Specification • Cleanliness is an important design consideration which can be mitigated by the mechanical structure and processes. Systems adjacent to an optical payload may have more strict cleanliness requirements than non-optical payload. The following sections describe the requirements which deal with Cleanliness considerations for the JAS mechanical structure.
Implementation
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Custom Communications
Specification • Custom communications specifications by definition are not described by any single specification. The electrical parameters will be determined by the components involved in the design. For example, if the communications utilize gigabit (GTX) transceivers in an FPGA then the electrical requirements will be prescribed by the GTX specifications.
Data Types
Specification • The JAS standard does not require a specific length or encoding format for data types. Systems can define these based on what best suits their needs. Sizes, endianness, byte ordering, and bit ordering are typically driven based on the processing and memory architectures that are used. However, in order to...
Design Constraints
Specification • The following sections define some important design constraints that the program will levy on the system. The constraints will drive many of the choices in designing the mechanical system.
Device Access Service
Specification • The device access service, service type address 128, is used to request parameters from or command parameters to a specific device. The currently defined device access service parameters are shown in the following table. Service Type Service Subtype Subtype Description Cmd Tlm Service Parameters Data Types and Description 128 1...
Environmental Test Flow
Specification • Programs using JAS should practice testing per industry standards wherever possible. The following tests and operational environments shall be applied to the components or structure in the following order. Events 1 through 5 shall be used for qualification acceptance testing. Events 1-6 shall be considered for fatigue calculations. 1) 24ea,...
Exposure to Space Environment
Specification • This section is a system level consideration and is included for information purposes only. The view to space shall be considered for both thermal and radiation effects. Thermal-related issue: heat-dissipation Radiation-related: TID (lifetime), SEE, shielding and impact on mass
File Access Service
Specification • The file access service, service type address 129 is used to read from or write to files within a file system. The currently defined file access service parameters are shown in the following table. Service Type Service Subtype Subtype Description Cmd Tlm Service Parameters Data Types and Description 129 1...
Form Factor
Specification • While no specific form factor standard is specified in JAS it is highly recommended that programs make use of a standards-based mechanical design such as VPX defined by VITA. Although VPX is preferred, other standards may be considered for use as well. The consideration of alternate standards should carefully consider...
Humidity
Specification • The JAS housing shall meet all performance specifications during exposure to relative humidity varying from 0% to 60%.
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).
Loads
Specification • Loads shall be determined per the program Strength Qualification Plan.
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.
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.
Packaging for Thermal Dissipation
Specification • The preliminary JAS mounting details are defined by the baseplate details in ICD drawing xxxxxx. The JAS electronics box is meant to mount through the blue baseplate shown in the figure below. The figure shows a nominal 3x3 stack in an exploded view. JAS Mounting Exploded View Conducted Self-radiated panels...
Platform Management Service
Specification • The platform management service, service type address 130 is used to configure, manage, and monitor network specific resources. The currently defined platform management service parameters are shown in the following table. Service Type Service Subtype Subtype Description Cmd Tlm Service Parameters Data Types and Description 130 11 Network Topology Upload...
Pressure
Specification • The JAS structure shall meet all performance specifications during and after exposure to pressures varying from atmospheric to the space environment of 10-14 Torr. All thermal-vacuum ground based testing shall be conducted at pressures less than 10-6 Torr.
Pressure Change
Specification • The structure shall be designed to survive the change of pressure specified in the figure below. The launch and ascent pressure environment will lie between Pc(Max) and Pc(MIN). Pressure Change Within the envelope defined in figure above, the local rates of change will remain between the values shown in the...
Quasi-Static Loads
Specification • Quasi-static loads shall be applied per the program Strength Qualification Plan. The axial and radial acceleration loads are to be applied simultaneously for an 11 g (TBD?) load in the worst case direction.
Radiation Effects Mitigation
Specification • The primary space effect requiring mitigation is the radiation environment, which causes gradual degradation of electronic devices and single event effects (SEE). Parts that have demonstrated destructive SEE, such as SEL or SEGR, should not be incorporated into the node unless absolutely necessary. It is equally important to test the...
Survival Temperatures
Specification • The JAS support shall meet all performance specifications after being exposed to a minimal temperature range from -40 C to +60 C.
Time Management Service
Specification • The time access service, service type address 131 is used to access and manage time. The currently defined platform management service parameters are shown in the following table. Service Type Service Subtype Subtype Description Cmd Tlm Service Parameters Data Types and Description 131 1 Time Set X Time Time...
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