PSR Section 13

1
Section 13 Attitude Control Data System (ACDS)
. . . Steve Schumacher Swales Aerospace
2
Agenda

• ACDS Qualification Test Flow
• ACDS Box Block Diagram
• Changes Since CDR
• Command Data Handling (CDH) Status
• Attitude Control Electronics (ACE) Status
• ACDS Problems/Issues

3
ACDS Qualification Test Flow(GSFC MIDEX Design,
also used for MAP)
4
ACDS Box Block Diagram
Power System Electronics (PSE)
1773 Fiber Optic Data Bus
ACE
CDH
Inertial Reference Unit (IRU)
Coarse Sun Sensors (4x)
GPS Receiver (GPS)
Three-Axis Magnetometer (TAM)
HOP Actuators (HOPS)
Autonomous Star Tracker (AST)
Light Flex Solar Array (LFSA)
Reaction Wheels (RWA, 3x)
WARP Science Data Recorder
Magnetic Torquer Bars (MTB, 3x)
S-band Transponder
Reaction Control System (RCS)
Spacecraft Heaters (Bays 1-6)
Pulsed Plasma Thruster (PPT)
Spacecraft Temperature Sensors
Solar Array Drive (SADA/ECU)
Solar Array (Hinge pots and Htr)
Solar Array (Dep HTR and pot)
Solar Array Drive Temperature
Umbilical and APTS Racks
5
Verification Matrix
6
Changes Since CDR

• Modifications to HK RSN board
• Design changes and repairs for GPS data flow
  control and Sub-Second Timer Latch
• 1773 Type 3 changed to Type 4
• Comm RSN special command changed from warm start
  to cold start

7
Command Data Handling (CDH) Status

• M5 processor interfaces to 1773 bus, Comm RSN
  (medium speed serial port), WARP science data
  recorder and APTS Rack are integrated
• Comm RSN interfaces to PSE and for 1773 bus,
  Special Command Resets, S-band transponder
  status/commands/telemetry, Umbilical Rack and
  APTS Rack are integrated
• HK RSN interfaces for 1773 bus, HOP Deployment,
  Solar Array Hinge Deployment potentiometers, GPS
  Receiver power/control/data/timing, numerous
  spacecraft temperature sensors, Lightweight
  Flexible Solar Array (LFSA), WARP PLS Command,
  Umbilical Rack (separation signals) and APTS Rack
  are integrated
• CDH LVPC interfaces to PSE and for GPS Power
  Unit, HOP Deployment power, Bay 1, 2, 3, 4, 5, 6
  Heaters and Nadir Deck Secondary Heater are
  integrated

8
CDH Electronics Overview

• CDH Boards CDH LVPC, M5 Processor, H/K RSN,
  Comm RSN
• CDH LVPC Board
• Unswitched 5V, 15V, and -15V to M5 Processor
  and H/K RSN
• Switched 28V to GPS, Bay Heaters, and HOP
  Deployment
• Unswitched 28V, 5V, 15V, and -15V to LFSA via
  H/K RSN
• M5 Flight Computer
• S/C processor runs ACS and CDH flight software
• AS1773 Spacecraft Bus Controller
• SSR stores up to 1.8G bits of spacecraft
  housekeeping data
• Up to 32 Mbytes additional memory available for
  program/command storage
• Serial output to Comm RSN for data downlink
• Input multiplexer to send science data to Comm
  RSN in backup mode
• H/K RSN Board
• Embedded UT69R000 controller and AS1773 interface
  as remote terminal
• Controls CDH LVPC via backplane
• Interfaces to GPS, S/A, LFSA and S/C for
  telemetry collection
• Interface to separation switches
• Provides WARP pulse command
• Comm RSN Board

9
Mongoose V Flight Computer Requirements Met

• Mongoose 5 Requirements
• Perform 1773 bus controller functionality
• Distribute spacecraft commands via 1773
• Receive and store all spacecraft housekeeping
  telemetry
• Perform housekeeping telemetry processing for
  fixed frame format
• Downlink housekeeping data to Comm RSN via
  high-speed RS-422 link with no gaps in between
  downlink frames
• Perform ACS flight software calculations
• Use real-time operating system
• Perform spacecraft time calculations
• Distribute spacecraft time via 1773 bus
• Process and issue X-band phased array antenna
  pointing commands via 1773
• Downlink real-time housekeeping data to Comm RSN
  via 1773 interface during ground station contact
• In the event the X-band phased array antenna is
  not functional, the Mongoose V Flight Computer
  will multiplex science data to Comm RSN

10
Housekeeping RSN Card Electrical Requirements Met

• H/K RSN requirements
• Control and process spacecraft thermistors
• Control solar array deployment
• Process solar array hinge status
• Control flexible solar array deployment
• Control and process flexible solar array
  housekeeping telemetry
• Process separation indicator status
• Distribute housekeeping packets to M5 via 1773
  interface
• Receive 1pps from GPS via RS-422 interface
• Receive and process GPS telemetry via RS-422
  interface
• Control CDH LVPC switched services via backplane

11
CDH LVPC Requirements Met

• CDH LVPC REQUIREMENTS
• Draw 28 VDC Power from PSE Output Module 1
• Provide unswitched 5V, 15V and -15V power to
  Housekeeping RSN, Mongoose 5, and LFSA (via H/K
  RSN)
• Provide unswitched 28 VDC to H/K RSN for LFSA
  deployment
• Provide switched 28 VDC, 1-amp services
• Control LVPC switched services via RSN backplane
• Provide current, temp and status telemetry

12
Mongoose V System Tests

• Verified downlink rate, encoding schemes and
  filter table operation
• Verified proper operation of all virtual
  recorders and telemetry output function
• Science data dumps over S-band via MSSP
• Verified all 1773 modes of operation
• Verified stored command processor function
• Extensive TSM / RTS testing (Special Topic)
• Verified robust operation of all M5 software tasks

13
HK RSN System Tests

• Extensive deployment testing
• Extensive GPS and timing tests (Special Topic)
• Verified all LVPC modes of operation including
  FDC
• Verified spacecraft health and safety telemetry
  gathering

14
ACDS Special Tests

• Mongoose V Stress Test
• 1773 Bit Buster
• Optical Margins
• Verified heater operation in T/V
• Spacecraft timing
• Extensive deployment testing

15
CDH Significant Changes Upgrades

• Deployment code upgrades to HK RSN
• Fusing of all CDH LVPC services
• Improvement of timing software in HK RSN
• Simplified TSM / RTS system

16
CDH Problems / Issues

• Global Positioning System -- covered by Special
  Topic
• Nadir Deck Heater Anomaly -- covered by Special
  Topic

17
Attitude Control Electronics Overview

• Four ACE Boards ACE RSN, ACE I/O, Propulsion
  I/O, ACE LVPC
• ACE RSN
• Embedded UT69R00 controller and 1773 interface.
• Backplane I/O interface and control of other 3
  ACE boards.
• Interfaces to ACS subsystems TAM, CSS, Reaction
  Wheels.
• ACE I/O
• Interfaces to IRU, MTBs, PPT, AST, SADE/ECU.
• Prop I/O
• Controls, Heaters, and Telemetry interface to
  tank, lines, valves, and thrusters.
• ACE LVPC Board
• Provides 5V, 15V, and 28V power to ACE half of
  ACDS box
• Provides switched power to IRU, AST, TAM, MTB,
  Latch Valve, and Heaters

18
ACE Functional Requirements

• 1773 Remote Terminal bus I/F
• Power Distribution for ACS boards, sensors,
  actuators and heaters
• Command and Data interface to
• Coarse Sun Sensors (CSS)
• Three Axis Magnetometer (TAM)
• Inertial Reference Unit (IRU)
• Reaction Wheel Assys (RWAs)
• Magnetic Torquer Bars (MTB)
• Autonomous Star Tracker (AST)
• Solar Array Drive Electronics and Control Unit
  (SADA/ECU)
• RCS Valves, Thrusters, CB Heaters, Lines, and
  Tank
• Pulsed Plasma Thruster

19
ACE Cards Diagram
28 VDC from PSE OPM (10-A switched service)
ACE LVPC
IRU
CSS (4x)
ACE RSN
1773 to M5
RW
RW
RW
UART to GSE
SAD
SADE/ECU
RSN Backplane Control with 5V, 15V, and 28V
Power
TAM Electronics
TAM Head
Magnetic Torquer Bars
AST
PROP I/O
PROP (Tank, Valves, CB
Heaters, Thrusters)
28 VDC from PSE OPM (10-A switched service to
CB Heaters, Hydrazine Thrusters, and PPT.)
PPT (Pulsed Plasma Thruster)
20
Attitude Control Electronics (ACE) Status

• Successfully verified all ACE RSN interfaces
• 1773 bus communications with M5, including Bus
  Buster test
• Three-Axis Magnetometer (TAM), Reaction Wheels
  (3x), Coarse Sun Sensors (4x) during
  sub-component integration tests
• APTS Rack sub-component simulator
• Successfully verified all ACE I/O interfaces
• IRU, Magnetic Torquer Bars (3x), ECU S/A Drive
  Actuator, S/A Yoke Deployment pot, PPT, AST,
  APTS Rack are integrated
• Successfully verified all PROP I/O interfaces
• RCS temperatures tank pressure, latch valve
  thrusters are integrated
• Successfully verified all ACE LVPC power
  interfaces
• ACE power distribution system
• IRU, TAM, MTB converter, IRU relay converter,
  AST, Latch Valve Tank Pressure Sensor S/A
  Deployment Damper Heater during sub-component
  integration tests

21
ACE Problems/Issues

• Problem Records
• 4 open PR that is category Green
• 3 open PRs that are category Yellow
• 5 category Red problem reports in progress
• PR 346-20-4 MTB Converter load not tested for
  turn-on voltage oscillations and current spikes.
  Elevated to PAR 47. Addressed as Special Topic
• PR 346-20-2 Section 8.0, step 11. Expected no
  voltage transients on Y and Z. Voltage
  transients occurred, see scope snap TEK00005.BMP,
  time tag 2315.
• PR 681-20-12 ACEMTBP15K (regulated supply)
  bouncing 14.84 then 15.15 this one should not
  move.
• PR 670-40-3 ACECSS2CUR exhibited 200 uA step
  changes during SAD rotation CSS4 also caused
  alarms. Other CSS currents were very steady.
• PR 674-20-23 YH Limit on RWZ supply voltage (ACE
  RWZRVK 5.31 then 4.99).
• PR 682-20-2 Telemetry for ACE RSN 2.5 volts
  Reference (ACERSN2-5VK) hit 2.33 yellow low.
  Related to others. Happened again_at_ 0105

22
ACDS Problems/Issues

• Problem Records
• 9 open PRs that are category B (Procedural /
  pending verification or corrective action planned)

23
Special Topic Timing Issues
. . . Harry Culver EO-1 Timing Guru
24
Timing Issues

• In September, AETD (Code 561) was asked to verify
  the EO-1 on-board timing
• Findings
• When GPS was ON, spacecraft time was randomly
  changing with a maximum increment of 2 seconds --
  fixed with a software change to the H/K RSN
• Subsequently, determined that the H/K RSN was not
  time tagging the GPS pulse properly -- fixed with
  another software change
• The above change was also made to the Comm RSN
• Most recent problem is a random changing of
  exactly 1 second
• When GPS is OFF, the spacecraft time drifts at
  10-15 microseconds / second
• Will exceed 10 millisecond spec in about 10-15
  minutes
• Compensation software will be necessary to stay
  within spec
• Timing correlation with the MOC is also in work