Jim Head: GK Gilbert Awardee

VOLUME 20, NUMBER 2 JANUARY, 2003 design contest. Please see the rules on page 2. Submit GSA Annual Meeting Events your design(s) early; the decision will be made in July, to Tracy K.P. Gregg, Chair be announced in our Fall newsletter—and printed on new T-shirts for the GSA Annual Meeting in Seattle. Your division worked hard to make the Annual The Annual Business Meeting was a huge success, Meeting successful for you, and all the activity at the thanks largely to Jack Schmitt’s talk entitled “A Lunar Planetary Division booth in the exhibit hall, the crowd at Field Geologist’s Perspective 30 Years Later: Shocking the Business Meeting, and attendance at the sessions Revelations about the Moon, Mars, and Earth.” In spite of indicate that we all had a fun and productive time! A hearty GSA’s poor advertising of the event, and a last-minute thanks to all who stopped by our booth to lend a helping room change, Schmitt spoke to a filled room about his hand (or just to say “hello”). We particularly would like to experiences and insights into extraterrestrial exploration. thank NASA/Goddard for donating full-color, laminated posters of MOLA maps and spiffy 3-D models of Olympus Mons. Most of the maps were gone by Monday morning, so the lesson for next year is: stop by our booth early!

Ken Edgett (MSSS) and Susan Sakimoto (NASA/Goddard) talking science at the Division booth. H. Schmitt answering a question about lunar exploration

Toys with a planetary theme could also be found at the THANKS TO THE FOLLOWING PUBLISHERS WHO booth this year, and proved to be an effective fund-raiser for GRACIOUSLY DONATED BOOKS TO OUR RAFFLE: our division. We were pleased to present the final printing Cambridge University Press of our Planetary Division T-shirts with the “flying Mountain Press, Inc. hammer” logo, in new colors. Your division officers have Oxford University Press decided, however, that it’s time for a new design, particularly because GSA has redesigned their logo (go to Thanks also to KEN EDGETT for donating a copy http://www.geosociety.org/aboutus/logo.htm for a of his book, Touchdown Mars. description). We’re therefore happy to sponsor a T-shirt 2 Planetary Geology Division Sean Solomon (last year’s G.K. Gilbert Award recipient) was the citationist for Jim Head, this year’s G.K. TABLE OF CONTENTS PAGE Gilbert Awardee. As GSA requested, Sean provided the text of his citation to Jim several weeks in advance. What Meeting updates 1 Sean did not provide, however, was his lively slide T-shirt Design Contest 2 presentation centered on the main themes of Jim’s life: S. Solomon: G.K. Gilbert Award Citation 8 planetary geology, beer, and rock ‘n’ roll (not necessarily J. Head: G.K. Gilbert Acceptance 9 in that order). Please see the Division website H. Schmitt: Lunar Exploration 3 ( http://www.acsu.buffalo.edu/~tgregg/gsa.html ) to Questionnaire XX download Sean’s wonderful tribute to Jim and his research. The text of Sean’s citation and Jim’s acceptance can be found on page 7 and 9, respectively. Ode to “The Gilbert” Harrison H. Schmitt, University of Wisconsin-Madison

The rock breaker was Shoemaker, Then nebulous thrill in Wetherill.

Soon a dino fez from Alvarez, And a lunar limb with Baldwin.

Shocking gestalt came with Gault, While early films produced Wilhelms.

A lunar bit gave us Schmitt, With blue sky from Masursky.

Out of crater nests jumped Guest, Sean Solomon presenting Jim Head with the Gilbert Award. With meteors good to Wood. What Can Your Division Do for You? We’d like to make the Planetary Geology Division as Then Mars gave us Carr's, helpful to you, the members, as possible. To accomplish And the Moon favors Taylor's. that, we need some input from you. Please take approximately 5 minutes to fill out our questionnaire. Orange tephra added Lucchitta, You can either fill out the Adobe Acrobat form found at Under desert tarp came Sharp. http://www.buffalo.edu/~tgregg/etc . and snail-mail it, or you may e-mail your responses to Secretary/Treasurer Size-frequency provided Greeley, Aileen Yingst at [email protected] . We With spectrums giving Adams. can’t wait to improve our services to you! A maria omen in Solomon, Led the boom of Soderblom.

Finally, a Venusian bed grew Head, And soon a rhyme to go with Io?

Tom Watters and Danny Bloomberg at the G.K. Gilbert Award dinner 3 Planetary Geology Division Design a New Planetary elemental and isotopic data on the lower mantle of the Moon suggest that lunar origin by giant impact is Geology Division T-Shirt! unlikely. The apparent existence of a relatively undifferentiated lunar lower mantle indicates that all the Although our Division T-shirts have been wildly terrestrial planets began with a cool chondritic proto-core popular, the change in GSA’s logo has led us to conclude on the order of 1200km in radius. The proto-core of Mars the time has come for a new Division T-shirt design as may have be catastrophically displaced upwards by metallic well. core formation and its remnants may reside beneath the Please submit a line drawing (maximum of 2 colors), Southern Uplands. The terrestrial equivalents of the very preferably as JPEG or TIFF. Size doesn’t matter, but large lunar basins, such as South Pole-Aitken and please keep in mind that the best T-shirt designs are Procellarum, may have seeded the first continents through relatively simple. Preference will be given to designs that differentiation of thick, hydrous melt sheets, resulting in reflect the mission of the Planetary Geology Division and the late stage crystallization of zircons of 4.4-4.2 billion our connection with the national organization of the year ages. Sampling of impact glasses indicating an Geological Society of America. We would prefer designs apparent lunar cataclysm ~3.85 billion years ago may have that would go on the front or back of the T-shirt only been biased by late, young large basin-forming impacts (these are cheaper to manufacture), but will consider that resurfaced the crust. Clay minerals probably were the exceptional designs that feature a small “logo” on one side dominant mineral species at the surfaces of the Earth and or sleeve with the main design on the other side. Mars during the periods of intense impact activity prior to All designs must be original, and not copyrighted. 3.8 b.y. and may have been critical catalysts to the Please e-mail your designs to Tracy Gregg at formation of complex organic molecules. Mars appears to [email protected] by July 1, 2003. Current have had both early and late oceans due to two major officers of the Planetary Geology Division will judge the episodes of intense volcanic activity, the oldest triggered by submissions at that time. In the event of a tie, past Chair metallic core formation and the youngest by remelting of Ralph Harvey (creator of the current T-shirt) will provide the Martian mantle. And finally, the Martian water-ice the tie-breaking vote. boundary in the crust is probably the most stable, long- The winner will receive 4 free T-shirts of their design. lived ecological niche for simple life forms. You may submit as many different designs for Introduction consideration as you wish. Debate over the origin and evolution of the Moon has Good luck! remained lively and productive since the last human exploration 30 years ago. More recently, issues related to the evolution of Mars, Venus and Mercury increasingly get their share of our community's and the public's attention. A number of conventional hypotheses relative to the Moon and the terrestrial planets deserve both questioning and unconventional thought based on the profound advances in planetary research made by so many in recent years. How much do the known, probable and possible events in lunar history (Fig.1) constrain what may have occurred on and in Mars (Fig 2.)? Or, indeed, on and in the Earth? Let's consider some possible headlines that might appear in the scientific press over the next few years. Moon Origin By Giant Impact Unlikely! The Giant Impact hypothesis for the origin of the A Lunar Field Geologist’s Moon (Hartman and Davis, 1975; Hartman, 1986; Canup and Agnor, 2000) has become well entrenched in both the Perspective 30 Years Later: scientific literature and the popular scientific press and for Shocking Revelations about the good reason. It is an attractive hypothesis (but too often called a theory). The impact on the young Earth by a Moon, Mars, and Earth Mars-sized planetesimal primarily would explain the high Harrison H. Schmitt, University of Wisconsin-Madison angular momentum of the Earth-Moon system, and its G.K. Gilbert Lecture large-scale physical characteristics can be reproduced Abstract convincingly in computer models. The timing of this A number of conventional hypotheses relative to the proposed event now is constrained to have occurred within Moon and the terrestrial planets deserve both questioning the first ~30 m.y. of solar system history (starting 4.57 and unconventional thought based on the profound advances b.y. ago) by the systematics of hafnium-182, an extinct in planetary research in recent years. For example, 4 Planetary Geology Division isotope with a 9 m.y. half-life, and its daughter isotope material below ~550km, never melted significantly and is tungsten-182 (Yin et al, 2002; Kleine et al, 2002). The relatively undifferentiated. Logic then would suggest that estimated iron content of the Moon (Taylor and Esat, 1996) the Moon and other terrestrial planets initially had early and hafnium/tungsten systematics (Jones and Palme, 2000) chondritic cores, or proto-cores, similar to that of the further constrain at least 90% of its parent to be the Moon or about 1200km in radius. The existence of such a impactor rather than the differentiated Earth's mantle, cool proto-core beneath the magma oceans of the fully assuming, of course, that the impactor had the composition accreted terrestrial planets would delay, to varying degrees, of the Moon. This latter constraint essentially turns the the migration of iron-sulfur liquid to form metallic cores in Giant Impact hypothesis into an "impact assisted capture" these planets. In the case of the Moon, remnant magnetic hypothesis. A final constraint is that the impactor needed fields at the antipodes of the four youngest large basins to have evolved as a large, co-orbiting planetesimal in the (Anderson and Wilhelms, 1979; Lin et al, 1988; Lin et al, same oxygen isotope reservoir as did the Earth (Jones and 1998) suggest that core formation and an active dynamo- Palme, 2000). driven magnetic field were delayed by its proto-core until about 3.9 b.y., the estimated age of Nectaris, the oldest of MAJOR STAGES OF LUNAR EVOLUTION these four basins (Wilhelms, Chapters 9-10). Because of greater gravitational potential to drive core 1 BEGINNING (LARGE EARTH IMPACT OR CAPTURE) formation, and increased heating because of it, one would 2 MAGMA OCEAN/CRUST AND UPPER MANTLE FORM expect that there would have been progressively less delay 3 CRATERED HIGHLANDS/VERY LARGE BASINS than in the Moon in the sequence for Mercury, Mars, 4 LARGE BASINS Venus, and Earth, respectively. This is contrary to the

4A OLD LARGE BASINS/CRUSTAL STRENGTHENING conclusions reached by Kleine (2002) and Yin (2002) in STAGE 4B YOUNG LARGE BASINS / CORE FORMATION their analyses of hafnium-182/tungsten-182 systematics for CATACLYSM ? 5 ? BASALTIC MARIA ? samples potentially representative of the mantles of the

5A CRYPTOMARIA Earth and Mars. The inconsistency may be, in part, the result of incomplete mixing after proto-core displacement. 5B MARIA ? TI-RICH TI-POOR TI-RICH In fact, this possibility leads to the next predicted headline. 5.0 4.0 3.0 2.0 1.0 BILLIONS OF YEARS BEFORE PRESENT RED = MAJOR UNCERTAINTY MAJOR STAGES OF MARTIAN EVOLUTION BEGINNING Figure 1. Graphical representation of the major stages of lunar 1 2 MAGMA OCEAN / CONVECTIVE OVERTURN evolution [Schmitt, 2003]. 3A ? ? CRATERED UPLANDS / VERY LARGE BASINS The major problem with the Giant Impact hypothesis 3B ? CORE FORMATION/GLOBAL MAGNETIC FIELD is that the interior of the Moon is not cooperating. The 3C 4.5 - 1.3 GLOBAL MAFIC VOLCANISM

DENSE WATER / CO2 ATMOSPHERE lower lunar mantle, based on analyses of the Apollo 17 ? ? 3D EROSION / LAKES / NORTHERN OCEAN orange pyroclastic glass has chondritic signatures for ? ? tungsten (Lee et al, 1997), lead (Nunes et al, 1994) and STAGE 4 LARGE BASINS CATACLYSM? THARSIS UPLIFT AND VOLCANISM siderophile and chalcophile elements (Neal, 2001). ? Further, analysis of Apollo seismic data indicates a 5 NORTHERN HEMISPHERE BASALTIC / ANDESITIC VOLCANISM ? 1.3 - 0.2 velocity discontinuity below about 550km (Goins et al, SUBSURFACE HYDROSPHERE / CRYOSPHERE 6 ? PRESENT SURFACE CONDITIONS 1981; Kahn et al, 2000). These data also suggest that the LUNAR 4.6 4.2? 3.8 ? lower lunar mantle is significantly more aluminous that 5.0 4.0 3.0 2.0 1.0 BILLIONS OF YEARS BEFORE PRESENT the upper mantle (Neal, 2001), suggesting that melting and ITALICS = SNC DATES RED = MAJOR UNCERTAINTY fractional crystallization in the lower mantle was limited. Figure 2. Graphical representation of the major stages of If the Giant Impact hypothesis cannot explain this martian evolution [Schmitt, 2003]. spectrum of geological evidence, alternatives to it should Mars Chondritic Core Lurking under Southern be considered. Uplands! The most plausible alternative to the Giant Impact Remnant magnetic striping in the Southern Uplands of hypothesis appears to be the capture of an independently Mars (Connerney et al, 1999) occurred before the end of evolved planetesimal co-orbiting the sun with the Earth large basin formation ~3.8 billion years ago (Fig. 3) and (Alfven and Arrhenius, 1972; Schmitt, 1991; Schmitt, probably before the last of the very large basins formed 2003). It would seem that modeling studies of the pure about at ~4.2 b.y. (Schmitt, 2003). These relationships "capture" hypothesis should be emphasized to see if the indicate that metallic core formation and dynamo activation angular momentum constraint can be satisfied as it appears in Mars occurred significantly earlier than in the Moon. In to be in "impact assisted capture." Mars, unlike in the Earth, continuous convective mixing Terrestrial Planets Had Chondritic Before of the solidified mantle may not have broadly dispersed the Metallic Cores! displaced proto-core. The flattened remnants of that proto- Seismic, isotopic and elemental evidence, as discussed core may now reside under the Southern Uplands, above, indicates that the lower mantle of the Moon, accounting in part for the apparently thicker Martian crust 5 Planetary Geology Division in that hemisphere. A offset of three kilometers in the (Wilhelms, 1987, p. 157; Schmitt, 2003), occurring in center of mass, relative to the center of figure, toward the water-rich environments such as the Earth and Mars, would south pole of Mars (Smith and Zuber, 1996) and create thick sheets of impact generated rock melt more than hemispheric differences in geological provenance also may a 2500km across and many kilometers thick. As these be the result of selective displacement of the proto-core. In magma sheets crystallized, zirconium concentrations may this context, there is increasing speculation on broad have reached levels that produced the zircons. Erosion of heterogeneity in the composition of the Earth's mantle these proto-continents would release the zircon crystals for (Albarède et al, 2000; Meibom and Frei, 2002;,Bizzarro et inclusion as sand grains in ancient sediments. As zircons al, 2002; Ballentine, 2002) some of which may record are extremely hard and durable, they can survive several incomplete mixing of the Earth's proto-core after cycles of erosion. The very old terrestrial zircons that have displacement during core formation. been dated and had their oxygen isotopic ratios determined apparently formed in the presence of water (Wilde et al, COMPARISON OF LUNAR AND MARTIAN EVOLUTION 2001; Mojzsis et al, 2001) consistent with this hydrous impact melt sheet hypothesis.

MAJOR STAGES OF MARTIAN EVOLUTION MAJOR STAGES OF LUNAR EVOLUTION Lunar Cataclysm 3.9 B.Y. Ago Faked by Late 1 BEGINNING 1 BEGINNING (LARGE EARTH IMPACT OR CAPTURE) 2 MAGMA OCEAN / CONVECTIVE OVERTURN Impacts! 3A 2 MAGMA OCEAN/CRUST AND UPPER MANTLE FORM ? ? CRATERED UPLANDS / VERY LARGE BASINS CORE FORMATION/GLOBAL MAGNETIC FIELD 3B ? 3 CRATERED HIGHLANDS/VERY LARGE BASINS GLOBAL MAFIC VOLCANISM 4.5 - 1.3 The suggestion (Tera et al, 1974) that a "cataclysm" of 3C 4 LARGE BASINS DENSE WATER / CO ATMOSPHERE ? ? 3D EROSION / LAKES / NORTHERN OCEAN 4A OLD LARGE BASINS/CRUSTAL STRENGTHENING ? ?

STAGE impacts at about 3.85 b.y. was responsible for the vast

STAGE 4 LARGE BASINS 4B YOUNG LARGE BASINS / CORE FORMATION CATACLYSM ? CATACLYSM? THARSIS UPLIFT AND VOLCANISM BASALTIC MARIA majority of craters visible on the lunar surface has gained 5 ? ? ? 5 NORTHERN HEMISPHERE BASALTIC / ANDESITIC VOLCANISM CRYPTOMARIA 5A ? 1.3 - 0.2 SUBSURFACE HYDROSPHERE / CRYOSPHERE increasing adherents in recent years (Ryder, 1990; Ryder et 5B MARIA ? 6 ? TI-RICH TI-POOR TI-RICH PRESENT SURFACE CONDITIONS LUNAR 4.6 4.2? 3.8 ? 5.0 4.0 3.0 2.0 1.0 5.0 4.0 3.0 2.0 1.0 al, 2000). In its most extreme manifestation, essentially BILLIONS OF YEARS BEFORE PRESENT RED = MAJOR UNCERTAINTY BILLIONS OF YEARS BEFORE PRESENT ITALICS = SNC DATES RED = MAJOR UNCERTAINTY all pre-maria impact cratering is attributed to this

CRATERING HISTORY CORRELATION cataclysm. More modest proposals include only the 50 or

CORE FORMATION DIFFERENCE so craters greater than a few hundred kilometers in diameter. The primary rationale for the cataclysm hypothesis is the almost compete absence of impact glass older than ~3.9 Figure 3. Graphical representation of a comparison of lunar b.y. in the Apollo sample collection and in lunar and Martian evolution, including the apparent relative delay in meteorites examined to date. metallic core formation. The primary argument against this hypothesis is, of Melt from Huge Impacts Produced First course, possible sampling bias in both the Apollo suite Continents! and the lunar meteorites (Schmitt, 2001; Chapman et al, The 2500km diameter basin on the far-side of the 2002). The possibility for sampling bias comes from the Moon (Wilhelms, 1987, p. 145), known as South Pole- strong evidence that the surface of the Moon has been Aitken, records an impact of an extraordinarily energetic effectively resurfaced by debris thrown from and affected by object near the end of the period smaller scale saturation the ~14 youngest of ~50 large impacts. Schmitt (1989) cratering that followed the solidification of the lunar crust. has discussed the clear temporal and geological distinctions South Pole-Aitken is just the most obvious manifestation between young and old large basins. The fresher appearing, of possibly four or five other such huge early impacts, so-called "mascon" basins (Muller and Sjogren, 1968) now including the 3200km diameter front-side basin, represent these 14 impacts, that is, basins that have Procellarum (Schmitt, 2003). On the basis of the degree to undergone little isostatic adjustment since they formed. which on-going saturation cratering has affected their Those such basins for which reasonable ages have been impact morphologies, Schmitt (2003) estimates that the assigned (Wilhelms, 1987, Chapters 9-10), that is, more highly degraded Procellarum basin formed at about Nectaris, Serenitatis, Imbrium and Orientale, range in age 4.3 b.y and South Pole-Aitken at about 4.2 b.y. If the between 3.9 and 3.8 b.y., also the proposed period of formation ages for South Pole Aitken and Procellarum are cataclysm. Geologic mapping in the 1960s and 1970s (see about right, an explanation is suggested for the recent Wilhelms, 1987) had established that ejecta blankets and discovery of detrital zircon (ZrSiO4) crystals of about the effects of secondary ejecta from these 14 impacts were same ages in very old sedimentary rocks on Earth (Wilde et widely distributed around the Moon. This fact has been al, 2001). more recently emphasized by the lunar-wide identification Zircon crystallizes from silica-rich igneous magmas in of "cryptomaria" (Bell and Hawke, 1984; Antonenko, the late stages of crystallization when zirconium 1999) through mapping the distribution of dark ejecta concentrations get sufficiently high due to most other around small impact craters that penetrate overlying, lighter minerals having crystallized. Late stage crystallization also colored material. These pre-mare basalt volcanic eruptions tends to produce other, silicate minerals that are clearly preceded the formation of the 14 young large basins, characteristic of those that make up the Earth's continents. or they would not have been covered by basin ejecta. The Early impacts on the continental scale of South Pole- cryptomaria eruptions, possibly the result of pressure Aitken and Procellarum, as well as possibly others 6 Planetary Geology Division release melting, also probably were temporally associated surface magmatic activity. Such activity may have been with and immediately followed the formation of the ~35 triggered by the upward displacement of Mars' chondritic old large basins, otherwise, they would have been destroyed proto-core discussed above and associated pressure release by such events. melting of that material and overlying Martian mantle. Whether there was a 100 m.y. long cataclysm at about 3.85 b.y. or a 400 m.y. period of large basin formation between 4.2 and 3.8 b.y., it is clear that a discrete new source of impactors appeared in the solar system (Schmitt, 1999; Dones, 2002). Of particular interest in this regard would be the break-up of the proto-planet of the Main Asteroid Belt, the interaction of the Gas Giants with the Kuiper Belt, and the disturbance of the Öort Cloud by a passing stellar object. The identification of this impactor source is not only an intriguing challenge but also one with many implications to unraveling the evolution of the solar system and the terrestrial planets. Clay Minerals Dominated Before Life Appeared! Prolonged and intense impact cratering took place in the inner solar system from about 4.5 b.y up to 3.8 b.y. following the solidification of magma oceans recorded by Magnetic striping on Mars [Connery et al., 1999] planetary crusts. These impacts would have produced abundant glassy and pulverized silicate material in the Up to 3.8 b.y., intense impact cratering and solar wind upper several kilometers of those crusts. On the water-rich erosion probably depleted primordial water initially retained terrestrial planets, this material would alter rapidly to clay at the Martian surface and in the atmosphere. Significant minerals, minerals with great variations in composition, water reservoirs in the Martian mantle, however, would structural dimensions, and environmental niches. Crystal have been mobilized by early magmatic activity. First, the structural patterns of broad variability on the surfaces of the proto-core would have retained its primordial water if its clay mineral grains, possibly in association with sulfide displacement were catastrophic rather than gradual as may minerals (Huber and Wächtershäuser, 1998), may have have been the case in the Moon. Secondly, high-pressure assisted in the aggregation of complex organic molecules, crystallization of hydrous silicates, particularly sodium-rich possible precursors to the first replicating forms of such amphibole and mica, during the Martian magma ocean molecules (Ferris, 1996). Indeed, replication may have stage and their retention in the mantle would represent an first been symbiotic with the forms, growth, and/or additional water reservoir. Thus, water may have been expansion of clay mineral structures. Tubular forms of introduced at high rates during the early volcanic episode. clay minerals also may have been initially incorporated in Two possible strand lines for ancient oceans on Mars the earliest single cell organisms to assist in the movement have been identified (Head et al, 1999), including one from of fluid, only to be replaced later by organic compounds. a possible early northern ocean. This line has highly The evidence of isotopic fractionation by organic variable elevations, creating doubt as to its reality as an processes associated with with ~3.8 b.y. terrestrial rocks actual strand line. On the other hand, the variable (Mojzsis et al, 1996) may not be a timing coincidence. elevations appear to be where a level line would have been The end of the large basin forming events in the inner solar most affected by uplift of the Tharsis bulge, and its system also appears to be at about ~3.8 b.y. Although antipodal response in Arabia Terra, and the Elysium uplift. simple organic replication, and possibly single cell As the effects of Tharsis bulge post-date the large basin organisms, may have existed on Earth prior to ~3.8 b.y., stage of impact cratering as well as the early volcanic the catastrophic effects of large impacts may have prevented period, this irregular, possible strand line may well be significant biological activity until after that time. The evidence of an early northern ocean. If the correlation of an cratering history of the Moon has alerted us to the potential early northern ocean with an early volcanic period is pervasiveness of clays on the early crusts of Earth, Mars, correct, it would indicate that this volcanism was after the and Venus. Mars, therefore, may be the arrested crucible of formation of the very large basins that in aggregate form early organic processes now lost to us on Earth. the Northern Lowlands of Mars but before the end of other Mars had both Early and Late Oceans! large basin forming events. Volcanic constructional features (Carr, 1996) and More clearly evident than the strand line for an early remnant magnetic striping (Connerney, 1999) identified in northern ocean is a later one that post-dates the crustal the Martian Southern Uplands, and partial erasure of the deformation associated with the Tharsis-Arabia bulges. striping by very large impact crater formation, such as This second northern ocean has a well-defined and largely Hellas, indicates the early existence of surface or near- level strand line. Its water would have been evolved during 7 Planetary Geology Division hydrogen in the near-surface of Mars: Evidence for sub-surface Tharsis-Elysium eruptions and related volcanic activity and ice deposits, Science 297:81-85. persisted after the major deformations associated with that Canup, R. M., and Agnor, C. B., 2000, Accretion of the Terrestrial Planets and the Earth Moon System, in R. M. Canup and K Richter, activity. This ocean may have been in part re-mobilized eds., Origin of the Moon and the Earth: University of Arizona water from the earlier ocean stored as ice and water in the Press, Tucson, p. 113-129. Carr, M. H., 1996, Water on Mars: Oxford University Press, Oxford, Martian subsurface. 229 p. Simple Life Forms At Martian Ice-Water Chapman, C. R., Cohen, B. A., and Grinspoon, D. H., 2002, What are the real constraints on commencement of the late heavy Boundary! bombardment?: LPSC XXXIII, Abstract #1627. It has long been evident from geological evidence that Connerney, J. E. P., M. Acuña, M. H, Wasilewski, P. J., Ness, N. F., Rème, H., Mazelle, C., Vignes, D. Lin, R.P., Mitchell, D. L., and water ice was present in much of the Martian subsurface at Cloutier, P. A., 1999, Magnetic lineations in the ancient crust of high latitudes and that liquid water (the hydrosphere) likely Mars: Science 284:794-798. Dones, L., 2002, Dynamics of possible late heavy bombardment existed below this ice (the cryosphere) due to heat flow impactor population: LPSC XXXIII, Abstract #1662. induced temperature increases with depth (Carr, 1996). The Ferris, J. P., Hill, A. R. Jr., Liu, R. and Orgel, L., E., 1996, Synthesis of Long Prebiotic Oligomers on Mineral Surfaces: Nature 381:59-61. recent epithermal neutron data from Mars Odyssey more Goins, N. R., Dainty, A. M., and Toksöz, M. N., 1981, Lunar seismology: precisely defines the distribution of water ice (Boynton et The internal structure of the Moon: J. Geophys. Res. 86:5061-5074. Hartmann, W. K., 1986, Moon origin: The impact trigger hypothesis, in al, 2002). The boundary region between the hydrosphere W. K. Hartmann, R. J. Phillips, and G. J. Taylor, eds., Origin of the and the cryosphere of Mars is a stable, long-term ecological Moon: Lunar and Planetary Institute, Houston, p. 579-608. Hartmann, W. K., and D. R. Davis, 1975, Satellite-sized planetesimals niche that could harbor simple life forms, including their and lunar origin: Icarus 24:504-515. evolutionary derivatives, since a more Earth-like Head, J. W, 1999, Possible ancient oceans on Mars: Evidence from Mars Orbitor laser altimeter data: Science 286:2134-2137. environment disappeared from the Martian surface a few Huber, C., and Wächtershäuser, G., 1998, Peptides by activation of billion years ago. Certainly, this niche would be no more amino acids with CO on (Ni,Fe)S surfaces: Implications for the origin of life: Science 281:670-672. hostile to life than similar subsurface environments on Jones, J. and Palme, H., 2000, Geochemical constraints on the origin of Earth (Wharton, 2002). the Earth and the Moon, in R. M. Canup and K Richter, eds., Origin of the Moon and the Earth: University of Arizona Press, Tucson, p. Discussion 197-216. So there you have it - some headlines that may appear Kahn, A., Mosegaard, K, and Rasmussen, K. L., 2000, Lunar models obtained from a Monte Carlo inversion of the Apollo seismic P and in our more public literature in the next quarter century. S. waves, LPSC XXXI, #1341. Sooner, if the first investors for a lunar Helium-3 fusion Kleine, T., Münker, C., Jezger, K., and Palme, H., 2002, Rapid accretion and early core formation on asteroids and the terrestrial planets power initiative step forward. In that way, we can have the from Hf-W chronometry: Nature 418:952-955. return of science to the Moon and the human exploration of Lee, D., Halliday, A. N., Snyder, G. A., and Taylor, L. A., 2000, Age and origin of the Moon: Science 278:1098-1103. Mars largely paid for by power-hungry Earthlings. Lin, R. P., Anderson, K. A., and Hood, L., 1988, Lunar surface magnetic field concentrations antipodal to young large impact basins: Icarus Eugene M. Shoemaker Award 74:529-541. Lin, R. P., Mitchell, D., Curtis, D., Anderson, K, Carlson, C. McFadden, The Shoemaker fund is self-sustaining at a base level, be J., Acuña, M., Hood, L., and Binder, A., 1998, Lunar surface we welcome your donations to help us increase the magnetic fields and their interaction with the solar wind: Results from Lunar Prospector, Science 281:1480-1484. “impact” of this important award. As a reminder, the Meibom, A., and Frei, R., 2002, Evidence for an ancient osmium isotopic deadline for 2003 student nominations is September 1st, reservoir in Earth: Science 296:516-518. Mojzsis, S. J., Arrhenius, G., McKeegan, K. D., Harrison, T. M., 2003. For more details and on-line application forms, Nutman, A. P., and Friend, C. R. L., 1996, Evidence for life on please see: http://www.lpl.arizona.edu/Shoemaker_Award/ Earth before 3800 million years age: Nature 384:55-59. Mojzsis, S. J., Harrison, T. M., and Pidgeon, R. T., 2001, Oxygen-isotope Donations to the Shoemaker Award are evidence from ancient zircons for liquid water at the Earth's welcomed surface 4,300 Myr ago: Nature 409:178-181. Muller, P. M., and Sjogren, W. L., 1968, Mascons: Lunar mass concentrations: Science 161:680-684. Neal, C. R., 2001, Interior of the Moon: The presence of garnet in the References primitive deep lunar mantle: J. Geophys. Res. 106:27865-27885. Albarède, F., Blichert-Toft, J, Vervoort, J. D., Gleason, J. D., and Nunes, P. D., Tatsumoto, M., and Unruh, D. M., 1974, U-Th--Pb Rosing, M., 2000, Hf-Nd isotope evidence for a transient dynamic systematics of some Apollo 17 lunar samples and implications for a regime in the early terrestrial mantle: Nature 404:488-490. lunar basin excavation chronology: Lunar Sci. Conf. 5:1487-1514. Alfven, H. and Arrhenius, G., 1972, Origin and evolution of the Earth Ryder, G., 1990, Lunar samples,lunar accretion, and the early Moon system: The Moon 5:216. bombardment history of the Moon: EOS 71:313 and 322-323. Anderson, K. A., and Wilhelms, D. E., 1979, Correlation of lunar farside Ryder, G., Koeberl, C., and Mojzsis, S. J., 2000, Heavy bombardment of magnetized regions with ringed impact basins: Earth Planet. Sci.. the Earth at ~3.85 Ga: The search for petrographic and 46:107-112. geochemical evidence, in R. M. Canup and K Richter, eds., Origin Antonenko, I, 1999, Global estimates of cryptomare deposits: of the Moon and the Earth: University of Arizona Press, Tucson, Implications for lunar volcanism: LPSC XXX, Abstract #1703. pp. 475-492. Ballentine, C. J., 2002, Tiny tracers tell tall tales: Science 296:1247- Schmitt, H. H., 1989, Lunar crustal strength and the large basin-KREEP 1248. connection; in G. J. Taylor and P. H. Warren, eds., Workshop on Bell, J., and Hawke, B., 1984, Lunar dark-haloed impact craters: Origin Moon in Transition: Apollo 14, KREEP, and Evolved Lunar Rocks: and implications for early mare volcanism: J. Geophy. Res. Technical Report #89-03, Lunar and Planetary Institute, Houston, 89:6899-6910. p. 111-112. Bizzarro, M, Simonetti, A, Stevernson, R. K., David, J., 2002, Hf isotope Schmitt, H. H., 1991, Evolution of the Moon: The Apollo Model: Am. evidence for a hidden mantle reservoir: Geology 30:771-774. Mineral. 76:775-776. Boynton, W. V., Feldman, W. C., Squyres, S. W., Prettyman, T, Schmitt, H. H., 1999, Early lunar impact events: terrestrial and solar Brückner, Evans, J. L. G., Reedy, R. C., Starr, R., Arnold, J. R., system implication: Geological Society of America Annual Drake, D. M., Englert, P. A. J., Metzger, A. E., Mitrofanov, I, Meeting Abstract #50440. Trombka, J. I., d'Uston, C., Wänke, H., Gasnault, O., Hamara, D. Schmitt, H. H., 2001, Lunar cataclysm? Depends on what "cataclysm' K., Janes, D. M., Marcialis, R. L., Maurice, S., Mikheeva, I., means: LPSC XXXII, #1133. Taylor, G. J., Tokar, R., and Shinohara, C., 2002, Distribution of 8 Planetary Geology Division Schmitt, H. H., 2003, Apollo 17 and the Moon, in H. Mark, ed., Encyclopedia of Space: Wiley, New York, in press. geological training of the Apollo astronauts, and the Smith, D. E., and Zuber, M. T., 1996, The shape of Mars and the planning of their traverses while on the lunar surface, topographic signature of the hemispheric dichotomy: Science 271:184-188. contributing enormously to maximizing the scientific Taylor, S. R., and Esat, T. M., 1996, Geochemical constraints on the return from the Apollo missions. In the three decades that origin of the Moon; in A. Basu and S. Hart, eds., Earth Processes: Reading the Isotopic Code: Geophysical Monograph 95, AGU, p. he has been on the faculty of Brown University, Jim has 43. been a guest investigator or a member of a science or Tera, F. Papanstassiou, D. A., and Wasserburg, G. J., 1974, Earth Planet. Sci. Lett. 22:1. instrument team on at least 10 missions that collectively Wharton, D. A., 2002, Life at the Limits: Organisms in Extreme have orbited (or will orbit) every planet from Mercury to Environments: Cambridge University Press, Cambridge, 320 p. Wilde, S. A., Valley, J. W., Peck, W. H., and Graham, C. M., 2001, Jupiter. Evidence from detrital zircons for the existence of continental Trained in stratigraphy as a graduate student focused on crust and oceans on the Earth 4.4 Gyr ago: Nature 409:175-178. Wilhelms, D. E., 1987, The Geologic History of the Moon: U.S. Appalachian geology, Jim followed in the scientific Geological Survey Professional Paper 1348, U.S. Government footsteps of G. K. Gilbert. The first extraterrestrial body Printing Office, Washington, 302 p. Yin, Q., Jacobsen, S. B., Yamashita, K., Blichert-Toft, J., Télouk, and to which Jim applied his classical training was the Moon, Albarède, 2002, A short timescale for terrestrial planet formation where his earliest emphasis was on the nature of lunar from Hf-W chronometry of meterorites: Nature 418:949-952. craters and impact basins and on the styles and history of lunar volcanism. It was because he was a leading authority on the structure and evolution of lunar mare basins that he Support The Dwornik Fund and I began a collaboration, about 25 years ago, on the history of volcanism in and lithospheric loading by mascon The Dwornik fund is currently self-sustaining at a base maria. In an early conversation in Jim’s office on mare level, but hope the fund will continue to grow and provide basin dimensions, we discovered that his dimensions were new opportunities, and thus encourage your donations. In systematically twice those of mine. We quickly realized addition, anyone interested in serving as a judge for the that we were approaching this simple question from Dwornik competition at LPSC XXXIV should contact Eric complementary perspectives. For Jim — whose Grosfils (the Division’s 2nd Vice-Chair) at perceptions are based strongly on sensory input — the size [email protected] to volunteer. metric was basin diameter, whereas for me the immediate Donations to the Dwornik fund are application of mathematical models led me to think in welcomed terms of basin radius. An appreciation of our distinct approaches has helped to sustain our collaboration through more than 30 papers. Sean Solomon: G.K. Gilbert Another, even more prolific collaboration has produced some of Jim’s most widely cited work. With Lionel Award Citationist Wilson of Lancaster University, Head developed Sean Solomon, Carnegie Institute quantitative models for the ascent, eruption, and fate of The G. K. Gilbert Award is presented annually for magma, and he applied those models systematically to a outstanding contributions to the solution of fundamental wide range of volcanic features on the planets. From the problems in planetary geology. There have been few, if conditions favoring explosive volcanism to those favoring any, whose professional work exemplifies this description plutonism, from the formation of domes to that of rilles, in greater breadth than this year’s awardee. Jim Head is the from an assessment of time-dependent volcanic flux to an recipient of the 2002 G. K. Gilbert Award for his many explanation for chemical variations among lunar volcanic scientific publications addressing a wide range of geological samples, Jim and Lionel have matched theory and problems on the planets and satellites of our solar system, observation to gain insight into volcanic landforms on for his sustained efforts in undergraduate education and every terrestrial planet and several of the Galilean satellites. graduate research supervision in planetary geology, and for In explaining succinctly one of the reasons for the success his leadership role in fostering international of their highly productive collaboration, Wilson writes that communication on planetary exploration. Jim “is a powerhouse of constructive ideas.” Jim Head is the author or coauthor of approximately The planet about which Jim has written more papers 300 papers in books and refereed journals. A scientist of than any other is Venus, and the largest source of fuel for prodigious energy and sweeping curiosity, his publications his creative Cytherean fires was the Magellan mission. treat most of the large solar system objects with solid Even more than a decade prior to Magellan’s arrival at surfaces. His principal source of inspiration has been the Venus, Jim made the most of the data from the Pioneer regular stream of new data from planetary missions, and his Venus Orbiter, the images from the Venera landers and personal involvement in those missions has been orbiters, and Earth-based radar images of ever-improving enormously varied and characteristically intense. In the resolution to develop and test hypotheses for Venus’s early 1970s, while on the staff at Bellcomm, Jim played a geological workings. During the heady days when the key role in the study of potential Apollo landing sites, the stream of new data from Magellan gushed the strongest, 9 Planetary Geology Division Jim led the analysis of mission observations of volcanic important than mere numbers has been that an landforms. His interests were much broader in scope, overwhelming majority of Jim’s students have gone on to however, and his stratigraphic roots gave him the tools to productive careers in planetary science. Many are now in synthesize observations and hone his ideas for how the positions of leadership where they are helping to chart the Venus surface evolved on both regional and planetary future directions of our field. scales. The global geological history that Jim and several On the international level, Jim has done probably more colleagues have developed is not without controversy, but than any other individual to promote scientific it is the most clearly espoused and most broadly developed communication and collaboration between the planetary among competing scenarios, and it is the benchmark geology communities in Russia and the west. At the against which all others are measured. height of the Cold War era, when there were no ties In the last five years, the Mars Global Surveyor (MGS) between NASA and the Soviet space agency, Jim guided mission and particularly the Mars Orbiting Laser Altimeter the establishment of a formal agreement between Brown (MOLA) experiment have given Jim a phenomenally rich University and the Vernadsky Institute of Geochemistry and source of information. Like the proverbial kid in the candy Analytical Chemistry in Moscow. The Brown-Vernadsky store, Jim has seen clues in the MOLA data that touch on Microsymposia, held twice per year since 1985, have the full spectrum of geological processes that shape provided a forum for Russian, American, and European planetary surfaces. From volcanic eruption mechanisms to scientists to hold discussions and interact on collaborative large-scale deformation patterns, from glacial processes to research efforts. The continuation of these meetings after polar cap evolution, from fluvial and hydrological the break-up of the Soviet Union has permitted Russian processes to testing ideas for ancient Martian oceans, Jim planetary scientists to travel and carry out research in the and his students have wrung new geological insights from west at a time when the levels of government support for the latest data wherever they’ve looked. science in Russia have been far from generous. Whereas most of us are usually hard pressed to keep up with the new findings from a single spacecraft mission, G.K. Gilbert Award throughout the operation of MGS Jim has been in the All members are strongly encouraged to submit thick of mission operations and data analysis for the nominations for the G.K. Gilbert Award. This is the Galileo mission to Jupiter and its geologically fascinating Division’s highest award, presented annually for satellites. Jim and his students and colleagues have outstanding contributions to the solution of fundamental developed novel tectonic models for the origin of surface problems in planetary geology in the broadest sense. features of Europa and Ganymede and have tested ideas for Nominations (which include a letter detailing the magmatic and volcanic processes on Io. They have accomplishments of the nominee) should be submitted weighed in strongly on the nature of the icy lithosphere of directly to the current Division Chair (Tracy Gregg, at st Europa, its thickness, and the possibility of an underlying [email protected] ) prior to March 1 each ocean, arguing on the basis of photogeology, chemical year. remote sensing, and physical models that convection Jim’s international diplomatic efforts also facilitated an within a thick ice layer can account for most of Europa’s exchange of mission scientific data that benefited the surface features. planetary geological communities in both the west and the In the area of planetary geological education, Jim east. Jim brought some of the first data to the west from Head’s contributions are without equal. At the Venera lander missions. As a guest investigator on the undergraduate level, Jim’s introductory “Geo 5” class Venera 15/16 orbital missions, which obtained the first (currently titled Mars, Moon, and the Earth) each fall draws high-resolution radar images of much of the northern enthusiastic enrollments that have averaged 200 students hemisphere of Venus, Jim played an important role in per year. Extending back to the mid-1970s, this class now making these images available to western scientists. It is has as many as 5000 alumni. To put this astounding perhaps under-appreciated that it was the arrival of Venera number into some perspective, Jim Head has single- 15/16 data in the U.S. that provided key arguments to handedly introduced planetary geological thinking to more persuade NASA to improve the radar image resolution than 20% of the graduates of Brown University over the planned for the Magellan mission that would fly 6 years past quarter century. later. At the graduate level, Jim has supervised more than G. K. Gilbert, were he alive today, would be fascinated three dozen master’s theses and two dozen Ph.D. theses. with Jim Head’s scientific contributions and would soundly Rumor has it that Jim can be a challenging taskmaster. applaud Jim’s achievements in education and international Nonetheless, he provides his students with countless scientific cooperation. It is my honor and great pleasure to avenues for fieldwork, involvement in spacecraft missions, introduce the recipient of this year’s G. K. Gilbert Award. and interaction with the larger scientific community, and I have watched with appreciation as he encourages his students to make the most of those opportunities. More 10 Planetary Geology Division

Jim Head: G.K. Gilbert Jim Head, Brown University Awardee

Dear Fellows and Members of the Division: Please help us to help you by responding to the following questionnaire. You may snail-mail your responses to Aileen Yingst or email them to: Please respond by March 1 so that the officers can discuss the results at our business meeting held at the Lunar and Planetary Science Conference. Thank you! 1) What services does the Division currently provide for you?

2) Please rate in importance to you the following Division services and activies. 1 = least important; 5 = most important. Gilbert Award 1 2 3 4 5 Dwornik Student Paper Awards 1 2 3 4 5 Best Student Journal Paper Award 1 2 3 4 5 Shoemaker Impact Cratering Award 1 2 3 4 5 Division Website 1 2 3 4 5 Division Newsletter 1 2 3 4 5 GSA Division Business Meeting 1 2 3 4 5

3) Nearly all of our current funds are raised through the GSA Planetary Geology Division Booth at the annual meeting. What other fundraising activities would you be willing to support? (Circle all that apply.) Donate materials for fundraising (e.g., autographed books, posters, etc.) Provide capitol funds for division operating expenses, e.g.: • subsidize T-shirts for fundraising • sponsor refreshments at business meeting • sponsor award materials purchases (plaques, certificates, bruntons, etc.) Others? Please describe.

4) Are you interested in volunteering your time for Division activities? (Circle all that apply.) • Serving on the GSA Annual Meeting Joint Technical Program Committee • Serving as a Dwornik Student Paper judge • Assisting with staffing at the Division booth at the GSA Annual Meeting • Others? Please describe.