Northwest Africa 011: A “eucritic” basalt from a non‐eucrite parent body

Abstract— We have carried out a detailed petrographic, mineralogical, and trace element study of Northwest Africa (NWA) 011. This meteorite bears many similarities to the eucrites it was initially identified with, although oxygen isotopic compositions rule out a genetic relationship. Like many eucrites, NWA 011 crystallized from a source with approximately chondritic proportions of REE, although a slightly LREE‐enriched bulk composition with a small positive Eu anomaly, as well as highly fractionated Fe/Mg ratios and depleted Sc abundances (Korotchantseva et al. 2003), suggest that the NWA 011 source experienced some pyroxene and/or olivine fractionation. Thermal metamorphism resulted in homogenization of REE abundances within grains, but NWA 011 did not experience the intergrain REE redistribution seen in some highly metamorphosed eucrites. Despite a similarity in oxygen isotopic compositions, NWA 011 does not represent a basaltic partial melt from the acapulcoite/lodranite parent body. The material from which NWA 011 originated may have been like some CH or CB chondrites, members of the CR chondrite clan, which are all related through oxygen isotopic compositions. The NWA 011 parent body is probably of asteroidal origin, possibly the basaltic asteroid 1459 Magnya.     

The Danebury Iron Age meteorite—An H5 ordinary chondrite “find” from Hampshire,England

What remains of a 30 g sample, first recognized as a meteorite in 1989 during characterization of metalworking debris from Danebury, an Iron Age hillfort, in Hampshire, England, has been classified as an H5 ordinary chondrite. Its arrival on Earth has been dated as 2350 ± 120 yr BP, making it contemporary with the period of maximum human activity at the recovery site. Despite its considerable terrestrial residence age, the interior of the specimen is remarkably fresh with a weathering index of W1/2. There is, however, no evidence of human intervention in its preservation. Its near‐pristine state is explained in terms of its serendipitous burial during the back‐fill of a pit dug into chalk by prehistoric people for the storage of grain. This chance discovery has interesting ramifications for the survival of meteorites in areas having a high pH because of a natural lime content arising as a result of the local geology.     

On the variability of the “blue objects”

The reality of the high percentage of variability among Blue Objects which was found in previous investigations was examined on 170 Tautenburg Schmidt plates of two test fields near M 31. The high percentage could not be confirmed. Spurious amplitudes can be explained by the large probable errors of the photometry (especially near the plate limit) and by bad suitability of good-looking plates. Out of 37 Blue Objects examined, only two (van den Bergh 5 and 12) are distinctly variable, but the final examination of Blue Objects which are suspected of variability can only be done by photoelectric photometry.     

Analysis of a “flickering” Geminid fireball

Abstract— In the early morning hours of December 13, 2002, a bright Geminid fireball with an absolute magnitude of ?9.2 ± 0.5 was observed from Southern Saskatchewan, Canada. The fireball displayed distinct small‐scale oscillations in brightness, or flickering, indicative of the parent meteoroid being both non‐spherical and rotating. Using the light curve derived from a calibrated radiometer, we determine a photometric mass of 0.429 ± 0.15 kg for the meteoroid, and we estimate from its initial rotation rate of some 6 Hz that the meteoroid was ejected from the parent body (3200) Phaethon some 2500 ± 500 years ago. We find that 70% of Geminid fireballs brighter than magnitude ?3 display distinct flickering effects, a value that is in stark contrast to the 18% flickering rate exhibited by sporadic fireballs. The high coincidence of flickering and the deep atmospheric penetration of Geminid fireballs are suggestive of Geminid meteoroids having a highly resilient structure, a consequence, we suggest, of their having suffered a high degree of thermal processing. The possibility of Gemind material surviving atmospheric ablation and being sampled is briefly discussed, but the likelihood of collecting and identifying any such material is admittedly very small.     

“Sweating meteorites”—Water‐soluble salts and temperature variation in ordinary chondrites and soil from the hot desert of Oman

The common appearance of hygroscopic brine (“sweating”) on ordinary chondrites (OCs) from Oman during storage under room conditions initiated a study on the role of water‐soluble salts on the weathering of OCs. Analyses of leachates from OCs and soils, combined with petrography of alteration features and a 11‐month record of in situ meteorite and soil temperatures, are used to evaluate the role of salts in OC weathering. Main soluble ions in soils are Ca²⁺, SO₄^2?, HCO₃^?, Na⁺, and Cl^?, while OC leachates are dominated by Mg²⁺ (from meteoritic olivine), Ca²⁺ (from soil), Cl^? (from soil), SO₄^2? (from meteoritic troilite and soil), and iron (meteoritic). “Sweating meteorites” mainly contain Mg²⁺ and Cl^?. The median Na/Cl mass ratio of leachates changes from 0.65 in soils to 0.07 in meteorites, indicating the precipitation of a Na‐rich phase or loss of an efflorescent Na‐salt. The total concentrations of water‐soluble ions in bulk OCs ranges from 600 to 9000 μg g^?1 (median 2500 μg g^?1) as compared to 187–14140 μg g^?1 in soils (median 1148 μg g^?1). Soil salts dissolved by rain water are soaked up by meteorites by capillary forces. Daily heating (up to 66.3 °C) and cooling of the meteorites cause a pumping effect, resulting in a strong concentration of soluble ions in meteorites over time. The concentrations of water‐soluble ions in meteorites, which are complex mixtures of ions from the soil and from oxidation and hydrolysis of meteoritic material, depend on the degree of weathering and are highest at W3. Input of soil contaminants generally dominates over the ions mobilized from meteorites. Silicate hydrolysis preferentially affects olivine and is enhanced by sulfide oxidation, producing local acidic conditions as evidenced by jarosite. Plagioclase weathering is negligible. After completion of troilite oxidation, the rate of chemical weathering slows down with continuing Ca‐sulfate contamination.     

Petrographic studies of “fallout” suevite from outside the Bosumtwi impact structure,Ghana

Abstract— Field studies and a shallow drilling program carried out in 1999 provided information about the thickness and distribution of suevite to the north of the Bosumtwi crater rim. Suevite occurrence there is known from an ?1.5 km² area; its thickness is ≤15 m. The present suevite distribution is likely the result of differential erosion and does not reflect the initial areal extent of continuous Bosumtwi ejecta deposits. Here we discuss the petrographic characteristics of drill core samples of melt‐rich suevite. Macroscopic constituents of the suevites are melt bodies and crystalline and metasedimentary rock (granite, graywacke, phyllite, shale, schist, and possibly slate) clasts up to about 40 cm in size. Shock metamorphic effects in the clasts include multiple sets of planar deformation features (PDFs), diaplectic quartz and feldspar glasses, lechatelierite, and ballen quartz, besides biotite with kink bands. Basement rock clasts in the suevite represent all stages of shock metamorphism, ranging from samples without shock effects to completely shock‐melted material that is indicative of shock pressures up to ?60 GPa.     

A study of “chorus” observed at Australian stations

The very-low-frequency emission known as “chorus” has been studied for four Australian recording stations. The phenomenon exhibits a maximum of occurrence at about geomagnetic latitude 60° and occurs only about one-tenth as frequently at geomagnetic latitude 45°. It was never definitely observed at geomagnetic latitude 35°. Marked diurnal variations are present with morning peaks for all stations and also an evening peak at Adelaide and Hobart. Analysis of the diurnal variations suggests that two different mechanisms are involved. The average strength of chorus increases with increasing value of K-index at lower latitude stations and shows a maximum at moderate values of the index for geomagnetic latitude 61°. This is interpreted as meaning that the region of maximum average-chorus-strength moves towards lower latitudes at times of magnetic disturbance.     

The “European Fireball Network”: Current status and future prospects

Abstract— Among the three large camera networks carrying out fireball observations through the seventies and eighties, the “European Fireball Network” is the last one still in operation. The network today consists of more than 34 all-sky and fish-eye cameras deployed with ～100 km spacing and covering an area of ～10⁶ km², in the Czech and Slovak Republics, Germany, as well as parts of Belgium, Switzerland, and Austria. Network operation results in ～10 000 image exposures per year, which represent on average 1200 h of clear sky observations—as imaging periods are restricted due to daylight, moonlight, and clouds. The cameras detect currently large meteors at a rate of ～50 per year; this is in good agreement with the encounter rates determined in previous fireball studies. From sightings of “meteorite candidates” (fireballs that may have deposited meteorites) and meteorite recoveries in the network area, we estimate that 15% of the influx of meteoritic matter is currently observed by the cameras, whereas <1% is recovered on the ground. Issues to be addressed by future fireball observations include the study of very large meteoroids (>1000 kg) for which statistics are currently very poor and an examination of their relationship to NEOs (near-Earth objects) identified by current NEO search programs.     

An anthropogenic origin of the “Sirente crater,” Abruzzi,Italy

Abstract— In this paper, we review the recent hypothesis, based mostly on geomorphological features, that a ～130 m‐wide sag pond, surrounded by a saddle‐shaped rim from the Sirente plain (Abruzzi, Italy), is the first‐discovered meteoritic crater of Italy. Sub‐circular depressions (hosting ponds), with geomorphological features and size very similar to those exhibited by the main Sirente sag, are exposed in other neighboring intermountain karstic plains from Abruzzi. We have sampled present‐day soils from these sag ponds and from the Sirente sags (both the main “crater” and some smaller ones, recently interpreted as a crater field) and various Abruzzi paleosols from excavated trenches with an age range encompassing the estimated age of the “Sirente crater.” For all samples, we measured the magnetic susceptibility and determined the Ni and Cr contents of selected specimens. The results show that the magnetic susceptibility values and the geochemical composition are similar for all samples (from Sirente and other Abruzzi sags) and are both significantly different from the values reported for soils contaminated by meteoritic dust. No solid evidence pointing at an impact origin exists, besides the circular shape and rim of the main sag. The available observations and data suggest that the “Sirente crater,” together with analogous large sags in the Abruzzi intermountain plains, have to be attributed to the historical phenomenon of “transumanza” (seasonal migration of sheep and shepherds), a custom that for centuries characterized the basic social‐economical system of the Abruzzi region. Such sags were excavated to provide water for millions of sheep, which spent summers in the Abruzzi karstic high pasture lands, on carbonatic massifs deprived of natural superficial fresh water. Conversely, the distribution of the smaller sags from the Sirente plain correlates with the local pattern of the calcareous bedrock and, together with the characteristics of their internal structure, are best interpreted as natural dolines. In fact, reported radiocarbon ages for the formation of the main sag pond and of the smaller sags differ (significantly) by more than two millennia, thus excluding that they were all contemporaneously formed by a meteoritic impact.     

Performances and prospects of the “ROSEBUD” dark matter search experiment

A cryogenic search for WIMP Dark Matter with small sapphire bolometers through the WIMP scattering off Al₂O₃ nuclei, the ROSEBUD (Rare Objects SEarch with Bolometers UndergrounD) experiment, is being installed in the Canfranc Underground Laboratory (Spain) at 2450 m water equivalent. The performances of the bolometers, the radioactive background expected from the measurement of the radiopurity of the ROSEBUD components and the estimated sensitivity of the experiment for low mass WIMP detection are presented.     

A “division” treatment of the sky background in CCD images

Considering the errors transmitted from all pre-treatments, I suggest a “division” method for removing the sky background including interference fringes in CCD images. Compared to the traditional method, which may be called a “subtraction” method, the “division” method is easier to carry out and gives more accurate brightness measurement especially for the fainter images.     

Genesis—An artificial,low velocity “meteor” fall and recovery: September 8, 2004

Abstract— On September 8, 2004, Genesis, a manmade space capsule, plummeted to Earth after almost three years in space. A ground‐based infrasound array was deployed to Wendover, Nevada, to measure the “hypersonic boom” from the reentry, since the expected initial reentry speed of the body was about 11 km/sec. Due to the complete failure of its dual parachute system, we had a unique opportunity to assess the degree of reliability of our previously developed relations for natural meteors and bolides to analyze this well‐characterized manmade body. At ?20–50 km from the nominal trajectory, we succeeded in recording over two minutes of infrasonic signals from Genesis. Here we report on subsequent analyses of these infrasonic data, including an assessment of the expected entry characteristics on the basis of a bolide/meteor/fireball entry model specifically adapted to modeling reentering manmade objects. From these simulations, we were able to evaluate the line source blast wave relaxation radius, the differential acoustic efficiency, etc., to compute an approximate total power balance during entry. Next, we analyzed the detailed signals arriving from Genesis using a numerical, signal detection and wave processing software package (Matseis/Infra_Tool). We established the initial and subsequent arrivals and evaluated its plane wave back azimuths and elevation arrival angles and the degree of maximum, pair‐wise cross‐correlation, its power spectrum, spectrogram analysis, standard seismic f‐k analysis, etc. From the associated entry parameters, we computed the kinetic energy density conservation properties for the propagating line source blast waves and compared these predictions against observed ground‐based infrasound amplitude and wave period data as a function of range. We discovered that previously computed differential acoustic efficiencies were unreliable at Mach numbers below about 10. This is because we had assumed that a line source explosion was applicable, whereas at very low Mach numbers, typical of recovered meteorites, the detailed source characteristics are closer to those of supersonic objects. When corrections for these unphysical, very high efficiencies were made, agreement between theory and observations improved. We also made an assessment for the energy of the blast wave source from the ground‐based infrasound data using several other techniques that were also adapted from previous bolide studies. Finally, we made a top‐down‐bottom‐up assessment of the line source wave normals propagating via refraction downward into the complex middle atmospheric environment. This assessment proved to be generally consistent with the digital signal processing analysis and with the observed time delay between the known Genesis reentry and the infrasonic observations.     

On Spinor Equations of Motion and their “Possible Integrals”

The motion of one point mass of the classical mechanics is treated by means of the relativistic spinor regularization (KUSTAANHEIMO 1975). Most general spinor equations of motion (2.9)‒(2.10)and the differential equations(3.16)‒(3.25)for the “possible integrals” (3.2)‒(3.11)of these quations of motion are deduced. If the force is a superposition of a conservative central force and of another force perpendicular to radius vector and velocity (Chapter 4, Case D), then the theory yields scalar and spinor integrals (4.7), (4.10)‒(4.12), (4.14)‒(4.15), (4.17), (4.28) that enable a parametric representation of the orbit by quadratures, as soon as one solution of a RICCATI differential equation (4.33) has been found.     

The two Suvasvesi impact structures,Finland: Argon isotopic evidence for a “false” impact crater doublet

The two neighboring Suvasvesi North and South impact structures in central‐east Finland have been discussed as a possible impact crater doublet produced by the impact of a binary asteroid. This study presents ⁴⁰Ar/³⁹Ar geochronologic data for impact melt rocks recovered from the drilling into the center of the Suvasvesi North impact structure and melt rock from glacially transported boulders linked to Suvasvesi South. ⁴⁰Ar/³⁹Ar step‐heating analysis yielded two essentially flat age spectra indicating a Late Cretaceous age of ~85 Ma for the Suvasvesi North melt rock, whereas the Suvasvesi South melt sample gave a Neoproterozoic minimum (alteration) age of ~710 Ma. Although the statistical likelihood for two independent meteorite strikes in close proximity to each other is rather low, the remarkable difference in ⁴⁰Ar/³⁹Ar ages of >600 Myr for the two Suvasvesi impact melt samples is interpreted as evidence for two temporally separate, but geographically closely spaced, impacts into the Fennoscandian Shield. The Suvasvesi North and South impact structures are, thus, interpreted as a “false” crater doublet, similar to the larger East and West Clearwater Lake impact structures in Québec, Canada, recently shown to be unrelated. Our findings have implications for the reliable recognition of impact crater doublets and the apparent rate of binary asteroid impacts on Earth and other planetary bodies in the inner solar system.     

The programme “Milky Way”: the physical and kinematical investigation of galactic structures

Das Programm “Milky Way” zur Komplexuntersuchung von Struktur, Kinematik und Evolution der Galaxie wird beschrieben. Im Rahmen dieses Programms werden neue astrometrische und astrophysikalische Beobachtungen ausgeführt. Vorläufige Ergebnisse bezüglich der Struktur von Sternentstehungsgebieten, der Bewegungen und der Struktur des lokalen Spiralarmes werden dargestellt. Die Abhängigkeit der kinematischen Parameter von der Entfernung von der galaktischen Ebene wird abgeleitet. Diese Untersuchungen stützen sich auf neue Beobachtungen und auf Daten aus bereits veröffentlichten Katalogen.     

Stardust—An artificial,low‐velocity “meteor” fall and recovery: 15 January 2006

Abstract— On January 15, 2006, Stardust, a man‐made space capsule, plummeted to Earth for a soft landing after spending seven years in space. Since the expected initial speed of the body was about 12.9 km/s, a four‐element ground‐based infrasound array was deployed to Wendover, Nevada, USA, to measure the hypersonic booms from the re‐entry. At a distance of ～33 km from the nominal trajectory, we easily recorded the weak acoustic arrivals and their continued rumbling after the main hypersonic boom arrival. In this paper, we report on subsequent analyses of these data, including an assessment of the expected entry characteristics (dynamics, energetics, ablation and panchromatic luminosity, etc.) on the basis of a bolide/meteor/fireball entry model that was specifically adapted for modeling a re‐entering man‐made object. Throughout the infrasonic data analyses, we compared our results for Stardust to those previously obtained for Genesis. From the associated entry parameters, we were also able to compute the kinetic energy density conservation properties for the propagating line source blast wave and compared the inviscid theoretical predictions against observed ground‐based infrasound amplitude and wave period data as a function of range. Finally, we made a top‐down bottom‐up assessment of the line source wave normals propagating downward into the complex temperature/sound speed and horizontal wind speed environment during January 15, 2006. This assessment proved to be generally consistent with the signal processing analysis and with the observed time delay between the known Stardust entry and the time of observations of infrasound signals, and so forth.     

TEM studies and the shock history of a “mysterite” inclusion from the Krymka LL chondrite

Abstract— The microstructure and composition of the matrix of one carbonaceous inclusion (K1) in the Krymka LL3.1 chondrite were studied using transmission electron microscopy (TEM). K1 has previously shown an enigmatic nature and similarities with volatile‐rich, fine‐grained, dark inclusions of Krymka called “mysterite.” In the present study, four minerals were identified by TEM. Olivine, pyroxene, and pyrrhotite typically have grain sizes of one micrometer; graphite occurs as flakes of a similar size. Olivine shows a moderately high dislocation density most probably caused by shock. Pyroxene shows coexisting ortho‐ and clinoenstatite lamellae that probably originated from shear stress after a shock event or from the rapid cooling of the protoenstatite stability field. However, we demonstrate that in this case, a shock trigger is more likely. Pyrrhotite in the studied sample occurs as a 4C monoclinic superstructure. The graphite flakes in the fragment are well crystallized, as can be seen by discrete spots in the diffraction pattern. In graphite, the degree of crystallization increases with the metamorphic grade. Based on the microstructure of this mineral we conclude that after a first moderate shock event, the residual temperature between 300 °C and 500 °C led to thermal metamorphism. A second shock event, possibly at excavation from the parent body, is responsible for the shock features observed in olivine, pyroxene, and graphite.