This animation shows how the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument on LRO works. It starts with a wide view of the LRO spacecraft with cosmic rays buzzing by around it then graduallly pushes in on the CRaTER instrument. We see a cutaway of the instrument as a cosmic ray enters the telescope and passes through layers of tissue-equivalent plastics with sensors laid in between.
By detecting the amounts, types, and sources of radiation passing through medical-grade tissue equivalent plastics, CRaTER gives researchers an idea of what risks a human in the lunar environment might encounter. This image shows the animated cutaway of the instrument and points out what the different parts are.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 188.8.131.52.0