Department News

LPL Fieldtrip Fall 2012 – Circum-Tucson

Despite our tendency to crisscross the whole southwestern U.S. on these trips, there is an incredibly interesting geologic story sitting on our doorstep here in the Tucson area.  There has been growing interest among the fieldtrip group in understanding more about the processes that have fashioned the local landscape around Tucson and that was finally satisfied this semester.

Department News

LPL Fieldtrip Fall 2012 – Circum-Tucson

by Shane Byrne

Despite our tendency to crisscross the whole southwestern U.S. on these trips, there is an incredibly interesting geologic story sitting on our doorstep here in the Tucson area.  There has been growing interest among the fieldtrip group in understanding more about the processes that have fashioned the local landscape around Tucson and that was finally satisfied this semester.

From a geological point of view, we’re fortunate here in the Southwest to be so close to the edge of North America.  Our geologic story is largely shaped by our proximity to this active plate boundary over the past hundred million years or so.  Prior to that, southern Arizona had a mix of dry periods and marine incursions.  One of these marine periods led to the formation of limestone rocks, which would likely have remained obscure were it not for the fabulous caves that formed within them. We had the chance to visit one of these caves at Kartchner Caverns, discovered less than 40 years ago by Gary Tenen and Randy Tufts (an LPL alum).  Other sedimentary rocks that predate the main volcanic and tectonic stories recorded at Tucson can be seen east of the Tucson Mountains too.  However, most of the geologic story we followed started in the late Cretaceous – just before the disappearance of the dinosaurs.

About seventy million years ago there was an oceanic plate (called the Farallon plate), to our west, that was in the process of disappearing beneath North America.  As younger and younger portions of this oceanic plate were dragged beneath our continent they began to float higher and eventually grate along the underside of North America compressing our continent and building mountains.  A wave of volcanic activity passed eastward through the Tucson area ahead of this and large ash-flow calderas dotted the landscape. We visited the remnants of one of these in the Tucson Mountains.  Here, large quantities of volcanic ash are welded together forming the rocks we see (and can be comfortably examined at Gate’s Pass).  During this period, hydrothermal circulation around the subterranean magma chambers led to the concentration of much of Arizona’s copper and other minerals that we continue to mine today.

Probably the most shocking part of this part of the story is that the Tucson Mountains are no longer sitting above the magma chamber that fed them.  That magma chamber is likely part of the Catalina and Rincon mountains on the other side of town! How then did the surface volcanoes end up so far away from where they started?  As the trailing edge of the Farallon plate disappeared beneath North America its angle of descent steepened and it stopped compressing the continent. The mountain ranges produced earlier began to collapse and the crust to spread outward. This crustal spreading manifested itself on the surface in the Tucson area as nearly horizontal faults. Thus the Tucson mountains were able to slide, nearly horizontally, westward off the top of their (now solidified) magma chamber.  Without the weight of the Tucson Mountains above it, the buried granite could rise up buoyantly above the surface.  The Rincon and Catalina Mountains are these magma chambers. We visited the fault where the surface rocks slid off the buried magma chambers to the south and east of these mountains.  Having the surface volcanoes scrapped off like this has consequences for the granite of the magma chamber too. The heat and pressure generated in the region being sheared metamorphoses the granite into mylonite – a rock with a texture that can tell you details of the direction of the shear.  We saw plenty of examples of mylonite on the Catalina Highway – this metamorphism progressed to different extents in different places and is barely apparent at all behind the steep Catalina forerange.  These uplifted partly-metamorphosed magma chambers, where the original surface rocks have been moved off, are called metamorphic core complexes.  They are known to be widespread now, but were first recognized in this classic Tucson example.

Stretching of the crustal rocks continued in a different form as the Farallon plate peeled away from the underside of North America and volcanic activity returned producing dikes that are visible today in the Tucson Mountains.  Steeper faults now formed and occurred in sets that allowed intervening valley floors to drop downward nearly intact.  The alternating basins and mountain ranges this produced can be seen throughout the southwest. Tucson itself sits in one of these basins and we visited a classic example of one of these basin-and-range faults near Oracle named the Pirate Fault.

With the basin floors dropping, the surrounding mountains shed material that began to fill in these low areas.  This continues to this day and we saw examples of bedrock channels and debris flows that have contributed material to the basin fill.  As the mountains erode backward and shed more debris both alluvial fans and pediment surfaces can form.  Compaction of sediment above buried pediments can also lead to fissures opening up on the surface – a process that we saw has accelerated around Wilcox in recent times as groundwater is mined for agriculture.

Within the infilling basins, lakes alternated with playas as climatic conditions shifted. Eventually the basins became so full of sediment that they began to overflow allowing drainage waters to move from basin to basin.  After the basins were integrated in this way lakes gave way to thoroughgoing rivers. The San Pedro river sediments tell this complete story very well and there are great exposures of them in the Saint David’s Formation near Benson.

Despite all the buildings, agriculture and people around Tucson there’s still a lot of geology to see.  This trip has certainly provided us with an appreciation of the local story and how it fits into the broader forces at work as Earth’s tectonic plates (and perhaps those of some extrasolar planes) jostle past each other over geologic time.


Photo courtesy Ali Bramson


Photo courtesy James Keane.


Photo courtesy Christa Van Laerhoven


Photo courtesy Ali Bramson


Photo courtesy Melissa Dykhuis.


Photo courtesy James Keane

Asteroid 1999 RQ36 is now Bennu

On May 1, NASA announced that the OSIRIS-REx target asteroid 1999 RQ36 was renamed Bennu. The name Bennu was selected from over 8,000 entries submitted to the Name that Asteroid! contest. Bennu was an important avian deity in ancient Egypt and one of the symbols of the god Osiris. Egyptians usually depicted Bennu as a gray heron.

Department News

Asteroid 1999 RQ36 is now Bennu

On May 1, NASA announced that the OSIRIS-REx target asteroid 1999 RQ36 was renamed Bennu. The name Bennu was selected from over 8,000 entries submitted to the Name that Asteroid! contest. Bennu was an important avian deity in ancient Egypt and one of the symbols of the god Osiris. Egyptians usually depicted Bennu as a gray heron. The double nature of asteroids delivering life’s molecules and sometimes bringing destruction such as the recent fall in Chelyabinsk, Russia, inspired the mission name, OSIRIS-REx, and now the asteroid’s name. Nine-year old Mike Puzio submitted the winning entry, stating, 
“The winged OSIRIS-REx and its heron-like TAGSAM evoke attributes of Bennu, as does the egg shape of the asteroid itself.”

OSIRIS-REx will launch in 2016, rendezvous with Bennu in 2018, and take a sample in 2019.

More information about how Bennu got its name is available here and in the UA News press release.

Asteroids (75562) Wilkening and (25760) Annaspitz

Early this year, the International Astronomical Union announced the naming of asteroids after two women with strong ties to LPL.

Department News

Asteroids (75562) Wilkening and (25760) Annaspitz

Early this year, the International Astronomical Union announced the naming of asteroids after two women with strong ties to LPL.

Laurel Wilkening Anna Spitz

Asteroid 1999 YV 22 (discovered December 31, 1999, MPC 79104) has been officially designated (75562) Wilkening and asteroid 2000 BF34 (discovered December 31, 2000, MPC 82401) has been officially designated (25760) Annasptiz. Both asteroids were discovered by LPL's Catalina Sky Survey.

Laurel Wilkening was on the LPL faculty from 1973 to 1983 and served as PTYS/LPL Head and Director from 1981 to 1983. She is now retired and living in Tucson. More about Laurel Wilkening's fascinating life is available from a 2001 NASA oral history project ("Herstory") interview available online from NASA Johnson Space Center.

Anna Spitz received her Ph.D. working with Professor William Boynton in 1991 and is currently Education and Public Outreach lead for the OSIRIS-REx mission.

Congratulations to Dr. Wilkening and Dr. Spitz!

LPL Board of Advisors

The LPL Board of Advisors, the external group chartered with helping LPL and its director improve interactions with the world beyond campus and NASA, has been reformulated after a several year absence. The group will have its initial meeting in June to set goals and begin work. The Board members range from LPL alumni to Tucson community leaders who have not been part of the LPL family before. You’ll be hearing more from the Board as time progresses. Board members are:

Department News

LPL Board of Advisors

The LPL Board of Advisors, the external group chartered with helping LPL and its director improve interactions with the world beyond campus and NASA, has been reformulated after a several year absence. The group will have its initial meeting in June to set goals and begin work. The Board members range from LPL alumni to Tucson community leaders who have not been part of the LPL family before. You’ll be hearing more from the Board as time progresses. Board members are:

David Acklam is a retired engineer who has been very active in astronomical outreach in the Tucson area. As well as being the chair of LPL’s Kuiper Circle Community Outreach committee, he is also an OSIRIS-REx Ambassador, a volunteer telescope operator at Flandrau Science Center, a Friend and docent at the Planetary Science Institute, and a volunteer Project ASTRO astronomer partner. Acklam is also a member of the Tucson Amateur Astronomy Association and the Planetary Society. He received his BSEE and MS from the University of Arizona and was a career Air Force officer, before moving to Texas Instruments and then Raytheon Missile Systems.

Dan Cavanagh is a 1974 Communications graduate of the University of Arizona. His varied background includes being President of the American Chamber of Commerce Government Relations Council and being a leading contributor to radio networks and wire services though out North America. He has spent 40 years in Southern Arizona developing/serving on successful efforts impacting public policy, taxation, the arts and education. Cavanagh's most recent position was Southern Arizona Manager of Government Affairs for the world's largest publicly traded copper company, Freeport McMoRan.

Chris Lewicki is the President and Chief Engineer of Planetary Resources, the asteroid mining company. He received his bachelor’s and master’s degrees in Aerospace Engineering from UA, and worked at LPL with Professor Bill Boynton’s group. He was then intimately involved with the lifecycle of NASA’s Mars Exploration Rovers and the Phoenix Mars Lander. Lewicki performed system engineering development and participated in assembly, test and launch operations for both Mars missions. He was Flight Director for the rovers Spirit and Opportunity, and the Surface Mission Manager for Phoenix. The recipient of two NASA Exceptional Achievement Medals, Lewicki has an asteroid named in his honor, 13609 Lewicki.

Laura McGill is Engineering Deputy of Raytheon Missile Systems, the largest private employer in southern Arizona. A principal engineering fellow, McGill was formerly deputy director for Advanced Medium Range Air-to-Air Missiles and Special Programs. She holds a bachelor’s degree in aeronautical and astronautical  engineering from the University of Washington and a master’s degree in aerospace systems through a General Dynamics engineering development program. She is a lifetime fellow of the American Institute for Aeronautics and Astronautics (AIAA) and a member of its board of directors.

Jani Radebaugh, who obtained her PhD in planetary science from LPL in 2005, is an associate professor of geological sciences at Brigham Young University. She specializes in landform geomorphology in the solar system. As an associate member of the Cassini RADAR Team, she studies dunes, mountains, cryovolcanoes, rivers and lakes on Saturn's moon Titan, and she studies volcanoes and mountains on Jupiter's moon Io from Galileo, Cassini, and Voyager observations. Radebaugh has done field work in the Egyptian Sahara, the Ethiopian Afar Rift Valley, Hawaii, the desert southwestern US, and Antarctica.

Timothy Reckart is a Tucson attorney whose commercial and corporate practice focuses on intellectual property transactions and the representation of emerging-growth, technology-based companies. Reckart’s broad experience includes 22 years as General Counsel for technology-based enterprises, 19 of them with Research Corporation Technologies in Tucson. He holds a law degree and an MBA from Stanford University, a master’s degree in nuclear engineering from the University of California at Berkeley and a bachelor’s degree in nuclear engineering from the Massachusetts Institute of Technology.

Kjell Stakkestad is the President of Northstar, a wholly-owned subsidiary ofKinetX Aerospace in Tempe, Arizona. He received both his bachelor and master degrees in mathematics from the University of California at Davis, and then accepted a position as a staff orbit analyst at Lockheed Missiles and Space Company (LMSC).  In 1993, Stakkestad left LMSC to help found KinetX Aerospace and serve as its first President and Chief Financial Officer.  As the orbit dynamics lead for the development of the IRIDIUM satellite ground control system, he developed the initial orbital dynamics requirements for the ground system.  He also led a variety of KinetX software, hardware, and system engineering projects for the IRIDIUM project. KinetX is a partner with LPL in the OSIRIS-REx mission.

Passing of Gerard Droege

We regretfully forward the sad news of the death of LPL staffer and Boynton team member Gerard Droege. Jerry's colleague and friend, Bill Boynton, remembers Jerry:

Department News

Passing of Gerard Droege

We regretfully forward the sad news of the death of LPL staffer and Boynton team member Gerard Droege. Jerry's colleague and friend, Bill Boynton, remembers Jerry:

"Jerry was an amazing man. He came to LPL in 2006 after retiring from his medical practice and joined my group as a NASA Space Grant Intern. He worked on the Phoenix TEGA instrument and later worked on data analysis of the Lunar Exploration Neutron Detector, a Russian made high spatial resolution neutron detector on LRO.

"Jerry had nearly 20 years practicing as an OB/GYN before he decided to go back to school to learn a new field. He loved his job here even if he had to put with my regularly introducing him as my gynecologist.

"Jerry was an avid sailor (lived on a sailboat while practicing in San Diego), hiker (conquering Aconcagua), and juggler. He even has a certificate from Guinness Book of World Records for the `Most Prepositions at the End of a Sentence.' He will be missed greatly by all who knew him."

Giacalone Named Assistant Department Head

Joe Giacalone

Department News

Giacalone Named Assistant Department Head

Joe Giacalone

Professor Joe Giacalone has been named Assistant Department Head for the Department of Planetary Sciences. As Assistant Head, he oversees academics and student affairs, including admissions and curriculum, for the Department of Planetary Sciences. An expert in solar and heliospheric physics, Joe has been with LPL since starting as a postdoctoral research associate in 1993. More information about Joe is available from his web page.

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