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Tuesday, February 2 • 10:55 - 11:15
Structural Design Considerations for On-Orbit Service of Satellite Constellation

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Though it is not clear that currently proposed constellation satellites will be designed for robotic handling, it will happen eventually. Accessibility is a major issue. And the placement of components and the areas of structural stiffness are significant ‘real estate’ considerations. ‘Hard points’ are normally the high value locations. 

The presentation will assume the satellite is to be launched in a conventional fashion (as opposed to assembled on-orbit). This implies accepting launch authority rules (launcher interface configuration, minimum frequency requirement and finite element model for coupled launch analysis). Thus a stiff base plate will be assumed in this design approach. 

The selection of components to be considered as potential ORU’s (orbit replaceable units) is a major design driver with long term mass implications (Canadarm 1 vs 2 is a stark example). If there are any ORU’s, obviously they need to be accessible. And if a robot is to handle the structure, either before operation, or after, one stiff easy to access, robotic interface is needed. But the rest of the backbone structure can be buried. 

The first major constellation to include a robotic interface has the potential to set the standard. 

The design and finite element analysis of a small satellite configured for robotic release from ISS will be used to illustrate a microsat with robotic handling considered. It is based on maximizing stiffness/mass ratio. It is also based on performing very early FE analysis (www.gve.on.ca/FEfirst.html) to allow for early prediction of resonant frequencies and component vibration spectra. 

Designers of mass produced satellites should particularly consider early stage predictions of launch vibration spectra, because the spectra will drive cost and reliability of components. Specifying vibration levels for components is sometimes done by applying significant margins of safety to vibration spectra levels. But such an approach increases cost, at the same time as lowering reliability. Over tested components are more likely to fail. 

The issue of minimizing mass is very important for large satellites, but less so for the very smallest ones. It is unlikely that a large constellation of mid-sized satellites will ignore mass considerations. For groups of satellites to be released from the same launch vehicle, it would be desirable that no significant satellite resonances coincide with that of the launcher.

avatar for Andre Dupuis

Andre Dupuis

President and CEO, Space Strategies Consulting Ltd

avatar for Sherry Draisey

Sherry Draisey

Pres, Good Vibrations Engineering Ltd.

Tuesday February 2, 2016 10:55 - 11:15
Provence Room 45 The Esplanade, Toronto, ON M5E 1W2

Attendees (11)