Modelling long-term trends in lunar exposure to the Earth's plasmasheet - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Annales Geophysicae Année : 2007

Modelling long-term trends in lunar exposure to the Earth's plasmasheet

M. Hapgood
  • Fonction : Auteur
  • PersonId : 853367

Résumé

This paper shows how the exposure of the Moon to the Earth's plasmasheet is subject to decadal variations due to lunar precession. The latter is a key property of the Moon's apparent orbit around the Earth ? the nodes of that orbit precess around the ecliptic, completing one revolution every 18.6 years. This precession is responsible for a number of astronomical phenomena, e.g. the year to year drift of solar and lunar eclipse periods. It also controls the ecliptic latitude at which the Moon crosses the magnetotail and thus the number and duration of lunar encounters with the plasmasheet. This paper presents a detailed model of those encounters and applies it to the period 1960 to 2030. This shows that the total lunar exposure to the plasmasheet will vary from 10 h per month at a minimum of the eighteen-year cycle rising to 40 h per month at the maximum. These variations could have a profound impact on the accumulation of charge due plasmasheet electrons impacting the lunar surface. Thus we should expect the level of lunar surface charging to vary over the eighteen-year cycle. The literature contains reports that support this: several observations made during the cycle maximum of 1994?2000 are attributed to bombardment and charging of the lunar surface by plasmasheet electrons. Thus we conclude that lunar surface charging will vary markedly over an eighteen-year cycle driven by lunar precession. It is important to interpret lunar environment measurements in the context of this cycle and to allow for the cycle when designing equipment for deployment on the lunar surface. This is particularly important in respect of developing plans for robotic exploration on the lunar surface during the next cycle maximum of 2012?2019.
Fichier principal
Vignette du fichier
angeo-25-2037-2007.pdf (256.65 Ko) Télécharger le fichier
Origine : Accord explicite pour ce dépôt
Loading...

Dates et versions

hal-00318386 , version 1 (18-06-2008)

Identifiants

  • HAL Id : hal-00318386 , version 1

Citer

M. Hapgood. Modelling long-term trends in lunar exposure to the Earth's plasmasheet. Annales Geophysicae, 2007, 25 (9), pp.2037-2044. ⟨hal-00318386⟩

Collections

INSU EGU
85 Consultations
72 Téléchargements

Partager

Gmail Facebook X LinkedIn More