Section 5 Part 1 Spacecraft

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Section 5 - Part 1Spacecraft
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Top-Level S/C Requirements for Hyperion

• Electrical
• 1773 interface for command, telemetry, and 1-Hz
  timing signal. Hyperion will meet I/F
  requirements in EO-1 1773 ICD.
• 2 power services HEA/CEA and heaters, 28V ?7
• Provide about 78 watts orbit-average power (200 W
  peak)
• Mechanical
• Modify spacecraft layout, structure, mechanical
  GSE to accommodate HSA (35kg) two electronics
  boxes (7.0 kg each)
• Provide clear FOV for Hyperion while maintaining
  FOV of other components
• Thermal
• Hyperion components must comply with the
  cold-biased, low-heater power design philosophy
  of EO-1 passive radiators and survival heaters
• HSA thermally isolated from S/C, HEA and CEA
  dissipate most heat through radiators, but also
  thermally coupled to nadir deck
• ACS
• Assess ACS performance with Hyperion impacts from
  increased moments of inertia, and vibration and
  magnetic emissions from the cyrocooler
• Effects include reduced stability/performance
  margins, increased jitter, slower slews,
  calibration, alignment

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Overview of Spacecraft Changes for Hyperion

• Mechanical
• Two platforms built to mount three units HEA,
  CEA, HSA
• Mass increase from 529 kg to 588 kg, including
  structure modifications
• Structure safety factors reduced from 2.0/2.6 to
  1.6/2.0 (yield/ultimate)
• S-Band and X-Band antennas raised to maintain FOV
  and X-Band rotated
• Lifting fixtures re-designed
• Electrical
• Orbit-average power demand increase from 250
  watts to 320 watts
• Add louvers to battery panel and add solar cells
  to mitigate power increase
• PSE hardware modifications ACDS and PSE software
  modifications
• Additional harness added (Hyperion, solar array)
  and some harness re-routed
• Launch vehicle umbilical modified
• ACS performance reduced slew rate, pointing
  accuracy
• ALICE radiator removed FPE radiator partially
  blocked
• Delta V capability reduced from 90m/s to 80m/s
  due to mass increase

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EO-1 Avionics Configuration
ACDS Box
RWAs
PPT
ACE LVPC
CSS
Key
ACS
TAM
ACE RSN
Star Camera
NMP Technology
ACE I/O
IRU
New Technology
MTBs
Off-the-Shelf Technology
PROP I/O
Thrusters
CDH LVPC
Temperature
GPS
H/K RSN
Flex S/A
CDH
1773 Data Bus
M5
Comm RSN
S-Band
X-Band
RSN
PSE Box
Modulator
Power RSN
LVPC
WARP
RSN
Solar Array
SAD
S/A Module
ALI
RSN
RS-422
Batteries
Battery I/F
RT
AC
Output (2)
RT
Hyperion
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EO-1 Spacecraft Stowed Layout
(Pre-Hyperion)
Bay 1
Bay 3
Bay 6
Bay 4
Nadir View
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Spacecraft Mechanical Requirements

• Accommodate the Hyperion Sensor Assembly (HSA)
  with a NTE mass of 35 kgs two electronics boxes
  with a NTE mass of 7.0 kgs each
• The HSA shall be hard mounted by way of an
  instrument shelf to the S/C nadir deck on the -Y
  side with 12 fasteners. The HSA mounting surface
  shall be flat to within .25 mm provide for a
  4.84 0.05 inclination in the -Y direction
• The HSA hard mounted fundamental mode shall not
  be less then 70Hz
• Reduced from 75 Hz contingent on CLA results
• TRW shall provide the interface drill template
  for the mounting hole pattern. The drill fixture
  alignment to the S/C is 0.01 degrees, using
  tooling pins and optical alignment cube.
• The HSA FOV shall be clear of all S/C
  obstructions within 15 cone about optical
  centerline 30 cone about solar-calibration
  centerline
• Provide on orbit thermal stability within 10
  arcsec
• Provide the HSA with a dry nitrogen purge
• The Hyperion to S/C Interface Control Drawing
  defines the location mounting hole pattern for
  the electronic box assemblies

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Fields of View
Solar Cal intrusion into ALI FOV
S-Band Intrusion
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Spacecraft Configuration

• EO-1 Spacecraft Configuration with Hyperion
  (CONTINUED)

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Clearance with ALI FPE

• HEA/CEA Clearance with ALI FPE Radiator

HEA/CEA clearance w/ ALI Pallet
HEA clearance w/ FPE Radiator
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Spacecraft GSE Alterations

• The spacecraft lifting points and sling will
  require modifications to allow for vertical
  lifting.
• All outrigger hardware shown will need to be
  installed and removed during vertical lifting
  ops. All new GSE hardware is non-flight.
• Solar array assembly will not be impacted by GSE
  changes.

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S/C Mechanical Accommodations Summary

• Provided shelf over Z launch restraint for
  mounting HSA
• Provided baseplate on nadir deck for HEA/CEA
  mounting
• Rotated and raise X-Band S-Band antenna booms
  on nadir deck
• Modification of spacecraft lifting sling and new
  outrigger hardware required to replace lifting
  points blocked by HSA support structure
• ALI integration time will increase due to
  hardware addition
• Spacecraft alignment requirements increased
  substantially by HSA addition
• Overall S/C IT impacted by hardware additions.
  Partial obstruction of Z SA launch restraint
  will increase solar array integration time.

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Thermal Design Philosophy and Accommodation

• EO-1 spacecraft is a cold-bias design
• Passive Radiators
• Redundant survival heaters
• Designed to minimize make-up heater power
• Baseline estimates are 0 Watt for nominal orbit
  and 12 - 15W for battery panel during standby
  (not safemode)
• Louver to be added to reduce battery heater power
• Switch MLI blankets from black Kapton to
  aluminized Kapton on Nadir deck, except for areas
  identified by MIT/LL (e.g., nadirdeck surface in
  front of FPA radiator)
• Four available inputs for temperature sensors
• Final thermal accommodation in process. Delta
  Thermal CDR next week

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Hyperion Power Service

• Hyperion requires two power services
• Implementation
• All three RWAs powered from a single Solid State
  Power Circuit (SSPC). This makes two services
  available for Hyperion
• The cryocooler, its control electronics, and HEA
  power will be serviced by a single SSPC
• Heater power will be provided via the remaining
  SSPC. This includes survival heater power.
• Entire accommodation is performed via harness and
  software modifications (possible jumper change in
  the output module of the Power System Electronics
  (PSE) for power-on state)
• During launch and safe-mode, only the heater
  service is ON
• Addition of extra solar array circuit to increase
  available power

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Expected Targeting Capability
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ACS Actions

• All ACS Actions to be addressed in future TIM
• Establishing revised requirements and
  capabilities with Program Office
• Hyperion can be inserted into EO-1 without
  imposing mission critical obstacles

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Hyperion Software and Data Requirements

• All 1773 formats and protocol defined in 1773 ICD
• Telemetry and commands defined in Hyperion ICD
• Telemetry
• State of Health Packet, lt127 Words (123 data),
  1Hz
• Cooler Packet, lt511 Words (503 data), 1/4Hz
• Command
• Instrument Command, lt32 Words (29 words data), up
  to 16 per sec
• Cooler Command, lt512 Words (509 words data),
  1/4Hz
• Spacecraft will monitor Hyperion telemetry for
  health safety
• We have not yet identified which telemetry to
  monitor or action taken
• Hyperion will safe the instrument if UTCF packet
  not received for 5 consecutive seconds
• Spacecraft will issue Go to idle command prior
  to shutting off Hyperion power in controlled
  situations