REACT: Resettable Hold Down and Release Actuator for Space Applications

A new Hold Down and Release Mechanism (HDRM) for space applications has been developed as an alternative to current devices. A HDRM is a mechanism in charge of holding an element to the spacecraft structure during launch and releasing it under the user demand. These devices have to support a high load during launch and to be able to release this load when required. The HDRM, called REACT, shown in this work is able to work in a wider range of temperatures with respect to similar devices available in the market. The temperature restriction is one of the most critical limitations of current HDRMs for their use in space and other applications.

REACT is triggered by an SMA actuator, substituting the pyrotechnic actuators commonly used. The use of Shape Memory Alloys substituting pyrotechnic elements provides a number of advantages, such as the minimization of shock associated to the device during its actuation; the reduction of safety measurements during the installation and handling of these devices; and the possibility to perform activation tests repeatedly without having to remove/reinstall pin pullers devices.

These mechanisms are able to operate in the temperature range -90ºC to +125ºC and under hard vacuum conditions. The use of Shape Memory Alloys in the triggering actuators allows the developed devices to have minimum mass, one of the most critical requirements in space applications. A preliminary design of REACT and a set of analyses will be shown in this paper. The results obtained during the initial tests of breadboard models of REACT devices will be part of this work. Engineering Models of both mechanisms are currently being built and tested. The main characteristics of these devices as well as the results of test campaigns will be reported in this work.