Star Tracker Mechanical Requirements

1
Star Tracker Mechanical Requirements
ASTS Requirements

• Angular Camera Stability 36 ArcSecconds
  (0.01deg) (Factor 2-3 lower also acceptable)
• Baffle Stability Angular 1.5º translational
  several mms (design dependent)
• Camera Operational Temperature Range -20º to 40º
  C
• Stay alive temps -40º to 40º C
• Baffle survival temps TBD (v-low to v-high)
• Power 4W each

Mechanical Design Constraints

• Lens weight 800g, Camera, electronics
  box700g. Camera cantilever weight 1.5KG (each)
• Baffle 400g (mounting bracket not incl.)
• Bracket, Camera Baffle to fit in envelope
  specified in dwg INTst01 -(avoiding cabling and
  TR cooling cables/tubing)
• Tracker interface to be finalized -will be a
  bolted interface
• 4 existing upper honeycomb inserts can be used
  an additional 2 inserts may be added
• Conical flange screw holes proposed dwg INTst03
  Tracker interface to be finalized

• 0 CTE material to be used for the bracket

2
Conclusions from April and October 2002
Discussions
Geometry Structure

• Star tracker achievable angle 38 deg from
  horizontal (AMS X-axis).
• Inboard Camera should be skewed 30 in th xy
  plane (X, -Y) this means the 2 brackets will not
  be identical.
• Isatecs FEA analysis indicates that mounting the
  star tracker to the Tracker is feasible!
• C. Gariulo (INFN Rome) will continue analysis for
  composite brackets using FEA. (with design input
  from E.Perrin, R.Siedling, R.Becker)
• Outgassing/thermal deformation study on tracker
  needed! Plane1 honeycomb Conical flange -in
  order to assess angular stability
• 1-piece composite camera box and bracket will be
  investigated. -camera box will maintain 1mm Al
  equivalent thickness (3mm composite) for particle
  shielding.
• Baffle is mounted separately to either the vacuum
  case (preferred) or the TRD M structure
• Cables 3 power, 3 signal (12V power required)
• Connector TBD

3
Conclusions from April and October 2002
Discussions
Thermal Design

• We are considering connecting the cameras to the
  Tracker cooling circuit to cool the 8W power, and
  obtain temperature stability and possibly better
  structural stability.
• Not much additional structure is needed to attach
  to the cooling circuit since the circuit passes
  only several cm from the star tracker. The
  circuit will most likely be supported by the ASTS
  bracket
• This option still needs discussion with the
  Tracker cooling group
• Outgassing/Thermal deformation study on tracker
  needed! Plane1 honeycomb Conical flange -in
  order to assess angular stability.
• Baffle (Black Anodized Aluminum!) needs to be
  studied and insulated from the VC /
  TRDMstructure
• Cameras/baffles should be included in CGS
  overall thermal model

4
Two design proposals
Conical Support
Tube Support