Center for Lunar Origin and Center for Lunar Origin and Evolution (CLOE)Evolution (CLOE)

PI: William Bottke, Southwest Research InstitutePI: William Bottke, Southwest Research Institute

““Understanding the Formation and Understanding the Formation and Bombardment History of the Moon”Bombardment History of the Moon”

SwRI’s Role in NASA’s New Lunar Science InstituteSwRI’s Role in NASA’s New Lunar Science InstituteClark R. Chapman, Deputy P.I.Clark R. Chapman, Deputy P.I.

Presented on the occasion of the 15Presented on the occasion of the 15 thth Anniversary of SwRI/DoSS Anniversary of SwRI/DoSSBoulder, Colorado 24 September 2009Boulder, Colorado 24 September 2009

The CLOE TeamThe CLOE Team

William BottkeHal Levison

Clark ChapmanSteve Mojzsis

Amy BarrLuke Dones

Robin Canup

Jay MeloshErik HauriDavid NesvornyStephanie ShippBill Ward

CLOE Themes and OrganizationCLOE Themes and Organization

PI:PI: William Bottke William Bottke (SwRI)

Deputy PI: Deputy PI: Clark Chapman Clark Chapman (SwRI)

Theme I LeadTheme I Lead: Robin Canup : Robin Canup (SwRI) Co-Is: Amy Barr (SwRI), Bill Ward (SwRI), Jay

Melosh (Purdue), Erik Hauri (Carnegie DTM) Collaborator: Roger Phillips (SwRI)

Theme II LeadTheme II Lead: Clark Chapman: 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: LeadTheme III: Lead: Hal Levison : 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:E/PO Lead: Stephanie Shipp Stephanie Shipp (LPI) Co-I: Amy Barr (SwRI)

The Seven Centers of NLSIThe Seven Centers of NLSI

http://lunarscience.arc.nasa.gov/

Why Should We Study the Moon?Why Should We Study the Moon?

Besides the fact that the Moon is Besides the fact that the Moon is “cool” and scientifically “cool” and scientifically fascinating…and the Apollo fascinating…and the Apollo explorations were cut short…explorations were cut short…

The Moon is also a “Rosetta The Moon is also a “Rosetta Stone” for telling us about: Stone” for telling us about:

– The unknown nature and The unknown nature and environment of the primordial Earth!environment of the primordial Earth!

– The critical later stages of planet The critical later stages of planet formation throughout the solar formation throughout the solar system! system!

Lunar Science ConceptsLunar Science Concepts

Three fundamental scientific concepts Three fundamental scientific concepts have emerged from exploration of the have emerged from exploration of the Moon to date:Moon to date:

1.1. Lunar origin by giant impactLunar origin by giant impact

2.2. The existence of an early lunar The existence of an early lunar magma ocean, and magma ocean, and

3.3. The potential of an impact The potential of an impact cataclysm at 3.9 billion years ago. cataclysm at 3.9 billion years ago.

CLOE research addresses all of these vital elements of lunar origin and evolution.

Three fundamental scientific concepts Three fundamental scientific concepts have emerged from exploration of the have emerged from exploration of the Moon to date:Moon to date:

1.1. Lunar origin by giant impactLunar origin by giant impact

2.2. The existence of an early lunar The existence of an early lunar magma ocean, and magma ocean, and

3.3. The potential of an impact The potential of an impact cataclysm at 3.9 billion years ago. cataclysm at 3.9 billion years ago.

CLOE research addresses all of these vital elements of lunar origin and evolution.

2007 study by National 2007 study by National Research Council.Research Council.

CLOE Scientific Theme ElementsCLOE 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 MoonTheme 1: Formation of the Moon

Iron core vs. stony mantleAnimation from Robin Canup

Impactor

Trajectory

Early Earth

Giant impact of Earth and Giant impact of Earth and Mars-sized protoplanet Mars-sized protoplanet forms a disk of forms a disk of rocky/vapor material.rocky/vapor material.

However, we still do not However, we still do not know whether such a know whether such a disk can evolve into the disk can evolve into the Moon that we see today!Moon that we see today!

ObjectiveObjective:: Determine the Determine the implications of Giant implications of Giant Impact hypothesis for the Impact hypothesis for the Moon’s physical and Moon’s physical and compositional statecompositional state

ApproachApproach: : Self-Self-consistent model of lunar consistent model of lunar origin, starting from an origin, starting from an impact and ending with a impact and ending with a fully-formed Moonfully-formed Moon

Simulating Moon-Forming ImpactsSimulating Moon-Forming Impacts

SPH/particle code: first 24-hours CTH/grid code: first week

Goal: Determine initial dynamical, thermodynamical, and compositional properties of impact-generated proto-lunar disk

Proto-lunar Disk EvolutionProto-lunar Disk Evolution

GoalsGoals:: Determine extent of Earth-Moon chemical mixing, Determine extent of Earth-Moon chemical mixing, volatile loss, rate & nature of Moon’s accumulationvolatile loss, rate & nature of Moon’s accumulation

Two-part coupled model: Evolution of vapor-melt disk inside Roche limit Two-part coupled model: Evolution of vapor-melt disk inside Roche limit + simulations of Moon’s accretion outside Roche limit+ simulations of Moon’s accretion outside Roche limit

Initial Thermal State of the MoonInitial Thermal State of the Moon

GoalGoal: Determine extent of melting in the early Moon: Determine extent of melting in the early Moon

Simulate the Moon’s Simulate the Moon’s thermal state as it forms, thermal state as it forms, including impact heating including impact heating and radiative cooling.and radiative cooling.

Estimate magma ocean Estimate magma ocean depth, crustal thickness, depth, crustal thickness, and degree of metal & and degree of metal & silicate equilibrationsilicate equilibration

Theme 2: Observational Constraints on the Theme 2: Observational Constraints on the Bombardment History of the MoonBombardment History of the Moon

Objective:Objective: Find new “ground truth” to determine the Find new “ground truth” to determine the lunar impact rate over its early (and late) history. lunar impact rate over its early (and late) history.

Approaches:Approaches: (1) Use zircons to date early basin-(1) Use zircons to date early basin-forming events on Earth/Moon/asteroids; (2) Measure forming events on Earth/Moon/asteroids; (2) Measure crater densities on LHB and post-LHB lunar surfaces.crater densities on LHB and post-LHB lunar surfaces.

Bombardment Thermochronometry of Bombardment Thermochronometry of Early Moon, Earth, and AsteroidsEarly Moon, Earth, and Asteroids

GoalGoal. Study datable massive heating events in ancient zircons . Study datable massive heating events in ancient zircons and other minerals from the Earth, Moon, and asteroids to and other minerals from the Earth, Moon, and asteroids to determine ancient impact rates on these objects.determine ancient impact rates on these objects.

ApproachApproach. Many ancient zircons (ZiSiO. Many ancient zircons (ZiSiO44) have overgrowths that ) have overgrowths that record thermal pulses. Using secondary ion mass spectrometry record thermal pulses. Using secondary ion mass spectrometry (SIMS), we will date these events and provide new constraints on (SIMS), we will date these events and provide new constraints on the timing, intensity, and duration of lunar bombardment. the timing, intensity, and duration of lunar bombardment.

Trail et al. (2005)

Relative Lunar Cratering ChronologyRelative Lunar Cratering Chronology

Baldwin counted small Baldwin counted small craters (0.5 < craters (0.5 < DD < 4 km) within < 4 km) within large lunar nearside craters large lunar nearside craters to get their ages.to get their ages.

His method reproduces His method reproduces (within 20-(within 20-30 My) the known 30 My) the known ages of Tycho (~110 My) and ages of Tycho (~110 My) and Copernicus (~800 My).Copernicus (~800 My).

GoalGoal. Establish . Establish relativerelative chronology of observable chronology of observable lunar geology using new lunar geology using new crater counts.crater counts.

Approach. Approach. Use Baldwin’s Use Baldwin’s and other modern crater and other modern crater statistical analysis methods. statistical analysis methods. ((AbsoluteAbsolute ages will come ages will come from Theme 3.)from Theme 3.)Baldwin (1985)Baldwin (1985)

Theme 3: Determining Lunar Impact RatesTheme 3: Determining Lunar Impact Rates

Goal. Goal. Calculate the nature of the impact flux between 3.8-4.5 Ga.Calculate the nature of the impact flux between 3.8-4.5 Ga.

Approach. Approach. New simulations that track how planetesimals evolved in the inner New simulations that track how planetesimals evolved in the inner solar system prior to the Nice model event. Link work back to Theme 2.solar system prior to the Nice model event. Link work back to Theme 2.

[For illustration purposes only!]

The Post Late Heavy Bombardment EraThe 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?A late, terminal impact cataclysm?

Leftovers from planetary accretion?Leftovers from planetary accretion?

Post-Accretion and the LHBPost-Accretion and the LHB

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”.

Comets

Primordial disk of comets

Old view. Gas giants/comets formed near present locations (5-30 AU) and reached current orbits ~4.5 Gy ago.

Tsiganis et al. (2005)Tsiganis et al. (2005)

Fernandez and Ip (1986); Malholtra (1995); Thommes et al. (1999; 2003)Fernandez and Ip (1986); Malholtra (1995); Thommes et al. (1999; 2003)

The Nice ModelThe 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 Gravitational interactions with massive disk of comets causes migration. In this simulation, at 850 My, Jupiter/Saturn enter 1:2 MMR. this simulation, at 850 My, Jupiter/Saturn enter 1:2 MMR.

This pushes Uranus & Neptune into comet disk: comets fly everywhere in the This pushes Uranus & Neptune into comet disk: comets fly everywhere in the solar system, the asteroid belt is destabilized, so a cratering cataclysm occurs.solar system, the asteroid belt is destabilized, so a cratering cataclysm occurs.

Leftovers of AccretionLeftovers of Accretion

Sea of bodies:Sea of bodies:

– Moon to Mars-Moon to Mars-sized bodiessized bodies

– Smaller Smaller planetesimals.planetesimals.

Some bodies Some bodies pushed to high pushed to high eccentricities & eccentricities & inclinations.inclinations.

Here they (may) Here they (may) live long enough live long enough to strike the Moon to strike the Moon between 3.8-4.5 between 3.8-4.5 Ga.Ga.

Plan

etes

imal

s

Plan

etes

imal

s

Prot

opla

nets

Prot

opla

nets

Location ofLocation ofAsteroid BeltAsteroid Belt

Other Institute ObjectivesOther Institute Objectives

TrainingTraining

– We are hiring 4 junior scientists and 3 graduate students.We are hiring 4 junior scientists and 3 graduate students.

Graduate seminar on the formation and evolution of the MoonGraduate seminar on the formation and evolution of the Moon

– Based at the University of Colorado; joint Planetary/Geology Based at the University of Colorado; joint Planetary/Geology departmentsdepartments

Origin of the Earth-Moon System II: Conference and BookOrigin of the Earth-Moon System II: Conference and Book

– Conference designed to present new work on the Origin of the Moon Conference designed to present new work on the Origin of the Moon

– The conference will lead to a book published through Cambridge Univ. The conference will lead to a book published through Cambridge Univ. Press.Press.

– Many opportunities for joint efforts with the NLSI teams.Many opportunities for joint efforts with the NLSI teams.

Solar System Bombardment Focus GroupSolar System Bombardment Focus Group

Education and Public Outreach (E/PO)Education and Public Outreach (E/PO)

LPI’s “Explore!” library programLPI’s “Explore!” library program– After-school programs in lunar science and After-school programs in lunar science and

exploration in partnership with state libraries exploration in partnership with state libraries across 6 western states.across 6 western states.

– Targeted toward under-represented populationsTargeted toward under-represented populations

Summer Science Program, Inc.Summer Science Program, Inc.– Work with gifted high school and provide Work with gifted high school and provide

challenging lunar science program.challenging lunar science program.– Develop next generation of lunar scientists in Develop next generation of lunar scientists in

collaboration with established SSP program.collaboration with established SSP program.

Develop CLOE web portal with high school Develop CLOE web portal with high school students at Denver School for Science and students at Denver School for Science and Technology.Technology.

LeadLead: Stephanie Shipp (LPI). Co-I: Amy Barr (SwRI): Stephanie Shipp (LPI). Co-I: Amy Barr (SwRI)

Any Questions?Any Questions?

CLOE Education/Public OutreachCLOE Education/Public Outreach

Partnership with Summer Science Program, Inc. to Partnership with Summer Science Program, Inc. to inspire and educate future scientistsinspire and educate future scientists

Impact: 288 HS Students

• 72 high school students/ year72 high school students/ year

• 6 week science experience 6 week science experience observing and analyzing orbital observing and analyzing orbital elements of asteroidselements of asteroids

• 2-day CLOE science project 2-day CLOE science project integrated into experience integrated into experience

• Students encouraged to present Students encouraged to present at LPSC/NLSI conferenceat LPSC/NLSI conference

• Materials available for other Materials available for other institutions to replicate.institutions to replicate.

LeadLead: Stephanie Shipp (LPI). Co-I: Amy Barr (SwRI): Stephanie Shipp (LPI). Co-I: Amy Barr (SwRI)

CLOE E/POCLOE E/PO

Library programsLibrary programs toto engage young explorers in engage young explorers in lunar sciencelunar science

• A suite of hands-on activities for A suite of hands-on activities for library learning environments library learning environments

• 90 children’s librarians prepared to 90 children’s librarians prepared to bring lunar science into programs bring lunar science into programs through 2-day workshops (CO and through 2-day workshops (CO and WY / ND and SD / ID, and MT)WY / ND and SD / ID, and MT)

• Web-training of an existing Web-training of an existing nationwide network of 480 nationwide network of 480 librarianslibrarians

• Continued support of networkContinued support of network

Impact: 10,800 children Impact: 10,800 children annually in 4 yearsannually in 4 years

CLOE E/POCLOE E/PO

CLOE Web page designed by students to engage CLOE Web page designed by students to engage the general public in NLSI sciencethe general public in NLSI science

• Denver School of Science and Denver School of Science and Technology high school students Technology high school students and facultyand faculty

• High-school students learn about High-school students learn about CLOE and NLSI science, scientists, CLOE and NLSI science, scientists, and careersand careers

• Design and maintain a web page Design and maintain a web page that engages the publicthat engages the public

• Traditional and new mediaTraditional and new media

Impact: Enhanced student Impact: Enhanced student and public engagement and public engagement

Destabilizing the Outer Solar SystemDestabilizing the Outer Solar System

Watch what happens after 850 My!Watch what happens after 850 My!

Tsiganis et al. (2005); Morbidelli et al. (2005); Tsiganis et al. (2005); Morbidelli et al. (2005); Gomes et al. (2005)Gomes et al. (2005)