English: CRaTER is one of seven instruments aboard NASA’s Lunar Reconnaissance Orbiter spacecraft

CRaTER (Cosmic Ray Telescope for the Effects of Radiation) characterizes the global lunar radiation environment and its biological impacts by measuring galactic and solar cosmic ray radiation behind a "human tissue-equivalent" plastic.

CRaTER investigation goals:

Measure and characterize the deep space radiation environment in terms of LET spectra of galactic and solar cosmic rays (particularly above 10 MeV). Develop a novel instrument, steeped in flight heritage, that is simple, compact, and comparatively low-cost, but with sufficiently large geometric factor to measure LET spectra and its time variation in the lunar orbit. Investigate the effects of shielding by measuring LET spectra behind tissue-equivalent plastic.

Test models of radiation effects and shielding by verifying/validating model predictions of LET spectra with LRO measurements.