ARTEMIS from a Planetary Perspective 1 September 9, 2008 THEMIS Extended Phase = THEMIS baseline +...
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Transcript of ARTEMIS from a Planetary Perspective 1 September 9, 2008 THEMIS Extended Phase = THEMIS baseline +...
![Page 1: ARTEMIS from a Planetary Perspective 1 September 9, 2008 THEMIS Extended Phase = THEMIS baseline + ARTEMIS Vassilis Angelopoulos, and the ARTEMIS team.](https://reader036.fdocuments.net/reader036/viewer/2022062804/5697bf7b1a28abf838c8384a/html5/thumbnails/1.jpg)
ARTEMIS from a Planetary Perspective 1 September 9, 2008
THEMIS Extended Phase=
THEMIS baseline + ARTEMIS
Vassilis Angelopoulos, and the ARTEMIS team
ARTEMIS Contributions to Planetary Exploration
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ARTEMIS from a Planetary Perspective 2 September 9, 2008
• THEMIS Extended Phase (FY10, FY11, FY12)– Extended THEMIS Baseline (3 probes) + ARTEMIS (2 probes)
– ARTEMIS = Acceleration Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun (Heliospheric Objectives, as accepted)
• The magnetosphere
• The solar wind
• The lunar wake
– ARTEMIS Planetary Capabilities • Surface composition and weathering
• Exospheric composition, structure, and dynamics
• Electric fields and dust
• Interior structure
• Support for other planetary missions (LRO, LADEE, GRAIL, etc.)as solar wind monitor, provide low energy particle spectrum andcharacterize source populations of particle radiation
Overview
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ARTEMIS from a Planetary Perspective 3 September 9, 2008
ARTEMIS payload, operations concept
BGS
Mission OpsUCB
Probe instruments:ESA: ElectroStatic Analyzer (i,e: 3eV-25keV; Carlson & McFadden)SST: Solid State Telescopes (i,e: 25-1000keV; Larson)FGM: FluxGate Magnetometer (0-128Hz; Glassmeier, Auster & Baumjohann)SCM: SearchCoil Magnetometer (1Hz-4kHz; Roux & LeContel)EFI: Electric Field Instrument (0-8kHz; Bonnell & Mozer)
SST
ESA
EFIa
EFIs
FGM
SCM
Tspin=3s
DSNProducts:
2hr latency
Relay:3hr daily
Data volume: 100Mbits/dayOrbit periods at moon: ~1 day
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ARTEMIS from a Planetary Perspective 4 September 9, 2008
ARTEMIS mission phasesInsertion: FY10; Science: FY11,12
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ARTEMIS from a Planetary Perspective 5 September 9, 2008
Lunar WakeFormation/Evolution
Diffusive Particle
Acceleration
Shock tangent
Foreshock waves
Turbulent wake?
Last closed field lineGeotail
THEMISMoon
P1P2
P1 P2Solar Wind
X
Magnetotail
ARTEMIS Heliophysics objectivesInsertion FY10; Science: FY11,12
FY10: Translunar injectionFY11-12: 6mo Lissajous + 18 mo Lunar
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ARTEMIS from a Planetary Perspective 6 September 9, 2008
For purposes of addressing planetary objectives:Periselene of P1 can be lowered to 100km (P2 remains high)Orbit stable for >3years; longer with little fuel
P1 P2
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ARTEMIS from a Planetary Perspective 7 September 9, 2008
•Removing 11Hz noise in magnetometerDue to internal EMI from particle sectoringNot a show stopper
•Need to change energy ranges to measure pickup ionsBest to have fine dE/E.Not mission critical
Issues
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ARTEMIS from a Planetary Perspective 8 September 9, 2008
• In the Magnetosphere, study:– Particle acceleration– Reconnection: 3D character and
global effects– Turbulence: Drivers and effects
• Reveal 3D distant tail, dynamics• First two-point measurements;
from gyroradius to RE scales
• In the Solar Wind, study:– Particle acceleration at shocks – Nature and extent of reconnection– Inertial range of turbulence
• First two-point measurements, at 1-10RE
Heliophysics from the Moon
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ARTEMIS from a Planetary Perspective 9 September 9, 2008
The Electrodynamic Environmentof the Moon: Lunar Wake
• The Moon is an ideal plasma laboratory for studying magnetized plasmas.• The simple geometry of the Moon and its absorbing boundary produces a
system that can be readily modeled with computers.• This allows the codes to be tested and the physics to be understood.• ARTEMIS measurements are particularly useful for such tests.
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ARTEMIS from a Planetary Perspective 10 September 9, 2008
Dust Levitation in Electric Fields• Apollo observers saw dust
elevated above the lunar surface to possibly high altitudes.
• LADEE will probably have a dust detector, but has no capability of measuring the solar wind electric and magnetic fields.
• ARTEMIS measures the solar wind velocity, the interplanetary magnetic field and hence the solar wind electric field. It also can measure surface potentials with electron reflectometry.
• ARTEMIS plus LADEE will enable us to determine the response of charged lunar dust to the lunar and solar wind electric fields.
ARTEMIS-1ARTEMIS-1
ARTEMIS-2ARTEMIS-2
LADEE
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ARTEMIS from a Planetary Perspective 11 September 9, 2008
ExosphericPickupIon
ARTEMIS-1
ARTEMIS-2
H+
He+H2O+ S+
ARTEMIS mass spectrometryof pickup ions assumed “protons”
V,x
V,y
Solar Wind
• Apollo’s ALSEP package contained a suprathermal ion detector (SIDE) that detected ions accelerated by electric field toward lunar surface.WIND observations confirmed presence of heavy ions around moon.
• Temporal history of ion fluxes on SIDE suggested that the moon might be episodically outgassing. Alpha particle observations of localized concentrations of radon also support this viewpoint.
• This observation needs confirmation. If true, there may be a source of lunar volatiles at low latitudes, not just at the poles.
• ARTEMIS has an ion detector and measures the solar wind electric field so it can test the SIDE hypothesis of an outgassing moon.
Lunar Exosphere
Hartle et al., 2005
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ARTEMIS from a Planetary Perspective 12 September 9, 2008
ARTEMIS and Lunar Surface
• Lunar Surface:– Study composition and distribution of sputtered ions– Understand crustal magnetic fields, surface charging– Remotely sense surface properties of lunar regolith
• Result:– Advance our understanding of fundamental plasma
interactions with planetary surfaces.
• Using first of kind:– …two point measurements
of ions and electrons near the Moon, with unprecedented energy coverage and resolution; beyond LP electron reflectometry capability
Trace sputtered ionsback to lunar surface
Secondary and photo-electronsaccelerated from charged lunar surfacereveal regolith surface properties
Secondary electronsmeasured by LunarProspector [Halekas et al. 2008]
ARTEMIS
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ARTEMIS from a Planetary Perspective 13 September 9, 2008
Interior Structure of the Moon
• Apollo orbital measurements provided evidence of an iron core of about 400 km radius.• Lunar Prospector made similar (single instrument) measurements and confirmed the
Apollo subsatellite result.• Two-point measurements are needed to go beyond the current two-layer model of the
interior electrical conductivity.• ARTEMIS will provide measurements of both the “exciting” field and the resulting induced
magnetic field at about 100 km over a range of frequencies and sound the electrical conductivity profile above the core.
Core?
P2P1
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ARTEMIS from a Planetary Perspective 14 September 9, 2008
• In support of LRO:– ARTEMIS can provide comprehensive monitoring of Lunar Space Environment– Complements LRO/CRATER providing measurements below 6MeV• Note: ARTEMIS has been already supporting LRO via White Sands G/N testing
• Supports NAS’s Scientific Content of Exploration of the Moon to:– Understand the lunar atmosphere
ARTEMIS and Planetary
• In support of all missions– ARTEMIS provides comprehensive
monitoring of plasma conditions and lunar surface electric fields
– Allows study of the response of the lunar exosphere and dust to external drivers
– ARTEMIS provides solar wind monitoring
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ARTEMIS from a Planetary Perspective 15 September 9, 2008
Summary
• ARTEMIS consists of two well-instrumented spacecraft measuring the Moon’s plasma and magnetic environment.
• ARTEMIS can determine
– How dust is levitated
– The interior electrical conductivity of the Moon
– Whether the Moon has significant outgassing episodes
– The effect of the exploration program on the lunar exosphere
– The fundamental physical processes at work in a magnetized plasma
• ARTEMIS is effectively a new mission with high science return at low cost
– Can provide high value science return to the community
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