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Potter, A. E.

Publications and source records attributed to Potter, A. E..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Discovery of sodium and potassium vapor in the atmosphere of the moon

A ground-based telescopic study of the lunar surface with high resolution spectroscopy has led to the discovery of sodium and potassium vapor 'atmospheres'. The scale height for the sodium atmosphere is 120 + or - 42 km, and for potassium 90 + or - 20 km; these values imply that the effective temperature of the two elements closely approximates that of the lunar surface. The sodium density at the south polar region is similar to that at the subsolar point, indicating widespread distribution of the vapor. The ratio of sodium to potassium densities, at 6 (+ or - 3):1, is close to the lunar surface ratio and suggests that the atmosphere originated in the vaporization of surface minerals.

Potter, A. E.↗
NASA NTRS1988

Atmospheric and surface compositional studies of Mercury and the moon

The atmosphere of the Moon and Mercury will be studied by means of high resolution spectroscopy of sodium and potassium resonance line emissions. The variation of metal vapor abundances with time, and with location will be measured with a view to understanding the origin and evolution of these elements in the atmospheres of the Moon and Mercury. Infrared spectroscopic measurements will be made of Mercury to determine the surface mineralogy, predicated on the availability of the Kuiper Airborne Observatory and infrared charge coupled device (CCD). During the past year, an excellent series of measurements were completed of the spatial distribution of sodium on Mercury. Sodium was found to be concentrated at the polar regions, and to be displaced towards the terminator by solar radiation pressure. Sodium and potassium were discovered in the atmosphere of the Moon. The ratio of sodium to potassium approximates that of the lunar regolith. Thermal infrared measurements of Mercury showed that the Christiansen peak was located shortwards of 8 micrometer, which indicates an acidic mineralogy.

Potter, A. E.↗
NASA NTRS1988

Impact-driven supply of sodium and potassium to the atmosphere of Mercury

The Mercury atmosphere is supplied with sodium atoms from both impacting meteoroids and the impacted regolith; the production of vaporized sodium due to such impact varies with the instantaneous distance of Mercury from the sun, in a way that differs from the distance-dependence of those source-and-sink processes driven by solar radiation. Such impact-driven vaporization will yield the Na/K ratio noted in the Mercury atmosphere only if both the meteoroids and the regolith of the planet are deficient in K relative to other solar system objects sampled, other than comets.

Morgan, T. H.↗
NASA NTRS1987

Variation of sodium on Mercury with solar radiation pressure

It has been suggested that nonthermal Na atoms with velocities in excess of 2.1 km/sec in the Mercury atmosphere can be accelerated off the planet by solar radiation pressure; Na abundance may accordingly be expected to decrease with increasing radiation pressure. While this is confirmed by the present measurements, high resolution line profile measurements on Na emission indicate that very little, if any, of the Na is nonthermal, while the bulk is at a temperature approaching that of the planetary surface. Attention is given to explanations for the observed variation.

Potter, A. E.↗
NASA NTRS1986

Potassium in the atmosphere of Mercury

Spectral data are reported from a search for potassium in the Mercury atmosphere. The data were collected with instrumentation at Kitt Peak (7699 A) and at McDonald Observatory (7698.98 and 7664.86 A). The equivalent mean widths of the potassium emission lines observed are tabulated, along with the estimated abundances, which are compared with sodium abundances as determined by resonance lines. The average column abundance of potassium is projected to be 1 billion atoms/sq cm, about 1 percent the column abundance of sodium.

Potter, A. E.↗
NASA NTRS1985

Measurements

The debris population is divided into small and large regimes. NORAD is the source of data in the size range above 10 cm. For the small ( 10 cm) debris particles, satellite-borne instrumentation could be used to obtain the necessary data. These results can then be fed into models of the debris population. These measurements are designed to give some reality to the models which estimate the number of particles produced from an explosion or an impact.

Potter, A. E.↗
NASA NTRS1985

Examination of returned solar-max surfaces for impacting orbital debris and meteoroids

Previous theoretical studies predicted that in certain regions of earth orbit, the man-made earth orbiting debris environment will soon exceed the interplanetary meteoroid environment for sizes smaller than 1 cm. The surfaces returned from the repaired Solar Max Mission (SMM) by STS 41-C on April 12, 1984, offered an excellent opportunity to examine both the debris and meteoroid environments. To date, approximately 0.7 sq. met. of the thermal insulation and 0.05 sq. met of the aluminum louvers have been mapped by optical microscope for crater diameters larger than 40 microns. Craters larger in diameter than about 100 microns found on the initial 75 micron thick Kapton first sheet on the MEB (Main Electronics Box) blanket are actually holes and constitute perforations through that blanket. The following populations have been found to date in impact sites on these blankets: (1) meteoritic material; (2) thermal paint particles; (3) aluminum droplets; and (4) waste particles.

Kessler, D. J.↗
NASA NTRS1985

Optical detection of large meteoroids in space

CCD sensors placed across the focal plane of large Schmidt telescopes have great potential for detecting and measuring the very low flux in space of meteoroids with diameters larger than 1 meter. With the Palomar 'Big Schmidt', a detection rate of 1.4 per hour is obtained for meteoroids between 0.6 and 200 meters in diameter. For the Baker-Nunn 'Satellite Tracking Camera', the corresponding rate is about 0.8 per hour. The key to obtaining such high detection rates derives from approximately setting the sensor integration time equal to the time it takes a meteoroid to cross a pixel field of view. This minimizes signal to noise problems and is accomplished, in practice, by multiple summing of short integration time data records to obtain data records of longer effective integration times.

Zook, H. A.↗
NASA NTRS1984

Lunar luminescence and the filling-in of Fraunhofer lines in moonlight

The filling-in of Fraunhofer lines in moonlight has been attributed to lunar luminescence. In order to test mechanisms proposed for this effect, measurements were made of the filling-in of the H-alpha line, the Na D doublet, and a number of lines near the doublet. The degree of filling-in was not correlated with wavelength in a way expected from a broadband luminescence, such as thermoluminescence. However, it was correlated with equivalent width of the Fraunhofer line, such that it increased as equivalent width decreased. This suggests that the Fraunhofer line filling at the moon's surface is caused by inelastic scattering of sunlight with a small wavelength shift, as for example, photon-phonon scattering.

Potter, A. E.↗
NASA NTRS1984

Experimental studies of scaling laws for plasma collection at high voltages

Current-voltage characteristics were determined for stainless steel in a laboratory with a simulated ionospheric environment of 5 x 10 to the 11th to 2.5 x 10 to the 12th electrons/cu m. Panels with areas differing by a factor of up to 100 were biased between 0 and -2300 V. Secondary emission was corrected for using experimental data. The results indicate that the current-voltage characteristics are almost linear and that for voltages above about -500 V the current scales with characteristic panel length as L exp 1.2. Comparison with some theoretical predictions is discussed. Because of orbital velocity associated ion ram effects, the results of this study must be used with caution when applied to an orbiting spacecraft.

Konradi, A.↗
NASA NTRS1984

The Skylab lunar multispectral scanner data

Skylab S-192 multispectral scanner data, in 12 bands covering wavelengths from 0.41 to 2.3 microns, have been investigated to identify and classify geologic units of the lunar surface. Seventeen spectral cluster classes have been identified, seven in the highlands, seven in the maria, and three of which occur in both or in border regions. This finding may be roughly indicative of the relative heterogeneity of these regions. It implies that there is as much heterogeneity in the highlands as in the maria. This work extends the spectral and aerial coverage of similar studies of the lunar surface and provides useful data for comparison for most of the lunar near side.

Seeger, C. R.↗
NASA NTRS1983

Effects of Shuttle environment on instrument performance

Examination of the OSTA-1 payload instruments carried in the shuttle bay during the 54.25 hour mission of STS-2 indicates that the shuttle environment has no measurable effect on the Earth-viewing experiments. Operation of the payload shows that flight simulations are essential and experiment replanning practice is needed. Ground control of experiments is desirable since malfunctions of totally automated experiments cannot be fixed in flight. Alarm limits for experiments must be realistic since the crew loses interest after a few alarms. The quality and number of hours of data obtained for each experiment are listed.

Potter, A. E.↗
NASA NTRS1983

Environmental effects of Shuttle launch and landing

The areas of concern were the toxic exhaust cloud produced by Shuttle launch, the effect of launch operations on the total ecology, and the sonic boom produced by Orbiter re-entry. Wet acidic dust fell from the exhaust cloud for about ten minutes after launch. The fallout was not entirely unexpected, but the intensity and duration was larger than anticipated. The fallout material is not considered a significant health hazard. Previously announced in STAR as N82-15729

Potter, A. E.↗
NASA NTRS1980

Proceedings of Shuttle Environmental Effects Program Review

Measurements of Titan exhaust cloud effluents are documented and compared, mesoscale and microphysical acid rain models are described, and a submesoscale model is proposed. Various instruments and facilities for measuring ice nuclei and other constituents of solid rocket motor exhaust effluents are discussed. Regional air quality monitoring and rain collection systems are described, and the ecological impact of solid rocket motor exhaust effluents is examined. The potential effect of space shuttle launches is estimated where data are adequate.

Potter, A. E.↗
NASA NTRS1980

Near-infrared spectral imaging Michelson interferometer for astronomical applications

The design and operation of an imaging Michelson interferometer-spectrometer used for near-infrared (0.8 micron to 2.5 microns) spectral imaging are reported. The system employs a rapid scan interferometer modified for stable low resolution (250/cm) performance and a 42 element PbS linear detector array. A microcomputer system is described which provides data acquisition, coadding, and Fourier transformation for near real-time presentation of the spectra of all 42 scene elements. The electronic and mechanical designs are discussed and telescope performance data presented.

Wells, C. W.↗
NASA NTRS1978

Revised estimates for ozone reduction by shuttle operation

Previous calculations by five different modeling groups of the effect of space shuttle operations on the ozone layer yielded an estimate of 0.2 percent ozone reduction for the Northern Hemisphere at 60 launches per year. Since these calculations were made, the accepted rate constant for the reaction between hydroperoxyl and nitric oxide to yield hydroxyl and nitrogen dioxide, HO2 + NO yields OH + NO2, was revised upward by more than an order of magnitude, with a resultant increase in the predicted ozone reduction for chlorofluoromethanes by a factor of approximately 2. New calculations of the shuttle effect were made with use of the new rate constant data, again by five different modeling groups. The new value of the shuttle effect on the ozone layer was found to be 0.25 percent. The increase resulting from the revised rate constant is considerably less for space shuttle operations than for chlorofluoromethane production, because the new rate constant also increases the calculated rate of downward transport of shuttle exhaust products out of the stratosphere.

Potter, A. E.↗
NASA NTRS1978

Environmental effects of the Space Shuttle

Rocket exhaust products, acoustic noise, and a sonic boom are produced during launch of the Space Shuttle. Their environmental effects have been assessed and found to be small and transient, or controllable by the choice of launch azimuth or launch conditions. Reentry of the Orbiter will produce a very low-level sonic boom over populated areas.

Potter, A. E.↗