Center for Lunar Origin and Evolution (CLOE) 4/22/2017 Center for Lunar Origin and Evolution (CLOE) “Understanding the Formation and Bombardment History of the Moon” PI: William Bottke, Southwest Research Institute SwRI’s Role in NASA’s New Lunar Science Institute Clark R. Chapman, Deputy P.I. Presented on the occasion of the 15th Anniversary of SwRI/DoSS Boulder, Colorado 24 September 2009

The CLOE Team Luke Dones Steve Mojzsis Hal Levison Robin Canup Amy Barr Clark Chapman William Bottke Stephanie Shipp Bill Ward David Nesvorny Erik Hauri Jay Melosh

CLOE Themes and Organization PI: William Bottke (SwRI) Deputy PI: Clark Chapman (SwRI) Theme I Lead: Robin Canup (SwRI) Co-Is: Amy Barr (SwRI), Bill Ward (SwRI), Jay Melosh (Purdue), Erik Hauri (Carnegie DTM) Collaborator: Roger Phillips (SwRI) Theme II Lead: Clark Chapman (SwRI) Co-I: Steve Mojzsis (Univ. Colorado) Staff Scientist: Michelle Kirchoff (SwRI) Collaborators: Herb Frey (GSFC), Barb Cohen (MSFC), Tim Swindle (U. Ariz.), Dave Kring (LPI), Scott Anderson (SwRI) Theme III: Lead: Hal Levison (SwRI) Co-Is: Luke Dones & David Nesvorny (SwRI) Collaborators: Alessandro Morbidelli (Obs. Nice), David Vokrouhlicky (Charles U., Czech Rep.), David O’Brien (PSI) E/PO Lead: Stephanie Shipp (LPI) Co-I: Amy Barr (SwRI)

The Seven Centers of NLSI http://lunarscience.arc.nasa.gov/

Why Should We Study the Moon? Besides the fact that the Moon is “cool” and scientifically fascinating…and the Apollo explorations were cut short… The Moon is also a “Rosetta Stone” for telling us about: The unknown nature and environment of the primordial Earth! The critical later stages of planet formation throughout the solar system!

Lunar Science Concepts Three fundamental scientific concepts have emerged from exploration of the Moon to date: Lunar origin by giant impact The existence of an early lunar magma ocean, and The potential of an impact cataclysm at 3.9 billion years ago. CLOE research addresses all of these vital elements of lunar origin and evolution. 2007 study by National Research Council.

CLOE Scientific Theme Elements Theme 1: Formation of the Moon Moon-forming giant impacts (e.g. simulations of giant impact and disk formation) Evolution of the proto-lunar disk (e.g. degree of chemical equilibration with Earth) Accretion of the Moon (e.g. time scale for final assembly of the Moon) Initial lunar thermal state (e.g. depth of magma ocean and crust) Theme 2: Observational Constraints on the Bombardment History of the Moon Bombardment thermochronometry of the early Moon, Earth, and asteroids (using zircons) Relative lunar cratering chronology (during and after Late Heavy Bombardment) Theme 3: Determining Lunar Impact Rates Post Late Heavy Bombardment era (dynamics-based asteroid break-up chronology) Post-accretion and the Late Heavy Bombardment (e.g. “Nice Model” simulations) Leftovers of accretion (can remnant planetesimals still hit after lunar crust solidified?)

Theme 1: Formation of the Moon Giant impact of Earth and Mars-sized protoplanet forms a disk of rocky/vapor material. However, we still do not know whether such a disk can evolve into the Moon that we see today! Objective: Determine the implications of Giant Impact hypothesis for the Moon’s physical and compositional state Approach: Self-consistent model of lunar origin, starting from an impact and ending with a fully-formed Moon Impactor Trajectory Early Earth Iron core vs. stony mantle Animation from Robin Canup

Simulating Moon-Forming Impacts Goal: Determine initial dynamical, thermodynamical, and compositional properties of impact-generated proto-lunar disk SPH/particle code: first 24-hours CTH/grid code: first week

Proto-lunar Disk Evolution Goals: Determine extent of Earth-Moon chemical mixing, volatile loss, rate & nature of Moon’s accumulation Two-part coupled model: Evolution of vapor-melt disk inside Roche limit + simulations of Moon’s accretion outside Roche limit

Initial Thermal State of the Moon Goal: Determine extent of melting in the early Moon Simulate the Moon’s thermal state as it forms, including impact heating and radiative cooling. Estimate magma ocean depth, crustal thickness, and degree of metal & silicate equilibration

Theme 2: Observational Constraints on the Bombardment History of the Moon Objective: Find new “ground truth” to determine the lunar impact rate over its early (and late) history. Approaches: (1) Use zircons to date early basin-forming events on Earth/Moon/asteroids; (2) Measure crater densities on LHB and post-LHB lunar surfaces.

Bombardment Thermochronometry of Early Moon, Earth, and Asteroids Trail et al. (2005) Goal. Study datable massive heating events in ancient zircons and other minerals from the Earth, Moon, and asteroids to determine ancient impact rates on these objects. Approach. Many ancient zircons (ZiSiO4) have overgrowths that record thermal pulses. Using secondary ion mass spectrometry (SIMS), we will date these events and provide new constraints on the timing, intensity, and duration of lunar bombardment.

Relative Lunar Cratering Chronology Baldwin counted small craters (0.5 < D < 4 km) within large lunar nearside craters to get their ages. His method reproduces (within 20-30 My) the known ages of Tycho (~110 My) and Copernicus (~800 My). Goal. Establish relative chronology of observable lunar geology using new crater counts. Approach. Use Baldwin’s and other modern crater statistical analysis methods. (Absolute ages will come from Theme 3.) Baldwin (1985)

Theme 3: Determining Lunar Impact Rates [For illustration purposes only!] Goal. Calculate the nature of the impact flux between 3.8-4.5 Ga. Approach. New simulations that track how planetesimals evolved in the inner solar system prior to the Nice model event. Link work back to Theme 2.

The Post Late Heavy Bombardment Era Catastrophic family-producing asteroid collisions (whose fragments make lunar craters) can be dated precisely, an alternative to lunar rock ages for dating geological events. Goal. Establish an absolute chronology for the relative ages found in the Theme 2 crater task. Approach. Use dynamics and collisional physics to model the post-LHB impact rate on the Moon.

What Formed the Lunar Basins ~3.9 Ga and Before? A late, terminal impact cataclysm? Leftovers from planetary accretion?

Post-Accretion and the LHB Comets Old view. Gas giants/comets formed near present locations (5-30 AU) and reached current orbits ~4.5 Gy ago. Primordial disk of comets  New view. Gas giants formed in more compact formation between 5 to ~20 AU. Massive comet population existed out to ~30 AU. Best developed and most successful scenario of the new view is the “Nice Model”. Fernandez and Ip (1986); Malholtra (1995); Thommes et al. (1999; 2003) Tsiganis et al. (2005)

The Nice Model Tsiganis et al. (2005); Morbidelli et al. (2005); Gomes et al. (2005) Jupiter/Saturn enter 1:2 mean motion resonance Gravitational interactions with massive disk of comets causes migration. In this simulation, at 850 My, Jupiter/Saturn enter 1:2 MMR. This pushes Uranus & Neptune into comet disk: comets fly everywhere in the solar system, the asteroid belt is destabilized, so a cratering cataclysm occurs.

Leftovers of Accretion Sea of bodies: Moon to Mars-sized bodies Smaller planetesimals. Some bodies pushed to high eccentricities & inclinations. Here they (may) live long enough to strike the Moon between 3.8-4.5 Ga. Location of Asteroid Belt Protoplanets Planetesimals

Other Institute Objectives Training We are hiring 4 junior scientists and 3 graduate students. Graduate seminar on the formation and evolution of the Moon Based at the University of Colorado; joint Planetary/Geology departments Origin of the Earth-Moon System II: Conference and Book Conference designed to present new work on the Origin of the Moon The conference will lead to a book published through Cambridge Univ. Press. Many opportunities for joint efforts with the NLSI teams. Solar System Bombardment Focus Group

Education and Public Outreach (E/PO) LPI’s “Explore!” library program After-school programs in lunar science and exploration in partnership with state libraries across 6 western states. Targeted toward under-represented populations Summer Science Program, Inc. Work with gifted high school and provide challenging lunar science program. Develop next generation of lunar scientists in collaboration with established SSP program. Develop CLOE web portal with high school students at Denver School for Science and Technology. Lead: Stephanie Shipp (LPI). Co-I: Amy Barr (SwRI)

Any Questions?

CLOE Education/Public Outreach Partnership with Summer Science Program, Inc. to inspire and educate future scientists 72 high school students/ year 6 week science experience observing and analyzing orbital elements of asteroids 2-day CLOE science project integrated into experience Students encouraged to present at LPSC/NLSI conference Materials available for other institutions to replicate. Three foci to CLOE E/PO Focus 1 Overall Summer Science Program, Inc. begun in 1959, is one of the oldest and most successful summer enrichment programs for academically gifted high-school students. Most graduates enroll at highly selective universities; 60% pursue STEM careers and, of these, 20% select space science-related fields. Each year students, mostly rising seniors from around the U.S. and world, are selected through a competitive application process. 72 are selected and participate in the 6-week experience at New Mexico Tech in Socorro, New Mexico, and Besant Hill School in Ojai, California. Students undertake authentic space science research encompassing telescopic observations of an asteroid and calculation of its orbital elements. Evaluation will focus on content learning and perceptions and will be integrated into the existing SSPI evaluation protocol. CLOE Component Projects will be developed by the CLOE team, led by SSP alumna and Trustee Barr. CLOE team members will deliver six hours of background and methodology, and conclude by posing the scientific question. On the second day, CLOE team members interact with and advise student teams. Students present a brief summary of their scientific findings, successes, and challenges to their peers and the CLOE team. Students will be encouraged to submit abstracts to LPSC and/or an NLSI conference. The materials developed will be added to SSPI’s curriculum database for use by other faculty. Diversity / Financial Aid and Plans to Encourage Participation by Underserved and Underrepresented Audiences SSP student body of 2004 to 2008 is 58% Caucasian, 30% Asian, 5% Hispanic, 2% Black, 1% American Indian, and 3% other. (Note: Current US Hispanic population is 15.1% --- rising to 24.4% by 2050, and current US Black population is 12.8%) Program costs per student ($6800) are substantially greater than student fees ($3600); 60% receive financial aid. In 2008, 12 students were accepted tuition-free. SSPI recently received a grant from the Ahmanson Foundation to provide free tuition to minority and disadvantaged students from the Los Angeles County Unified School District. Through partnerships with the NM State Legislature, SSP is tuition-free for NM residents. To reach more Hispanic, Native American, and rural students, the CLOE E/PO team will work with SSPI to inform state science teachers and school councilor associations of this opportunity in the central western corridor (AZ, CO, ID, KS, MT, NE, NM, NV, ND, OK, SD, TX, UT, WY). The CLOE team will strongly encourage DSST students to apply and will mentor candidates and help them acquire scholarships. Impact: 288 HS Students Lead: Stephanie Shipp (LPI). Co-I: Amy Barr (SwRI)

CLOE E/PO Library programs to engage young explorers in lunar science A suite of hands-on activities for library learning environments 90 children’s librarians prepared to bring lunar science into programs through 2-day workshops (CO and WY / ND and SD / ID, and MT) Web-training of an existing nationwide network of 480 librarians Continued support of network Focus 2 Overall Expand an existing LPI program, Explore!, that has provided training and space science materials to children’s librarians for over a decade. activities for children ages 8 to 13 Module includes facilitator content and suggested books, websites, and other opportunities for further exploration. It is designed for informal learning environments, but aligned with national educational standards. Workshops and Web casts are advertised and hosted in partnership with state library systems. Evaluation uses existing evaluation instruments (developed in part for NSF evaluation of the trainings) to assess changes in participant content knowledge, as well as participant perceptions of lunar science and exploration, activities undertaken, workshop design, preparation and plans to implement with children, preparation and plans to train colleagues, etc. CLOE Component Module explores the Moon’s formation and Earth/Moon evolution: CLOE scientists ensure accuracy, work with E/PO team to design CLOE scientists attend workshops and interact with librarians, and present CLOE/NLSI science in the Web casts Free access sustained through the CLOE and Explore! websites Diversity / Financial Aid and Plans to Encourage Participation by Underserved and Underrepresented Audiences Library partners will recruit children’s and youth librarians who primarily work with underserved American Indian, Hispanic, and rural populations in: CO (high Hispanic population) WY, ND, SD, MT (high Native American population) ND, SD, MT, ID (high rural population) Impact: 10,800 children annually in 4 years

Impact: Enhanced student and public engagement CLOE E/PO CLOE Web page designed by students to engage the general public in NLSI science Denver School of Science and Technology high school students and faculty High-school students learn about CLOE and NLSI science, scientists, and careers Design and maintain a web page that engages the public Traditional and new media Focus 3 Overall DSST teachers and students will build an understanding of CLOE’s science and resources Students will design the website and integrate content in consultation with science and technology faculty. By the close of Year 1, a live public website will present CLOE and NLSI. The site may include: animations, images, data, video clips interviews, pod casts, student blogs, links to social networking sites (e.g., Facebook) related events and opportunities for public involvement – including library programs public lectures by NSLI scientists as live webcasts and archived Evaluation will include assessing changes in student content knowledge and perceptions of lunar science and exploration and the design of the project, as well as web-based evaluations to assess public learning, engagement, plans to learn more, interaction with web site, etc. CLOE Component CLOE scientists will interact with students and teachers through monthly school visits and e-mail Through the four project years, CLOE scientists visit classrooms and correspond with students, share new scientific findings, and serve as role models. Students will be invited to visit SwRI to interview scientists and tour the facilities, and will be encouraged to “report on” NLSI events in which they participate Site will be hosted by CLOE Diversity / Financial Aid and Plans to Encourage Participation by Underserved and Underrepresented Audiences DSST is a public charter high school with 35% Caucasian, 29% Black, 25% Hispanic, 11% other; 40% low-income students Students encouraged to participate in SSPI experiences Underrepresented students will be exposed to NASA, NLSI, lunar science, careers, and scientists Impact: Enhanced student and public engagement

Destabilizing the Outer Solar System Tsiganis et al. (2005); Morbidelli et al. (2005); Gomes et al. (2005) Watch what happens after 850 My!