Search NASA⌕ Search

SEARCH · Search NASA

Results for “PmS”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Three-dimensional trajectory analyses of two drop sizing instruments - PMS OAP and PMS FSSP

Flow-induced distortions of water drop fluxes and speeds as seen by the PMS optical array probe (OAP) and the PMS forward scattering spectrometer probe (FSSP) are estimated via three-dimensional flow and trajectory calculation methods. The sensitivities of the instruments to water drop diameter, angle of attack, and free stream air speed are determined. The instruments are first placed in isolation and then mounted under the wing of a Twin Otter airplane. For the wing-mounted OAP at 4-deg angle of attack, partial flow stagnation under the uptilted wing causes a significant decrease in both the flux and speed for small water drops. For the wing-mounted FSSP, sensitivity is found to both angle of attack and free stream air speed.

Norment, H. G.↗
NASA NTRS1988

Three-dimensional trajectory analyses of two drop sizing instruments: PMS OAP and PMS FSSP

Flow induced distortions of water drop fluxes and speeds seen by the instruments were predicted by use of three dimensional flow and trajectory calculation methods. Sensitivities were determined for the instruments, in isolation and mounted under the wing of an airplane, to: water drop diameter (2 to 1000 microns), angle of attack and free stream air speed. For the optical array probe in isolation and on the airplane at 0 deg angle of attack, flux distortions of practical consequence are not found. At 4 deg airplane angle of attack, partial flow stagnation under the uptilted wing causes significant decreases in both flux and speed for cloud size droplets. For the forward scattering spectrometer probe in isolation, only marginally significant sensitivities to free stream air speed are found, and no sensitivity is found to angle of attack. Both speed and flux of cloud size droplets are predicted to be undermeasured by from 12 to 24 percent depending on airplane angle of attack. For the wing-mounted instruments, effects of flow about the instruments themselves are found to be equal in importance to effects of flow about the airplane. Preferred orientation (canting) angles of distorted water drops are found to be functions of drop size, angle of attack and air speed.

Norment, Hillyer G.↗
NASA NTRS1988

Three-dimensional trajectory analyses of two drop sizing instruments - PMS OAP and PMS FSSP

Flow induced distortions of water drop fluxes and speeds seen by the instruments were predicted by use of three dimensional flow and trajectory calculation methods. Sensitivities were determined for the instruments, in isolation and mounted under the wing of an airplane, to: water drop diameter (2 to 1000 microns), angle of attack and free stream air speed. For the optical array probe in isolation and on the airplane at 0 deg angle of attack, flux distortions of practical consequence are not found. At 4 deg airplane angle of attack, partial flow stagnation under the uptilted wing causes significant decreases in both flux and speed for cloud size droplets. For the forward scattering spectrometer probe in isolation, only marginally significant sensitivities to free stream air speed are found, and no sensitivity is found to angle of attack. Both speed and flux of cloud size droplets are predicted to be undermeasured by from 12 to 24 percent depending on airplane angle of attack. For the wing-mounted instruments, effects of flow about the instruments themselves are found to be equal in importance to effects of flow about the airplane. Preferred orientation (canting) angles of distorted water drops are found to be functions of drop size, angle of attack and air speed.

Norment, Hillyer G.↗
NASA NTRS1990

Platform Management System (PMS) evolution

In fiscal year 1988 a study was begun to define the platform management system (PMS) functions required for the mature platform operations era. The objectives of the task include: (1) defining how to increase the operational productivity of the platform by providing enhanced capability for responding to changing events, (2) influencing the initial PMS design by identifying required 'hooks and scars', and (3) evaluation potential automation techniques that are appropriate given predicted onboard computing resources. Initial platform operations scenarios were defined. The focus was on PMS-related functions where operations enhancements are likely to occur. Operations productivity was defined in terms of scientific productivity of the platform as well as the level of automation of the ground system. The Platform Operations Productivity Enhancement Report was completed earlier this year documenting system enhancements to increase science productivity and ground system automation. Using the baseline PMS defined in the PMS Definition Document as a starting point, the resulting PMS-specific enhancements were molded into a sequence of progressively more sophisticated operations management capabilities. This sequence of upgrades to the PMS has been documented in a PMS Evolution Plan. The plan includes enhancements in the areas of resources scheduling, resource modeling, system and payload anomaly management, and transaction sequence interpretation. A plan for migration of functions from the ground portion of the PMS to the flight portion is also included. The impacts of this plan on the platform are now being documented to ensure that the required 'hooks and scars' are included in the baseline system. Future plans include a prototype of some of the PMS enhancements to address the feasibility of and techniques for implementing these enhancements in the onboard computing environment.

Tilley, Mike↗
NASA NTRS1999

A Deep HRI Survey of Low-Mass PMS Stars in NGC 2264

Brian Patten is the Principal Investigator of the NASA ADP project 'A Deep HRI Survey of Low-Mass PMS Stars in NGC 2264'. This project was funded to support primarily the data reduction and analysis for new ROSAT data to be acquired in ROSAT AO8. For AO8 we were awarded two deep (100 ks) exposures with the ROSAT HRI instrument of a rotation and proper-motion selected sample of young (3 Myr - 15 Myr), low-mass, PMS stars in the populous star-forming region NGC 2264. These X-ray data were to be combined with an extensive rotation database for members of this cluster to allow us, for the first time, to probe the early evolution of magnetic dynamo activity for both fully convective stars and those stars found lower on the Hayashi tracks which have developed radiative cores. This database would have been used to study the interrelationship between coronal activity level, interior structure, and rotation rate as a function of mass and age.in the PMS and to define empirical constraints for theoretical models of angular momentum and magnetic dynamo evolution.

Patten, Brian↗
NASA NTRS1987

Space station Platform Management System (PMS) replanning using resource envelopes

One of the responsibilities of the Space Station Platform Management System (PMS) is to maintain constraint-free, short-term plans for platform and free-flyer activities. Both the replanning function and the associated constraint-checking function are viewed as potentially requiring expert system assistance. The PMS Resource Envelope Scheduling System (PRESS) expert system, which is currently under development, is described. The PRESS capabilities will include the following: plan, replan, and perform constraint checking using resource envelopes resembling those required for telescience; initialize itself using the results fo a previous run; infer the replanning needs associated with a change in resource availability; allow the user to determine the level of interaction (including an advisory capability) with the system during execution; and generate both a graphic timeline and a report as output. The PRESS is being developed on an IBM PC/AT using TeKnowledge, Inc.'s M.1 expert system shell. The PRESS activity definitions and constraints are based on those defined for the Cosmic Background Explorer (COBE) mission scheduled for launch in early 1989.

Bush, Joy Lee↗
NASA NTRS2001

A Deep X-Ray Survey of Low Mass PMS Stars in NGC 2264

We have proposed to make a deep X-ray survey of a rotation- and proper-motion selected sample of young (3-15 Myr old), low-mass, pre-main sequence (PMS) stars in the populous star-forming region NGC 2264. These X-ray Multimirror Mission (XMM) data will be combined with an extensive set of rotation data for members of this cluster to allow us, for the first time, to probe the early evolution of magnetic dynamo activity for both fully convective stars and those stars found lower on their Hayashi tracks, which are developing radiative cores. We will use these data to study the interrelationship between rotation, interior structure, and coronal activity as a function of mass and age in the PMS and to define empirical constraints for theoretical models of angular momentum/dynamo evolution.

Patten, Brian M.↗
DOE OSTI2020

Materials Data on PmS by Materials Project

PmS is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pm is bonded to six equivalent S atoms to form a mixture of edge and corner-sharing PmS6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Pm–S bond lengths are 2.85 Å. S is bonded to six equivalent Pm atoms to form a mixture of edge and corner-sharing SPm6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
NASA NTRS1994

An x-ray search for PMS stars in translucent molecular clouds

The work outlined in this paper identifies 108 plausible T Tauri candidates in the regions of two high latitude translucent molecular clouds. Follow-up optical spectroscopy of these candidates is needed to resolve the question of whether or not star formation is present in these clouds. We have recently submitted a proposal to use the Kitt Peak National Observatory 2.1 meter telescope to take medium resolution spectra of the 14 PMS candidate X-ray sources in MBM 40 to determine spectral types and search for indicators of youth (strong Li absorption; H alpha emission) and we will submit a similar proposal to study the X-ray sources in MBM 55. Only spectra will provide an unambiguous determination of their pedigree. As part of an ongoing study of star formation at high galactic latitude we intend to analyze data in the ROSAT archives to investigate the possibility of star formation in all of the high latitude translucent molecular clouds observed. We believe that this project may yield a significant increase in our understanding of the star formation process for low-mass stars and of the nature of the translucent clouds.

Caillault, Jean-Pierre↗
NASA NTRS1994

The Mg 2 lines as diagnostic of PMS nature in Herbig Ae/Be stars

The main objective of this program was to observe some newly discovered and previously unobserved Herbig Ae/Be (HAeBe) stars with IUE. A previous archival study suggested that there was a full range of profiles in the Mg II lines for these objects; ranging from the double peak emission to the narrow absorption lines. It has been found that by studying the IUE data of main sequence B and classical Be stars that the P Cygni profiles in the Mg II lines in HAeBe stars are truly unique and are the signature of accelerating winds in their extended circumstellar material. The arguement, for the purposes of this proposal, that the structure of the Mg II lines was a superior diagnostic of the dynamical activity and ultimately the PMS nature of these objects. This program was a follow up study of several interesting intermediate-mass stars with the goal of classifying these objects based on the shape of their MG II lines. A list of publications resulting from this research is included.

Source record↗
NASA NTRS2026

Space Suit Material Compatibility with Space Vehicle Coolant PMS-1.5R

During a survey of 82P on February 11, 2023, a shiny substance was detected on the Progress vehicle. The suspected material was PMS-1.5R, a low volatility silicone oil coolant used in the vehicle. Crew exposure to the coolant was a concern as the low volatility would increase residence time, the time a material will stay on a surface after exposure to vacuum. A review of space suit materials revealed several materials with compatibility concerns that could impact Extravehicular Activity (EVA) operations and safety. To understand the risk, space suit materials were exposed to a simulant and tested. This testing provided the basis for rationale generated to continue with EVA operations for US EVA 86 on April 2, 2023. This testing also served as the basis to assess impacts to ISS EMU hardware due to potential contamination brought inside ISS on Russian space suits during RS EVA 61 on October 25, 2023, following an ISS Russian Multipurpose Lab Module (MLM) radiator leak of the same fluid on October 9, 2023. This paper will discuss the testing performed and analyze test results impacts to EVA operations. Additional work was conducted to determine coolant evaporation rates in space vacuum and demonstrate that no significant unreacted coolant from the MLM leak would remain on ISS surfaces long enough to contaminate the EMU or affect the ISS ECLSS water separator.

Space Suit Materials↗
NASA NTRS2005

A Deep X-ray Survey of Low-Mass PMS Stars in NGC 2264

Two X-ray images were obtained with the XMM-Newton spacecraft of more than 300 members of the NGC 2264 Open Cluster and its associated molecular cloud in order to investigate their magnetic activity. The X-ray fluxes extracted from those observations were used to study the dependence of stellar dynamo activity upon age and rotation for the optically revealed T Tauri stars and to place empirical constraints on theoretical models of angular momentum/dynamo evolution. The observations were also used to study the role of magnetic fields in the formation of low mass stars through the observation of very young protostars that are deeply embedded in the molecular cloud located behind the visible open cluster.

Simon, Theodore↗
NASA NTRS2006

Narrow-band Imagery with the Goddard Fabry-Perot: Probing the Epoch of Active Accretion for PMS Stars

The STIS coronagraphic imaging sample of I'MS stars was surveyed with the Goddard Fabry-Perot (GFP) interferometer to determine what fraction of the stars drive jets, whether there is any difference in behavior for a group of intermediate-mass stars as compared with T Tauri stars, and to search for evolutionary effects. Compared to broad band imaging, the FGP achieves an emission-line nebulosity-to-star contrast gain of between 500 and 3000. To date, we have detected jets associated with classical T Tauri stars spanning a factor of 280 in mass accretion rate in approximately 50% of the STIS coronagraphic imaging sample. We also detected jets or Herbig-HARO knots associated with 5 Herbig Ae stars, all younger than 8 Myr, for a detection fraction which is smaller than the T Tauri survey.

Woodgate, Bruce E.↗
NASA NTRS2011

NEXT Propellant Management System Integration With Multiple Ion Thrusters

As a critical part of the NEXT test validation process, a multiple-string integration test was performed on the NEXT propellant management system and ion thrusters. The objectives of this test were to verify that the PMS is capable of providing stable flow control to multiple thrusters operating over the NEXT system throttling range and to demonstrate to potential users that the NEXT PMS is ready for transition to flight. A test plan was developed for the sub-system integration test for verification of PMS and thruster system performance and functionality requirements. Propellant management system calibrations were checked during the single and multi-thruster testing. The low pressure assembly total flow rates to the thruster(s) were within 1.4 percent of the calibrated support equipment flow rates. The inlet pressures to the main, cathode, and neutralizer ports of Thruster PM1R were measured as the PMS operated in 1-thruster, 2-thruster, and 3-thruster configurations. It was found that the inlet pressures to Thruster PM1R for 2-thruster and 3-thruster operation as well as single thruster operation with the PMS compare very favorably indicating that flow rates to Thruster PM1R were similar in all cases. Characterizations of discharge losses, accelerator grid current, and neutralizer performance were performed as more operating thrusters were added to the PMS. There were no variations in these parameters as thrusters were throttled and single and multiple thruster operations were conducted. The propellant management system power consumption was at a fixed voltage to the DCIU and a fixed thermal throttle temperature of 75 C. The total power consumed by the PMS was 10.0, 17.9, and 25.2 W, respectively, for single, 2-thruster, and 3-thruster operation with the PMS. These sub-system integration tests of the PMS, the DCIU Simulator, and multiple thrusters addressed, in part, the NEXT PMS and propulsion system performance and functionality requirements.

Sovey, James S.↗