Portal de Periódicos da CAPES

Trapped solar wind helium and neon in Surveyor 3 material

1971; Elsevier BV; Volume: 10; Issue: 3 Linguagem: Inglês

10.1016/0012-821x(71)90034-3

1385-013X

F. Bühler, P. Eberhardt, J. Geiss, J. Schwarzmüller,

Ionosphere and magnetosphere dynamics

The Apollo 12 astronauts salvaged an unpainted Al-tube from the Surveyor 3 spacecraft. We measured He and Ne in sectors cut from a small ring from this tube. The lower side of the tube is contaminated by lunar dust, which cannot be completely removed by ultrasonic cleaning. The upper half shows very little or no dust contamination and contains trapped solar wind He and Ne with 4He/20Ne= 295 in the trapped gas. This value is lower than the ratios measured by the Apollo 11 and 12 SWC experiments. This could be due to4He diffusion loss or to a small residual dust contamination. The4He distribution around the Al-tube is in agreement with the theoretically expected distribution and corresponds to an average solar wind4He flux of 7 × 106 cm−2 sec−1. If4He diffusion loss had occurred the average4He flux could be as high 13 × 106 cm−2 sec−1. Neglecting the small influences of a possible dust contamination or of diffusion loss we obtain the following average isotopic compositions for the solar wind during the exposure of the Surveyor 3 material: 4He/3He= 2700±130;20Ne/22Ne= 13.3±0.4 and 22Ne/21Ne= 31±5. Compared with the Apollo 11 and 12 SWC results the4He/3He ratio is unexpectedly high.