Sub-keV Atom Reflecting Analyser (SARA – ESA/ISRO)
The Sub-keV Atom Reflecting Analyser, developed by ESA with the Swedish Institute of Space Physics and ISRO's Space Physics Laboratory, mapped the lunar surface composition using low-energy neutral atoms sputtered from the surface by the solar wind.
SARA made an unexpected discovery: a substantial fraction of the solar wind protons striking the Moon are reflected back to space as energetic neutral hydrogen atoms, rather than being fully absorbed by the regolith as previously assumed. It also imaged "mini-magnetospheres" — regions where local magnetic anomalies shield the surface from the solar wind — advancing understanding of how airless bodies interact with space weather.