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EPSRC Reference: GR/J88975/01
Title: AN INVESTIGATION INTO MULTIPLE-BIT UPSET AND SINGLE-EVENT LATCH-UP IN SPACECRAFT SOLID-STATE DATA RECORDERS
Principal Investigator: Sweeting, Professor Sir M
Other Investigators:
Underwood, Professor CI
Researcher Co-Investigators:
Project Partners:
Pre Nexus Migration QinetiQ
Department: Satellite Engineering Research
Organisation: University of Surrey
Scheme: Standard Research (Pre-FEC)
Starts: 01 August 1994 Ends: 31 July 1996 Value (£): 91,422
EPSRC Research Topic Classifications:
RF & Microwave Technology
EPSRC Industrial Sector Classifications:
Communications Aerospace, Defence and Marine
Related Grants:
Panel History:  
Summary on Grant Application Form
1. To investigate the mechanisms of single-event multiple-bit upset and single-event latch-up in spacecraft semiconductor memories;2. To characterise device behaviour with respect to the measured space radiation environment;3. To provide design criteria for the construction of cost-effective, yet reliable solid-state data recorders from commercial high-density RAMs for use in space.Progress:(First Six Months)This initial part of the research programme has been devoted to the development of various software tools, together with the accumulation and analysis of in-flight data on Single-Event Effects (SEEs) in the Solid-State Data Recorders (SSDRs) on-board Surreys UoSAT-3, UoSAT-5, S80/T, KITSAT-I and PoSAT-I satellite missions. Data on the radiation environment inside these spacecraft has also been gathered from DRAs Cosmic-Ray Effects & Dosimetry (CREDO) payload on-board UoSAT-3, and Surreys Cosmic-Ray Experiments (CREs) on-board KITSAT- I and PoSAT- 1.We have successfully produced software tools to analyse the radiation environment data from the CREDO and CRE payloads, and through these have established the veracity of the AP8 and CREME radiation environment models (which are currently the engineering standards). We have found that the predictions of these models for low-Earth orbits is generally good for the trapped radiation population and for galactic cosmic-rays, but there are major deficiencies in the solar flare models. As a by-product of this analysis, we have also detected the long-term changes in the near-Earth radiation environment associated with the11-year solar cycle, including the doubling of the cosmic-ray flux since 1990. Having established the radiation environment for the memory devices on-board the spacecraft, we have used this information, together with SEE cross-section data derived from particle accelerator tests, to make predictions of SEE rates using the standard CREME and Bendel 2-parameter models. Simultaneously, we have been developing our own software model of the detailed particle interactions within the memory devices, which allow us to examine the effect of direct ionisation and particle-induced nuclear reactions (and their products) upon the sensitive volumes within the devices. When completed, we shall use this tool to investigate the various multiple-bit upset mechanisms we have identified. We have also carried out total ionising radiation dose studies on commercial off-the-shelf data-processing components using the Co-60 gamma-ray source at Surrey. These tests, coupled with our SEE analysis, will allow us to make recommendations as the use of such devices in the construction of inexpensive yet highly capable spacecraft data handling systems. Further flight tests of advanced memory devices will be carried out on the Chilean FASat-A satellite mission which will be launched in July 1995. A Further space environment monitoring payload (CEDEX) is also under construction for flight in early 1996 into a GTO/ Molniya orbit on-board the German Phase IIID satellite. Both these programmes are sponsored by Surrey Satellite Technology Ltd.
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Organisation Website: http://www.surrey.ac.uk