Space Research

The CAPS Launch Latch


Marman clamp ring
The Marman clamp ring.

VTT developed a Marman-type launch latch for the 20 kg CAPS instrument onboard NASA's Cassini orbiter. The launch latch is a part of a rotary actuator for the Cassini Plasma Spectrometer (CAPS) instrument developed by VTT under contract to the South-West Research Institute in San Antonio, TX, USA. The actuator includes a Marman-type, or a V-band launch latch machined from a single piece of aluminum. The latch, only 22 cm (8.7 in) in diameter, carries launch loads of the TV-set size, 20 kg (44 lb.) weighing CAPS instrument. The fully resettable latch is operated with a redundant Wax Thermal Actuator equipped with a specialized Latch Actuating Mechanism.

An integrated over-center mechanism is used to decrease the high tension in the latch ring suitable for the Latch Actuating Mechanism. Dimensioning of the latch is based on analytical study of the latch geometry and FEM modeling.

The launch latch is easily adjusted for different diameters and load cases while the resettable nature ensures low development and testing costs. The Wax Thermal Actuator may also be replaced with other non-explosive or explosive devices.

(c) VTT 2004
           Updated on Febuary 11, 2004