Engineering topics

Stanley, J. E.

Publications and source records attributed to Stanley, J. E..

6 records

NASA NTRS1991

First spatio-temporal results from the LDEF Interplanetary Dust Experiment

The LDEF Interplanetary Dust Experiment is unique in providing a time history of impacts of micron-sized particles on six orthogonal faces of the vehicle over a span of nearly a full year. Over 15,000 hits were recorded, representing a mix of zodiacal dust, meteor-stream grains, orbital debris, perhaps beta-meteoroids, and possibly interstellar matter. Although the total number was higher than predicted, the relative panel activity distribution was near expectations. Detailed deconvolution of the impact record with orbital data is underway, to examine each of these populations. Very preliminary results of the fairly crude 'first-look' analysis suggest that debris is the major particle component at 500 km. The data show clear evidence of some known meteor streams as sharp, tightly-focused events, unlike their visible counterparts. Some apparent debris events show similar signatures. Data from the leading and trailing edges suggest a detection of beta-meteoroids, but the analysis is not yet conclusive. Absolute fluxes and flux ratios are not yet known, since the detector status analysis is yet incomplete.

Singer, S. F.↗

NASA NTRS1985

The LDEF interplanetary dust experiment

Explorer 46 data and the Long Duration Exposure Facility (LDEF) interplanetary dust experiment are examined. Analysis of the Explorer 46 data reveals the existence of particles of 0.1 micron and a mass of 1 x 10 to the -16th gm, the injection of the submicron particles directly by a comet (injection mass of about 5000 tons), and a submicron particle lifetime of about three years. The applications of LDEF data to particles in hyperbolic orbits, particle swarms, morning-to-evening asymmetry, the effects of the earth's orbit eccentricity, and the presence of interstellar dust are discussed. The effects of space debris on data collection are considered.

Singer, S. F.↗

NASA NTRS1984

Interplanetary dust experiment (A0201)

The objective of this experiment is to study interplanetary dust, variously referred to as cosmic dust, cometary dust, zodiacial dust, or meteoric dust particles. Specific objectives are to obtain information regarding particle mass and velocity, and to undertake correlative analyses with other experiments, both on LDEF or near the time of the LDEF flight.

Singer, S. F.↗

NASA NTRS1982

Comets produce submicron particles in the solar system

Observational evidence for the existence of submicron particles issuing from meteor streams and comets is examined. The MTS Explorer 46 carried a meteoroid detector which measured the rate of impact of particles with masses on the order of 10 to the -16th gram. Particle enhancements were observed in association with meteor streams, such as the Taurid and Orionids. The ratio of radiation pressure to gravity is employed to examine the effects of radiation pressure on the particles. When the ratio is higher than one, particles become smaller, unless they are dielectrics. Particles with radii less than 0.1 micron, having a potential of +3.3 V, are projected to have a lifetime of about 3 yr. Several thousands of tons of submicron particles are expected to be produced during a cometary perihelion passage. Launch of a long duration exposure facility with the Shuttle is recommended for studies of the decay of the particles over time.

Singer, S. F.↗

NASA NTRS1980

Submicron particles in meteor streams

Submicron particles (mass less than 10 to the -15th g) were observed in certain meteor streams by impact detectors on satellite Explorer 46. This unexpected finding leads to conclusions about the nature and origin of the particles and about the importance of nongravitational forces.

Singer, S. F.↗

NASA NTRS1979

Interplanetary dust between 1 and 5 AU

Analyses of data from the Meteoroid Detection Experiment (MDE) and the Imaging Photopolarimeter (IPP) aboard Pioneer 10 and 11 have led to contradictory conclusions. While the MDE indicates a significant particle environment in the outer solar system (out to at least 5 AU), the IPP sees no zodiacal light (therefore implying no small particles) past 3.3 AU. These two results are reconciled by noting that the spectral index p (relating particle radius and particle concentration) is not a constant in the solar system but changes from less than 2 near 1 AU to more than 2.5 at 5 AU for particles in the range of 10 microns.

Stanley, J. E.↗