Technologies and science archives for ultraviolet astronomy

This paper summarizes 17 talks presented during the Technological sessions at the “Challenges in UV Astronomy” conference. It is based on summaries submitted by the presenters, on the slides of their talks, on notes written by the authors, and on additional material kindly submitted to the lead author. In many instances the summaries were written by the presenters themselves and are included as-submitted to the authors with just minor editorial interference. In other cases one of the editors wrote the summary based on their notes and on the files of the actual presentations. The contributions are placed in the general context of the current knowledge in the field. The sessions were devoted to: [a] detectors, [b] optics, [c] integration and verification procedures for vacuum UV instruments and [d] calibration and archival research. A cautionary note: this is not a regular article in these proceedings presenting one idea, an experiment, of a result. It is rather a distillation of what was presented at the NUVA/ESO/IAG meeting at the sessions deemed technological, therefore it will lack an overall coherence although the individual sections and subsections should be logically connected.     

Size and shape of near-spherical Allegan chondrules

Chondrules were extracted from a disaggregated sample of the Allegan meteorite. Individual chondrules were examined with apparatus incorporating two orthogonal binocular microscopes, and their three major axes measured. Maximum chondrule diameters ranged from 0.15 to 2.75 mm with a peak in distribution between 0.35 and 0.75 mm. The chondrule size distribution was found not to conform to Rosin's law. The chondrules were found to depart from sphericity by only small amounts. The authors still believe that the melting of nebula dust-ball agglomerates by some high-energy event was the most probable mechanism for the formation of chondrules.     

Living with limits: growth,resources, and climate change

Is it possible for all of humanity to enjoy the standards of living of today's high-income countries? What would happen if these limits were reached, perhaps because of climate change or a shortage of natural resources essential to production? How would society manage – or fail to manage – such limits? Notwithstanding the current financial and economic crises, these are perhaps the biggest questions confronting our species (and of a host of other species, who are the victims of our decisions). The article begins by considering the biggest economic event of our lifetimes – the ‘great convergence’ and its implications for the demand for resources. The discussion then turns to a specific limit on our development, climate change, which is different from most other limits, because it involves a global public good: the atmosphere. What such limits might mean for our civilization is discussed. One can persuade people to tackle climate change only if those concerned with the dangers persuade ordinary people that action will not come at the expense of their prosperity.     

Doppler radar observation, CG lightning activity and aerial survey of a multiple downburst in southern Germany on 23 March 2001

Two downburst events from one thunderstorm are investigated, which occurred on 23 March 2001, in Germany's climatologic annual minimum of downburst activity. Observations by two Doppler radars are combined with hail reports, ground lightning detection and an aerial survey conducted after the event. The downburst-producing storm had formed at a synoptic convergence line within the warm sector of a cyclone. It had a remarkably high propagation speed of up to 31 m s^− 1 corresponding to the mid-tropospheric flow. Thus, by superposition with the storm motion, even two weak downbursts were sufficient to cause the observed damage of F1 and F2 intensity, respectively. While in its late stages, the storm was dynamically characterized by lower- and mid-tropospheric divergence; at about the time of the first downburst, a mesocyclonic vortex signature was verified. Aside from mid-tropospheric dry air entrainment, a thermodynamic explanation for the triggering of the two downbursts by melting of small hail according to recent findings by Atlas et al. [Atlas, D., Ulbrich, C.W., Williams, C.R., 2004. Physical origin of a wet microburst: observations and theory. J. Atmos. Sci. 61, 1186–1196] appears probable. Despite the lack of warnings to the public, the storm's potential for hail and strong straight-line winds was detected by the German weather service radar software CONRAD more than a half hour before the downbursts occurred.     

MINERALOGY,PETROLOGY AND CHEMISTRY OF LUNAR ROCK 12039

Rock 12039 belongs to the olivine-depleted group of magmatic rocks characterized by normative and modal SiO₂, absence or very low abundance of olivine, and high FeO/(FeO + MgO), Ti/Cr, and CaO/MgO ratios. Clinopyroxenes in this rock show a complex, essentially continuous, compositional zonation from augite cores through ferroaugite to ferrohedenbergite with an abrupt discontinuity at the pyroxferroite contact and, thus, are different from pyroxene in most other Apollo 12 rocks. Two grains contain thin subcalcic pigeonite zones. Texture, presence of very fine (< 1 μm) exsolution lamallae, and pyroxene zoning indicate a relatively rapid cooling history and pronounced in situ chemical fractionation. Rock 12039, on the basis of mineralogy and bulk composition, is the most highly differentiated member of the olivine-depleted basalt group     

Magmatic inclusions and felsic clasts in the Dar al Gani 319 polymict ureilite

Abstract— Magmatic inclusions occur in type II ureilite clasts (olivine‐orthopyroxene‐augite assemblages with essentially no carbon) and in a large isolated plagioclase clast in the Dar al Gani (DaG) 319 polymict ureilite. Type I ureilite clasts (olivine‐pigeonite assemblages with carbon), as well as other lithic and mineral clasts in this meteorite, are described in Ikeda et al.(2000). The magmatic inclusions in the type II ureilite clasts consist mainly of magnesian augite and glass. They metastably crystallized euhedral pyroxenes, resulting in feldspar component‐enriched glass. On the other hand, the magmatic inclusions in the large plagioclase clast consist mainly of pyroxene and plagioclase, with a mesostasis. They crystallized with a composition along the cotectic line between the pyroxene and plagioclase liquidus fields. DaG 319 also contains felsic lithic clasts that represent various types of igneous lithologies. These are the rare components not found in the common monomict ureilites. Porphyritic felsic clasts, the main type, contain phenocrysts of plagioclase and pyroxene, and their groundmass consists mainly of plagioclase, pyroxene, and minor phosphate, ilmenite, chromite, and/or glass. Crystallization of these porphyritic clasts took place along the cotectic line between the pyroxene and plagioclase fields. Pilotaxitic felsic clasts crystallized plagioclase laths and minor interstitial pyroxene under metastable conditions, and the mesostasis is extremely enriched in plagioclase component in spite of the ubiquitous crystallization of plagioclase laths in the clasts. We suggest that there are two crystallization trends, pyroxene‐metal and pyroxene‐plagioclase trends, for the magmatic inclusions and felsic lithic clasts in DaG 319. The pyroxene‐metal crystallization trend corresponds to the magmatic inclusions in the type II ureilite clasts and the pilotaxitic felsic clasts, where crystallization took place under reducing and metastable conditions, suppressing precipitation of plagioclase. The pyroxene‐plagioclase crystallization trend corresponds to the magmatic inclusions in the isolated plagioclase clast and the porphyritic felsic clasts. This trend developed under oxidizing conditions in magma chambers within the ureilite parent body. The felsic clasts may have formed mainly from albite component‐rich silicate melts produced by fractional partial melting of chondritic precursors. The common monomict ureilites, type I ureilites, may have formed by the fractional partial melting of alkali‐bearing chondritic precursors. However, type II ureilites may have formed as cumulates from a basaltic melt.     

Further finds of the Derrick Peak meteorite,Transantarctic Mountains,and implications for terrestrial age

Abstract— Nine additional iron meteorite fragments weighing a total of 72 kg were recovered from the Derrick Peak area by a Canterbury Museum geological party in late 1988. One iron was located in the Onnum Valley, 6 km south of the previous finds. Geochemical analysis indicates that all irons belong to a single meteorite shower, greatly increasing the known extent of the fall zone. Kamp and Lowe (1982) have previously estimated the terrestrial age of the meteorite from glacial geological evidence. The location of the 1988 finds supports Kamp and Lowe's interpretation that the meteorites lie in situ, but recent revisions of the chronology of Cenozoic glacial history of the region reduce the interpreted terrestrial age. An age of between Oxygen Isotope stages 6 and 2 is probable (190–125 to 35–12 ka BP). This conflicts with a terrestrial age estimate of 1.0 ± 0.1 Ma BP from cosmogenic radionuclides.     

Spheroidal pyroxenite aggregates in the Bushveld Complex — a special case of silicate liquid immiscibility

Spherical aggregates of orthopyroxene are reported from some parts of the Bushveld Complex in a variety of host rocks.Detailed mapping has shown that these spherical aggregates, comprising pyroxenite spheroids in a quartz-norite matrix, are contact phenomena and not stratigraphic markers. Orthopyroxene, biotite and amphibole are enriched in spheroids relative to matrix; their mineral chemistry showing a fairly constant orthopyroxene and plagioclase composition through the spheroids and into the matrix, indicating in-situ formation.Bulk chemistry shows spheroid to matrix tie-lines orthogonal to those generally accepted for silicate liquid immiscibility, but other chemical information is consistent with the occurrence of immiscibility.The formation of the aggregates may be related to the industrial process of spherical agglomeration, by which spheroids are formed by the introduction of an immiscible “bridging liquid” to the melt — probably derived from the floor rocks in this case. The mechanism accounts for the field relationships, petrography and chemistry of the aggregate-matrix system. The petrology of the process equates with a special case of silicate liquid immiscibility induced by local contamination and ageing of the original magma.A similar “bridging liquid” mechanism could also account for the formation of the so-called “boulder bed” beneath the Merensky Reef.