Experimental studies of lunar exosphere

O.I. Korablev1, A.A. Petrukovich1, E. Quémerais2, V.I. Gnedykh1, K.I. Marchenkov1

1 Space research Institute (IKI), Moscow2 LATMOS, Guyancourt, France

Brief history• Pre-Apollo searches:

– Polarization measurements: Fessenkov, Dollfus 10-9-10 bar

– Radioccultations (Mariner 7) : <3 10-9 H; 8 10-10 He; 8 10-12 Ar

– Lunar Transient Phenomena

• Apollo– SIDE: Suprathermal ion detector: 20Ne and 40Ar

detections– Cathode gauges: N2 assumption: 2 107cm-3 day …

2 105cm-3 night– LACE mass spectrometer: Ar, He H2O, CH4, N2,CO,

CO2– α-particle spectrometers (A15): 222Rn, 210Po– Orbital mass spectrometers (A15-16)– UV spectrometer (A17)

• Ground-based discovery of K and Na [Potter & Morgan 1988]

Hodges 1985

Sodium and Potassium

Potter & Morgan 1988

Images of the lunar sodium exosphere during total lunar eclipses Mendillo et al 1999

Sodium and Potassium II

Mechanisms

Stern 1999

Sprague et al1992

Mechanisms

Lucey 2009

Stern 1999

Recent space observations

• SARA /Chandrayan-1: low energy neutral atom sensor 10 eV – 3.3 keV and ion mass spectrometer (10 eV – 15 keV)

• UPI-TVIS/SELENE: UV and visible (Na D2, OI) narrow-band imager

• LAMP/MRO

UV-spectrometry from space

LRO/LAMP:-Spectral range 57–196 nm-Observation of the LCROSS plume-Mapping of lunar poles in L-alpha

LADEE mission: NASA 2012-UVS : 200–800 nm-NMS

UV-spectrometry from Luna Globe Orbiter LEVUS: Lunar Exosphere EUV/UV

spectrometer

• On the basis of PHEBUS/Bepi Colombo• French PI of PHEBUS: Eric Quémerais, 2 co-PIs• Detectors from Japan (customized Hamamatsu design)• Scanner system from IKI/Russia• LEVUS = spare of PHEBUS provided by France with interfaces

and scanner modified by IKI. IKI provides all prototypes for Luna Globe.

LEVUS : Science objectives

• To detect/reduce upper limits of expected components of the lunar exosphere

• To study the sources, sinks and transport mechanisms of exosphere species

• To explore the EUV range, not covered so far• To map the surface in the UV range• To study the solar wind and its interaction with the moon• UV observatory: comets,…• Terrestrial exosphere (geocorona)

LEVUS:

• EUV channel: 55–155 nm• FUV channel: 145–315 nm• 2 PMTs: 404, 422 nm: K, Ca lines• Scanner 360°

LEVUS optical scheme and detectors

Detectability of exospheric components

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