Summary of Level 1 Requirements

1
Summary of Level 1 Requirements

• Multispectral imaging Capability
• Perform 200 paired-scene comparisons with
  Landsat-7 / ETM
• Gather multispectral images that encompass one
  entire growing season (March-October) in the
  Northern Hemisphere
• Use periodic lunar and solar observations to
  demonstrate a calibration technique to ensure 5
  absolute radiometric accuracy in future science
  missions
• Wide Field, High Resolution, Reflective Optics
• Demonstrate how well the ALI optical performance
  supports the Level 1 Requirements of the
  Multispectral Imaging Capability, the Wedge
  Imaging Spectrometer, and the Grating Imaging
  Spectrometer

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2
Summary of Level 1 Requirements (Continued)

• Silicon Carbide Optics
• Demonstrate how well the silicon carbide optics
  support the ALI optical performance
• Atmospheric Corrector
• Retrieve atmospheric water vapor, aerosols, and
  clouds from Atmospheric Corrector data to correct
  ALI and Landsat-7 / ETM images for the effects
  of atmospheric extinction
• Assess the use of the 250m pixel size in the
  corrections obtained from the Atmospheric
  Corrector with those from the WIS and GIS
• X-Band Phased Array Antenna
• Provide an electronically steerable antenna to
  support a science data downlink in excess of 100
  Mb/sec

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3
Summary of Level 1 Requirements(Continued)

• Enhanced Formation Flying
• Demonstrate the capability to fly over the
  Landsat 7 ground track 3 Km within a one minute
  separation while an image is being collected
• Lightweight Solar Array
• Demonstrate a solar array capability greater than
  100 W/Kg throughout the first year on orbit
• Carbon-Carbon Radiator
• Demonstrate modeled thermal performance
  throughout the first year on orbit
• Pulsed Plasma Thruster
• Demonstrate the modeled control capability in
  terms of pointing accuracy, response
  characteristics, and stability
• Confirm that the thruster plume is benign to the
  ALI optical surfaces as assessed in ALI images

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4
Summary of Level 1 Requirements(Continued)

• Hyperion (Requirements To Be Approved)
• Gather hyperspectral images of 30m resolution
  over at least 220 channels spanning 0.4-2.5
  micrometers over a swath width of 7.5 Km from a
  Landsat 7 orbit
• Use spectral image data to synthesize
  Landsat-type images to be used in Comparison with
  Images produced by Landsat-7/ETM and ALI
• Perform TBR paired-scene comparisons with
  Landsat-7/ETM and ALI
• Gather hyperspectral images that encompass one
  entire growing season (March-October) in the
  Northern Hemisphere
• Use periodic lunar and solar observations to
  demonstrate improved radiometric calibration
  accuracy in future science missions.

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5
Significant changes since CDR

• Addition of the Hyperion
• Mechanically and electrically accommodate the
  telescope and supporting electronics electronics
  on the S/C
• Add an extra Solar Array circuit to increase
  power and Battery Louvers to reduce heater loads
• Modify the RS-422 input to the WARP
• Change ALI Control Electronics radiative cooling
  to conductive cooling into the Spacecraft Nadir
  deck.
• Deletion of the Wedge Imaging Spectrometer and
  Grating Imaging Spectrometer from the ALI
• Deletion of the Fiber Optic Data Bus (FODB)
• Addition of Safehold Mode, as recommended at the
  CDR

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6
Key Resources

• Power, Mass, Delta-V (Propellant) are driven by
  the addition of the Hyperion.

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7
Key ResourcesPower

• Goals for power balance
• Adequate margin so as to not risk the safety of
  the Satellite and
• Minimal operational constraints, particularly
  turning off Instruments
• Maintaining power balance on an multi-orbit basis
  as opposed to an orbital basis is required (a CDR
  recommendation).
• Addition of the Hyperion requires changes to the
  Spacecraft power and thermal systems.
• 15 watts (orbital average) Solar Array
  augmentation by adding an additional solar array
  string
• 10 watts (orbital average) heater load reduction
  by adding Battery Louvers
• 315 watt (orbital average) system, EOL, increase
  from 300 watts
• Operational constraints required to maintain
  power balance and to not violate NiCd battery 20
  DOD limit. (EO-1 has a very large 50 A-hr
  battery)
• During a 15 orbit day no more then 8 Data
  Collection orbits per day
• No more then 3 Data Collection orbits in a row

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Key ResourcesPower (continued)

• Data Collection Event Orbits consist of
• 10 minutes of ALI operations
• 1145 minutes of Hyperion operations
• 10 minutes of Atmospheric Corrector operations
• X- and S- band Downlink of data
• Storage of Science (WARP) data from image taking
  to downlink (then purge memory)
• Non- Data Collection Event Orbits consist of
• All three instruments capable of operations, but
  not taking data
• No X- or S-band Downlinks
• WARP storing data for later downlink
• Standby Orbits consist of
• All three instruments capable of operations, but
  not taking data
• No X- or S-band Downlinks
• WARP in low power mode (no data stored)
• Power consumption values are based on above
  operational assumptions, measured and predicted
  values with margin.

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9
Power Consumption
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10
Key ResourcesPower (continued)

• Power balance cannot be maintained on an orbital
  basis if imaging is assumed for all orbits, but
  it can be by
• Assuming (realistically) that not all orbits will
  involve scene taking
• Adding additional SA power
• Reducing loads on the Spacecraft by adding a
  battery louver to eliminate the need for battery
  heater power
• Risk is further reduced by
• Providing conservative, yet realistic,
  constraints for designing daily mission plans
• Providing power balance software that the Flight
  Ops Team will used to test daily mission plans
• An option exists and is being pursued to utilize
  a new SA cell technology (GaIn P2/GaAs/Ge cascade
  multi-junction) that will increase the system to
  a 325 watt system. The Project will meet with
  the Goddard SA experts to discuss this very
  attractive option.

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11
Key ResourcesMass

• Mass is primarily a driver on loads within the
  spacecraft (discussed later in the Spacecraft
  section of the presentation).
• Mass also affects launch vehicle performance, but
  Boeing analysis indicates that our increased mass
  is not an issue. We are awaiting Headquarters
  response to our request for additional mass.
• New mass request 588 kg.
• Previous mass allocation 529 kg.

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Key ResourcesMass (continued)
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13
Propellant

• EO-1 is required to carry 18 months of
  expendables, including propellant
• Addition of the Hyperion increases the amount of
  propellant required to meet this requirement, but
  EO-1 still has adequate propellant (22.3 kg
  capacity).
• With Hyperion 19.9 Kg required (10.9 Kg for
  deorbit)

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14
Key Environment Radiation

• Spacecraft and ALI required to meet 15 Krad, 50
  mil Al assumed
• Hyperion required to meet 5 Krad, 130 mil Al
  asumed

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15
Significant Changes to Testing Since CDR

• An extra Thermal Balance/Thermal Vacuum test has
  been added to the flow.
• The first, before Hyperion integration, will
  include the Spacecraft, ALI, and a thermal model
  of the Hyperion
• The second, after Hyperion integration, will
  include the Spacecraft, ALI, and the Hyperion.
• A radiance cross calibration test between the ALI
  and Hyperion has been added.
• Post-Environments End-to-End test to test for
  movement or damage of the ALI or Hyperion mirrors
  as a result of testing.

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16
Radiometric Cross Calibration of the ALI
Hyperion

• Radiometric cross calibration is needed between
  the instruments to help support image comparisons
  between ALI and Hyperion
• Will to be run as close to launch as possible to
  minimize any effect of time on radiometric
• Will be run with both instruments at
  approximately the same time to also minimize the
  effects of time
• The test will be run during the last Thermal
  Vacuum test using the Enhanced Thematic Mapper
  Plus Radiometric Tester (ERT) developed by the
  Landsat 7 Project
• The ERT covers ETM bands 1 through 5 with seven
  steps.
• Works in vacuum and at ambient pressure.
• Does not require extremely precise positioning.
• Swales will design vacuum compatible MGSE to
  position the ERT over the ALI and Hyperion.
• A team will be formed to develop the test in
  detail and identify any changes to the ERT, such
  as different filters, that may be required.

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17
Radiometric Cross Calibration of the ALI
Hyperion
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18
Post Environments End-to-End Test

• The Post Environments Focus Test (PEFT) will
  verify the ALI and the Hyperion survived acoustic
  and thermal vacuum testing.
• The PEFT will verify that no ALI optical elements
  and most optical elements of the Hyperion are
  undamaged and still in their proper positions.
• This Ambient test cannot verify the condition of
  the Hyperion SWIR spectrometer optics because the
  SWIR detectors will not function properly at
  Ambient temperatures.
• A practical and cost/schedule effective thermal
  Vacuum test cannot be designed.
• A team will be formed to develop the test in
  detail and identify any changes that may be
  required.

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19
Issues / Concerns

• The Thermal analysis of the Hyperion is not to
  CDR level yet, although the design appears sound.
  A delta TCS CDR will be held.
• The Attitude Control analysis is not at CDR level
  yet. A Delta ACS CDR will be held.
• Significant improvements have been made with
  regards to parts quality over that of the Lewis
  instrument, however, schedule will inevitably
  require that some parts that will not meet our
  requirements will have to be used. This risk is
  understood and the team is working aggressively
  to minimize it.

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20
Backup Slides
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Action / Response Summary
Action Summary Response Summary
Consider a safe attitude mode Determine the
duration the S/C can minimize jitter for WIS
imaging. Consider a master reset of all
electronics from a special or ground command.
Also, consider a special command to reset the
ACS. Consider capability to deploy S/A by
special command from the ground or breakwire.

• ACE RSN Safehold mode added.
• Approximately 2 minutes can be supported.
• Each processor (M5 and RSNs) can be reset
  separately by special or ground command. EO-1 is
  an asynchronous distributed system and each
  processor operates independently (only
  synchronized via time stamp). Considered a risk
  to reset working processors.
• Ground command or the breaking of 2 of 3
  breakwires will deploy the S/A.

1 2 3 4
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Action / Response Summary
Action Summary Response Summary
5 6 7a 7b 7c 7d 7e
EO-1 should have a representative on various MAP
control / review boards. Team with MAP LVPC
designers and SEs to address FDC, DC/DC converter
redundancy in the ACDS, and LVPC services to
power ACS hardware. Thermal test of PSE before
flight environments. Perform thermal analysis of
battery during launch. Get battery expert
concurrence on handling and reconditioning
plan. Test EO-1 specific PSE S/W code. Will
Hot LAPSS testing be performed on S/A?

• EO-1 is on distribution for CCB actions and
  invited to attend the MAP CCB and reviews.
• Teams formed. Common FDC trip conditions for the
  LVPCs agreed to. EO-1 decided not to implement
  redundancy. ACS hardware services configured to
  optimize current draw for each LVPC used.
• Test performed on MAP PSE - showed EO-1 cases
  acceptable.
• Temp rise lt 1C.
• Modified TRMM plan to be used.
• Completed as part of MAP PSE tests. (Flight
  PSE/Workhorse battery tests planned in 9/98).
• ??????????

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Action / Response Summary
Action Summary Response Summary
Perform WCA on primary power circuits. Consider
energy balance over multiple orbits. Perform
WCA on all circuits. Establish fusing /
overcurrent protection philosophy. Consider
checking RAM from EEPROM before downloading
executable code.

• Completed. No large current draws over derated
  values.
• CDR case showed that balance over one orbit
  possible. (Delta CDR case, with new loads balance
  over multiple orbits is required).
• WCA performed for the two boards that are
  significantly different from MAP. AI 8 refers to
  power WCA.
• Completed. Details documented in Electrical
  specification.
• With Code 735, every effort has been made to
  remove dependencies upon a given area on RAM
  during boot. However, the R3000 architecture does
  not allow this for fixed locations of exception
  handlers.

8 9 10 11 12
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24
Action / Response Summary
Action Summary Response Summary
Recommend bake-out of spacecraft harness before
integration. EMI / EMC testing on the PSE and
ACDS at the box level. Describe shielding
implementation. Describe WARP CCA
testing. Describe post-launch S/W maintenance.

• External harnesses will be baked-out. Internal
  harness outgassing products are vented away from
  the instruments.
• Testing planned at the box level. (Due to delays
  in the delivery of the PSE and ACDS and conflicts
  between them for EGSE, EME testing will not be
  performed at the box level. It will be run at the
  spacecraft level).
• Description provided. See EO-1 System Level
  Electrical Requirements.
• Response provides description of testing in
  detail.
• Effort budgeted for by the Project. Same
  personnel and equipment will be used that
  developed FSW.

13 14 15 16 17
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Action / Response Summary
Action Summary Response Summary
Provide a list of interrupt priorities. Consider
a routine to check hardware discrete, ground
commandable latching relays to decide which
version of code (protected or writeable EEPROM)
to use at boot up. Or consider having the WDT
ping pong between the versions. Consider an IM
OK signal from the M5 to reset it if not
OK. Develop a co-alignment plan for the LEISA,
ALI, AST, and gyro. Consider drum-peel test to
the panel acceptance.

• List provided.
• These options were not pursued to minimize
  differences between the MAP and EO-1 H/W and S/W
  and because H/W changes to the M5 are not
  possible with the EO-1 schedule. Ground command
  can direct to either EEPROM and addition of the
  ACE RSN-based safehold minimizes the risk.
• Suggestion not implemented for cost and schedule
  reasons and, more importantly, because the ACE
  RSN-based safehold was added.
• Alignment plan developed.
• A flatwise tension test is more applicable to the
  loading conditions and is part of the plan.

18 19 20 21 22
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Action / Response Summary
Action Summary Response Summary
Recommend a solid rivet in each panel for bonding
of facesheets. Verify that the Battery air
cooling approach is sufficient. Backup MGSE
recommended for use at the pad. Investigate any
need for Safe / Arm plugs and resultant fairing
access needs. Consider a modal survey test for
strength verification.

• Bonding requirements have been established and
  will be verified. If panels fail the test,
  corrective action will be taken. None is
  expected.
• Analysis indicates that battery temperatures are
  not exceeded.
• Considered a low probability that this hardware
  will be needed. Therefore, not being pursued.
• Safe / Arm plugs are not needed for paraffin
  actuators and fairing access is, therefore not
  required.
• Meeting held with Orin Sheinman and Bob
  Coladonato. They agreed that the approach
  proposed was adequate.

23 24 25 26 27
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Action / Response Summary
Action Summary Response Summary
Recommend a dab of Bray 601 between vespel
bearing and quill shaft to reduce vespel
dust. Recommend sealing the contamination cap of
the dampers with epoxy or RTV to make air
tight. Recommend adding a tuna can on the
output side of the SA drive for thermal
reasons. Perform thermal analysis in all EO-1
mission modes, transient states. Consider the
impact of leakage of lubricants on the ALI
instrument. Perform thermal design and analysis
of SA deployment mechanisms.

• Agreed and incorporated.
• Design incorporates epoxy seal, as recommended.
• Tuna can incorporated.
• Work planned.
• Bray 601, a low outgasser, is used. ALI optics
  are not subject to direct flux. Given this, it is
  not considered an issue.
• Analysis performed, tests with ETUs planned.

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Action / Response Summary
Action Summary Response Summary
Integrate a reduced ALI math model and perform
integrated thermal analysis. Consider
increasing cooling capability for the battery,
on-orbit. Consider shields. Consider providing a
bread board of the thermal control circuit to the
gyros to the IRU vendor. Perform thermal
analysis of the prop system for failed-on heater
conditions and determine the max temp caused by a
failed-on valve. Determine who provides
spacecraft / instrument constraints, cal curves,
limits and contingency procedures.

• Work planned.
• The battery cooling was checked again and the
  analysis showed adequate cooling.
• The circuit included inside the IRU by the
  vendor the spacecraft provides switched services
  only.
• Analysis performed and fault tolerance and safety
  features were described.
• The S/C and Instrument providers provide this
  information and coordinate with the Flight Ops
  Team who assemble the documentation.

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Action / Response Summary
Action Summary Response Summary
Identify which stations are launch critical.

• Launch critical stations are Spitzbergen and
  TDRSS, back-ups are Poker Flats, Wallops, and
  McMurdo.

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