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Impacts and tectonism in Earth and moon history of the past 3800 million years

The moon's surface, unlike the Earth's, displays a comparatively clear record of its past bombardment history for the last 3800 Myr, the time since active lunar tectonism under the massive premare bombardment ended. From Baldwin's (1987) tabulation of estimated ages for a representative sample of large lunar craters younger than 3800 Ma, six major cratering episodes can be discerned. These six bombardment episodes, which must have affected the Earth too, appear to match in time the six major episodes of orogenic tectonism on Earth, despite typical resolution errors of +/- 100 Myr and the great uncertainties of the two chronologies. Since more highly resolved events during the Cenozoic and Mesozoic Eras suggest the same correlation, it is possible that large impacts have influenced plate tectonics and other aspects of geologic history, perhaps by triggering flood basalt eruptions.

Stothers, Richard B.↗

Exposure history of the lunar meteorite, Elephant Moraine 87521

We report the noble gas concentrations and the Al-26, Be-10, Cl-36, and Ca-41 activities of the Antarctic lunar meteorite Elephant Moraine 87521. Although the actual exposure history of the meteorite may have been more complex, the following model history accounts satisfactorily for the cosmogenic nuclide data: A first stage of lunar irradiation for about 1 Ma at a depth of 1-5 g/sq cm followed, not necessarily directly, by a second one for 26 Ma at about 565 g/sq cm; launch from the moon less than 0.1 Ma ago; and arrival on earth 15-50 ka ago. The small concentration of trapped gases shows that except for some material that may have been introduced at the moment of launch, EET 87521 spent less than 1 Ma at a lunar depth less than 1 g/sq cm. EET 87521 has a K/Ar age in the range 3.0-3.4 Ga, which is typical for lunar mare basalts.

Vogt, S.↗

Chondrite thermal histories from Low-CA pyroxene microstructures: Autometamorphism versus prograde metamorphism revisited

In order to constrain the thermal histories of chondritic meteorites, a detailed study of the microstructures of low-Ca pyroxenes produced experimentally and in types 4 and 5 ordinary chondrites was carried out. Cooling experiments on synthetic MgSiO3 at cooling rates between 2 and 10000 C/hr from the protopyroxene stability field into that of orthopyroxene (OPX) were performed and the products of these experiments were annealed for a variety of annealing times. There are clear microstructural differences between samples which were cooled and those which were subsequently annealed. A comparison of the microstructures observed in the experimental samples with those in H4-5 ordinary chondrites shows that they cannot have experienced a single stage cooling history, as proposed for the autometamorphism model.

Brearley, Adrian J.↗

Contributions of the Clementine mission to our understanding of the processes and history of the Moon

The Clementine mission will provide us with an abundance of information about lunar surface morphology, topography, and composition, and it will permit us to infer the history of the Moon and the processes that have shaped that history. This information can be used to address fundamental questions in lunar science and allow us to make significant advances towards deciphering the complex story of the Moon. The Clementine mission will also permit a first-order global assessment of the resources of the Moon and provide a strategic base of knowledge upon which future robotic and human missions to the Moon can build.

Spudis, Paul D.↗

NSWC Crane Aerospace Cell Test History Database

The Aerospace Cell Test History Database was developed to provide project engineers and scientists ready access to the data obtained from testing of aerospace cell designs at Naval Surface Warfare Center, Crane Division. The database is intended for use by all aerospace engineers and scientists involved in the design of power systems for satellites. Specifically, the database will provide a tool for project engineers to review the progress of their test at Crane and to have ready access to data for evaluation. Additionally, the database will provide a history of test results that designers can draw upon to answer questions about cell performance under certain test conditions and aid in selection of a cell for a satellite battery. Viewgraphs are included.

Brown, Harry↗

The history of space exploration

Presented are the acknowledgements and introduction sections of the book 'Space: Discovery and Exploration.' The goal of the book is to address some basic questions of American space history, including how this history compares with previous eras of exploration, why the space program was initiated when it was, and how the U.S. space program developed. In pursuing these questions, the intention is not to provide exhaustive answers, but to point the reader toward a more varied picture of how our venture in space has intersected with American government, politics, business, and science.

Collins, Martin J.↗

Statistical properties of the time histories of cosmic gamma-ray bursts detected by the BATSE experiment of the Compton gamma-ray observatory

The main scientific objectives of the project were: (1) Calculation of average time history for different subsets of BATSE gamma-ray bursts; (2) Comparison of averaged parameters and averaged time history for different Burst And Transient Source Experiments (BASTE) Gamma Ray Bursts (GRB's) sets; (3) Comparison of results obtained with BATSE data with those obtained with APEX experiment at PHOBOS mission; and (4) Use the results of (1)-(3) to compare current models of gamma-ray bursts sources.

Sagdeev, Roald↗

The thermal history of interplanetary dust particles collected in the Earth's stratosphere

Fragments of 24 individual interplanetary dust particles (IDPs) collected in the Earth's stratosphere were obtained from NASA's Johnson Space Center collection and subjected to pulse-heating sequences to extract He and Ne and to learn about the thermal history of the particles. A motivation for the investigation was to see if the procedure would help distinguish between IDPs of asteroidal and cometary origin. The use of a sequence of short-duration heat pulses to perform the extractions is an improvement over the employment of a step-heating sequence, as was used in a previous investigation. The particles studied were fragments of larger parent IDPs, other fragments of which, in coordinated experiments, are undergoing studies of elemental and mineralogical composition in other laboratories. While the present investigation will provide useful temperature history data for the particles, the relatively large size of the parent IDPs (approximately 40 micrometers in diameter) resulted in high entry deceleration temperatures. This limited the usefulness of the study for distinguishing between particles of asteroidal and cometary origin.

Nier, A. O.↗

Exploring the Unknown: Selected Documents in the History of the US Civil Space Program: Organizing for Exploration - Volume 1

A selection of key documents in the history of the U.S. civil space program is presented. This volume deals with organizational developments of the space program. More than 200 documents are printed. Each is introduced by a headnote providing context, bibliographical information, and background information necessary to understanding the document. These are organized into four major sections, each beginning with an introductory essay that keys the documents to major events in the history of the space program.

Logsdon, John M.↗

The history of transportation, with a peak into the future

In the first part of this presentation, a general historical review of the heydays of various modes of transportation will be given, where 'heydays' will be interpreted as periods of fundamental technological development. With this as background, focus will then be placed on the airplane -- the mode of transportation that has changed the world in the 20th century, and which in the minds of many has been the most important technological development in this century. The technical history of air transportation (the airplane) will be reviewed, with special emphasis on the aerodynamic evolution of the airplane. Some specific examples of pivotal technical advances (and breakthroughs) from the history of applied aerodynamics will be discussed. Finally, this historical perspective will be used to help us peek into the future of transportation in the 21st century.

Anderson, John D., Jr.↗

Chemical and physical studies of type 3 chondrites 12: The metamorphic history of CV chondrites and their components

The induced thermoluminescence (TL) properties of 16 CV and CV-related chondrites, four CK chondrites and Renazzo (CR2) have been measured in order to investigate their metamorphic history. The petrographic, mineralogical and bulk compositional differences among the CV chondrites indicate that the TL sensitivity of the approximately 130 C TL peak is reflecting the abundance of ordered feldspar, especially in chondrule mesostasis, which in turn reflects parent-body metamorphism. The TL properties of 18 samples of homogenized Allende powder heated at a variety of times and temperatures, and cathodoluminescence mosaics of Axtell and Coolidge, showed results consistent with this conclusion. Five refractory inclusions from Allende, and separates from those inclusions, were also examined and yielded trends reflecting variations in mineralogy indicative of high peak temperatures (either metamorphic or igneous) and fairly rapid cooling. The CK chondrites are unique among metamorphosed chondrites in showing no detectable induced TL, which is consistent with literature data that suggests very unusual feldspar in these meteorites. Using TL sensitivity and several mineral systems and allowing for the differences in the oxidized and reduced subgroups, the CV and CV-related meteorites can be divided into petrologic types analogous to those of the ordinary and CO type 3 chondrites. Axtell, Kaba, Leoville, Bali, Arch and ALHA81003 are type 3.0-3.1, while ALH84018, Efremovka, Grosnaja, Allende and Vigarano are type 3.2-3.3 and Coolidge and Loongana 001 are type 3.8. Mokoia is probably a breccia with regions ranging in petrologic type from 3.0 to 3.2. Renazzo often plots at the end of the reduced and oxidized CV chondrite trends, even when those trends diverge, suggesting that in many respects it resembles the unmetamorphosed precursors of the CV chondrites. The low-petrographic types and low-TL peak temperatures of all samples, including the CV3.8 chondrites, indicates metamorphism in the stability field of low feldspar (i.e., less than 800 C) and a metamorphic history similar to that of the CO chondrites but unlike that of the ordinary chondrites.

Guimon, R. Kyle↗

Pyroxene structures, cathodoluminescence and the thermal history of the enstatite chondrites

In order to explore the thermal history of enstatite chondrites, we examined the cathodoluminescence (CL) and thermoluminescence (TL) properties of 15 EH chondrites and 21 EL chondrites, including all available petrographic types, both textural types 3-6 and mineralogical types alpha-delta. The CL properties of EL3(alpha) and EH3(alpha) chondrites are similar. Enstatite grains high in Mn and other transition metals display red CL, while enstatite with low concentrations of these elements show blue CL. A few enstatite grains with greater than 5 wt% FeO display no CL. In contrast, the luminescent properties of the metamorphosed EH chondrites are very different from those of metamorphosed EL chondrites. While the enstatites in metamorphosed EH chondrites display predominantly blue CL, the enstatites in metamorphosed EL chondrites display a distinctive magenta CL with blue and red peaks of approximately equal intensity in their spectra. The TL sensitivities of the enstatite chondrites correlate with the intensity of the blue CL and, unlike other meteorite classes, are not simply related to metamorphism. The different luminescent properties of metamorphosed EH and EL chondrites cannot readily be attributed to compositional differences. But x-ray diffraction data suggests that the enstatite in EH5(gamma),(delta) chondrites is predominantly disordered orthopyroxene, while enstatite in EL6(beta) chondrites is predominantly ordered orthopyroxene. The difference in thermal history of metamorphosed EL and EH chondrites is so marked that the use of single 'petrographic' types is misleading, and separate textural and mineralogical types are preferable. Our data confirm earlier suggestions that metamorphosed EH chondrites underwent relatively rapid cooling, and the metamorphosed EL chondrites cooled more slowly and experienced prolonged heating in the orthopyroxene field.

Zhang, Yanhong↗

To See the Unseen: A History of Planetary Radar Astronomy

This book relates the history of planetary radar astronomy from its origins in radar to the present day and secondarily to bring to light that history as a case of 'Big Equipment but not Big Science'. Chapter One sketches the emergence of radar astronomy as an ongoing scientific activity at Jodrell Bank, where radar research revealed that meteors were part of the solar system. The chief Big Science driving early radar astronomy experiments was ionospheric research. Chapter Two links the Cold War and the Space Race to the first radar experiments attempted on planetary targets, while recounting the initial achievements of planetary radar, namely, the refinement of the astronomical unit and the rotational rate and direction of Venus. Chapter Three discusses early attempts to organize radar astronomy and the efforts at MIT's Lincoln Laboratory, in conjunction with Harvard radio astronomers, to acquire antenna time unfettered by military priorities. Here, the chief Big Science influencing the development of planetary radar astronomy was radio astronomy. Chapter Four spotlights the evolution of planetary radar astronomy at the Jet Propulsion Laboratory, a NASA facility, at Cornell University's Arecibo Observatory, and at Jodrell Bank. A congeries of funding from the military, the National Science Foundation, and finally NASA marked that evolution, which culminated in planetary radar astronomy finding a single Big Science patron, NASA. Chapter Five analyzes planetary radar astronomy as a science using the theoretical framework provided by philosopher of science Thomas Kuhn. Chapter Six explores the shift in planetary radar astronomy beginning in the 1970s that resulted from its financial and institutional relationship with NASA Big Science. Chapter Seven addresses the Magellan mission and its relation to the evolution of planetary radar astronomy from a ground-based to a space-based activity. Chapters Eight and Nine discuss the research carried out at ground-based facilities by this transformed planetary radar astronomy, as well as the upgrading of the Arecibo and Goldstone radars. A technical essay appended to this book provides an overview of planetary radar techniques, especially range-Doppler mapping.

Butrica, Andrew J.↗

A Petrographic History of Martian Meteorite ALH84001: Two Shocks and an Ancient Age

ALH84001 is an igneous meteorite, an orthopyroxenite of martian origin. It contains petrographic evidence of two shock metamorphic events, separated by thermal and chemical events. The evidence for two shock events suggests that ALH84001 is ancient and perhaps a sample of the martian highlands. From petrography and mineral chemistry, the history of ALH84001 must include: crystallization from magma, a first shock (impact) metamorphism, thermal metamorphism, low-temperature chemical alteration, and a second shock (impact) metamorphism. Originally, ALH84001 was igneous, an orthopyroxene-chromite cumulate. In the first shock event, the igneous rock was cut by melt-breccia or cataclastic veinlets, now bands of equigranular fine-grained pyroxene and other minerals (crush zones). Intact fragments of the cumulate were fractured and strained (now converted to polygonized zones). The subsequent thermal metamorphism (possibly related to the first shock) annealed the melt-breccia or cataclastic veinlets to their present granoblastic texture and permitted chemical homogenization of all mineral species present. The temperature of metamorphism was at least 875 C, based on mineral thermometers. Next, Mg-Fe-Ca carbonates and pyrite replaced plagioclase in both clasts and granular bands, producing ellipsoidal carbonate globules with sub-micron scale compositional stratigraphy, repeated identically in all globules, The second shock event produced microfault offsets of carbonate stratigraphy and other mineral contacts, radial fractures around chromite and maskelynite, and strain birefringence in pyroxene. Maskelynite could not have been preserved from the first shock event, because it would have crystallized back to plagioclase. The martian source area for ALH84001 must permit this complex, multiple impact history. Very few craters on young igneous surfaces are on or near earlier impact features. It is more likely that ALH84001 was ejected from an old igneous unit (Hesperian or Noachian age), pocked by numerous impact craters over its long exposure at the martian surface.

Treiman, Allan H.↗

Way Station to Space: A History of the John C. Stennis Space Center

A history of the NASA John C. Stennis Space Center is presented. A study of the Apollo era is provided. This new addition to the NASA history series is also an allegory of the Center's relationship to the local communities in Mississippi and Louisiana, its sister Centers, and to NASA Headquarters.

Herring, Mack R.↗

History of NASA/Native People Native Homelands Initiative

This workshop is one of the follow-on local assessment activities from the US National Assessment on the Impact of Climate Change on the US. N. Maynard (for NASA) helped create and get under way an initiative which brought together climate change scientists from around the US with Native Americans to bring together classic Western European scientists with knowledge from native peoples - from such sources as oral histories of drought, major fires, etc. The purpose of this was to encourage not only joint science but also bring NASA resources and education materials to Tribal schools and encourage joint preparation of educational and training materials. N. Maynard's talk will provide history of that process and discuss possible ways to collaborate in the future, building on this effort.

Maynard, Nancy↗

Examination of a Deep Subsurface Mars Polar Cap Mission to Address Climate History

We have examined the technological readiness of a mission to the Mars north polar area for the science objective of developing a climate history. We argue that the polar regions are scientifically extremely important mission sites from the perspectives of both climate history and astrobiology and that a polar deep subsurface mission would constitute a serious challenge and significant accomplishment. Thus a key question is: What is the technical readiness status of such a mission? Additional information is contained in original extended abstract.

Carsey, F. D.↗