New Millennium EO1 Advanced Land Imager 23 January 1998

1
System Testing forEarth Observing-1
Mark Perry EO-1 Lead Systems Engineer Swales
Aerospace
2
Agenda

• System Testing Topics
• Overview of System Tests
• Details of Aliveness Test
• Development of the EO-1 CPT
• Details of Functional Test
• EO-1 CPT Design
• CPT Sections
• Highlights of the First CPT
• Overview of Successful Tests from the First CPT
• Omissions During the First CPT
• Problems During Execution
• Problems during Execution
• Status of System-Level Testing
• Objectives of First CPT
• Summary

3
System Testing Topics

• Description of system tests
• Detailed description of comprehensive performance
  test
• Results of first comprehensive performance test
• Plans for system testing through launch

4
Overview of System Tests

• Aliveness
• Verifies that each subsystem and payload
  operates, including basic functionality
  mechanical motion, (configuration or life time
  limited)
• Used when system configuration or time
  limitations prevents a full functional test
• Quick verification of satellite health after a
  move
• After each axis of vibration
• Prior to acoustics test
• During launch countdown and during countdown
  simulations
• Functional
• Verify every interface, command, telemetry point,
  and function
• Uses EGSE as stimulus and to test systems more
  fully than aliveness test
• Performed after vibration and acoustic tests, and
  on the LV

5
Overview of System Tests (CONTINUED)

• Comprehensive Performance Test (CPT)
• Measures performance of each subsystem, and EO-1
  as a system
• Dry-run of the CPT performed at Swales in May
  baseline in July
• Three other CPTs during thermal-vacuum test,
  after environmental tests, and at the launch site
• Special tests. These tests need special support
  equipment, or are conducted only a single time.
  Some FDC tests are special tests.
• Some examples of special tests
• RCS high-pressure test (tank has limited
  permissible high-pressure cycles)
• High/low-voltage test (single-time verification
  of function)
• Exhaustive command permutation test (not
  necessary every CPT)
• 1773 SEU test (requires special GSE)
• Inserted into the schedule when procedures and
  equipment available

6
Details of Aliveness Test

• Every component, subsystem, instrument, and
  payload is turned on
• Nominal telemetry provides initial
  state-of-health verification
• Includes imaging and end-to-end data flow which
  is extensive test of ALI, Hyperion, AC, WARP, and
  X-band
• ACS modes and components tested
• All power-system functions tested
• All CDH tasks tested
• All downlink rates tested, S-band and X-band

7
Development of the EO-1 CPT

• Based on Spacecraft Test Operating Language
  (STOL) Procedures as much as possible
• Automatic command verification and limit checking
• Executes quickly
• Can repeat with precision
• Procedures are directly transportable to
  operations team
• Can check STOL procedures before running first
  CPT
• Bottoms-up, modular approach
• Using tests developed for box testing and
  integration
• Some tests also used in aliveness and functional
  tests
• Each subsystems tests verify all subsystem
  functions and requirements. These tests are
  listed and cross-referenced to CPT sections.
• Where possible, conduct tests of different
  subsystems in parallel to shorten the duration of
  the CPT
• TRMM and XTE CPTs used for reference

8
Details of Functional Test

• Same as the CPT with the following exceptions
• Performance-only tests are eliminated, such as
  the long (spin-down) RWA test
• The launch and B-dot timelines are shortened
• Specialized instrument tests eliminated, because
  they are fully tested in a max-data-rate,
  end-to-end test
• LFSA deployment has a limited number of cycles,
  so its test is eliminated
• EFF test is shortened to a few cycles
• Multiple-permutation test of s/a release
  redundancy eliminated (redundant side still
  tested)
• Dedicated s/a drive test eliminated, since the
  s/a drive is continuously tested in the
  background
• Orbit tests are eliminated
• The total duration is about 24 hours, instead of
  the 48-72 hours needed for the CPT
• As in the CPT, much of the system subsystem
  health, function, performance is confirmed and
  determined from nominal telemetry

9
EO-1 CPT Design

• Three general phases with 11 sections
• Begin with a launch, ascent, deployment, and
  sun-acquisition simulation to verify the most
  critical timelines on the mission and to stress
  the power system
• Follow with a series of tests to verify all
  satellite functions and to measure system
  performance
• End with several real-time, nominal orbit-cycle
  tests
• The CPT is designed for ambient testing, with the
  solar arrays un-mounted and all the instruments
  and payloads integrated
• Modified for first CPT (without Hyperion)
• Modified for thermal-vacuum testing (Hyperion
  cryocooler operations, PPT firing, and RCS
  pressurization will be different)
• Modified for launch site (solar arrays will be
  mounted)
• Data used to begin subsystem trending of key
  parameters

10
CPT Sections

• CPT0 Launch configuration. The S/C is turned on
  configured as for launch. Nominal performance
  is verified through telemetry
• CPT1 Ascent through sun acquisition. From switch
  to internal power, through launch, ascent,
  separation, deployment, rate nulling, sun
  acquisition following a worst-case timeline. Real
  time enables assessment of ACS timers the power
  system. During the coast phase, additional
  subsystem tests gain experience in operating the
  S/C with 2kb/s telemetry.
• CPT2 ACS nominal S/C operations. Nominal
  configuration, except instruments, payloads,
  WARP are off. Timeline driven by ACS tests
  phasing, sensor stimulation, actuator operation,
  GPS, coupling. Power, S-Band, M5 tests
  conducted in parallel. S-Band requires some
  dedicated time.
• CPT3 Instrument turn-on, including payloads
  WARP. Verify health of instrument most
  functions excluding imaging.

11
CPT Sections (CONTINUED)

• CPT4 Comprehensive instrument payload tests.
  Each payload performs exhaustive testing,
  including image data, where possible
• CPT4A ALI. Dark images, cal lamps, heater
  functions, FDC, mechanisms, processor loads,
  timers.
• CPT4B Hyperion. Dark images, cal lamps, heaters,
  cryocooler, mechanism, timers, FDC.
• CPT4C AC. Dark images, lab image, gain
  variations, temperature control
• CPT4D LFSA. Launch release, deploy,
  current/voltage
• CPT4E PPT. Single multiple firings, both
  tubes, long short pulses
• CPT4F EFF
• CPT5 Comprehensive ACS testing. Complete
  performance testing of ACS S/W component
  functions. RCS testing.

12
CPT Sections (CONTINUED)

• CPT6 Solar-array drive. Orbit rate, ramp up,
  ramp down, open loop test, blind acquisition of
  index, min/max travel limits, rewind,
  potentiometers, glitch test.
• CPT7 WARP/RF. Correct image data through X-Band,
  correct data through MSSP to X-Band at 2 Mb/s
  (compare X- and S-Band data), correct pointing of
  X-Band.
• CPT8 End-to-end tests maximum rate. Correct
  data from instruments, through WARP X-Band to
  ground storage. Test maximum data ingest all
  instruments operating at the same time for 60
  seconds.
• CPT9 Safemode load shed. Transition to
  safemode, ACS, all subsystems put into correct
  configuration. Safemode recovery
• CPT10 Special command. Test each special
  command reset processors switch to alternate
  PROMs.
• CPT11 Orbit-cycles. As a minimum
  data-collection orbit with downlink,
  lunar-calibration orbit, delta-V orbit.

13
Highlights of the First CPT

• The first iteration of the CPT took about 72
  hours. Most tests were successful
• Tests with the most problems during the first
  execution were re-run on the fourth day, with
  success. These tests were CPT0, CPT1 (launch),
  and some ACS tests from CPT2.
• There were 36 problem records (PRs), which
  represent hardware or software anomalies. Most
  are resolved.
• There were about 100 discrepancies in the CPT
  procedures, most of which had not been tested
  previously. Most of the deviations caused test
  delays. Most of the deviations have been
  incorporated into new versions of the procedures.
  
• The FOT developed orbital timelines, which were
  tested successfully and resulted in improved
  command sequences

14
Overview of Successful Tests from the First CPT

• ALI comprehensive Health Safety and imaging
• All WARP functions, performance and evaluation
• Power system solar-array drive, power switching,
  and battery-charge management
• ACS End-to-end open loop phasing of all major
  ACS modes of operation were performed. Completed
  a full performance test of RWAs, IRU, MTBs
• CDH all thirteen of the M5 CDH tasks performed
  without error
• GPS update of spacecraft time tested
• Command sequence (ATS and RTS) tested
• RCS thruster valves and flow tested

15
Overview of Successful Tests from the First CPT
(CONTINUED)

• Some contingency and FDC tested
• HOP (solar-array release) redundancy and backup
  activation
• ACS timers to delay transitions
• Transition to safemode
• 1773 redundancy
• Watchdog timers, special commands, and re-starts.
• EFF loaded and executed

16
Omissions During the First CPT

• Hyperion, Atmospheric Corrector, LFSA and
  Autonomous Star Tracker were not integrated. (AST
  I/F and interaction with the ACS was tested
  verified.)
• Due to ALI concerns, the PPT was not tested
• Most FDC was not tested (exceptions stated above)
• CDH uplink-error tests not performed. (Tested
  at box-level.)
• RF The S-band RF not tested (GSE Transmitter in
  repair RF was tested during integration.)
• RF X-band not tested (critical X-band tlm not
  calibrated). X-Band passed all performance tests
  during integration
• Solar-array drive redundant drive and encoder,
  orbital-motion control by M5 ACS FSW, including
  imaging profile

17
Omissions (CONTINUED)

• ACS use of GPS position and velocity vectors
  (tested previously during integration)
• Since the ACE software is just completing
  development, ACE safehold control of the
  actuators (MTB, RWA, SAD) not tested
• End-to-end phasing for the M5 ACS B-dot control
  mode
• Thermal thermostatically-controlled heaters will
  not draw power unless the temperature is below 4
  to 8 Celsius
• Since the ACDS required some software patches, we
  did not perform some M5-reset tests (for example,
  memory-scrub errors), which requires re-loading
  the patches. The re-sets were tested during
  integration and at the box level.
• Comprehensive testing of PSE and CDH commands
  Some seldom-used commands not tested

18
Problems during Execution

• About 100 procedure deviations. Most of these
  have been incorporated, already, into corrected
  STOL
• TSMs did not operate at first. (TSMs were not
  available for testing prior to the CPT). The
  launch TSMs were fixed and re-tested.
• GPS telemetry had intermittent dropouts, even
  after new s/w (PTR ___ )
• The ACE software, version 2.03, contained errors
  (2.03 had not been tested prior to the CPT).
  After using an earlier version of the code for
  about 24 hours, ACE 2.04 was loaded and used
  successfully for the remainder of CPT.
• The magnetic field around the spacecraft was
  different from the previous TAM calibration ALI
  integrated and SAS wiring
• There is a still-undiagnosed problem using the
  AST load box (EGSE)
• EFF hogged the M5 CPU for too long and caused a
  warm re-start

19
Status of System-Level Testing

• Working on STOL procedures
• Finish building tests that were omitted from the
  first CPT due to insufficient preparation.
• Complete revisions of all existing STOL
  procedures
• Perform test-run of all new and revised
  procedures so that the next CPT executes smoothly
• Each subsystem working on improving tests
• Final review of subsystem requirements
• Complete red and yellow limits for parameters
  that have limits
• Yellow limits are just outside nominal or
  expected operation and permit a controlled
  response by the TC
• Red limits indicate impending damage to flight
  hardware and require immediate action
• Completed two aliveness tests that were
  abbreviated due to missing hardware

20
Objectives of First CPT

• Met all objectives of first CPT
• Perform as much functional and performance
  testing of EO-1 as is possible
• Refine our knowledge of operating EO-1
• Identify problems and additional work necessary
  before baseline CPT and environmental tests
• Test the CPT STOL procedures

21
Summary

• First dry run of CPT was successful, but
  incomplete
• Successfully tested most of EO-1 but some
  omissions due to lack of hardware (AST, Hyperion,
  etc.) and problems with GSE (S-band and X-band)
• Some testing also reduced due to some incomplete
  procedures (redundant s/a drive, etc.)
• Demonstrates that smooth CPT can be completed
  within 72 hours
• Missing procedures are nearly complete
• All components and payloads will be mounted for
  the baseline CPT
• Nearly all Problem Records have been resolved
  only Category C issues remaining
• Telemetry filter tables for 2 kb/s downlink rate
• AST interface?
• FEDS crash
• Anomalous warm starts (intermittent problem with
  probable causes based on configuration do not
  expect during baseline CPT)

22
Spacecraft Testing
23
Agenda

• Mechanical Alignment
• Vibration Testing
• Shock Testing
• Mass Properties
• Acoustic Testing

24
Mechanical Alignment

• Satellite ground alignment plan (SAI-PLAN-206)
  establishes system requirements
• The following alignment measurements shall be
  performed to establish the spacecraft primary
  reference frame
• S/C MRC to S/C datums
• S/C SRC to MRC
• IRU SRC will be mapped to the S/C MRC star
  tracker reference cube
• ALI HSA reference cubes will be mapped to the
  S/C MRC
• ALI ACI Optics Module shall be co-aligned to
  within 2 arc-mins. Bushings have been fabricated
  to allow adjustment in the position of the ACI OM.

25
Mechanical Alignment Flow

• Baseline measurements shall be performed after
  all flight components have been installed
• Alignment measurements shall be performed of the
  IRU and star tracker to S/C MRC prior to
  vibration testing. Post vibration measurements
  will be made to verify that alignment has been
  maintained between components
• Measurements are taken with one sec accuracy
  theodolites (Model Wild T2) with autocollomating
  eyepieces

26
Satellite Vibration Testing

• The Delta 7320-10 launch vehicle payload
  environment includes sustained sinusoidal
  vibration as well as quasi-sine transients during
  the launch phase of flight
• Three separate and distinct sustained oscillation
  conditions typically occur, resulting in both
  lateral and thrust-axis responses. These
  conditions, in the order they occur in flight,
  and the associated frequency bands and sweep
  rates are
• First pre-MECO (Main Engine Cutoff)25 to 30
  Hz1.5 octaves per minute
• Second pre-MECO30 to 35 Hz1.5 octaves per
  minute
• Prior to MECO15 to 20 Hz4 octaves per minute

27
Satellite Vibration Testing

• Satellite Sine Vibration Test Plan (SAI-PLAN-307)
  has been drafted and is in review by project,
  facility spacecraft personnel
• The vibration test shall be run in three axes.
  The X Y-axis tests shall be run on the lateral
  slip table the Z-Axis test shall be run on the
  exciter in the vertical configuration with the
  use of a head expander
• The launch vehicle contractor shall provide a
  Test Payload Adapter Fitting for use during this
  vibration test
• The MAP S/C vibration test fixture is being used
  for this test. The fixture assembly consists of
  three parts, 1) a force ring plate, 2) six
  multidimensional force transducers, 3) adapter
  test plate

28
Satellite Vibration Testing

• Approx. 30 tri-axial accelerometers have been
  identified on the spacecraft and payload. These
  accelerometers were installed at the Swales
  cleanroom facility, prior to shipment to GSFC
• The vibration test control instrumentation will
  consist of three tri-axial accelerometers mounted
  on the MAP adapter plate. The average in-axis
  response of these accelerometers will be used to
  control the test
• Three additional accelerometers will also be used
  to limit the input acceleration level to the
  spacecraft, ALI HSA. A predetermined, Not To
  Exceed (NTE), level will be specified for each
  limiting accelerometer and the test input levels
  shall be automatically adjusted, by the control
  system, if the NTE level of any of the limiting
  accelerometers is reached

29
Satellite Vibration Testing

• The following figures shows the proposed
  accelerometer placements

30
Satellite Vibration Testing

• The test specification is derived from latest
  flight coupled loads analysis times a 1.25 factor
  to obtain the protoflight levels below
• The sweep rates for the sustained oscillations
  have been selected to approximate the actual
  flight time it takes to sweep through the
  frequency bands shown

31
Satellite Vibration Testing

• The following plots are expected responses for
  the S/C, ALI HSA

ltltlt Response Plots gtgtgt
32
Satellite Shock Testing

• The satellite shock test procedure will be
  incorporated within the sine vibration test
  procedure
• Two shock tests will be performed at the
  conclusion of the vibration test
• The satellite will be lifted, by a crane, approx
  3 with the test PAF installed. A sheet of foam
  will be placed under the PAF and the clampband
  shall be released and allowed to drop onto the
  foam sheet
• All accelerometer instrumentation used during the
  vibration test shall remain installed on the
  satellite and will be recorded during the shock
  test

33
Satellite Mass Properties

• The satellite mass properties test plan,
  SAI-PLAN-319, will be created to provide the
  facility test requirements
• The satellite center of gravity in the X-Y plane
  and the moment of inertia about the Z-axis will
  be measured and compared to the prediction from
  the CAD solid model
• This test will be performed prior to vibration
  testing and again before acoustic test with a
  fully integrated satellite
• The test will be preformed on the Miller mass
  properties table in building 15
• The satellite will be placed on the thermal
  vacuum test fixture with the clampband installed

34
Satellite Acoustic Testing

• The maximum acoustic environment for the EO-1
  satellite will occur during liftoff and transonic
  flight. Liftoff levels are typically higher than
  transonic levels at the payload location
• A satellite acoustic test plan, SAI-PLAN-320,
  will be created to provide the facility test
  requirements
• This test will be preformed on a fully integrated
  satellite in the GSFC acoustic test facility in
  Building 10
• A reduced set of accelerometer instrumentation
  will be installed and recorded during the test
• The satellite will be lifted off the
  transportation dolly and raised into the center
  of the microphones acoustic field

35
Satellite Acoustic Testing

• The predicted EO-1 acoustic environment is a
  function of the configuration of the launch pad,
  the vehicle (e.g., 7320 Delta with 3 GEM solid
  motors), the payload fairing (10-ft. composite,
  with 3-in. acoustic blankets) and the fill effect
  due to the satellite and DPAF volume and radial
  gap to the fairing wall
• The EO-1 protoflight acoustic levels are shown.
  The test duration is one minute for protoflight
  test. These estimated P95/50 probability levels
  are based on current McDonnell Douglas Aerospace
  Delta 7320-10 levels, with an adjustment for the
  EO-1 fill effect