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RADIATION ANALYSIS FOR A
CUBESAT DEPLOYER
A Thesis Seminar
April 9, 2015
MaryCarmen Gonzalez-Dorbecker
Advisor: Dr. Kira Abercromby
PRESENTATION OVERVIEW
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Project Overview
PDSD Overview
Need/Importance
OLTARIS
Current work
Thesis end point
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WHAT AM I DOING
•  Analyzing radiation environment inside current P-POD
design
- how much gets through
- are there hot spots/areas that need more protection
•  Then: can analyze radiation environment inside current
interplanetary deployer (PDSD) design
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P-POD
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PDSD
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PDSD PT. 2
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WHY AM I DOING THIS
•  P-POD design well-established but there is no thorough
radiation analysis
•  Can help CubeSat developers design satellites if P-POD
environment is better understood
•  Everyone is getting interested in sending CubeSats on
interplanetary missions
- no knowledge yet of how well they’ll survive
- people like to ignore radiation because it is hard
•  Can also potentially improve preliminary design for an
interplanetary deployer
•  Important: Want to keep CubeSats as secondary payload
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HOW AM I DOING THIS
•  Using OLTARIS program for radiation analysis
•  Takes XML file of P-POD thicknesses along rays starting
at a given point
•  Output will then be read into MATLAB
•  “Map” plot can be made
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WHAT HAVE I DONE
•  Step 1: read P-POD CAD file into MATLAB
-reads in CAD file in STL or SLP format, also plots it
-uses triangles à saves vertices, also labels “faces” they
correspond with
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P-POD IN MATLAB
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WHAT HAVE I DONE PT.2
•  Step 2: Load in downloaded ray distribution file (42), find
intersections to get thickness
-more fun code: take three vertices, two points along ray, lots of
loops [all the rays, all the vertices (in 3s)]
-find if ray intersects any triangle (“face”) and if so, where
-store intersection points and find distance between them
-intersects in 2s, can be multiple pairs
-find distances for each pair and add up, save as
thickness variable
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WHAT HAVE I DONE PT.3
•  Step 3: Create XML file
-downloaded example file from OLTARIS, has the
required format:
-heading including creator and info about the file
type
-body of ray vector values and thicknesses along
each ray
-file close (closes each argument, like “end” in
MATLAB)
-added a loop around the body section so that it loops through
all of the ray coordinates and all of the thicknesses without
typing them in one by one
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XML EXAMPLE
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OLTARIS BACKGROUND
•  On-Line Tool for Assessing Radiation in Space
- NASA Langley Space Radiation Group
-for scientists and engineers
•  Choose environment, geometry, shielding material
- given options vs. uploads
- receiving material: silicon vs. tissue
•  Outputs dose as a function of depth
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OLTARIS VERIFICATION
•  NASA STD 7009
- “to provide uniform engineering and technical requirements for
processes, procedure, practices, and methods that have been endorsed as
standard for models and simulations (M&S) developed and used in
NASA programs and projects, including requirements for selection,
application, and design criteria of an item” (NASA STD 7009)
•  Compare results to measured data from ISS TEPC, STS
-“Tissue Equivalent Proportional Counter”, shuttle measurements
•  Validation Test:
-Create output from given sphere option
-Create identical sphere in CAD
-use code to get output on CAD sphere
-check how it matches to results from OLTARIS sphere
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WHAT AM I CURRENTLY
WORKING ON
•  Uploading XML file to OLTARIS, running it to get output
-then read output into MATLAB and create “map” plot
•  Edits and Improvements
-instead of only 42 rays, can change to higher amount
(takes a long of computational effort = LOTS of time)
-use multiple different starting points for rays, more
accurate way to read radiation throughout P-POD rather
than at just one spot
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END POINT
•  Deliverables:
-Have P-POD radiation “map” information available to
CubeSat developers
- internal: improvements to P-POD design can be
suggested based on results
•  “Nice to Have”:
-Method can be used to look at how PDSD looks
-can help to move forward with design ideas
•  Leaves plenty of room for future work/developments
•  ALSO: any CAD model can be subjected to radiation analysis
using this method/code!
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