technologies and service-oriented architectures. For proof-of-concept purposes, sensor triggers are received from the United States Geological Survey (USGS) to determine targets for space-based sensors. The Surrey Satellite Technology Limited (SSTL) Disaster Monitoring Constellation satellite, the UK-DMC, is used as the space-based sensor. The UK-DMC's availability is determined via machine-to-machine communications using SSTL's mission planning system. Access to/from the UK-DMC for tasking and sensor data is via SSTL's and Universal Space Network's (USN) ground assets. The availability and scheduling of USN's assets can also be performed autonomously via machine-to-machine communications. All communication, both on the ground and between ground and space, uses open Internet standards

Walke, Jon G.↗
NASA NTRS2010

Virtual Mission Operations of Remote Sensors With Rapid Access To and From Space

This paper describes network-centric operations, where a virtual mission operations center autonomously receives sensor triggers, and schedules space and ground assets using Internet-based technologies and service-oriented architectures. For proof-of-concept purposes, sensor triggers are received from the United States Geological Survey (USGS) to determine targets for space-based sensors. The Surrey Satellite Technology Limited (SSTL) Disaster Monitoring Constellation satellite, the United Kingdom Disaster Monitoring Constellation (UK-DMC), is used as the space-based sensor. The UK-DMC s availability is determined via machine-to-machine communications using SSTL s mission planning system. Access to/from the UK-DMC for tasking and sensor data is via SSTL s and Universal Space Network s (USN) ground assets. The availability and scheduling of USN s assets can also be performed autonomously via machine-to-machine communications. All communication, both on the ground and between ground and space, uses open Internet standards.

Ivancic, William D.↗
DOE OSTI2024

Validation of NSFsim as a Grad-Shafranov equilibrium solver at DIII-D

Plasma shape is a significant factor that must be considered for any Fusion Pilot Plant (FPP) as it has significant consequences for plasma stability and core confinement. A new simulator, NSFsim, has been developed based on a historically successful code, DINA [1], offering tools to simulate both transport and plasma shape. Specifically, NSFsim is a free boundary equilibrium and transport solver and has been configured to match the properties of the DIII-D tokamak. This paper is focused on validating the Grad-Shafranov (GS) solver of NSFsim by analyzing its ability to recreate the plasma shape, the poloidal flux distribution, and the measurements of the simulated diagnostic signals originating from flux loops and magnetic probes in DIII-D. Five different plasma shapes are simulated to show the robustness of NSFsim to different plasma conditions; these shapes are Lower Single Null (LSN), Upper Single Null (USN), Double Null (DN), Inner Wall Limited (IWL), and Negative Triangularity (NT). The NSFsim results are compared against real measured signals, magnetic profile fits from EFIT [2], and another plasma equilibrium simulator, GSevolve [3]. EFIT reconstructions of shots are readily available at DIII-D, but GSevolve was manually ran by us to provide simulation data to compare against.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Experimental study of the influence of gas puff locations on H-mode boundary plasmas with argon seeding on EAST

To investigate the optimal scenario of impurity seeding to obtain divertor plasma detachment for target protection, experiments with Ar&D 2 seeding from two different poloidal locations, the upper outer (UO) divertor target and lower outer (LO) target, were carried out on EAST. Partial energy detachment (the electron temperature near the strike point T e,spt ≤ 10 eV) were obtained with Ar&D 2 mixture puffing from the UO target and, for the first time, from the LO target into H-mode plasmas in the upper single null (USN) configuration. The peak heat flux q t on the UO target was significantly reduced (by ~80%). The rollover of ion flux density j s did not appear probably due to insufficient momentum loss, which is independent of the puff locations. The poloidal asymmetries of particle and heat fluxes on the targets have also been investigated. The UO-dominant asymmetry of particle flux was reversed, while the UO-dominant asymmetry of heat flux was mitigated but not reversed. The plasma confinement dropped by only 14% and 8.2% in the LO-puff case and UO-puff case, respectively, during detachment. The high level of C may contributed greatly to the higher radiation in the bulk plasma region and the greater decline in W MHD in the LO-puff case.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

ELM and inter-ELM heat and particle flux to a secondary divertor in the DIII-D tokamak

DIII-D ELMing discharges with a secondary X-point (XPT) inside the vessel were used to evaluate the power distribution between the primary and secondary divertors. The magnetic balance, defined by the distance between the primary and secondary separatrices at the outer midplane (dRsep), was varied from -5 mm (lower-single-null, LSN) to +16 mm (upper-single-null, USN). In this work, we find that the secondary divertor receives up to 1/3 of the total heat flux (primary + secondary divertors), and it is dominated by the ELM-driven flux. Both the radially-integrated and the peak heat flux to the secondary divertor decay below ~50% of the maximum as dRsep is varied from -5 to +6mm, but the integrated heat flux decay flattens out and it would take dRsep above ~25mm to reduce the ELM heat flux to the secondary divertor below 10% of the one deposited to a well-defined SN. Both the secondary inner and outer strike points receive heat flux during ELMs. The peak heat flux is comparable in both strike points for dRsep < 10mm, but the inner strike point receives less than 15% of the total flux. Furthermore, this is experimental evidence that the secondary inner divertor region receives significant ELM flux which should be taken into account for the design of future generation tokamaks.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗