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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.

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NASA NTRS2016

Global Positioning System Energetic Particle Data: The Next Space Weather Data Revolution

The Global Positioning System (GPS) has revolutionized the process of getting from point A to point Band so much more. A large fraction of the worlds population relies on GPS (and its counterparts from other nations) for precision timing, location, and navigation. Most GPS users are unaware that the spacecraft providing the signals they rely on are operating in a very harsh space environment the radiation belts where energetic particles trapped in Earths magnetic field dash about at nearly the speed of light. These subatomic particles relentlessly pummel GPS satellites. So by design, every GPS satellite and its sensors are radiation hardened. Each spacecraft carries particle detectors that provide health and status data to system operators. Although these data reveal much about the state of the space radiation environment, heretofore they have been available only to system operators and supporting scientists. Research scientists have long sought a policy shift to allow more general access. With the release of the National Space Weather Strategy and Action Plan organized by the White House Office of Science Technology Policy (OSTP) a sample of these data have been made available to space weather researchers. Los Alamos National Laboratory (LANL) and the National Center for Environmental Information released a months worth of GPS energetic particle data from an interval of heightened space weather activity in early 2014 with the hope of stimulating integration of these data sets into the research arena. Even before the public data release GPS support scientists from LANL showed the extraordinary promise of these data.

Knipp, Delores J.↗
NASA NTRS2002

Manipulation of Micro Scale Particles in an Optical Trap Using Interferometry

This research shows that micro particles can be manipulated via interferometric patterns superimposed on an optical tweezers beam. Interferometry allows the manipulation of intensity distributions, and thus, force distributions on a trapped particle. To demonstrate the feasibility of such manipulation, 458 nm light, from an argon-ion laser, was injected into a Mach Zender interferometer. One mirror in the interferometer was oscillated with a piezoelectric phase modulator. The light from the interferometer was then injected into a microscope to trap a 9.75 micron polystyrene sphere. By varying the phase modulation, the sphere was made to oscillate in a controlled fashion.

Seibel, Robin↗
NASA NTRS1980

Motion of trapped electrons and protons in Saturn's inner magnetosphere

A summary is given of basic formulas for the guiding center motion of energetic charged particles trapped in a dipolar magnetic field. These formulas for longitudinal drift rates, latitudinal bounce periods, equatorial gyroradii, and equatorial gyroperiods are then stated in convenient numerical form for electrons and protons as functions of kinetic energy E, magnetic shell parameter L, and equatorial pitch angle alpha 0 for a slightly simplified model of the observed magnetic field of Saturn. To aid in the study of the interaction of charged particles with the rings and inner satellites of Saturn, additional formulas are given for the time interval between successive encounters of charged particles with a satellite in a circular prograde orbit and for the energy of electrons whose longitudinal angular velocity is resonant, or synchronous, with the Keplerian angular velocity of such a satellite.

Thomsen, M. F.↗
NASA NTRS2018

Investigating Astromaterials Curation Applications for Dexterous Robotic Arms

The Astromaterials Acquisition and Curation office at NASA Johnson Space Center is currently investigating tools and methods that will enable the curation of future astromaterials collections. Size and temperature constraints for astromaterials to be collected by current and future proposed missions will require the development of new robotic sample and tool handling capabilities. NASA Curation has investigated the application of robot arms in the past, and robotic 3-axis micromanipulators are currently in use for small particle curation in the Stardust and Cosmic Dust laboratories. While 3-axis micromanipulators have been extremely successful for activities involving the transfer of isolated particles in the 5-20 micron range (e.g. from microscope slide to epoxy bullet tip, beryllium SEM disk), their limited ranges of motion and lack of yaw, pitch, and roll degrees of freedom restrict their utility in other applications. For instance, curators removing particles from cosmic dust collectors by hand often employ scooping and rotating motions to successfully free trapped particles from the silicone oil coatings. Similar scooping and rotating motions are also employed when isolating a specific particle of interest from an aliquot of crushed meteorite. While cosmic dust curators have been remarkably successful with these kinds of particle manipulations using handheld tools, operator fatigue limits the number of particles that can be removed during a given extraction session. The challenges for curation of small particles will be exacerbated by mission requirements that samples be processed in N2 sample cabinets (i.e. gloveboxes). We have been investigating the use of compact robot arms to facilitate sample handling within gloveboxes. Six-axis robot arms potentially have applications beyond small particle manipulation. For instance, future sample return missions may involve biologically sensitive astromaterials that can be easily compromised by physical interaction with a curator; other potential future returned samples may require cryogenic curation. Robot arms may be combined with high resolution cameras within a sample cabinet and controlled remotely by curator. Sophisticated robot arm and hand combination systems can be programmed to mimic the movements of a curator wearing a data glove; successful implementation of such a system may ultimately allow a curator to virtually operate in a nitrogen, cryogenic, or biologically sensitive environment with dexterity comparable to that of a curator physically handling samples in a glove box.

Snead, C. J.↗
NASA NTRS1973

Nightside energetic particle decreases at the synchronous orbit

More than 100 cases of major decreases of proton and electron fluxes at the synchronous orbit have been observed and interpreted as a movement of the energetic particle trapping boundary earthward of 6.6 earth radii before the substorm expansion phase. These events are observed only between 1700 and 0800 LT and are consistent with the existence of a westward magnetospheric electric field of a few tenths of a millivolt per meter before substorm expansion. Most substorm particle events seen on the nightside do not exhibit this behavior, presumably because the trapping boundary moves inside 6.6 earth radii only during major events. Such events show evidence of particle acceleration, which probably was concentrated at higher L values, near the instantaneous location of the trapping boundary.

Bogott, F. H.↗
NASA NTRS1985

The AMPTE Charge Composition Explorer and the 4-7 September 1984 geomagnetic storm

The orbit and payload of the AMPTE (active magnetospheric particle tracer explorer) Charge Composition Explorer (CCE) satellite, which provide an exellent opportunity for observing the geomagnetically trapped particle population in general and the earth's ring current in particular, are described. A global view of the September 4, 1984 geomagnetic storm is presented and the initial findings of the CCE investigators on the earth's ring current are given. It is shown that the CCE ring-current results pertain to an unusual asymmetric ring current and may not be applicable to a more typical ring-current development and decay.

Williams, D. J.↗
NASA NTRS1992

The interstellar gas experiment: Analysis in progress

The interstellar gas experiment (IGE) exposed thin metallic foils in order to collect neutral interstellar particles which penetrate the solar system due to their motion relative to the sun. These atoms were entrapped in the collecting foils along with precipitating magnetospheric ions and with ambient atmospheric atoms. For the entire duration of the LDEF mission, seven of the foils collected particles arriving from seven different directions as seen from the spacecraft. In the mass spectrometric analysis of the trapped noble gas component, we detected the He-3, He-4, Ne-20, and Ne-22 isotopes. In order to infer the isotopic ratios in the interstellar medium from the measured concentrations found in the foil piece, several lines of investigation had to be initiated. The flux of incident noble gas atoms from the ambient atmosphere was estimated by detailed calculations. The contributions proved to be negligible, supporting the experimental evidence. Foil and machine backgrounds for the four isotopes which were measured had to be assessed individually. While this was easy for He-4, spurious foil background of He-3 had to be monitored carefully by analyzing unflown foil pieces. Trapped Ne concentrations are not far above the background. During the flight, a stuck electrical relay precluded the foil-trays from sequencing as designed. Therefore, we could not use the seasonal variation of the direction of the incoming interstellar atoms to make the distinction between interstellar and magnetospheric components of the trapped particles. Instead, we had to try the method of stepwise heating to extract the interstellar component at lower temperatures than we use to extract the magnetospheric component (the interstellars hit the foil with lower energies than most of the magnetospherics). New limiting values for the isotopic composition of the interstellar medium, unavailable yet from any other method of measurement, are emerging from this analysis.

Buehler, F.↗
NASA NTRS1993

The Interstellar Gas Experiment: Analysis in progress

The Interstellar Gas Experiment (IGE) exposed thin metallic foils aboard the LDEF spacecraft in low Earth orbit in order to collect neutral interstellar particles which penetrate the solar system due to their motion relative to the sun. By mechanical penetration these atoms were imbedded in the collecting foils along with precipitating magnetospheric ions and, possibly, with ambient atmospheric atoms. During the entire LDEF mission, seven of these foils collected particles arriving from seven different directions as seen from the spacecraft. After the foils were returned to Earth, a mass spectrometric analysis of the noble gas component of the trapped particles was begun. The isotopes of He-3, He-4, Ne-20, and Ne-22 were detected. We have given a first account of the experiment. In order to infer the isotopic ratios in the interstellar medium from the concentrations found in the foils, several lines of investigation had to be initiated. The flux of ambient atmospheric noble gas atoms moving toward the foils due to the orbital motion of LDEF was estimated by detailed calculations. Any of these particles which evaded the baffles in the IGE collector could be entrapped in the foils as a background flux. However, the calculations have shown that this flux is negligible, which was the intent of the experiment hardware design. This conclusion is supported by the measurements. However, both the concentration of trapped helium and its impact energy indicate that the flux of magnetospheric ions which was captured was larger than had been expected. In fact, it appears that the magnetospheric particles constitute the largest fraction of the particles in the foils. Since little is known about this particle flux, their presence in the IGE foils appears fortunate. The analysis of these particles provides information about their isotropic composition and average flux.

Buehler, F.↗
NASA NTRS1984

A stochastic model for photon noise induced by charged particles in multiplier phototubes of the space telescope fine guidance sensors

The Space Telescope (ST) is subjected to charged particle strikes in its space environment. ST's onboard fine guidance sensors utilize multiplier phototubes (PMT) for attitude determination. These tubes, when subjected to charged particle strikes, generate spurious photons in the form of Cerenkov radiation and fluorescence which give rise to unwanted disturbances in the pointing of the telescope. A stochastic model for the number of these spurious photons which strike the photocathode of the multiplier phototube which in turn produce the unwanted photon noise are presented. The model is applicable to both galactic cosmic rays and charged particles trapped in the Earth's radiation belts. The model which was programmed allows for easy adaption to a wide range of particles and different parameters for the phototube of the multiplier. The probability density functions for photons noise caused by protons, alpha particles, and carbon nuclei were using thousands of simulated strikes. These distributions are used as part of an overall ST dynamics simulation. The sensitivity of the density function to changes in the window parameters was also investigated.

Howell, L. W.↗
NASA NTRS1986

Stochastic model for photon noise induced by charged particles in multiplier phototubes of the Hubble Space Telescope fine guidance sensors

The Space Telescope (ST) is subjected to charged particle strikes in its space environment. ST's onboard fine guidance sensors utilize multiplier phototubes (PMT) for attitude determination. These tubes, when subjected to charged particle strikes, generate spurious photons in the form of Cerenkov radiation and fluorescence which give rise to unwanted disturbances in the pointing of the telescope. A stochastic model for the number of these spurious photons which strike the photocathodes of the multiplier phototube which in turn produce the unwanted photon noise are presented. The model is applicable to both galactic cosmic rays and charged particles trapped in the earth's radiation belts. The model which was programmed allows for easy adaption to a wide range of particles and different parameters for the phototube of the multiplier. The probability density functions for photons noise caused by protons, alpha particles, and carbon nuclei were using thousands of simulated strikes. These distributions are used as part of an overall ST dynamics simulation. The sensitivity of the density function to changes in the window parameters was also investigated.

Howell, L. W.↗
NASA NTRS1988

Generalized adiabatic theory applied to the magnetotail current sheet

The generalized first adiabatic invariant, an extension of the magnetic moment for regions of large field gradients, has been applied to the study of particles in the magnetotail current sheet. Boundaries in phase space are obtained which form a generalized loss cone and separate particles drifting into and out of the layer from particles trapped within the layer, and the boundaries can be employed in the moment integrals for densities and currents when the drifting particles differ in temperature. It is shown that the parallel pressure of the drifting particles must exceed the transverse pressure for self-consistent solutions to exist. Fully self-consistent solutions are obtained using bi-Maxwellian ion and Maxwellian electron distributions.

Rogers, Shelley H.↗
NASA NTRS1978

Particle-impact noise detector (PIND)

Package, in page assembly, is subjected to low-frequency vibration, and noise generated by particle impacts is picked up by transducer. Test procedure calls for three transverse shocks to be applied to page to dislodge any trapped particles.

Barr, R. J.↗
NASA NTRS1996

Measurement of LET distribution and dose equivalent on board the space shuttle STS-65

Space radiation dosimetry measurements have been made on board the Space Shuttle STS-65 in the Second International Microgravity Laboratory (IML-2). In these measurements, three kinds of detectors were used; one is a newly developed active detector telescope called "Real-time Radiation Monitoring Device (RRMD)" utilizing silicon semi-conductor detectors and others are conventional detectors of thermoluminescence dosimeters (TLDs) and CR-39 plastic track detectors. Using the RRMD detector, the first attempt of real-time monitoring of space radiation has been achieved successfully for a continuous period of 251.3 h, giving the temporal variations of LET distribution, particle count rates, and rates of absorbed dose and dose equivalent. The RRMD results indicate that a clear enhancement of the number of trapped particles is seen at the South Atlantic Anomaly (SAA) without clear enhancement of dose equivalent, while some daily periodic enhancements of dose equivalent due to high LET particles are seen at the lower geomagnetic cutoff regions for galactic cosmic ray particles (GCRs). Therefore, the main contribution to dose equivalent is seen to be due to GCRs in this low altitude mission (300 km). Also, the dose equivalent rates obtained by TLDs and CR-39 ranged from 146.9 to 165.2 microSv/day and the average quality factors from 1.45 to 1.57 depending on the locations and directions of detectors inside the Space-lab at this highly protected orbit for space radiation with a small inclination (28.5 degrees) and a low altitude (300 km). The LET distributions obtained by two different detectors, RRMD and CR-39, are in good agreement in the region of 15-200 keV/mm and difference of these distributions in the regions of LET < 15 keV/mm and LET > 200 keV/mm can be explained by considering characteristics of CR-39 etched track formation especially for the low LET tracks.

manned↗
NASA NTRS1976

Magnetospheric dynamics and wave-particle interactions

It has been demonstrated that two general classes of wave-particle interactions are of great importance for magnetospheric dynamics. Electromagnetic and electrostatic plasma instabilities give rise to relatively narrow-banded spontaneous emissions (e.g., ELF hiss, chorus, three-halves noise, ion cyclotron and ion-plasma-frequency turbulence) that can scatter trapped particles into the loss cone, leading to modified pitch-angle distributions, stable trapping limits, diffuse aurora, proton precipitation events, etc. The current-driven plasma instabilities give rise to impulsive ion acoustic or Buneman mode turbulence that provides very effective energy transfer (via the anomalous conductivity mechanism) at the bow shock and in regions where strong field-aligned currents are observed. We review these interactions and identify significant open questions that must be investigated during the IMS.

Scarf, F. L.↗
NASA NTRS1991

The ONR-602 experiment and investigation of particle precipitation near the equator

The global precipitation of radiation belt particles at low altitude was investigated, using the ONR-602 experiment on board U.S. Air Force mission S81-1. A combination of a main telescope, beginning analysis at a few MeV/nucleon, and a monitor system, giving results below 1 MeV/nucleon, was designed for measuring particle phenomena characterized by almost any energy spectrum. The monitor provides an indication of the presence of the particles at low energy, while the main telescope gives detailed flux and composition data for the higher energy events. Results of the instrument performance analysis indicate that, at the equator, the monitor telescope has the peak efficiency for particles of about 90 deg pitch angles. The large opening angle of 75 deg makes it possible to detect omnidirectional flux of quasi-trapped particles. The high-energy cosmic-ray background count is found to be very insignificant. It is demonstrated that the particle counting rates for the low-energy threshold have been almost entirely due to protons.

Miah, M. A.↗
NASA NTRS1979

Shock during PIND test frees particles

Recent study on Particle-Impact Noise-Detection (PIND) shows impact at 1,500 to 4,000 G normally imparted to hybrid microcircuits during testing knocks loose stray trapped particle that can be subsequentially removed. Process may be 80 to 90 percent effective in removal of particles depending on type of test utilized.

Caruso, S. V.↗
NASA NTRS1991

Radiation exposure and dose estimates for a nuclear-powered manned Mars sprint mission

A conceptual manned mission to Mars is analyzed in order to estimate potential ionizing radiation doses that may be incurred by crew members during the course of the mission. The scenario is set for a journey during the solar active period and includes a brief stay on the Martian surface. Propulsion is assumed to be provided by nuclear thermal rocket power, and estimates of the dose contributions from the reactors are included. However, due to effective shielding of the reactors by large propellant tanks, it is found that the incurred doses are principally due to the charged particle natural environment. Recent data (August-December 1989) for large solar proton events are used to simulate the flame environment, while standard models are used for the trapped particle and galactic cosmic ray contributions. Shield effectiveness for several candidate materials are investigated.

Nealy, John E.↗
NASA NTRS1993

Orbital resonances and Poynting-Robertson drag

The phenomenon of resonance trapping with Poynting-Robertson drag in the simplest case - the circular restricted three-body problem - is elucidated. Attention is given to what determines whether a grain of a given size passes through a given resonance or is trapped there, to how and why a trapped particle's orbit evolves with time, and to why Poynting-Robertson drag resonances are only temporary, while gas-drag resonances appear to be stable. The possibility of trapping a grain into resonance with a planet depends on the combination of the following parameters: the ratio of radiation pressure force to solar gravity, the mass of the perturbing planet normalized to the solar mass, an integer, and eccentricity. In general, the peak eccentricity and sometimes the threshold value are large enough so that crossing orbits and close approaches to the planet can inhibit capture and aid escape from resonance.

Weidenschilling, S. J.↗