Spacecraft Accommodation

1
Spacecraft Accommodation Resources
HMI00370A

• Brock Carpenter
• HMI System Engineering
• Brock.A.Carpenter_at_LMCo.com
• 650-424-2776

2
S/C Accommodations Resources Agenda

• S/C Accommodations
• Current Status
• Interface Control Documents
• HMI Resources
• Mass
• Power
• Data Rates
• Spacecraft Resources
• ICD Development (Open Action Items)

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S/C Accommodations Current Status

• No major spacecraft compatibility issues with HMI
• Spacecraft appears capable of providing
  sufficient critical resources volume, mass,
  power, stability, telemetry, and thermal
  fields-of-view
• Updated Optics Package and Electronics Box
  designs need to be incorporated into the
  Interface Control Document
• Electronics Box volume and mass have increased
  since the last interface working group
• Optics Package volume has increased since the
  last interface working group
• Informal technical exchanges show increases are
  acceptable
• Mechanical interface control drawings being
  updated for presentation to SDO

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S/C Accommodations S/C to HMI Interface
Control Document

• HMI00241 Sections 01 02 Cover , Signatures,
  Introduction
• HMI00243 Section 03 Mechanical
• HMI00244 Section 04 Thermal
• HMI00245 Section 05 Electrical
• HMI00246 Section 06 CDH
• HMI00247 Section 07 CDH Ops
• HMI00248 Section 08 GNC
• HMI00249 Section 09 Contamination
• HMI00250 Section 10 Environments
• HMI00251 Section 30 Mechanical Implementation
• HMI00252 Section 40 Thermal Implementation
• HMI00253 Section 50 Electrical Implementation
• HMI00254 Section 60 CDH Implementation
• HMI00255 Section 70 IT Implementation
• HMI00235 SDO Electrical System Specification
• HMI00285 SDO High-Speed Bus Interface Control
  Document (SpaceWire)

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HMI Installation on the SDO Spacecraft

• Thermal fields of view are sufficient for HMI.
• Radiators for the CCDs on the optics package have
  unobstructed view of deep space
• Camera electronics boxes require radiator
  extensions
• Main electronics box mounted on radiator which
  has nearly unobstructed view of deep space

HMI Optics Pkg.
HMI Electronics Box
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Optics Package Envelope

• Envelope Dimensions
• Overall 47" x 32.5" x 11.3"
• MLI, not shown, adds ½ inch to overall length
• For reference, X-Y rectangle encompassing
  mounting bolts/pins on the Inst. Module 34.5" x
  31.9"
• For reference, main box dimensions 33" x 21.5"
  x 6.3"
• Critical dimensions are controlled by the HMI
  Mechanical Interface Drawing, 2H00019

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HMI Electronics Box Envelope
8
HMI Resources - Mass

• Notes
• Margin for HMI exceeds the recommended 25 for
  PDR considering the S/C is holding 20 margin
• Mass Estimates from Nov. 2003 HMI Mass Summary
  Report - HMI00157H
• Harness Mass based on 4 meter maximum length
• Harness shielding requirements still being worked

9
HMI Resources - Average Power

• Notes
• Margin for HMI exceeds the recommended 25 for
  PDR considering the S/C is holding 20 margin
• Power Estimates from Nov. 2003 HMI Power Report -
  HMI00158G

10
HMI Resources Data Rates

• Science 1355 High-Speed Bus - SpaceWire
• Allocation of 55 Mbps is sufficient for HMI
• Compression will be tailored to fully utilize the
  available link
• Housekeeping 1553 Bus
• Nominal rate allocation of 2 kbps is sufficient
  for HMI
• Based on MDI and current preliminary telemetry
  list by using several packet types each with its
  own application identifier (APID). Expect to
  produce one Health Safety packet every 4
  seconds, one Image ID packet every 2 seconds and
  fill in remainder 2 slots every 8 seconds with
  diagnostic data, memory dumps, command summary,
  etc.
• Reduced rate allocation of 1 kbps is sufficient
  for HMI
• S/C will filter nominal rate based upon APID
• Critical (emergency) rate allocation of 100 bps
  is sufficient for HMI
• S/C will filter nominal rate based upon APID
• Command Uplink
• Allocation of 2 kbps is sufficient for HMI
• Expectation is to send a few commands each day

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Spacecraft Resources

• Spacecraft Pointing Stability
• The spacecraft shall maintain the HMI reference
  boresight to within 200 arc-seconds of sun
  center.
• The spacecraft shall maintain the HMI roll
  reference to within 100 arc-seconds of the
  projection of solar North onto the plane of the
  sky .
• The spacecraft shall maintain drift between the
  spacecraft and HMI reference boresights to within
  14 arc-seconds in the pitch and roll (Y Z) axes
  over a period not less than one week.
• The spacecraft jitter at the HMI mounting
  interface to the optical bench shall be less than
  5 arcsec (3 sigma) in the pitch, yaw, and roll
  (X, Y, Z) axes. (Frequency content is under
  study.)
• Spacecraft Thermal Environment
• The HMI Optics Package shall be thermally
  isolated from the spacecraft to allow independent
  thermal control.
• The spacecraft shall provide a sink temperature
  sufficient to maintain the HMI CCD at
  temperatures less than -70 C.
• Spacecraft Off-point Roll Capability
• The spacecraft shall be capable of 360 rolls
  while maintaining accurate sun pointing.
• The spacecraft shall be capable of off-points up
  to 12 arc-minutes from disk center while
  maintaining nominal jitter performance.

12
HMI ICD Open Action Items (1 of 2)

• M11 Comment on request to have Optics-Package
  mass simulator compatible with thermal/vac
  environments
• M12 Review SDO tolerance of Optics-Package
  mounting foot pin-to-pin tolerances on
  Instrument Module
• E2 Review SDO design that power-on transient to
  be controlled by SSPC switches in subsystem
  power nodes (SPNs)
• E11 Review requirement that the harnesses to the
  survival heaters/sensors will be provided by
  GSFC
• E13 Review CCD decontam heater relay-circuit
  requirement for Elect. Box
• E14 Review clarifications in Draft 3 of
  Electrical Section (5) of the ICD
• E15 Review voltage-rise time plot in section 5 of
  the ICD
• E17 Review documentation of requirement that
  Instruments must survive hard shut down
• C3 Review SDO decision to not provide S/C
  housekeeping parameters for inclusion in the
  HMI high-speed data stream.

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HMI ICD Open Action Items (2 of 2)

• C8 Review SDO decision to not provide S/C
  pointing data for inclusion in the HMI
  high-speed data stream.
• C11 Comment on SDO method of using two 1553
  channels to provide HMI with 2 polls/second
• C12 Comment on SDO clarification of data rate
  switching w/o notification
• C13 Review addition of a time jammed flag to
  the time tone message
• GC6 Determine whether degraded calibration
  accuracy is acceptable in the event of S/C
  wheel failures.
• GC8 HMI to provide an updated table of HMI
  mechanism characteristics for S/C jitter
  analysis
• CT2 Review Draft 3 of Contam. Section (9) of the
  ICD incorporating HMI input
• EN1 Review Draft 3 of Environments Section (10)
  to include only test environments, not radiation
  environments
• G3 Review clarification of location of fault
  tolerance requirements in documentation
  (regarding heater fault tolerance)