Date of Award

6-2011

Degree Name

MS in Aerospace Engineering

Department

Aerospace Engineering

Advisor

Dr. Jordi Puig-Suari

Abstract

The CubeSat standard originated in 1999. It was a joint development led by Dr. Jordi Puig-Suari of California State Polytechnic University San Luis Obispo and Professor Robert Twiggs of Stanford University. The engineering challenges that have come from this picosatellite class have created incredible educational opportunities for engineering students throughout the world. Since the challenges of engineering a CubeSat abound the designers are always looking at novel and even revolutionary solutions to each one. One of those opportunities is in thermal subsystem design, implementation and characterization. A potential solution for CubeSats is adaptive component usage.

This thesis is the written catalogue of my study of adaptive component utilization to solve the thermal management problem inherent in picosatellites. Inside the limited design space of a picosatellite’s electrical, mechanical and software subsystems active spacecraft thermal control often is a necessary forfeiture. This does not preclude CubeSat teams from addressing the thermal aspect of spacecraft design. To the contrary it forces them down a different route to ensuring the spacecraft is verified to meet appropriate environmental constraints. Most CubeSat teams, Cal Poly included, use punishing qualification testing, robust system design and a restricted spacecraft operational lifespan ensure their system will operate through all of the environments it will encounter during launch, separation, spacecraft activation and on until the end of operations.

The testing, engineering and modeling I performed were to answer the hypothesis, can a standard* 1-U CubeSat utilize existing hardware and software to improve its thermal condition and operational lifetime?

This hypothesis assumes thermal control or situational improvement would have to be gained without the addition of thermal control surfaces, active heaters, heat pipes or louvers and no additional flight software. Ground control software and operation alterations were explicitly not included in these assumptions.

The thesis began with defining the many unknowns that existed in the material properties. This required: research into the methods required, specialized measurement hardware to be obtained and set-up, controlled measurements to be taken and thorough testing procedures to be developed. Once the unknowns were better defined the thesis required a detailed satellite thermal analysis by multiple methods along with both thermal vacuum chamber simulation trials and finally on-orbit testing.

Based on the research, modeling and testing performed and results obtained through this study, yes, a standard* 1-U CubeSat utilizing existing hardware and software can improve its thermal condition and operational lifetime. As is shown in Section 3.0 and discussed in detail in Section 4.0, utilizing only the onboard electronics and existing flight software the orbital temperature delta that components are experiencing can be reduced by up to 35.8%. Further analyses in section 4.0 use the temperature data to show that by lowering the temperature deltas the satellite does in fact have the capability to both improve its lifetime and certain key subsystem performance parameters.

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