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Outline

1 Why a Mission to Mercury?

2 The MESSENGER Mission

3 The MESSENGER Spacecraft

4 Long-Wavelength Folding

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Why a Mission to Mercury?Last Visit: Mariner 10 in 1975

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Six Key Outstanding QuestionsWhy is Mercury so Dense?

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Six Key Outstanding QuestionsWhat is the geologic history of Mercury?

Credit: NASA/Johns Hopkins University

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Six Key Outstanding QuestionsWhat is the nature of Mercury’s magnetic field?

Credit: NASA/Johns Hopkins University

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Six Key Outstanding QuestionsWhat is the structure of Mercury’s core?

Credit: NASA/Johns Hopkins University

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Six Key Outstanding QuestionsWhat are the unusual materials at Mercury’s poles?

Credit: NASA/Johns Hopkins University

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Six Key Outstanding QuestionsWhat volatiles are important at Mercury?

Credit: NASA/Johns Hopkins University

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The MESSENGER MissionPrimary Mission

Primary mission at Mercury:Orbit for one Earth year (equivalent to just over four Mercuryyears, or two Mercury solar days), collecting data on thecomposition and structure of Mercurys crust, its topography andgeologic history, the nature of its thin atmosphere and activemagnetosphere, and the makeup of its core and polar materials.

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The MESSENGER MissionQuick Overview

MESSENGER = MErcury Surface, Space ENvironment,GEochemistry and Ranging

Cost $446MLaunch Date August 3, 2004

Launch Vehicle Delta II 7925HFlybys EVVMMMArrival March 2011Status Extended Mission in Progress (!)

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The MESSENGER MissionInterplanetary Trajectory

Credit: NASA/Johns Hopkins University

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The MESSENGER MissionMercury Orbit

Credit: NASA/Johns Hopkins University

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The MESSENGER MissionWebsite - Q & A

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The SpacecraftQuick Overview

Size 1.42 m tall, 1.85 m wide and 1.27 m deepMass 1,107 kg

Dry Mass 507.9 kgPropellant 599.4 kg

Power 640 WPropulsion

Large Maneuvers One Bipropellant ThrusterSmall Maneuvers 16 Monopropellant Thrusters

Instruments 7

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The SpacecraftChallenges of a Mercury Orbiter

Credit: NASA/Johns Hopkins University

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The SpacecraftAssembly

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The SpacecraftLaser Ranging at Interplanetary Distances

Credit: NASA/Goddard Space Flight Center

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The SpacecraftThe Instruments

Credit: NASA/Johns Hopkins University

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The SpacecraftThe Instruments: MLA

Credit: NASA/Johns Hopkins University

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Long-Wavelength FoldingObservations

Credit: NASA/Johns Hopkins University

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Long-Wavelength FoldingObservations

Klimczak et al. (2012)

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Long-Wavelength FoldingObservations

Credit: NASA/Johns Hopkins University

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Long-Wavelength FoldingA Theory

Lithospheric Folding caused by Global Contraction due to Cooling

Observed Amplitude: ∼ 2.5 kmObserved Wavelength: ∼ 1200 km

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Long-Wavelength FoldingFolding Mechanism

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Long-Wavelength FoldingResult Perturbing Flow

Fletcher and Hallet (1983)

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Long-Wavelength FoldingFolding on Earth: Basin and Range Province

Image from Marli Miller, University of Oregon

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Long-Wavelength FoldingAnalogy?

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Long-Wavelength FoldingLinear Stability Analysis

1 Formulate the Basic Flow

2 Add a Small Disturbance

3 Substitute the Sum into the Governing Equations andLinearize

4 Formulate an Eigenvalue Problem

5 Solve the Eigenvalue Problem

The flow is unstable if a solution grows in time.

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Long-Wavelength FoldingGrowth Rate for one Wavelength

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Long-Wavelength FoldingGrowth Rates

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Long-Wavelength FoldingDepth Brittle Layer

Zuber et al. (2010)

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Long-Wavelength FoldingDifferent Creep Laws

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Long-Wavelength FoldingInitial Results For Mercury

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Long-Wavelength FoldingProblems-Depth

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Long-Wavelength FoldingProblems-Wavelength

Radius Mercurius ≈ 2440km, Wavelength = 1200 km

Credit: NASA/Johns Hopkins University

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Long-Wavelength FoldingCompositional Layers

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Long-Wavelength FoldingMulti-Layer

Bassi and Bonnin (1988)

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Long-Wavelength FoldingGrowth Rate for Multiple Layers

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Long-Wavelength FoldingFuture Work

1 Solve Equations for a Spherical Body

2 Distinguish between Single or Mutli Layer Model

3 Incorporate Latest Findings on Mercury

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Future for MercuryMESSENGER

Credit: NASA/Johns Hopkins University

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Future for MercuryBepiColombo

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