Single-event upset effects on the Clementine solid-state data recorder

The sensitivity of the Clementine 2.1-Gbit solid-state data recorder (SSDR) to single-event upsets was characterized in ground tests. Subsequent in situ measurements of the ambient radiation environment by experiments onboard Clementine permitted evaluation of the ability of models of the single-event phenomenon in the SSDR to be tested using actual data. Initial results from the analysis reveal a nearly constant background upset rate of similar to 71 bit flips/day for the SSDR. There is no obvious correlation with a solar proton event recorded by Clementine and several other spacecraft on Feb. 20-21, 1994, indicating that the SSDR was not sensitive to protons. The constant rate is thus interpreted as being a function of the galactic cosmic-ray heavy-ion environment. A pronounced lunar orbit altitude dependence has also been identified in the data though the cause has not yet been unambiguously identified.