Mineralogical interpretation of reflectance spectra of Eros from NEAR near‐infrared spectrometer low phase flyby

Abstract— High signal‐to‐noise near‐infrared spectrometer (NIS) spectra acquired during the low phase flyby of the near‐Earth asteroid rendezvous (NEAR) mission to 433 Eros are analyzed to determine mineral chemistry and proportions of mafic silicates across the asteroid's surface at 2.68 × 5.50 km spatial resolution. Spectral band parameters are derived, and compared with those of laboratory samples of known mineral composition, grain size distribution and terrestrial, meteoritic and lunar pyroxene spectral properties. The NIS derived band parameters are consistent with ordinary chondrite meteorites. We invoke the presence of a clinopyroxene component in the spectra, which is consistent with ordinary chondrite mineralogy and/or some degree of partial melting of ordinary chondritic material. Spectra measured across the surface of Eros can reveal small but real spectral variations. Most relative spectra are uniform to within 1–2%. Some areas suggest compositional variations of a few percent. Spectral slope variations of a few percent are seen indicating a non‐uniform distribution of materials affecting the slope parameter but with no resolved absorption bands. We find no correlation of slope with viewing geometry or compositional variation. The band parameter values do not consistently indicate a specific ordinary chondrite class but Eros is definitely undifferentiated with possible compositional variations of no more than 1–2%.     

Spectroscopic Data for the 6it s6it p 3 P1 level of Lu+ for the Determination of the Solar Lutetium Abundance

We report spectroscopic measurements on the 6s6p ³P₁ level of Lu⁺ at 28503.16 cm^-1. The radiative lifetime of this level was measured to be 37.4 ± 1.9 ns using time-resolved laser-induced fluorescence of a slow ion beam. Branching fractions were determined from Lu spectra recorded using the 1.0 m Fourier transform spectrometer at the National Solar Observatory. Thelog(gf) values determined by combining the radiative lifetime and branching fractions for the 3507.39, 5983.90, and 6221.87 (air wavelengths) lines are - 1.16 ± 0.03, - 1.16 ± 0.06, and -0.76 ± 0.04, respectively. The 6221.87 line has been identified by Bord, Cowley, and Mirijanian (1997) as the best candidate for the determination of the solar lutetium abundance because it is only slightly blended in the solar spectrum. The present 6221.87 transition probability measurement brings their solar lutetium abundance into good agreement with the CI chondrite abundance.     

Photometry of 433 Eros from 0.65 to 2.2 μm

Lightcurves of 433 Eros are reported for 11 bandpasses ranging from 0.65 to 2.2 μm in wavelength. The relative spectral reflectance, R(λ), was not seen to vary during our observations. Eros has R(1.6 μm) = 1.5 ± 0.1 and R(2.2 μm) = 1.7 ± 0.1, where R(λ) is the spectral reflectance scaled to unity at λ = 0.56 μm. This spectral reflectance is suggestive of a mixture of silicates and material with high infrared reflectance, perhaps a metallic phase such as meteoritic “iron”.     

Hard X-ray and radio emission at the onset of great solar flares

A study of the onset phase often great hard X-ray bursts is presented. It is shown from hard X-ray and radio observations in different wavelength ranges that the energization of the electrons proceeds on a global time-scale of some tens of seconds. In nine of the bursts two phases of emission can be distinguished during the onset phase: the pre-flash phase, during which emission up to an energy limit ranging from some tens of keV to 200 keV is observed, followed ten to some tens of seconds later by the flash phase, where the count rate in all detector channels rises simultaneously to within some seconds. For two of the events strong -ray line emission is observed and is shown to start close to the onset of the flash phase.Proceedings of the Second CESRA Workshop on Particle Acceleration and Trapping in Solar Flares, held at Aubigny-sur-Nère (France), 23–26 June, 1986.     

Responses of <Emphasis Type=Italic>Avicennia germinans</Emphasis> (Black Mangrove) and the Soil Microbial Community to Nitrogen Addition in a Hypersaline Wetland

The responses of dwarf black mangroves (Avicennia germinans) and components of the microbial community to the addition of nitrate over a 2-year period were examined. The field study was conducted in the Indian River Lagoon (Florida) in a mangrove-dominated impoundment that was established for purposes of mosquito control. The responses of mangroves to the regular addition of nitrate were insignificant or relatively minor compared to responses of the components of the microbial community. Denitrification rates, measured in the field and laboratory, increased significantly in fertilized plots and nitrous oxide emission rates were almost six times higher in fertilized plots. Nitrogen fixation was significantly lower in fertilized plots. Results suggest that mangrove systems in the N-limited Indian River Lagoon are likely to be long-term sinks for any increases in N loading.     

Embracing cultural geography: an army imperative

As an instrument of national strategy, the United States Army has served the American people well for more than two centuries. Its fundamental mission has always been to fight and win America's Wars. As we have moved from the bi-polar nature of world dynamics to that of the new global neighborhood, the American Army has seen an increase in missions related to peacekeeping, disaster relief, and humanitarian actions. From a geography perspective, the Army must operate in numerous countries simultaneously. To succeed, the Army must go beyond physical accomplishments: it must interact and communicate with nations at a level of shared understanding and enthusiasm of each others culture. The American soldier must understand the cultural nature of geography as well as the physical. The hypothesis of this paper is: There is an urgent need for the men and women of the Unites States Army to have a firm conviction that people of other cultures have beliefs, value systems, and customs that result in behaviors and perceptions that may be vastly different than ours. . .and that those differences are legitimate. Beginning with mistakes made during the Vietnam war, the authors give examples, current as well as past, of cultural illiteracy on the part of the military. The role of the Army in the new world order is then addressed with emphasis on the types of missions to be expected in the 21^st Century. The authors point out that significant efforts to grasp customs of foreign countries to which Army units are deployed have been made during recent years; however, much remains to be accomplished. The solution to a lack of cultural awareness is given in the form of improvements to the Army military education system. An overview of the current training environment, with its strengths and weaknesses, is provided as a precursor to recommendations for future training. A multitiered education system is proposed in which cultural awareness education is provided at all levels of authority, from the basic training recruit to senior officers. Given that programs of instruction are already full, it will take a combination of command emphasis and innovation to accomplish the goal of inculcating cultural awareness in the American Army. The paper concludes with the position that the only way the Army can accomplish its changed global missions is by first winning its own war against cultural illiteracy.     

Evidence of correlations between nuclear decay rates and Earth–Sun distance

Unexplained periodic fluctuations in the decay rates of ³²Si and ²²⁶Ra have been reported by groups at Brookhaven National Laboratory (³²Si), and at the Physikalisch–Technische–Bundesanstalt in Germany (²²⁶Ra). We show from an analysis of the raw data in these experiments that the observed fluctuations are strongly correlated in time, not only with each other, but also with the time of year. We discuss both the possibility that these correlations arise from seasonal influences on the detection system, as well as the suggestion of an annual modulation of the decay rates themselves which vary with Earth–Sun distance.     

Solar and Heliospheric Observatory/Large Angle Spectrometric Coronagraph Polarimetric Calibration

We present a polarimetric characterization and correction for the Solar and Heliospheric Observatory/Large Angle Spectrometric Coronagraph (SOHO/LASCO) C2 and C3 white light coronagraphs. By measuring the uncorrected polarization angles in solar minimum C2 coronal images, we have determined that the coronagraph acts as an optical phase retarder which converts a small fraction of the incoming radiation polarization from linear to circular. In addition, from the measurements of polarization angle in C3 coronal images we have determined that a component of the instrumentally scattered light in that instrument is polarized. We infer the retardation angle for C2 and compute the corresponding Mueller matrix, and determine the polarized stray light spatial profile in C3. The C2 Mueller matrix and C3 polarized stray light profiles are used to correct for instrumental effects in solar minimum coronal observations to obtain polarized brightness between two and thirty-two solar radii, which show deep polar coronal holes extending to the limit of the field of view.     

Venus phase function and forward scattering from H2SO4

Ground-based and spacecraft photometry covering phase angles from 2° to 179° has been acquired in wavelength bands from blue to near infrared. An unexpected brightness surge is seen in the B and V bands when the disk of Venus is less than 2% illuminated. This excess luminosity appears to be the result of forward scattering from droplets of H₂SO₄ (sulfuric acid) in the high atmosphere of Venus. The fully sunlit brightness of Venus, adjusted to a distance of one AU from the Sun and observer, was found to be V=−4.38, and the corresponding geometric albedo is 67%. The phase integral is 1.35 and the resulting spherical albedo is 90%. Comparison between our data and photometry obtained over the past 50 years indicates a bias in the older photoelectric results, however atmospheric abundance variations suggest that brightness changes may have occurred too.     

The Hard X-Ray Burst Spectrometer on the Solar Maximum Mission

The primary scientific objectives of the Hard X-Ray Burst Spectrometer (HXRBS) to be flown on the Solar Maximum Mission are as follows: (1) To determine the nature of the mechanisms which accelerate electrons to 20–100 keV in the first stage of a solar flare and to > 1 MeV in the second stage of many flares; and (2) to characterize the spatial and temporal relation between electron acceleration, storage and energy loss throughout a solar flare.Measurements of the spectrum of solar X-rays will be made in the energy range from 20 to 260 keV using an actively-shielded CsI(Na) scintillator with a thickness of 0.635 cm and a sensitive area of 71 cm². Continuous measurements with a time resolution of 0.128 s will be made of the 15-channel energy-loss spectrum of events in this scintillator in anticoincidence with events in the CsI(Na) shield. Counting-rate data with a time resolution as short as 1 ms will also be available from a limited period each orbit using a 32K-word circulating memory triggered by a high event rate.In the first year after launch, it is expected that approximately 1000 flares will be observed above the instrument sensitivity threshold, which corresponds to a 20–200 keV X-ray flux of 2 × 10^–1 photons (cm² s)^–1 lasting for at least one second.