Specification • Margin of Safety (MS) is defined as MS = 1/R - 1, where R is the ratio of the factored applied load (or stress) to the allowable load (or stress) and shall be greater than 0. Margin of Safety Calculation The specific failure theory used to determine the allowable load...
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Mass Properties
Specification • The JAS mechanical structure shall attempt to optimize mass, center of gravity, and moments of inertia.
Material Properties and Allowables
Specification • The JAS mechanical structure design of the metallic parts shall use A Basis allowables from MIL-HDBK-5 or equivalent. The design of the composite parts shall use B Basis allowables generated using the methodology in MIL-HDBK-17 or equivalent.
Materials
Specification • The JAS mechanical structure shall be constructed of materials capable of performing at the specified orbit for a minimum of ten years after being stored in an inert gas environment and after exposure to clean air during testing, launch, and ascension. The use of the following materials is prohibited: Zinc,...
Mechanical
Profile • The recommended CH implementation is on a 6U VPX board, as defined in the VITA 46 standard and the Mechanical Specification. VPX is preferred for a number of reasons, a few of which include: 3U and 6U board formats to accommodate varying sizes High-density connectors and flexible pinout Availability of...
Mechanical
Profile • The recommended PS implementation is on a 6U VPX board, as defined in the VITA 46 standard and the Mechanical Specification. VPX is preferred for a number of reasons, a few of which include: 3U and 6U board formats to accommodate varying sizes High-density connectors and flexible pinout Availability of...
Mechanical Interface Design
Specification • The JAS mechanical structure as described in this Mechanical specification will support applications intended for a space environment and will provide stable mechanical structure for the electronics during launch and while operating in a high vacuum.
Mechanical Specification
Specification • The Mechanical Specification provides details about mechanical interface design, environmental impacts, and design constraints that should be considered for implementing mechanical structures in a JAS-based system. The figure below provides context of where the Mechanical Specification resides in the JAS standard. JAS Standard Hierarchy
Megabit Interfaces
Profile • There are several megabit interfaces that may be utilized on the CH node. Some examples of these include: SpaceWire RS-422, RS-232 MIL-STD-1553 CAN bus SpaceWire is the preferred solution for systems requiring data rates below 200 Mbps. SpaceWire links can scale from 2 to 200 Mbps at full duplex and...
Megabit-class Interfaces
Profile • There are several megabit-class interfaces that may be utilized on the PS node. Some examples of these include: SpaceWire RS-422, RS-232 MIL-STD-1553 CAN bus SpaceWire is the preferred solution for systems requiring data rates below 200 Mbps. SpaceWire links can scale from 2 to 200 Mbps and are well suited...
Memory Technologies
Profile • There are two types of memory technologies that are highly recommended for inclusion on the CH node: non-volatile flash or EEPROM, and higher-speed SRAM or SDRAM memory. Non-volatile memory is necessary to store the software that the microprocessor will execute upon power-up. Non-volatile memory may also be necessary to store...
Mezzanine Connector
Specification • A very useful option for plug-in modules is the ANSI/VITA 57 standard FPGA Mezzanine Card or FMC. This standard specifies an industry standard form factor utilizing a low profile, high-speed, high-pin count connector. The FMC connector can support very high bandwidths. The FMC approach solves the problem of how to...
Microprocessor
Profile • The CH Node is a microprocessor-based node that executes software stored in supplemental on-board memory. It is highly recommended that this microprocessor be radiation-hardened for reliability. The processor is typically attached to a non-volatile memory technology and a faster SRAM or SDRAM memory. A bus interface between the microprocessor and...
Mission Data Processing
Profile • This application employs the CH node as a mission data processor, utilizing the radiation-hardened microprocessor and on-board memories to perform computations in support of the payload’s mission. Additional optional memories or other board capabilities may be built onto the expansion port if desired. Mission Data Processing Instantiation This application is...
Molecular Contamination
Specification • For all components that will be in the vicinity of an optical payload and anywhere that contamination at the molecular level is an issue, all parts and materials must comply with ASTM E 595 for less than 1% Total Mass Loss (TML) and 0.1% CVCM. Thermal bake-out of all components...
Molecular Thermovac Testing
Specification • Thermovac temperature testing is required to determine dissipation at full power modes. A test plan needs to be developed and coordinated with the System Engineer.
Mounting Distortion Impact
Specification • The JAS mechanical structure shall maintain the electronics/PCBs listed below within given positions with distortions less than expected for the intended application.
Network Interfaces
Profile • All JAS nodes communicate through a standard set of interfaces that adhere to standard protocols. Refer to the Electrical Specification for physical layer technical information and Communication Specification for details on standard data protocols. This section describes two classes of network interfaces, megabit interfaces with line speeds below one gigabit...
Network Interfaces
Profile • All JAS nodes communicate through a standard set of interfaces that adhere to standard protocols. Refer to the Electrical Specification for physical layer technical information and Communication Specification for details on standard data protocols. This section describes megabit-class interfaces, with line speeds below one gigabit per second ( The protocols...
Network Topologies
Other • The selection of network topology is a critical component when developing multi-node or multi-point system architectures. A good choice of topology will require less power, have less complexity, higher reliability, and will orchestrate network traffic smoothly and quickly between nodes. Conversely, a poor choice of topology will introduce complex and...
Non-Volatile Memory Storage
Profile • Another common application of this profile is as an interface to non-volatile memories. These memories may contain firmware for FPGA nodes, mission data queued for transmission to the ground, payload configuration parameters, software, and more. Non-Volatile Memory Storage Instantiation In these applications, the CH node software is configured with services...
Obscuration
Specification • All JAS mechanical structure components shall be placed to prevent obscuration of the system view of space if the JAS electronics box will be used to radiate. Structural elements shall be kept an appropriate distance away from the JAS electronics housings.
Operating Temperatures
Specification • Operational temperatures are provided in thermal study for the nominal orbit. Excursions from predicted operational temperatures shall be increased by 11C (bilateral) when these temperatures are utilized in all fatigue analysis. For the purposes of fatigue the temperature excursion within an orbital season may be considered. For the purposes of...
Operational Vibrations
Specification • The JAS housing shall meet all of the displacement budgets, while subjected to the operational environment produced by the acceleration in file, TBD. These shall be used as base inputs.
Orientation
Specification • The JAS housing shall meet mechanical alignment performance specifications in any direction.
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