Specification • The JAS mechanical structure shall be designed to a prescribed Interface Control Drawing (ICD) as required by the application. Requirements called out in the ICD should include an answer to most of the design considerations in this specification.
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JAS Essential Elements
Other • The following essential elements are the minimum required to develop a JAS-compliant system. Communication Interface (physical, preferably serial) Protocols to communicate over the physical interface Network-connected nodes that implement the communication interface and protocols Network routing and addressing scheme(s) All of these items are tailorable based on recommendations in the...
JAS Profile Introductions
Other • The JAS architecture defines a small number of Profiles that form the basis for building the components required for a sensor interface and data processing electronics system. A node inherits the attributes of one or more Profiles. A Profile describes the purpose of that node within the Architecture and defines...
JAS Rationale and Motivation
Other • JAS is a versatile, scalable, tailorable, SWAP-efficient, node-based concept for implementing embedded systems. Such systems include sensor suites, host platform interfaces, signal and data processors, data buffering and storage, command and data handling, and other supporting hardware and software. JAS Origin Sandia National Laboratories, Los Alamos National Laboratories, and others...
JAS Toolbox Introduction
Other • The JAS standard is captured in the JAS Toolbox, and presented using a web-based content management system known as the Interactive Standards Publication Tool (ISPT). In addition to the JAS standard, the JAS Toolbox includes a set of Systems Engineering (SE) Tools, which provide system examples and modeling capabilities. The...
JAS versus PROPIN Trade Study
Other • Feature Comparison JAS has a number of positive impacts on budget, schedule, and performance. Below is a table that illustrates these advantages when comparing a JAS-based system to a PROPIN approach. Advantage Benefit Budget Schedule Performance Scalable processing systems Ability to add/remove as many nodes as are needed to support...
Joint Architecture Standard Overview
Other • The purpose of JAS is to realize a reusable set of common hardware and software module designs that can be easily scaled, configured, adapted, interconnected and integrated with industry standards and internally supported intellectual property (IP) to provide the functionality needed to support any payload sensor suite. JAS also provides...
Junction Temperatures
Specification • The design shall show positive margin against thermal design so junction temperatures do not exceed maximum component values for worst case orbits at beginning (BOL) and end of life (EOL).
Life
Specification • The JAS mechanical structure shall be constructed of materials capable of performing for the necessary mission life time (for example, 3 years storage in an inert atmosphere and 10 years on orbit). This analysis will require extensive parts and materials screening and processing.
Loads
Specification • Loads shall be determined per the program Strength Qualification Plan.
Local POL Power Conversion
Profile • PS Node Local POL Conversion The output power from the PS node is one or more secondary voltage rails that are distributed throughout the system. This distributed secondary voltage is typically a higher voltage than those required by the components on the other nodes in order to improve efficiency by...
MAGE Strength
Specification • The JAS mechanical structure shall consider tooling to hold it while installing and transporting components. Features for mounting the hardware that supports the system shall be included. A static 4 G load shall be used with positive margins per this document. Mechanical Aerospace Ground Equipment (MAGE)
Margins of Safety
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...
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 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-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...
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 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...
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