Reliability Risk in Electronic Applications due to Solar Energetic Particles
AND
Miniaturization of LIULIN-6U instrument for NASA DSTB Mission

by

Soleakhena Sam and Nathan G. Gabre
Undergraduate Student Research Program
Jim Adams and Mark Christl, Mentors

Friday, 7 December 2007
Socialization : 10:15 a.m.
Presentation : 10:30 a.m.
Location: NSSTC, Room 2096
320 Sparkman Drive
Huntsville, AL 35805

Abstract: Reliability Risk in Electronic Applications due to Solar Energetic Particles

Evidence is presented by Xapsos that solar particle events are a self-organized critical phenomenon. A probabilistic model based on daily fluences of solar protons measured by the Geostationary Operational Environmental Satellites (GOES) is used to extract plots of event-integrated spectra for proton and heavier ions. Spectra are given as a function of confidence level and mission time period during solar maximum. It is our hope to predict the absolute spectra of solar particle events at various confidence levels in order to aid spacecraft design applications. The goal is to provide a model that provides the designer with the worst case solar energetic particle event at a confidence level chosen by him for his mission. The elemental energy spectra from this event will be used in the Model for Radiation Effects on Electronics to estimate single effect rates during the designer's mission.

Abstract: Miniaturization of LIULIN-6U instrument for NASA DSTB Mission

Over the last several years, NASA's Deep Space Test-Bed (DSTB) Facility was developed to investigate the effects of galactic cosmic rays (GCRs), and more in general, ionizing radiation on crewed spacecraft during interplanetary missions to the Moon and Mars. A number of radiation-shielding tests have been conducted via space shuttle and ISS experiments; however, in terms of cost-effectiveness and convenience, it has been found that this is not the best approach. An alternate method is based on long duration, high-altitude polar balloon flights. This research can be conducted utilizing NASA's Scientific Balloon Facility (NSBF). The DSTB LIULIN-6U has not been flown in this balloon environment and we plan to test this instrument on a third-party balloon flight as a piggy-back payload.

The LIULIN-6U spectrometer system is designed to measure the deposited energy from primary and secondary radiation particles present in the atmosphere behind various shielding materials. The DSTB instrument consists of four mobile dosimeter units (MDUs) and one Control and Interface Unit for Management (CIUM) of the system. The CIUM is connected via a RS232 interface to a standard PC running the LIULIN software that records 512 bytes worth of radiation dose and flux data for each of the dosimeter units (for a total of 2048 bytes read at each interval into the program.) Testing has been conducted using this configuration; as a result, radiation value standards have been established for future testing. Because testing is being conducted via third-party balloon flights, it is necessary that the balloon package be compact and be self contained.

Various tests have been conducted to analyze the communication interface of the LIULIN system, in terms of how it reads in data and sends out commands between the CIUM and the MDUs. As a result, it has been determined that the entire system can be minimized down to the CIUM and one MDU. In addition, a Netburner Smart Data Connector (SDC) board will serve as a mini-computer for data recording. Using the supplied Netburner software, programming tests have been conducted to establish how the SDC will go about storing the incoming data. Overall, it is desired that the LIULIN system and the SDC board can be housed together in one small case on the balloon's gondola. Once the unit is powered up, the LIULIN system should immediately begin reading data into the SDC board and automatically stop once the memory is full. In the end, this setup provides for a safe and practical testing experience.

BIOGRAPHICAL SKETCH: Soleakhena Sam

My name is Soleakhena Sam which means prosperity in Cambodian. I'm currently a rising senior Electrical Engineering Technology major at Old Dominion University, located in Norfolk, Virginia. I grew up in Newport News, Virginia not too far from the beach and I am the youngest of three children as well as an avid basketball player.

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