Stas Barabash

Abstract Apart from positive ions and electrons, negative ions are expected in various astrophysical environments. However, they have never been detected on the Moon until the Chang’E-6 mission. The NILS instrument onboard Chang’E-6 lander is the first dedicated instrument for detecting negative ions beyond Earth and has successfully obtained H− spectra on the lunar surface, providing an unprecedented opportunity to investigate their origin and distribution.

An extremely strong CME impacted Mars on July 12, 2011 while the Mars Express spacecraft was present inside the nightside ionosphere. Estimated solar wind density and speed during the event are 39 particles cm?3 and 730 km/s, corresponding to nominal solar wind flux at Mars when the solar system was ?1.1 Ga old.

We report a new population of suprathermal H+(?1.5–3 times the solar wind energy) around the Moon observed by SWIM/SARA on Chandrayaan-1. These ions have large initial velocity (>100 km s?1), and are observed on the dayside, near the terminator, and in the near wake region (100–200 km above the surface), when the Moon is located outside Earth's bowshock. Backtracing suggests that the source is located >500 km above the dayside lunar surface.