Derek W. G. Sears

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The Sariçiçek howardite fall in Turkey: Source crater of HED meteorites on Vesta and impact risk of Vestoids

Ozan Unsalan, Peter Jenniskens, Qing‐Zhu Yin, Ersin Kaygisiz, more

Meteoritics & Planetary Science > 54 > 5 > 953 - 1008

The Sariçiçek howardite meteorite shower consisting of 343 documented stones occurred on September 2, 2015 in Turkey and is the first documented howardite fall. Cosmogenic isotopes show that Sariçiçek experienced a complex cosmic‐ray exposure history, exposed during ~12–14 Ma in a regolith near the surface of a parent asteroid, and that an ~1 m sized meteoroid was launched by an impact 22 ± 2 Ma ago...

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X‐ray computed tomography of extraterrestrial rocks eradicates their natural radiation record and the information it contains

Derek W. G. Sears, Alexander Sehlke, Jon M. Friedrich, Mark L. Rivers, more

Meteoritics & Planetary Science > 53 > 12 > 2624 - 2631

The radiation record of extraterrestrial rocks provides important insights into their thermal and radiation history. For meteorites this relates to their orbits, thermal history, terrestrial age, preatmospheric size and shape, and possibly cosmic ray exposure age. For meteorites from the Moon and Mars, the radiation record allows insights into transit times. For Martian surface samples, the radiation...

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X‐ray computed tomography imaging: A not‐so‐nondestructive technique

Derek W. G. Sears, Hazel Sears, Denton S. Ebel, Sean Wallace, more

Meteoritics & Planetary Science > 51 > 4 > 833 - 838

X‐ray computed tomography has become a popular means for examining the interiors of meteorites and has been advocated for routine curation and for the examination of samples returned by missions. Here, we report the results of a blind test that indicate that CT imaging deposits a considerable radiation dose in a meteorite and seriously compromises its natural radiation record. Ten vials of the Bruderheim...

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The Vicência meteorite fall: A new unshocked (S1) weakly metamorphosed (3.2) LL chondrite

Klaus Keil, Maria E. Zucolotto, Alexander N. Krot, Patricia M. Doyle, more

Meteoritics & Planetary Science > 50 > 6 > 1089 - 1111

The Vicência meteorite, a stone of 1.547 kg, fell on September 21, 2013, at the village Borracha, near the city of Vicência, Pernambuco, Brazil. It was recovered immediately after the fall, and our consortium study showed it to be an unshocked (S1) LL3.2 ordinary chondrite. The LL group classification is based on the bulk density (3.13 g cm⁻³); the chondrule mean apparent diameter (0.9 mm); the bulk...

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Fall, recovery, and characterization of the Novato L6 chondrite breccia

Peter Jenniskens, Alan E. Rubin, Qing‐Zhu Yin, Derek W. G. Sears, more

Meteoritics & Planetary Science > 49 > 8 > 1388 - 1425

The Novato L6 chondrite fragmental breccia fell in California on 17 October 2012, and was recovered after the Cameras for Allsky Meteor Surveillance (CAMS) project determined the meteor's trajectory between 95 and 46 km altitude. The final fragmentation from 42 to 22 km altitude was exceptionally well documented by digital photographs. The first sample was recovered before rain hit the area. First...

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Oral histories in meteoritics and planetary science—XXV: Vagn F. Buchwald

Derek W. G. Sears

Meteoritics & Planetary Science > 49 > 7 > 1271 - 1287

Vagn Buchwald (Fig. [Vagn F. Bu]) was born in Copenhagen where he attended school and college. Then after 18 months of military service, he assumed a position at the Technical University of Copenhagen. A few years later, he was presented with a piece of the Cape York meteorite, which led to an interest in iron meteorites. Through a campaign of informed searching, Vagn found the 20 ton Agpalilik meteorite...

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Oral histories in meteoritics and planetary science—XXIV: William K. Hartmann

Derek W. G. Sears

Meteoritics & Planetary Science > 49 > 6 > 1119 - 1138

In this interview, William Hartmann (Bill, Fig. ) describes how he was inspired as a teenager by a map of the Moon in an encyclopedia and by the paintings by Chesley Bonestell. Through the amateur journal “Strolling Astronomer,” he shared his interests with other teenagers who became lifelong colleagues. At college, he participated in Project Moonwatch, observing early artificial satellites. In graduate...

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Oral histories in meteoritics and planetary science – XXII: John T. Wasson

Derek W. G. Sears

Meteoritics & Planetary Science > 49 > 4 > 706 - 721

In this interview, John Wasson (Fig. ) describes his childhood and undergraduate years in Arkansas and his desire to pursue nuclear chemistry as a graduate student at MIT. Upon graduation, John spent time in Munich (Technische Hochschule), the Air Force Labs in Cambridge, MA, and a sabbatical at the University of Bern where he developed his interests in meteorites. Upon obtaining his faculty position...

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Oral Histories in Meteoritics and Planetary Science—XXI: Donald Burnett

Derek W. G. Sears

Meteoritics & Planetary Science > 48 > 9 > 1715 - 1732

In this interview, Donald Burnett (Fig. 1) describes how he applied to the University of Chicago, with considerable support from his father, where he took classes from Harold Urey and was inspired by Ed Anders to pursue a career in nuclear chemistry and, later, cosmochemistry. As a graduate student at the University of California at Berkeley, Don learned to use charged‐particle tracks as a detector...

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Oral Histories in Meteoritics and Planetary Science—XXIII: Dieter Stöffler

Derek W. G. Sears

Meteoritics & Planetary Science > 48 > 9 > 1733 - 1751

In this interview, Dieter Stöffler (Fig. 1) describes how his interest in meteorites and impact craters dates from his Ph.D. studies at the University of Tübingen when it was learned that the Ries crater was formed by impact. A paper by Dieter's advisor, Wolf von Engelhardt, also triggered an interest in meteorites. After graduation, Dieter helped to establish a laboratory for high pressure mineralogy...

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Oral Histories in Meteoritics and Planetary Science – XX: Dale Cruikshank

Derek W. G. SEARS

Meteoritics & Planetary Science > 48 > 4 > 700 - 711

Abstract– In this interview, Dale Cruikshank (Fig. 1) explains how as an undergraduate at Iowa State University he was a summer student at Yerkes Observatory where he assisted Gerard Kuiper in work on his Photographic Lunar Atlas. Upon completing his degree, Dale went to graduate school at the University of Arizona with Kuiper where he worked on the IR spectroscopy of the lunar surface. After an eventful...

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Oral Histories in Meteoritics and Planetary Science—XIX: Klaus Keil

Derek W. G. SEARS

Meteoritics & Planetary Science > 47 > 12 > 1891 - 1906

Abstract– Klaus Keil (Fig. 1) grew up in Jena and became interested in meteorites as a student of Fritz Heide. His research for his Dr. rer. nat. became known to Hans Suess who––with some difficulty––arranged for him to move to La Jolla, via Mainz, 6 months before the borders of East Germany were closed. In La Jolla, Klaus became familiar with the electron microprobe, which has remained a central...

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IRTF observations of S complex and other asteroids: Implications for surface compositions, the presence of clinopyroxenes, and their relationship to meteorites

Katherine M. GIETZEN, Claud H. S. LACY, Daniel R. OSTROWSKI, Derek W. G. SEARS

Meteoritics & Planetary Science > 47 > 11 > 1789 - 1808

Abstract– We have obtained near‐infrared spectra for near‐Earth asteroids (NEA) and Main Belt asteroids by using NASA’s Infrared Telescope Facility. Most of the S complex classes of the Tholen‐Bus‐DeMeo scheme and the S(I)–S(VII) classes are represented. To help interpret the results, we examined visible/near‐IR spectra for ordinary chondrites. The unequilibrated ordinary chondrites (UOC) spectra...

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Oral Histories in Meteoritics and Planetary Science – XV: John Wood

Derek W. G. SEARS

Meteoritics & Planetary Science > 47 > 5 > 903 - 915

Abstract– John Wood (Fig. 1) was trained in Geology at Virginia Tech and M.I.T. To fulfill a minor subject requirement at M.I.T., he studied astronomy at Harvard, taking courses with Fred Whipple and others. Disappointed at how little was known in the 1950s about the origin of the earth, he seized an opportunity to study a set of thin sections of stony meteorites, on the understanding that these might...

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Oral Histories in Meteoritics and Planetary Science – XVII: Joseph Goldstein

Derek W. G. SEARS

Meteoritics & Planetary Science > 47 > 5 > 916 - 926

Abstract– In this interview, Joseph Goldstein (Fig. 1) recounts how he became interested in meteorites during his graduate studies working with Robert Ogilvie at MIT. By matching the Ni profiles observed across taenite fields in the Widmanstätten structure of iron meteorites with profiles he computed numerically he was able to determine cooling rates as the meteorites cooled through 650–400 °C. Upon...

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Oral Histories in Meteoritics and Planetary Science––XVI: Grenville Turner

Derek W. G. SEARS

Meteoritics & Planetary Science > 47 > 3 > 434 - 448

Abstract– In this interview, Grenville Turner (Fig. 1) recounts how he became interested in meteorites during postdoctoral research with John Reynolds at the University of California, Berkeley, after completing a DPhil with Ken Mayne at the University of Oxford. At Berkeley, he worked on xenon isotopes with fellow students Bob Pepin and Craig Merrihue, but Reynolds’ insistence that they analyze all...

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Oral histories in meteoritics and planetary science: A commentary

Derek W. G. SEARS

Meteoritics & Planetary Science > 47 > 3 > 414 - 415

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Oral histories in meteoritics and planetary science—XVI: Donald D. Bogard

Derek W. G. SEARS

Meteoritics & Planetary Science > 47 > 3 > 416 - 433

Abstract– Donald D. Bogard (Don, Fig. 1) became interested in meteorites after seeing the Fayetteville meteorite in an undergraduate astronomy class at the University of Arkansas. During his graduate studies with Paul Kuroda at Arkansas, Don helped discover the Xe decay products of ²⁴⁴Pu. After a postdoctoral period at Caltech, where he learned much from Jerry Wasserburg, Peter Eberhardt, Don Burnett,...

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The natural thermoluminescence of Antarctic meteorites and their terrestrial ages and orbits: A 2010 update

Derek W. G. SEARS, Jordan YOZZO, Christina RAGLAND

Meteoritics & Planetary Science > 46 > 1 > 79 - 91

Abstract– We have examined the relationship between natural thermoluminescence (TL) and ²⁶Al in 120 Antarctic meteorites in order to explore the orbital history and terrestrial ages of these meteorites. Our results confirm the observations of Hasan et al. (1987) which were based on 23 meteorites. For most meteorites there was a positive correlation between natural TL and ²⁶Al, reflecting their similarity...

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The thermoluminescence of meteorites: A brief 2010 perspective

Derek W. G. Sears

Geochronometria > 2011 > 38 > 3 > 303-313

Early work on meteorite thermoluminescence, influenced by pottery dating and dosimetry applications, demonstrated a relationship between natural thermoluminescence and (1) the orbital perihelion of a meteorite and (2) the terrestrial age (time since fall) of a meteorite. For 14 years natural TL measurements were routinely made on newly recovered Antarctic meteorites to help identify unusual thermal...

INFONA - science communication portal

Search results for: Derek W. G. Sears

The Sariçiçek howardite fall in Turkey: Source crater of HED meteorites on Vesta and impact risk of Vestoids

X‐ray computed tomography of extraterrestrial rocks eradicates their natural radiation record and the information it contains

X‐ray computed tomography imaging: A not‐so‐nondestructive technique

The Vicência meteorite fall: A new unshocked (S1) weakly metamorphosed (3.2) LL chondrite

Fall, recovery, and characterization of the Novato L6 chondrite breccia

Oral histories in meteoritics and planetary science—XXV: Vagn F. Buchwald

Oral histories in meteoritics and planetary science—XXIV: William K. Hartmann

Oral histories in meteoritics and planetary science – XXII: John T. Wasson

Oral Histories in Meteoritics and Planetary Science—XXI: Donald Burnett

Oral Histories in Meteoritics and Planetary Science—XXIII: Dieter Stöffler

Oral Histories in Meteoritics and Planetary Science – XX: Dale Cruikshank

Oral Histories in Meteoritics and Planetary Science—XIX: Klaus Keil

IRTF observations of S complex and other asteroids: Implications for surface compositions, the presence of clinopyroxenes, and their relationship to meteorites

Oral Histories in Meteoritics and Planetary Science – XV: John Wood

Oral Histories in Meteoritics and Planetary Science – XVII: Joseph Goldstein

Oral Histories in Meteoritics and Planetary Science––XVI: Grenville Turner

Oral histories in meteoritics and planetary science: A commentary

Oral histories in meteoritics and planetary science—XVI: Donald D. Bogard

The natural thermoluminescence of Antarctic meteorites and their terrestrial ages and orbits: A 2010 update

The thermoluminescence of meteorites: A brief 2010 perspective

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