Hold Down and Release System: the reliable device for satellite appendages
The ARA Mk3 Hold Down and Release System employs the principle of gradually reducing pretension in a stack by cutting an aramid holddown cable with a Thermal Knife.
This method yields a very low deployment shock when compared to a pyrotechnic device. Because the Thermal Knife system is insensitive to electro-magnetic disturbances, a spontaneous release is impossible. The Hold Down and Release System further comprises stackable cylindrical titanium CupCones, which are integrated in the elements to be restrained and deployed (e.g. in case of a solar array: the solar panels).
The stack is preloaded by a Kevlar restraint cable running from the top of the stack to the HDRS bracket at the bottom. The preloaded stack transfers loads from the restrained appendages via the CupCones into the interfacing foot bracket. Various adapter brackets can be provided to accommodate the HDRS on different interfaces.
The Thermal Knives can be used repetitively without refurbishment. Thus, all standard performance tests can be executed on the actual flight hardware at subsystem and system level. The only consumables in this process are the holddown cables.