301 Critical Design Review  and were  further reduced for Acceptance/Qualification Testing . This progression  almost insures acceptable margins for the mechanism if all loads and frictions are accurately  determined  or are conservatively estimated at the beginning of the design phase . At delivery, because the initial design  will be driven by these higher factors of safety, the unit will assuredly have a higher torque margin than  required. The proof of concept tool provided the design team friction and load value s. 

Torque margin requirements can be managed effectively if unknown variables like friction and losses can  be anticipated or tested in a proof of concept model early during the program progression.  

Proof of concept testing is invaluable   The bolt design utilizes a shoulder bolt  to limit the travel of the bolt . Standard military part number shoulder  bolts are made of 300 series stainless steel . 300 series stainless steel  bolts have relatively low  strength,  low hardness , and are prone to gall . A shoulder bolt was manufactured from high -strength stainless steel  to prevent galling. Initial development testing  was performed used a 300 series shoulder bolt , before a highstrength shoulder bolt could be manufactured. The 300 series shoulder bolt galled as predicted and drag  increased over time.    Proof of concept test ing is invaluable to confirm design assumptions and identify possible issues . Testing  should be performed as early as possible to limit schedule impacts.  

Systematic analysis reduces s ystem risks   High latch stiffness is critical to the NICER system . Stiffness of a system is a combination of its  components  and joints . Slippage between mating surfaces reduces overall stiffness. The deployment and latch  mechanism uses  many different methods to assure high latch stiffness . The latch design has no play   between parts when latched, and all joints are sufficiently loaded to prevent slippage.  The deployment  latching system exceeded program expectations as analyzed.    When high stiffness is required, all play should be eliminated. A systematic tolerance analysis  should be  performed to minimize joint mismatch and slippage.  

Summary and Discussion  

The Deployment and Latching Mechanism for NICER, utilizes an innovative new latching system . Providing  a stable, high- stiffness structure in the two positions . The mechanism consists of two rotary  actuator s and  an over-center  slider crank mechanism latch. The system has successfully completed development,  protoqual  and life testin g. Moog delivered the Deployment and Positioning System containing the  deployment and latching mechanism on July 2015.    The deployment and latching mechanism solves many space systems problems : 

High stiffness deployable platform   The design utilizes Moog’s  high reliable space heritage actuators providing robust repeatable positioning.  The new latching system locks the platform firmly in place with very high stiffness, with no power applied.  

High stiffness in multiple positions  with repetitive latching   Design enables  repetitive  latching in multiple positions without any loss of stiffness  in both rotational  directions . 

NASA robotic interfaces   Design incorporates NASA ’s new Standard D exterous Grapple Fixtures , enabling robotic manipulation of  all actuators b y NASA’s Dextre, also known as the Special Pur pose Dexterous  Manipulator . 

High stiffness to weight  ratio  In comparison, an extremely large actuator would be required to be powered on to meet equivalent stiffness.