1. THEMIS baseline + ARTEMIS
ARTEMIS Contributions to Planetary Exploration
THEMIS Extended Phase =
THEMIS baseline + ARTEMIS

2. Overview 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 and characterize source populations of particle radiation

3. Data volume: 100Mbits/day Orbit periods at moon: ~1 day
ARTEMIS payload, operations concept
SST
ESA
EFIa
EFIs
FGM
SCM
Tspin=3s
Data volume: 100Mbits/day
Orbit periods at moon: ~1 day
Relay:
3hr daily
DSN
BGS
Products: 2hr latency
Mission Ops
UCB
Probe instruments:
ESA: ElectroStatic Analyzer (i,e: 3eV-25keV; Carlson & McFadden) SST: Solid State Telescopes (i,e: keV; Larson) FGM: FluxGate Magnetometer (0-128Hz; Glassmeier, Auster & Baumjohann) SCM: SearchCoil Magnetometer (1Hz-4kHz; Roux & LeContel)
EFI: Electric Field Instrument (0-8kHz; Bonnell & Mozer)

4. ARTEMIS mission phases
Insertion: FY10; Science: FY11,12

5. ARTEMIS Heliophysics objectives Insertion FY10; Science: FY11,12
FY10: Translunar injection
FY11-12: 6mo Lissajous + 18 mo Lunar

6. Orbit stable for >3years; longer with little fuel
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

7. Removed 11Hz noise in magnetometer
Issues
Removed 11Hz noise in magnetometer
Need to change energy ranges to measure pickup ions
Best to have fine dE/E. Not mission critical

8. Heliophysics from the Moon
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

9. The Electrodynamic Environment of 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. 9 9

10. 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.
LADEE
ARTEMIS-1
ARTEMIS-2 10 10

11. Lunar Exosphere Solar Wind Exospheric Pickup Ion
ARTEMIS mass spectrometry of pickup ions assumed “protons”
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.
V,y H+
V,x
He+
H2O+ S+
Solar Wind
ARTEMIS-2
Exospheric
Pickup
Ion
ARTEMIS-1
Hartle et al., 2005

12. ARTEMIS and 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
Secondary electrons
measured by Lunar
Prospector [Halekas et al. 2008]
Trace sputtered ions
back to lunar surface
ARTEMIS
Secondary and photo-electrons
accelerated from charged lunar surface
reveal regolith surface properties

13. Interior Structure of the MoonP1 P2
Core?
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. 13 13

14. ARTEMIS and Planetary 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
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

15. 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 15 15