Release Actuator Employing Components with Different Coefficients of Thermal Expansion

Reference#: P03089

Beginning in 1999, in an effort to reduce the costs of space science and exploration, academia developed the CubeSat, a miniaturized satellite. CubeSats could be made and launched for an estimated $65,000–$80,000 (2004). This price tag—far lower than most satellite launches, which cost tens of millions of dollars—has made the CubeSat a viable option for schools and universities around the world and the worldwide standard for small satellites. CubeSats are being used for everything from environmental sensing and fundamental biology research to testing of new spaceflight systems. As increasingly rigorous space objectives come online, overcoming power and volume limitations is becoming more crucial.

Researchers at The Johns Hopkins Applied Physics Laboratory were convinced that they needed a better release mechanism for use in restraining and releasing the CubeSat’s four solar-array panels. They developed an elegant, simple system that leverages the reliability and low-power needs of few moving parts (there are only two) and is compatible with the electrical power subsystems of small satellites and instruments. Shock has been virtually eliminated; the only stored energy resides in the kickoff spring. The few, simple parts translate into cost savings.

The principle of operation for the release mechanism is to use two parts that have complementary coefficients of thermal expansion (CTE). The interference is sized for the retaining force desired from the actuator. The low-CTE part is fastened to the part or assembly to be separated from the space vehicle. When the high-CTE part is reheated, the low-CTE part is freed, just as a bolt would be freed from a separation nut.

The device has been tested and has been shown to meet the stringent requirements of space systems, but it would also be beneficial on other platforms that operate autonomously in extreme environments, such as underwater vehicles and robots.

Mr. K. Chao
Phone: (443) 778-7927

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