LANETARY CIENCE NSTITUTE NEWSLETTER

F A L L 2 0 0 8 V o l . 9 , N o . 3

P L A N E T A R Y S C I E N C E I N S T I T U T E

Copyright © 2008 by Planetary Science Institute

N E W S L E T T E R

Inside this issue:

PANORAMA OF THE MOON 2

PSI RETREAT PHOTO GALLERY 3-5

COMETS POSING AS ASTEROIDS 6

CONGRATULATIONS SCIENTISTS 7

DIRECTOR’S NOTE 7

Tucson AZ Chandler AZ Phoenix AZ Angwin CA Altadena CA Cupertino CA Laguna Niguel CA Pasadena CA Ft. Collins CO Washington DC Honolulu HI Columbia MD Greenbelt MD Ft Kent ME Albuquerque NM Los Alamos NM Reno NV Houston TX San Antonio TX Medina WA Seattle WA Evansville WI Green Bay WI Sobieski WI Waunakee WI Wheeling WV

Est. 1972 www.psi.edu

See retreat photos pages 3-5

PSI members at the retreat, front row (l-r): Gil Esquerdo, Chris Holmberg, Kathi Gardner, Mary Bourke, Beatrice Mueller, Cathy Weitz, Kelly Yoder, Bill Hartmann. Second row: Scott Mest, Bill Feldman, Carol Neese, Betty Pierazzo, Candace Kohl, Elaine Owens, Kim Kuhlman, Bruce Barnett, Steve Metzger, Alexis Rodriguez, Paul Abell, Asmin Pathare. Back row: Mark Sykes, Jeff Morgenthaler, Ed Stiles, Melissa Lane, Matt Staid, Aileen Yingst, Tom Prettyman, Tamara Kemnitz-Michotte, Keith Holsapple, Andrea Philippoff, Rose Early, Jesse Stone, Larry Lebofsky, Nalin Samarasinha, Jack Drummond, Steve Kortenkamp, Anton Ivanov, Ben Smith, John Mason, Matt Balme, Stu Weidenschilling, Les Blea-master, Bryan Travis (guest) and David Crown. Attendees not pictured: Dan Berman, Frank Chuang, Don Davis, Lijie Han, Dave O’Brien, Pasquale Tricarico, and Becky Williams.

2008 PSI Retreat

Our fourth annual retreat was held late August at the Westward Look Resort in the Catalina Mountain foothills overlooking Tucson. About 50 PSI employees convened at the 80-acre oasis to hear about the sci-ence of new members and reacquaint with old friends. Off-site scien-tists traveled to PSI’s headquarters from California, Maryland, Maine, New Mexico, Nevada, Texas, Washington, Wisconsin, Virginia, Swit-zerland and the United Kingdom to attend the two-day meeting. In addition to the science presentations, this year’s format included several break-out sessions furthering brainstorming and collaborations between scientists. And the retreat banquet was not only a culinary and festive success but featured a surprise tribute to Stu Weiden-schilling honoring his 30 years with PSI. Visit our website for the complete retreat program: www.psi.edu/retreat/2008.

PSI NEWSLETTER

Fall 2008 2


A Web Site We Like: Panorama of the Moon by William K. Hartmann In October of 2007, the Japanese placed a probe named Kaguya (Selene), in orbit around the moon. One of its instruments is the first high-definition TV system to send back orbital photography. The Kaguya team set the camera to make wide-angle continuous photography toward the horizon, giving the impression of looking out a front window while orbiting the moon. Updated photography is on the Japanese space agency web site at: http://www.jaxa.jp/press/2007/11/20071107_kaguya_e.html . This site contains wonderful mini-movies of passages over fa-

mous landmarks on the moon. T h e i m a g e shown above is an enlargement of the central peak of the cra-t e r T y c h o . Tycho, 85 kms across, is one of the youngest of the moon’s large craters. Apollo

data suggested an age of 108 mil-lion years, still

unconfirmed. Tycho splashed bright rays of debris, visible to the naked eye from Earth, across much of the front side of the moon. Tycho’s floor is a hodge-podge of upheaved, fractured blocks and knobs, much rougher than most of the rest of the moon, which has been smoothed by aeons of “sandblasting” by micrometeor-ites. The central peaks of such craters are of special interest. As long ago as 1982, spectroscopy by one of the pioneering lunar astrono-

Wide-angle panorama from the Japanese probe Kaguya (Selene), looking across the floor of the lunar impact crater Tycho. The central peak, in the foreground, is composed of deep-seated material brought up by the impact explosion. The crater’s outer wall is on the horizon in the background. (Image courtesy Japanese Space Agency.)

A telescopic view from Earth showing the moon’s 85-km crater Tycho in a typical pre-Kaguya im-age.

This summer, PSI Senior Scientist Betty Pierazzo (right) and PSI Associate Research Scientist Natasha Artemieva enjoyed a field trip to the Vredefort structure — one of the oldest and largest impact structures on Earth — about 100 kilometers south west of Johannesburg. The two-day field trip, also attended by PSI Associate Research Scientist Joe Michalski, preceded the Large Meteorite Impacts and Planetary Evolution IV conference, Aug. 17-21, Vredefort, South Africa.

PSI Scientists in South Africa

mers, Carle Pieters, showed that the central peaks of some large lunar craters contain the mineral olivine, a mineral associated not with planetary crusts, but with the deeper interior, the mantle. 1999 data by Pieters’ group show that Tycho’s central peak con-tains deep-seated igneous rock of a type called “gabbro.” These observations confirm computer modeling of impacts, showing that central peaks are masses of very deep materials heaved up from the interior of the moon as the crater floor rebounds after an impact explosion. From such an image, we can imagine future astronauts making an arduous climb on the peak, collecting sam-ples that may tell us more about the moon’s interior.

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PSI NEWSLETTER Copyright© 2008 by Planetary Science Institute

PSI Retreat Photo Gallery

Above, Director Mark Sykes gave his opening presentation on “The State of PSI.” Top right, retreat members assembled in the Quail Room at Westward Look Resort. Anton Ivanov (at right and below) traveled from Switzerland and spoke about Martian polar layered terrains.

Gil Esquerdo, PSI Re-search Assistant and agile photographer, took the retreat pictures this year.

At right, Aileen Yingst gave a pres-entation on the Mars’ Spirit rover site particles, what they are and where they came from. At left, Alexis Rodriguez presented his research on recent sedimentary resurfacing in Planum Boreum (Mars), morphologic analogies of wind streaks in Patagonia and Ara-bia Terra (Mars), and morphology of secondary chaos.

At lunch (l-r): Frank Chuang, Dave O’Brien, Les Bleamaster, Bill Feldman and Lijie Han. (Steve Kortenkamp has his back to the cam-era.)

Yucca plants at the Westward Look Resort.

Matt Balme arrived from the U.K. to participate in the retreat. He outlined his studies of geological processes on Mars.

Kim Kuhlman led the Astrobiol-ogy breakout session.

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From left, Bill Hartmann and Mark Sykes with Board of Trustee members Ben Smith and John Mason.

Jeff Morgenthaler gave a presentation on wide-field high-resolution spectroscopy.

From left, Cathy Weitz, Aileen Yingst, Mary Bourke and Stu Weidenschilling during the Mars breakout session.

After lunch (l-r), Ed Stiles, Becky Williams, Matt Balme, Ben Smith and John Mason.

Luncheon roundtable discussions (l-r), Beatrice Mueller, Aileen Yingst, Jeff Morgenthaler, Don Davis, Larry Lebofsky, Nalin Samarasinha, Scott Mest and Matt Staid (with his back to the camera).

Tom Prettyman’s topic was the geochemistry of Vesta and Ceres from nuclear spectroscopy.

Entrance to the Westward Look Resort.

Asmin Pathare, center, was the group leader of the Mars breakout meeting.

Betty Pierazzo led the Planetary Geology and Geophysics breakout ses-sion.

(L-r), Les Bleamaster, Dan Berman, Mary Bourke and Melissa Lane in a Mars breakout session.

Paul Abell at the helm of the Moon breakout meeting.

Thanks, Gil!

PSI Retreat Photo Gallery

The Retreat Banquet at Janos Restaurant

Fall 2008 5

From top left: Mark Sykes presents Stu Weidenschilling with a 30-years-at-PSI commemorative vase; Scott Mest, Mary Bourke, Andrea Philippoff and fiancé, Kevin Jones at dinner; Asmin Pathare with Mary Lolos, Kelly and David Yoder in background. From lower left: Kathi Gardner, Tom Prettyman, Matt Balme, and Dave O’Brien surrounded by pre-banquet partygoers; Bruce Barnett, Tammi Palmer and Stu Weidenschilling: Don Davis and Bill Hartmann regale us with tales about Stu.


An agave on the hotel grounds. PSI is fortunate to have board members who take a keen inter-

est in our work! Matt Balme (left) and Bill Hartmann go over images and data from their current joint project on Mars, while PSI Board member Ben Smith (right) looks on.

Dave O’Brien (standing) led the Outer Planets/Solar System Formation/Dynamics session. In foreground, Jack Drummond and Bill Feldman (in blue).

Keith Holsapple gave a talk on the strength, spin and tidal limits of small bodies in space and the Deep Im-pact experiment.

Mountain view from the West-ward Look Resort.

Larry Lebofsky’s topic was “The Great Planet Debate: A Great Teaching Moment.”

Steve Kortenkamp led the session on National Science Foundation funding opportunities.

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Paul Abell Aims to Unmask Comets Posing as Asteroids by Ed Stiles Five to 10 percent of Near Earth Objects (NEOs) could be com-ets impersonating asteroids, according to PSI Research Scientist Paul Abell, who is finding ways to unmask them. NEOs are ob-jects whose orbits bring them close to Earth. Some NEOs could be dying comets, those that have lost most of the volatile materials that create their characteristic tails. Others could be dormant and might again display comet-like features after colliding with another object. Under a recently awarded NASA grant, Paul is using NASA’s Infrared Telescope Facility at the Mauna Kea Observatories in Hawaii and the MMT telescope on Mount Hopkins, south of Tucson, AZ, to uncover observational signatures that separate extinct or dormant comets from near-Earth asteroids. This is important for a few reasons. First, dormant comets in near-Earth space could become supply depots to support future exploration activities with water and other materials. Second, like other NEOs, they could pose a threat to Earth if they are on a collision course with our planet. Third, they can provide data on the composition and early evolution of the solar system be-cause they are thought to contain unmodified remnants of the primordial materials that formed the solar system. Unlike rocky asteroids that blast out craters when they slam into Earth, comets are structurally weak and likely to break up as they enter the atmosphere, leading to a heat and shockwave blast that would be much more devastating than the impact from an asteroid of the same size. Low-activity, near-Earth comets flashed onto the planetary sci-ence radar screen in 2001, when NEO 2001 OG108 was discov-ered by the Lowell Observatory Near-Earth Object Search tele-scope. It had an orbit similar to comets coming in from the Oort Cloud and was first thought to be one of the Damocloids, aster-oids that have Comet Halley-type orbits, but no cometary tails. Several groups began monitoring 2001 OG108 because it looked suspiciously comet-like. Serendipitously, it gave them a look at — and data on — a bare comet nucleus, an extremely unusual observation. The nuclei of comets are very dark and difficult to observe when they’re far from Earth. When they come closer to Earth, the Sun’s heat vaporizes some of the comet’s ice, creating the clouds of dust and gas that make up the comet’s coma and tail, which shroud the nucleus from view. In early 2002, NEO 2001 OG108 lit up with a coma — a bright cloud of dust and gas at the head of the comet, with the tail trail-ing out away from the Sun —and it was reclassified as C/2001 OG108 (LONEOS). That is what started Paul on this line of rea-soning and scientific investigation. Paul will be working with Faith Vilas, director of the MMT Ob-servatory and an Affiliate Senior Scientist at PSI, observing in the visible (0.35 - 1.0 microns) and near-infrared (0.7 to 2.5 mi-crons) spectral ranges. Paul hopes that by combining data from these two wavelength

regions they may be able to find an observational discriminator that will help them identify whether an object is an extinct comet or just an asteroid. He also hopes the data will show different spectral signatures for objects that originate in the Oort Cloud, the Kuiper Belt, and the recently discovered main-belt comets that come from the aster-oid belt between Mars and Jupiter. The Oort Cloud is located far out beyond Pluto and the Kuiper Belt is beyond Neptune, but only 1,000th the distance of the Oort Cloud from the Sun. “Are all these comets made of the same type of material or are they different?”, Paul asked. “If they’re composed of different materials, they may have different spectral signatures, and our preliminary work on Jupiter-family comets and Halley-type comets shows that this may be true. Why is that? Is it something to do with the initial conditions of their formation regions? Or is it due to the different environments in which they spend most of their time? All this is important to understanding their internal makeup, which will give us data on the material composition and evolution of the early solar system.” By combining orbital data with spectra and the albedos (brightness) of these objects, Paul hopes to identify which are low-activity comets and where they are coming from.

PSI Research Scientist Mary Bourke was the subject of a feature story in The Irish Examiner when she was home in Ireland this summer. The half-page article pointed out her connection to the search for life on Mars through her 2005 discovery of frozen dunes inside Kaiser Crater, a 210 km (130 miles) wide impact basin in the Hellespontus region of Mars. She found that the sand dunes in the planet’s northern hemisphere contained up to at least 40% water ice by mass in the upper meter and maybe more below. The article noted that Mary’s study of geological structures all over Earth —she has done field work on dunes in the American southwest, Australia and Namibia—gives her the background to analyze similar features on Mars.

PSI’s Bourke in Irish Newspaper

June 23, 2008

PSI NEWSLETTER

Fall 2008 7


Two Asteroids Named for PSI Scientists by Ed Stiles Two asteroids have been named for two Planetary Science Institute re-searchers: Keith Holsapple, of Seattle, WA, and David O'Brien, of Tuc-son, AZ. The recently discovered asteroids lie in the inner region of the main asteroid belt, between the orbits of Jupiter and Mars. 20360 Holsapple honors PSI Senior Scientist Keith A. Holsapple who is recognized for his work in modeling the response of planetary and aster-oidal material to stress and shock. 21774 O'Brien honors PSI Research Scientist David P. O'Brien for his studies of the collisional evolution of main-belt minor planets and crater-ing on 951 Gaspra and other objects. Hooray, Keith and David!

In August, PSI Trustee and Senior Scientist Donald Davis presented a plaque of apprecia-tion to former Trustee Carolyn S. Shoemaker in Flagstaff, AZ, for her eight years served on PSI’s Board of Trustees. We were so proud to have you. Thank you, Carolyn!

PSI Associate Research Scientist Amy Trueba Knudson gave birth to a beautiful baby boy, her second child, in June. Bravo, Amy and Arne!

Congratulations to our Scientists

Erase the image of scientists as dull, boring eggheads from your minds. Scientists are people too, just as opinionated, passionate and stubborn as anyone else. Last month about 100 scientists and educators converged on Baltimore, Maryland, to participate in "The Great Planet Debate: Science as Process." Scientists pre-sented a wide spectrum of views on how the term “planet” should be defined, from dynamical perspectives to geological and be-yond. The discussion was lively, and no consensus or agreement was reached on anything. It did highlight why it was silly for the International Astronomical Union (IAU) to think it could get away with imposing one viewpoint on everyone. At the same

Director’s Note

time it was rich in information, which the educators found very useful. On the first evening of the conference, there was an actual debate between myself and Neil de Grasse Tyson of Nova Science Now and the American Museum of Natural History. It was moderated by Ira Flatow of NPR's Science Friday. This debate moved from the lively to the theatrical (not surprising, given Neil's TV and my stage experience). Poor Ira was definitely stuck in the middle. Again no resolution, but the audience in the theater and online was at least entertained. I found the entire event served science well — it put conflicting ideas on the table where they clashed head to head. I was inspired to explore some new ideas for research, and to think about the issues of scientific categorization applied to objects in the universe in a yet broader way than I had before. Good stuff! Mark V. Sykes September, 2008

Planet debators and moderator on camera (l-r) Mark Sykes, Ira Flatow, and Neil de Grasse Tyson.

PSI Thanks Shoemaker

Photo credit: Siobhan Elias.

NON-PROFIT ORG. U.S. POSTAGE

PAID TUCSON AZ

PERMIT NO 356 PSI Board of Trustees Tim Hunter, MD, Chair Radiology, UA Candace Kohl, PhD, Vice Chair Chemistry, UCSD John L. Mason, PhD, Secretary Applied Research & Technology Brent Archinal, PhD U.S. Geological Survey Donald R. Davis, PhD Planetary Science Institute William K. Hartmann, PhD Planetary Science Institute David Levy, DSc, Jarnac Observatory Benjamin Smith, JD Attorney at Law Mark V. Sykes, PhD, JD Planetary Science Institute

1700 E. Fort Lowell Rd., Suite 106 Tucson, AZ 85719-2395 Phone: 520/622-6300 Fax: 520/622-8060 www.psi.edu

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PLANETARY SCIENCE INSTITUTE Newsletter Published Quarterly

Director Mark V. Sykes, PhD, JD Assistant Director David A. Crown, PhD Chief Financial Officer Bruce Barnett, CPA Senior Scientists Donald R. Davis, PhD Jack Drummond, PhD Mark Everett, PhD William C. Feldman, PhD Robert W. Gaskell, PhD Lijie Han, PhD William K. Hartmann, PhD Keith Holsapple, PhD Sumita Jayaraman, PhD Stephen Kortenkamp, PhD Kimberly R. Kuhlman, PhD Melissa D. Lane, PhD Beatrice E. A. Mueller, PhD Elisabetta Pierazzo, PhD Thomas H. Prettyman, PhD Nalin H. Samarasinha, PhD Edward F. Tedesco, PhD Stuart J. Weidenschilling, PhD Catherine Weitz, PhD Charles A. Wood, PhD R. Aileen Yingst, PhD Research Scientists Paul Abell, PhD Matt Balme, PhD Leslie F. Bleamaster, III, PhD Mary C. Bourke, PhD Jennifer A. Grier, PhD Anton Ivanov, PhD Jeffrey P. Morgenthaler, PhD

Planetary Science Institute

Fall 2008


David P. O’Brien, PhD Alexis Palmero Rodriguez, PhD Asmin Pathare, PhD Randall S. Perry, PhD Matthew Staid, PhD Rebecca Williams, PhD Senior Education Specialist Steven Croft, PhD Larry A. Lebofsky, PhD Associate Research Scientists Steven W. Anderson, PhD Natalia Artemieva, PhD Mark Bishop, PhD Nader Haghighipour, PhD Amy Trueba Knudson, PhD Scott C. Mest, PhD Stephen Metzger, PhD Joseph Michalski, PhD Eldar Z. Noe Dobrea, PhD Karly M. Pitman, PhD Nic Richmond, PhD Pasquale Tricarico, PhD R. Greg Vaughan, PhD Affiliate Senior Scientists Bruce Betts, PhD Gary Hansen, PhD Steven B. Howell, PhD Faith Vilas, PhD Affiliate Scientists Matthew A. Chamberlain, PhD Amara Graps, PhD James N. Head, PhD Karl Hibbitts, PhD Hideaki Hirdy Miyamoto, PhD Elizabeth P. Turtle, PhD

Visiting Senior Scientist Michael Snowden, PhD Science Support Staff Daniel C. Berman, MS Research Associate Frank C. Chuang, MS Research Associate/Software Specialist Rose Early Lead Software Developer Gilbert A. Esquerdo Research Assistant Jordan Marshall Student Software Developer Carol Neese, PhD Senior Research Associate Andrea Philippoff Research Assistant Jesse Stone Software Developer Administrative Staff Kathleen Gardner, MA Information Technology Technician Chris Holmberg Newsletter Editor/Assistant Administrator Tamara Kemnitz-Michotte, MBA Information Technology Manager Elaine Owens Office Manager Ed Stiles Public Information Officer Kelly Yoder Sponsored Projects Manager Education Field Trip Program (CA) Sylvia McDonald Field Trip Administrator William Schramm, MS Education/Science Support Specialist Dick Kenealy Program Coordinator (Volunteer)

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