Kimberly Ennico

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LCROSS Astronomy Workshop, NASA Ames Research
Center, February 29, 2008
LCROSS Payload Measurements
Kimberly Ennico
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Payload Description
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LCROSS Payload

• LCROSS Payload is located on the R6 Panel of the
  LCROSS Spacecraft (S/C).
• There are 9 Science Instruments (SI) plus a Data
  Handling Unit (DHU).
• DHU provides power commands to, and collects
  science data H/K telemetry from the Science
  Instruments.
• 26-35V from S/C EPS provides power to DHU and
  thermal circuits (heaters, thermistors,
  thermostats).

Science Payload
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LCROSS Payload
Payload Observation Deck (POD)
Visible Spectrometer (VSP)
R6 Panel
TLP Digital Electronics Module (DEM)
Data Handling Unit (DHU)
NIR Spectrometer2 (NSP2)
NIR Spectrometer1 (NSP1)
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Payload Observation Deck (POD)
NIR Camera 1 (NIR1)
NIR Camera 2 (NIR2)
Visible Camera (VIS)
Total Luminance Photometer (TLP)
MIR Camera 1 (MIR1)
NSP1 Nadir Fore-Optics
MIR Camera 2 (MIR2)
VSP Nadir Fore-Optics
NSP2 Solar Viewer Fore-Optics
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LCROSS Payload
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Science Instrument lt-gt Science Goals
Camera
Camera
Camera
Spectrometer
Spectrometer
Photometer
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Science Instrument lt-gt Science Goals
Camera
Camera
Camera
Spectrometer
Spectrometer
Photometer
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Science Instrument lt-gt Science Goals
Camera
Camera
Camera
Spectrometer
Spectrometer
Photometer
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Science Instrument Descriptions
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LCROSS Cameras
VIS
NIR1, NIR2
MIR1
MIR2
TLP SEM
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Cameras
NIR2
NIR1
VIS
MIR1
MIR2
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Camera Co-Alignment
Large Fields of View in the Cameras compared with
the FOV of the Near Infrared Spectrometer
NIR1
MIR2
VIS
Target distance (Jim with flashlight) is 21.5 m
(70.5 feet) from POD entrance. Flashlight is
aligned with the NSP1 nadir fore-optics. FOV of
NSP1 shown with yellow circle. In flight, LCROSS
S/C will center the bore-sight on the NSP1. This
will be checked during Starfield, Lunar Swing-by
and EarthMoon.
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Spectrometers
VSP
NSP1
NSP2
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Spectrometers

• VSP has Two Science Modes
• Single Spectra
• Provides R800-1700 spectra from 260-650 nm
• Sample rate is integration time dependent
• Bracket Spectra
• Three spectra taken in close order to bracket
  an acquisition.
• Sample rate is slower than single spectra mode
  (but you get 3 spectra at a time event).
• VSP can support (programmable) integration times
  between 10ms and 65s.

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Spectrometers

• NSPs have Two Science Modes
• Hadamard Spectrum Mode
• Provides R60-100 spectra from 1.2-2.4 um
• 1 Spectrum per 600ms (1.7Hz sample rate)
• Flash Mode
• Allows for 72 Hz sample rate
• Five spectral ranges chosen 1.402-1.444,
  1.566-1.606, 1.833-1.873, 1.991-2.029,
  2.285-2.322 um.
• NSP1 (Nadir-Looking) is used in both modes
• NSP2 (Side-Looking/Solar Viewer) is primarily
  used in Hadamard Mode

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Spectrometer Fore-Optics
VSP and NSP1 FO
NSP2 FO

• Orientated in -Y (S/C Coordinate System)
• Used for Solar Occultation Measurements during
  Final Descent
• Large FOV 130 deg

• Orientated in X (S/C Coordinate System)
• Called Nadir as they are positioned to look
  downward during final descent
• 3-inch telescope primary diameter, 2 mirror 1
  lens design
• Each scope optimized for NA of fiber
  wavelength range of spectrometer
• Each scope has 1 deg FOV
• Co-alignment between each scope was measured to
  be lt 0.1 deg at target distance 853.5 cm (28
  feet).

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Payload Performance Testing
Number of Tests in Payload Test Log
Thermal Vibe/Shock Calibration Interfaces
8 bake-out 4 shock 5 alignment events Electrical/Power
4 thermal calibrations 20 random vibe gt 10 radiometric tests Thermal Control System
18 thermal cycling tests 8 spectral tests HKIO interface
data throughput optimization Mass
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Payload Modes Data Sets
(and where Ancillary Data Sets from Ground
Other Assets can augment LCROSS Science)
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Mission Timeline
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Mission Timeline
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Bakeout QuickLook (L1-4d)

• Bake-Out
• Launch 1-2days
• Heater Circuits turned on R6 Panel (24-27deg C)
• (higher than operational temperatures 19-21 deg
  C)
• 48 hour bake-out goal
• Quick Look
• Between Launch 2 to 4 days
• Operate QuickLook Calibration Sequence
• Each Instrument (VIS, NIR1, NIR2, MIR1, MIR2,
  VSP, NSP1, NSP2, TLP) is powered sequentially to
  evaluate health/status
• No special pointing requirements
• TADA provides protection to nadir Fore-Optics
  and TLP
• 29 kbps downlink

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StarField (L4d)

• Launch 4 days (approx. 1 day before Lunar
  Swing-by)
• Star field is identified a priori such that
  solar array (R1) is in a sun normal orientation
  and omni is pointed towards Earth.
• Candidate stars are Canopus, Acheron, Fomalhaut
  and Adara.
• Starfield selection is launch-date dependent.
• Multiple images with NIR2 camera (FOV 28.7 x
  21.7) (long integration time/stare mode).
• Deploy TADA.
• Measurements taken by VSP and MIR1 before/after
  TADA.
• 220 kpbs downlink

Adara (Epsilon Canis Majoris) is the 24th
brightest star in sky (1.5 mag). Located in Canis
Major (RA 6h 58m 37.5s, Dec -28º 58m 20s). In 21
deg FOV above, there are 21 stars greater than
6.5 magnitude 11 over 5.5 magnitude, and two
over 3.5 magnitude. There are also two background
galaxies. This star field meets the requirements
for the launch opportunities in the late October
2007 launch window.
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Lunar Swing-By (L5d)

• At Launch 5days, LCROSS will swing-by the moon.

• PART I
• Sweep along Lunar Surface
• LCROSS will be between 2500 and 4500 km above
  lunar surface.
• To last over a 30 minute period
• 5 minute dwells on three calibration targets
• Provides data set to radiometrically and
  spectrally calibrate the instruments
• Demonstrates Science Mode pointing
• Demonstrates Final Hour operation
• Nominal 1 Mbps science rate
• Instruments On
• VIS image rate 0.816 Hz
• NIR1/NIR2 image rate 0.408 Hz
• MIR1/MIR2 image rate 3 Hz
• VSP (100, 200, 400 ms spectra) every 2.2 s
• NSP1 (nadir) and NSP2 (side) spectra every 600
  ms (1.7 Hz rate)

Actual altitude and track direction (over north
or south pole) depends on launch date.
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Lunar Swing-By (L5d)

• What we expect to see at 4500 km altitude.
• Shown here are the FOVs for VIS, NIR1 and MIR2,
  superimposed on how they should be orientated
  with respect to the NSP1 bore-sight.
• Excellent data set along the spacecraft track.
• Ground based observations can be used to support
  LCROSS spectra and image data.

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Lunar Swing-By (L5d)

• PART II
• Limb Crossing
• S/C Crossing rate 0.15 deg/sec
• Used for instrument pointing relative to S/C
  reference frame (primary goal)
• Only These Instruments Continuously On
• VIS camera rate 3 Hz
• NSP1 flash (fast rate 1 spectra every 14 ms or
  72 Hz) spectra
• VSP spectra (100, 200, 400 ms every 2.2 s)
• Snapshots with NIR1, NIR2, MIR1 and MIR2 at
  ends of each limb crossing.
• 1Mbps downlink

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EarthMoon (L20-80d)

• Earth and Moon looks will be taken at different
  times during the 3-4 month (80-120 day) Cruise
  Phase.
• Provides for additional health/status and
  contamination checks
• Additional alignment knowledge
• S/C will nominally be located
• 300,000 - 600,000 km from the Earth
• 500,000 - 700,000 km from the Moon
• Can come as close as 4,000 km to the Moon
• S/C drifts at a rate of 0.3 deg/s during these
  observations
• Instrumentation Serially, each about 2 minutes
  VIS at 0.45 Hz, NIR1/2 at 0.9 Hz, MIR1/2 at
  0.07Hz VSP, NSP1/2 on for calibration
  contamination check.
• 60 kps or 29 kbps downlink

Distance b/n LCROSS and Moon
What might we expect to see?
VIS
MIR
385,000 km
100,000 km
50,000 km
Equivalent to what Earth at d385,000 km would
look like.
Close-after Swing-by
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Separation (Impact-9hr,40min)
Simulated EDUS
MIR (15.0 x 11.0)

• At Impact minus 9 hours, 40 minutes the LCROSS
  S/C will separate from the Centaur Upper Stage
  (EDUS) and drift away at 0.5 m/s.
• LCROSS S/C undergoes 180-deg turn at 0.3/s to
  orientate sensors toward moon.
• Payload is powered 10 minutes after separation
  event.
• Centaur is 300 m away at this point.
• Payload remains powered to observe the Centaur
  separation tumble rates.
• Instrumentation Continuous VIS and MIR2 images
  at 0.8Hz rate.
• 220 kps downlink

t10min d300m
Centaur 5x25 pixels in this image
t20min d600m
t30min d900m
Notes Actual EDUS len12m, dia2.5m,
len4.8dia Simulated EDUS len19cm, dia6.35cm ,
len3dia, so the dashed red box in the MIR
images above reflect expected EDUS size in FOV.
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Final Hour - Pre-Impact (Impact-60 min)

• At Centaur Impact-60 min
• LCROSS is at 9,000 km lunar altitude
• Following behind Centaur 2.5 km/s
• During the Final Hour, we bring the instruments
  up to a steady state, monitoring their
  performance.
• If a failure is detected, the system can be
  rebooted up to a predetermined time.

VIS FOV at 6000km altitude (40 minutes to impact)

• Instrumentation
• VIS Image Rate 0.816 Hz
• NIR1/NIR2 Image Rate 0.408 Hz
• MIR1/MIR2 Image Rate 3 Hz
• VSP (nadir) sampling at 100ms, 500ms, 2500ms
  every 5 seconds
• NSP1 (nadir) sampling at 1.7 Hz
• NSP2 (side) sampling at 1.7 Hz

During the Final Hour, the instruments will drift
up in temperature within a tight range.
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Final Hour - Flash (Impact- few s)

• This is the Centaur Impact Event
• Goals
• Detect Impact Flash
• Measure Flash evolution at high speed (1000 Hz)
• Measure Flash spectra
• Duration 1 minute, set to start 50s before
  expected impact time
• Altitude LCROSS is at 600 km from lunar surface
  at Centaur impact
• Instrumentation (bandwidth limited)
• TLP at 1000Hz
• NIR1 Image Rate 3 Hz (fastest it can go for this
  ensemble)
• MIR1/MIR2 Image Rate 0.5 Hz
• VSP (nadir) sampling at 4s, timed to integrate
  over flash event
• NSP1 (nadir) sampling at 72 Hz (flash mode)
• NSP2 (side) sampling at 1.7 Hz
• No VIS or NIR2 to save the bandwidth

LCROSSs TLP is dedicated to make a hi-res (1000
samples/s) time curve of the event.
NIR1 FOV at this alt. is 340 km x 230 km We
should see something similar in spatial size to
SMART-1s measurement below
NIR FOV at 600 km altitude (at impact!)
This 2x2 (200 x 200 km) image of the SMART-1
Impact Flash
Canada-France-Hawaii Telescope / 2006
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Final Hour - Curtain (Impact10-120s)
Cameras will see an expanding (and dimming)
ejecta curtain

• Goals
• Monitor ejecta curtain
• Measure curtain evolution
• Measure ejecta thermal evolution
• Duration 3 minutes
• Altitude Dropping from 600km to 150 km at 2.5
  km/s
• Ejecta cloud radiance dropping rapidly
  expanding
• 5 to 0.5 W/m2 um sr at 550 nm
• 1 to 0.25 W/m2 um sr at 1.5 microns
• Instrumentation
• VIS Image Rate 0.816 Hz
• NIR1/NIR2 Image Rate 0.408 Hz
• MIR1/MIR2 Image Rate 3 Hz
• VSP (nadir) sampling at 100ms, 500ms, 2500ms
  every 5 seconds
• NSP1 (nadir) sampling at 1.7 Hz
• NSP2 (side) sampling at 1.7 Hz
• No TLP to save bandwidth

R5km
NIR FOV at 450 km alt (1 min after impact)
R15km
NIR FOV at 300 km alt (2 min after impact)
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Final Hour - Crater (Impact3m)
Change in thermal contrast between ejecta
crater expected
Impact

• Goals
• Image the Centaur Impact Crater
• Monitor ejecta cloud with side-viewing
  spectrometer
• Measure ejecta thermal evolution
• Duration 1 minute until LCROSS S/C impacts!
• Altitude Dropping from 150km to 0 km at 2.5
  km/s
• New Crater diameter predicted to be 20 meters
• 1x1 MIR pixel at 25km altitude
• 2x2 MIR pixel at 7.5 km alt (3 s to S/C impact)
  
• End of Mission -- LCROSS S/C impacts Moon!

NIR 0.12 km/pix

• Instrumentation
• NIR2 Image Rate 0.66 Hz
• MIR1/MIR2 Image Rate 3 Hz (fastest it can go
  for this ensemble)
• VSP (nadir) sampling at 100ms, 200ms, 400ms
  every 2.2 seconds
• NSP1 (nadir) sampling at 1.7 Hz
• NSP2 (side) sampling at 1.7 Hz
• No VIS, NIR1 and TLP to save bandwidth

• Loss of data 3 to 2s before (alt7.5, 5 km)

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Payload Summary
It may only be 4 minutes of data, but ...

• The LCROSS Impactor Mission is unique since it
  is a controlled impact event -- angle, velocity,
  mass -- to literally toss hundreds of metric tons
  30 miles high!
• LCROSS Payload has the unique advantage of being
  600 km away at time of Centaur impact with
  streaming image and spectroscopy of the event.
• LCROSS is designed to measure the time curve of
  the flash event (TLP) and locate the position of
  the flash with a large FOV camera (NIR1).
• The workhorse got water? spectroscopy
  measurements come at Impact0 to Impact2
  minutes, when the ejecta curtain is visible
  (comes into light), before it decays/dissipates.
  Best seat to measure the water over any other
  platform.
• Interpreting LCROSS measurements of the event
  relies heavily on cross-platform measurements --
  both on-board (e.g., cameras providing band-depth
  and context imagery) and also ground assets.

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Backup Slides
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Payload Data Summary
Essentially powered for 6 hours of science data
Modest Estimate for PDS (including. calibration
data)
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Payload Environmental Testing