Why is there no assembly level object at the s/c top level.  All the subsystems within the s/c bus need to be assembled because all the s/c bus subsystems are very much intertwined together. So there has to be an assembly object at the top of the bus?

Assembly I&T is performed by the Space Subsystem object.  Adding an additional Assembly object at the top of multiple subsystem-assembly pairings produces very high redundant costs.  However, the estimator can certainly perform organizational calibration and use worksheet set multipliers to adjust outputs at this top level if an overall assembly is added.

The Space Missions catalog estimates “Assembly & Integration”, “System Test”, and “Ground Support” Equipment supporting the following I&T functions: S/C system-level (any I&T beyond subsystem-level), Instrument-S/C I&T and Observatory-level I&T (w/ the S/C + Instruments). Subsystem-level support to this process is carried with the Subsystems in the I&T and Launch Ops phases.   {Please see response for this webinar Q&A for more detail regarding TPSM Assemblies.}

To watch the "Best Practices using the TruePlanning Space Missions" Webinar, click here.