Principle Investigator Payload Manager

Lunar CRater Observation and Sensing Satellite Project

LCROSS

Principle Investigator Payload Manager

Anthony Colaprete

2LCROSS Background

Lunar Prospector detected an increase in hydrogen concentration over the lunar poles.

The debate over the form, concentration and distribution has continued ever since.

If the hydrogen in an accessible and usable form, it could be a potential resource?

The form, distribution and concentration of [H] relevant to inner solar system asteroid/comet fluxes, lunar volatiles and planetary evolution.

Feldman et al., 1998

SP Hydrogen Abundance

LCROSS will provide the most unambiguous data set to date as to the nature of lunar hydrogen2

3 3Question Addressed by LCROSS

Nature and form of the hydrogen?• Water, hydrated minerals, hydrocarbons?• Grain size?• Distribution within regolith?

Nature of PSR regolith?• Strength? Depth?• Grain size?• Composition?• Is it similar to Apollo sites?

The Lunar Atmosphere / Volatile Processes?• How does the Lunar atmosphere respond?• What are the times scales for recovery?• How do volatiles/dust migrate?

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Deconvolved Hydrogen Maps (Elphic et al., 2007)

Lunar Polar Hydrogen: What we do know

Original Lunar Prospector Hydrogen Map (Maurice et la., 2003)

Water is heterogeneous from one crater to another Accumulation/retention processes differ at carter scales of ~50-100 km? Possibly different at smaller scales.

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Evenly Distributed, low concentrations“Smooth”

Higher, infrequent concentrations “Chunky”

The LCROSS Experiment: Smooth or Chunky?

Processes such as impacts, diffusion, topography and sputtering may effect the distribution.

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Launch stacked with LRO May 21, 2009

After Lunar swing-by, enter a 3.5 month cruise around Earth

August 28, 2009, target the Centaur Upper Stage and position S-S/C to fly four minutes behind

S-S/C observes impact, ejecta cloud and resulting crater, making measurements until impacting itself

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The LCROSS Mission

MoonEarth

LCROSS Orbit – Side View

MoonEarth

LCROSS Orbit – Side View

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East Crater ~30 meters

Predicted Centaur Crater Size

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Korycansky et al., 2008) Schultz et al., 2008)

SPH Modeling NASA AVRG Experiments

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0

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0 20 40 60 80

Impact Angle (degrees)

Eje

cta

Ma

ss

(M

etr

ic T

on

es

)

LCROSSSMART-1LPLCROSS S-S/C

SMART-1 (grazing impact) LP

Estimates of the total ejecta mass as a function of impact angle for four impactors: LCROSS, LCROSS S-S/C, Lunar Prospector (LP), and SMART-1

LCROSS

LCROSS S-S/C

SMART-1 (hill side impact)

The Impact – How Does it Compare?

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9The LCROSS Spacecraft

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10The LCROSS Payload

NIR SpectrometerUV/Visible Spectrometer

Visible Color

Camera

MIR Cameras

NIR Cameras Flash Radiometer

Solar NIR Spec

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Visible

NIR 2 NIR 1

MIR 1 MIR 2

Yours Truly…in Five Wavelengths

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VSP

NSP

NIR1VSP NIR2

LCROSS Wavelength Coverage

MIR1: 7-9 mMIR2: 7-12 m

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Impact @ 06:30 UTCHawaii lunar elevation = 39.9 deg @ impact

Ground Based Observations

Observatories Planning Observations:HSTOdin (EU)CFHTApache PointIRTFMMT (Az)UKIRTMROKeckGemini NorthSubaruASSI (Korea)

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Impact Expectations: Earth Brightness (per 1 sqr arc sec)

Curtain Area Average Brightness

15Summary

We’ll know in about 5 months!

•Earliest likely impact date August 28, 2009 (for an May 21 launch)

•Should be visible from Earth in the Pacific (including west coast)

• Impact target selection an on-going process, currently headed north

•LCROSS SC and Instrument development demonstrated a novel approach: High scientific return per dollar spent

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Backup Slides

17Expectations: LCROSS Water Detection

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0.04

0.09

0.14

0.19

0.24

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1.35 1.55 1.75 1.95 2.15 2.35

% A

bs

orp

tio

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dia

nc

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m-2

m

-1s

tr-1

)

Wavelength (microns)

IrradianceAbsorption11 bin average

Calculated ejecta cloud radiance (left axis) and synthetic NIR spectrometer data for 1% water content

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The radiance for the ejecta cloud only (derived be subtracting off the spectra from the lunar surface) for several times after Centaur impact.

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0 0.5 1 1.5 2 2.5 3 3.5

Wavelength (microns)

Ra

dia

nc

e (

W m

-2 m

icro

n-1

str

-1)

t=10

t=20

t=30

t=40

t=60

t=70

t=80

t=90

t=100

Expectations: Curtain Brightness

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19The LCROSS Experiment: Smooth or Chunky?

Aerial fraction for 10 m craters that is in equilibrium, i.e., “wet”, is:

~1 – Crater Diameter2/Crater Spacing2 = 1.-102/1002 = 99%

Top meter sensed by LP is near the derived value: high concentration pockets (water greater than few %) in the top meter not likely….the Smooth model is predicted.

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