Geometry Update

Spacecraft model

LAT electronics

LAT mass

Spacecraft

Plan: replace monolithic “spacecraft” cylinder with a collection of the more massive volumes, including

Primary structure, skirt, optical bench, propellant & tank, batteries, electronics boxes, reaction wheels, GBM detectors.

Spacecraft (cont'd)

Status: have enough information to make a stab at incorporating most of the components. Size and position information for some (e.g. reaction wheels) is very vague, but good enough to start with. Need to do something about GBM support material.

So far only primary structure volumes exist in xml description but most other volumes will follow quickly.

LAT + Primary Structure

LAT Electronics

With the spacecraft properly located it became obvious that something had to be done about the LAT electronics. Mike Huffer referred me to LAT-TD-00564, which had all the information required to quickly position boxes of the proper dimensions and masses in our model.

LAT shell
+ electronics
+ prim. struct.

LAT Electronics Improvements

Model boxes as an aluminum shell of proper thickness containing Cu/Si mixture (will be different densities for different boxes to make up correct total mass).

Add the copper cabling which runs from and between the boxes. Engineers estimate about half the mass is near the center (GASU) so will use 2 copper “materials” of appropriate densities.

Modeling
Electronics
Cables

(planned; not yet in

the model)

Mass Comparison

radiators (80 kg)

Known missing

cabling (30 kg)

BEA

See also

http://www.slac.stanford.edu/exp/glast/ground/LATSoft/geometry/notes/massSummary.shtml

Work estimates

LAT electronics refinement:

1-2 days

Spacecraft

a few days for most of the requested components

GBM detectors could take longer

Missing mass

??

Joanne Bogart

2007-03-02T15:43:47