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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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At least 109 records · Page 6
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NASA NTRS1974

Pioneer Solar Plasma and Magnetic Field Measurements in Interplanetary Space During August 2-17, 1972

Solar wind plasma and magnetic field measurements from Pioneers 9 and 10 during August 2-17, 1972, reveal complex and large-amplitude variations on a one-hour time scale and numerous discontinuities. During this time period an approximate radial alignment of the two spacecraft as seen from the Sun occurred with heliocentric distances of 0.8 AU for Pioneer 9 and 2.2 AU for Pioneer 10, both at 45 deg east of the Earth's solar longitude. The peak hourly average solar wind proton bulk velocity measured at Pioneer 9 was 990 km sec (exp -1) during hour 0 UT of August 5. The peak hourly average proton number density was 62 cm (exp -3) during hour 11 UT of August 3. The peak solar wind speeds are generally much reduced at Pioneer 10 compared with those observes at Pioneer 9. The peak 30 minute average magnetic field magnitude was 85 gamma during 1245 - 1315 UT of August 3. The Pioneer 9 data indicate passage of four fast forward interplanetary shocks, and one slow forward interplanetary shock.

Mihalov, J. D.↗
NASA NTRS1976

Venera-9 magnetic field measurements in the Venus wake - Evidence for an earth-like interaction

Venera-9 magnetic field measurements in the Venus wake provide additional support for the hypothesis that Venus has an intrinsic planetary field. The observed field is in the direction expected for a northward moment, and is similar to that observed in equivalent locations in the terrestrial magnetosphere, both in its temporal and spatial behavior. In particular, Venera-9 appears to have observed a plasma sheet expansion, field-aligned currents, and tail-field dipolarization.

Russell, C. T.↗
NASA NTRS1992

Magnetic Susceptibility Measurements for in Situ Characterization of Lunar Soil

Magnetic separation is a viable method for concentration of components of lunar soils and rocks for use as feedstocks for manufacture of metals, oxygen, and for recovery of volatiles such as He-3. Work with lunar materials indicates that immature soils are the best candidates for magnetic beneficiation. The magnetic susceptibility at which selected soil components such as anorthite, ilmenite, or metallic iron are separated is not affected by soil maturity, but the recovery of the concentrated components is. Increasing soil maturity lowers recovery. Mature soils contain significant amounts of glass-encased metallic iron. Magnetic susceptibility, which is sensitive to metallic iron content, can be used to measure soil maturity. The relationship between the ratio of magnetic susceptibility and iron oxide and the conventional maturity parameter, I(sub s)/FeO, ferromagnetic resonant intensity divided by iron oxide content is given. The magnetic susceptibilities were determined using apparatus designed for magnetic separation of the lunar soils.

Oder, R. R.↗
NASA NTRS1976

Structure of the lunar interior from magnetic field measurements

A network of lunar surface and orbiting magnetometers was used to obtain measurements of electrical conductivity and magnetic permeability of the lunar interior. An exceptionally large solar transient event, when the moon was in a geomagnetic tail lobe, enabled the most accurate lunar electromagnetic sounding information to date to be obtained. A new analytical technique using a network of two surface magnetometers and a satellite magnetometer superimposes many time series measurements to improve the signal-to-noise ratio and uses both the amplitude and phase information of all three vector components of the magnetic field data. Size constraints on a hypothetical highly conducting lunar core are investigated with the aid of the permeability results.

Dyal, P.↗
NASA NTRS2018

On the Spatial Coherence of Magnetic Ejecta: Measurements of Coronal Mass Ejections by Multiple Spacecraft Longitudinally Separated by 0.01 au

Measurements of coronal mass ejections (CMEs) by multiple spacecraft at small radial separations but larger longitudinal separations is one of the ways to learn about the three-dimensional structure of CMEs. Here, we take advantage of the orbit of the Wind spacecraft that ventured to distances of up to 0.012 au from the Sun-Earth line during 2000-2002. Combined with measurements from the Advanced Composition Experiment, which is in a tight halo orbit around L1, the multipoint measurements allow us to investigate how the magnetic field inside magnetic ejecta (MEs) changes on scales of 0.005-0.012 au. We identify 21 CMEs measured by these two spacecraft for longitudinal separations of 0.007 au or more. We find that the time-shifted correlation between 30 minute averages of the non-radial magnetic field components measured at the two spacecraft is systematically above 0.97 when the separation is 0.008 au or less, but is on average 0.89 for greater separations. Overall, these newly analyzed measurements, combined with 14 additional ones when the spacecraft separation is smaller, point toward a scale length of longitudinal magnetic coherence inside MEs of 0.25-0.35 au for the magnitude of the magnetic field, but 0.06-0.12 au for the magnetic field components. This finding raises questions about the very nature of MEs. It also highlights the need for additional "mesoscale" multipoint measurements of CMEs with longitudinal separations of 0.01-0.2 au.

CMEs↗
NASA NTRS1972

Imp 5 magnetic-field measurements in the high-latitude outer magnetosphere near the noon meridian.

Results of Imp 5 magnetic-field measurements at geomagnetic latitudes up to 75 deg and at distances beyond six earth radii, revealing the permanent existence of a broad depressed field region centered on the polar or dayside cusp. Field strengths at seven earth radii on cusp field lines that connect to the earth are typically only 50 to 70% of that of an undistorted dipole field. The transition region between the magnetosheath and the point where the fields are clearly of dipolar origin is characterized by large-amplitude fluctuations and the lack of a clear magnetopause boundary. Magnetic-field perturbations are observed in the cusp region with magnitudes up to 45 gamma and in directions that are approximately perpendicular to the average field. These perturbations are suggestive of field-aligned currents, and their magnitudes are consistent with the low-altitude measurements obtained on polar-orbiting spacecraft.

Fairfield, D. H.↗
NASA NTRS1994

Resolving the 180-degree ambiguity in vector magnetic field measurements: The 'minimum' energy solution

I present a robust algorithm that resolves the 180-deg ambiguity in measurements of the solar vector magnetic field. The technique simultaneously minimizes both the divergence of the magnetic field and the electric current density using a simulated annealing algorithm. This results in the field orientation with approximately minimum free energy. The technique is well-founded physically and is simple to implement.

Metcalf, Thomas R.↗
NASA NTRS1975

Measuring the magnetic fields of Jupiter and the outer solar system

The vector helium magnetometer, one of the Pioneer-Jupiter experiments, has measured the magnetic field of Jupiter and the interplanetary magnetic field in the outer solar system. The comprehensive scientific objectives of the investigations are explained and are then translated into the major instrument requirements. The principles of operation of the magnetometer, which involve the optical pumping of metastable helium, are discussed and the Pioneer instrument is described. The in-flight performance of the magnetometer is discussed and principal scientific results obtained thus far by the Pioneer investigation are summarized.

Smith, E. J.↗
NASA NTRS1973

Magnetic-field measurements for the Lewis Research Center cyclotron

The magnetic field of the Lewis Center cyclotron was mapped by using a Hall-effect magnetic-field transducer. Main-field Fourier coefficients were determined on a polar mesh of 40 radii for each of seven levels of main-field coil current. Incremental fields for eight sets of trim coils and two sets of harmonic coils were also determined at four of these main-field levels. A stored-program, digital computer was used to perform the measurements. The process was entirely automatic; all data-taking and data-reduction activities were specified by the computer programs. A new method for temperature compensation of a Hall element was used. This method required no temperature control of the element. Measurements of the Hall voltage and Hall-element resistance were sufficient to correct for temperature effects.

Fessler, T. E.↗
NASA NTRS1972

Lunar properties from transient and steady magnetic field measurements.

The electrical conductivity of the lunar interior has been determined from magnetic field step transients measured on the lunar dark side. The simplest model which best fits the data is a spherically symmetric three layer model having a nonconducting outer crust, an intermediate layer with electrical conductivity of .00035 mhos/m, and an inner core with conductivity of .01 mhos/m. Temperatures calculated from these conductivities in the three regions for an example of an olivine moon are as follows: crust, below 440 K; intermediate layer, 890 K; and core, 1240 K. The whole-moon relative permeability has been calculated from the measurements to be 1.03 plus or minus 0.13.

Dyal, P.↗
NASA NTRS1996

Force Measurements in Magnetic Suspension and Balance System

The description of an infrared telemetry system for measurement of drag forces in Magnetic Suspension and Balance Systems (MSBS) is presented. This system includes a drag force sensor, electronic pack and transmitter placed in the model which is of special construction, and receiver with a microprocessor-based measuring device, placed outside of the test section. Piezosensitive resonators as sensitive elements and non-magnetic steel as the material for the force sensor are used. The main features of the proposed system for load measurements are discussed and the main characteristics are presented.

Kuzin, Alexander↗
NASA NTRS1975

An improved method for measuring the magnetic inhomogeneity shift in hydrogen masers

The reported method makes it possible to conduct all maser frequency measurements under conditions of low magnetic field intensity for which the hydrogen maser is most stable. Aspects concerning the origin of the magnetic inhomogeneity shift are examined and the available approaches for measuring this shift are considered, taking into account certain drawbacks of currently used methods. An approach free of these drawbacks can be based on the measurement of changes in a parameter representing the difference between the number of atoms in the involved states.

Reinhardt, V. S.↗
NASA NTRS2004

Results of the Magnetometer Navigation (MAGNAV)lnflight Experiment

The Magnetometer Navigation (MAGNAV) algorithm is currently running as a flight experiment as part of the Wide Field Infrared Explorer (WIRE) Post-Science Engineering Testbed. Initialization of MAGNAV occurred on September 4, 2003. MAGNAV is designed to autonomously estimate the spacecraft orbit, attitude, and rate using magnetometer and sun sensor data. Since the Earth's magnetic field is a function of time and position, and since time is known quite precisely, the differences between the computed magnetic field and measured magnetic field components, as measured by the magnetometer throughout the entire spacecraft orbit, are a function of the spacecraft trajectory and attitude errors. Therefore, these errors are used to estimate both trajectory and attitude. In addition, the time rate of change of the magnetic field vector is used to estimate the spacecraft rotation rate. The estimation of the attitude and trajectory is augmented with the rate estimation into an Extended Kalman filter blended with a pseudo-linear Kalman filter. Sun sensor data is also used to improve the accuracy and observability of the attitude and rate estimates. This test serves to validate MAGNAV as a single low cost navigation system which utilizes reliable, flight qualified sensors. MAGNAV is intended as a backup algorithm, an initialization algorithm, or possibly a prime navigation algorithm for a mission with coarse requirements. Results from the first six months of operation are presented.

Thienel, Julie K.↗
NASA NTRS2004

Results of the Magnetometer Navigation (MAGNAV) Inflight Experiment

The Magnetometer Navigation (MAGNAV) algorithm is currently running as a flight experiment as part of the Wide Field Infrarad Explorer Post-Science Engineer- ing Testbed. Initialization of MAGNAV occured on September 4, 2004. MAGNAV is designed to autonomously estimate the spacecraft orbit, attitude, and rate using magnetometer and sun sensor data. Since the earth s magnetic field is a function of time and position, and since time is known quite precisely, the differences between the computed magnetic field and measured magnetic field components, as measured by the magnetometer throughout the entire spacecraft orbit, are a function of the spacecraft trajectory and attitude errors. Therefore, these errors are used to estimate both trajec- tory and attitude. In addition, the time rate of change of the magnetic field vector is used to estimate the spacecraft rotation rate. The estimation of the attitude and tra- jectory is augmented with the rate estimation into an Extended Kalman filter blended with a pseudc-linear Kalman filter. Sun sensor data is also used to improve the accu- racy and observability of the attitude and rate estimates. This test serves to validate MAGNAV as a single low cost navigation system which utilizes reliable, flight qualified sensors. MAGNAV is intended as a backup algorithm, an initialization algorithm, or possibly a prime navigation algorithm for a mission with coarse constraints.

Thienel, Julie↗
NASA NTRS1974

Electric and magnetic fields measured during a sudden impulse

The electric field in the ionosphere and the magnetic field at the earth's surface in the mid-latitude region were both measured during a sudden impulse. Ionospheric conductivities deduced from this data were consistent with expectations, thus suggesting that the fluctuations in the magnetic field at the earth's surface were caused by overhead ionospheric currents that were driven by an electric field associated with the sudden impulse.

Schutz, S.↗