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Commercial microprocessors could be useful computational platforms in space systems, as long as the risk is bound. Many spacecraft are computationally constrained because all of the computation is done on a single radiation-hardened microprocessor. It is possible that a commercial microprocessor could be used for configuration, monitoring and background tasks that are not mission critical. Most commercial microprocessors are affected by radiation, including single-event effects (SEEs) that could be destructive to the component or corrupt the data. Part screening can help designers avoid components with destructive failure modes, and mitigation can suppress data corruption. We have been experimenting with a method for masking radiation-induced faults through the software executing on the microprocessor. While triple-modular redundancy (TMR) techniques are very effective at masking faults in software, the increased amount of execution time to complete the computation is not desirable. In this paper we present a technique for combining duplication with compare (DWC) with TMR that decreases observable errors by as much as 145 times with only a 2.35 time decrease in performance.

Los Alamos National Laboratory has been testing COTS electronic parts for potential use in small spacecraft and high altitude telemetry systems. In this paper, we present results of neutron and total ionizing dose (TID) testing.

Commercial microprocessors could be useful for space missions that do not require radiation-hardened microprocessors. For these missions, commercial microprocessors provide a lower power and less costly solution for data processing than a radiation-hardened microprocessor. Commercial microprocessors are more likely to have issues with single-event effects (SEEs) that could make it difficult to compute without faults. It is possible through part selection and radiation testing to eliminate commercial microprocessors with the most destructive radiation effects. This paper presents data on recent testing of several commercial microprocessors.

ARMs and microcontrollers are low-cost, low-power microprocessors that are frequently used in embedded computing. While not immune to the naturally occurring radiation environment in space, these microprocessors can be worthwhile replacements for space-grade microprocessors for non-mission-critical computational tasks. In this paper results from radiation testing for several available ARMs and microcontrollers are presented.

Digital signal processors (DSP) are microprocessor- like processing elements that are specifically designed for signal and image processing algorithms. DSPs share many of the same failure mechanisms as microprocessors, including component crashes, program crashes and silent data corruption (SDC). The root of these problems is often single- event upsets (SEUs) in caches or control circuitry. In testing we have found DSPs are very sensitive to SDC, where computationally incorrect output data is produced but program execution is not affected. SDC can be problematic as it is hard to detect and could lead to the corruption of on-orbit data. We found that SDC could be reduced through the use of triple modular redundancy. In this paper we present data on how software on DSPs is susceptible to radiation-induced upsets and software techniques for reducing SDC.

In this paper, we will present results from testing commercially-available synchronous dynamic random access memory (SDRAM) in high-energy protons and neutrons. Broad spectrum neutron tests were conducted at Los Alamos National Laboratory's Los Alamos Neutron Science Center (LANSCE) Irradiation of Chips and Electronics (ICE) House in October 2010. Mono-energetic proton tests were conducted at the Massachusetts General Hospital Burr Center in May 2011.

Recently, engineers have been studying on-payload networks for fast communication paths. Using intrasystem networks as a means to connect devices together allows for a flexible payload design that does not rely on dedicated communication paths between devices. In this manner, the data flow architecture of the system can be dynamically reconfigured to allow data routes to be optimized for the application or configured to route around devices that are temporarily or permanently unavailable. To use intrasystem networks, devices will need network controllers and switches. These devices are likely to be affected by single-event effects, which could affect data communication. In this paper, we will present radiation data and performance analysis for using a Broadcom network controller in a neutron environment.

Records of bit flips in the Cray-1 computer installed at Los Alamos, NM, in 1976 lead to an upset rate in the Cray-1's bipolar SRAMs that correlates with the single-event upsets (SEUs) being induced by the atmospheric neutrons.

Radiation testing was performed on three generations of commercial SONOS-based NROM flash memory products fabricated at technology nodes of 220 nm, 110 nm, and 90 nm. Neutron irradiation was investigated for mitigating latchup in these unhardened, commercial products. Although the behavior of the NROM memory technology appears to be consistent and well-behaved in radiation environments across multiple fabrication technologies and manufacturing technology nodes, existing commercial designs are incompatible with the requirements typically associated with space applications because of the sensitivities associated with the commercial CMOS underlayer and unhardened control circuitry.

During the past few years there have been numerous reports of changes in coda wave attenuation occurring before major earthquakes. These observations are important because they may provide insight into stress-related structural changes taking place in the focal region prior to the occurrence of large earthquakes. The results of these studies led us to suspect that temporal changes in coda wave attenuation might also accompany volcanic eruptions. By measuring power decay envelopes for earthquakes at Mount St. Helens recorded before, during, and after an eruption that took place during September 3--6, 1981, we found that coda Q/sup -1/ for frequencies between 6 and 30 Hz was 20--30% higher before the eruption than after. The change is attributed to an increase in the density of open microcracks in the rock associated with inflation of the volcano prior to the eruption. Q/sup -1/ was found to be only weakly dependent on frequency and displayed a slight peak near 10 Hz. The weak frequency dependence is attributed to the dominance of intrinsic attenuation over scattering attenuation, since it is generally accepted that intrinsic attenuation is constant with frequency, whereas scattering attenuation decreases strongly at higher frequencies. The weak frequency dependence of Q/sup -1/more » at Mount St. Helens contrasts with results reported for studies in nonvolcanic regions. The peak in Q/sup -1/ near 10 Hz at Mount St. Helens is attributed to the scale length of heterogeneity responsible for generating backscattered waves. Results for nonvolcanic regions have shown this peak to occur near 0.5 Hz. Thus a smaller scale length of heterogeneity is required to explain the 10-Hz peak at Mount St. Helens. copyright American Geophysical Union 1988« less