 two block errors were noticed and correlated with the proton environment. To understand the source of the these errors, further analysis pointed to the need for additional proton testing with a larger sample size. After a second round of testing with a sample size of 100 die, it was determined that protons could lead to the block error condition, and 9 such events were noted on the 100 die sample set. Calculations of the error cross section and expected in-flight error rate showed good agreement with the anomaly rate. Fortunately, for the HST case the block errors were easily corrected with robust Reed- Solomon EDAC protection. The details of this example and others are found in [LaBe-98]. If the error condition were not easily corrected, or worse, if permanent failure resulted, the condition would not have been predicted with a small test sample set. When large numbers of a given device are flown either on the same spacecraft or across a large number of satellites, correspondingly large samples sizes must be used to assess all possible SEE modes. The exact number will be a function of both the orbit and the TID response of the DUT. If hard failure modes are possible, then large sample sizes may be warranted, even if only one device is to be flown. 4.1.3 Single Event Transients in Linear Devices: Transient effects in linear circuits were first reported by Koga, et al. in [Koga-93]. Their study examined transient signals that propagate to the output of analog circuits as a result of heavy ion irradiation. The following year, Ecoffet and coworkers confirmed the findings of Koga, et al., and extended the study to examine transients in several linear circuits, including LM 108 operational amplifiers, LM 111 voltage comparators, LM 218H operational amplifiers, and LM 211 voltage comparators [Ecof-94]. Their findings demonstrated the impact of the problem in each of these part types, and more importantly, showed that for some cases the heavy ion LET IV-27 threshold for initiating transients can be quite low (e.g. well