1 / 28

Center for Lunar Origin and Evolution (CLOE)

Center for Lunar Origin and Evolution (CLOE). PI: William Bottke, Southwest Research Institute. “Understanding the Formation and Bombardment History of the Moon”. SwRI’s Role in NASA’s New Lunar Science Institute. Clark R. Chapman, Deputy P.I.

velika
Download Presentation

Center for Lunar Origin and Evolution (CLOE)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Center for Lunar Origin and Evolution (CLOE) PI: William Bottke, Southwest Research Institute “Understanding the Formation and Bombardment History of the Moon” 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

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

  3. 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)

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

  5. 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!

  6. 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. • CLOEresearch addresses all of these vital elements of lunar origin and evolution. 2007 study by National Research Council.

  7. 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?)

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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.

  13. Bombardment Thermochronometry of Early Moon, Earth, and Asteroids • 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. Trail et al. (2005)

  14. 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)

  15. 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.

  16. 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.

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

  18. 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)

  19. The Nice Model Jupiter/Saturn enter 1:2 mean motion resonance Tsiganis et al. (2005); Morbidelli et al. (2005); Gomes et al. (2005) • 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.

  20. 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 Planetesimals Protoplanets

  21. 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

  22. 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)

  23. Any Questions?

  24. 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. Impact: 288 HS Students Lead: Stephanie Shipp (LPI). Co-I: Amy Barr (SwRI)

  25. CLOE E/PO Library programstoengage 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 Impact: 10,800 children annually in 4 years

  26. 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 Impact: Enhanced student and public engagement

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

More Related