LCROSS was a NASA impactor mission that launched in June 2009 with the goal of determining if water ice exists on the Moon. It consisted of a spent rocket stage that impacted a permanently shadowed crater at the Moon's south pole in October 2009, followed by the LCROSS spacecraft itself impacting 4 minutes later to observe the ejecta plume. The impacts excavated over 200 tons of lunar material and LCROSS's instruments detected evidence of water ice in the plume, confirming its presence on the Moon.

1. LCROSS
“the lunar hitch-hiker
that made an impact
(literally!) on how we
view our Moon and its
science secrets”
Dr. Kimberly Ennico (NASA Ames Research Center) poses with
LRO (silver), LCROSS (gold), Astrotech, Titusville, FL, May 2009)

2. LCROSS...at a glance...
Launch: June 18, 2009 Impact: October 9, 2009
(LCROSS was required to meet a 28 month, ATP to launch, schedule, and
to have minimal impact to LRO development and launch.)

3. Why LCROSS?
Mission Primary Objective:
To test whether or
not water ice deposits
exist on the Moon.
(Classic Scientific Method)

4. Why Look for Water?
• Humans exploring the
Moon will need water:
– Option 1: Carry it there*
– Option 2: Use water that
may be there already
• Learning to “Live off
the land” could make
(long-term) human
lunar exploration
easier.
(*At $10K/lb to orbit. $3-5K more to Moon. At 8 lbs/gallon, it could
cost >$100,000/gallon of water to the Moon.)

5. Early Evidence of Water
Clementine Lunar Prospector
(1994) (1999)
Two previous missions, Clementine and Lunar
Prospector gave us preliminary evidence that there
may be deposits of water ice at the lunar poles.

6. Controversial: ice or rough terrain?
Clementine bistatic radar – 1994
Ref: Nozette, S. et al. Science 274, 1495-1498 (1996)
• Circular polarization ratio (CPR) consistent with ice crystals in the south polar
regolith.
• Ground-based studies (Arecibo) confirmed high-CPR in some permanently-
shadowed craters.
– However, Arecibo scans also found high-CPR in some areas that are
illuminated, probably due to surface roughness.
Ref: Stacy, N. et al. Science, 276, 1527-1530 (1997)

7. Accepted, not conclusive re: ice
Lunar Prospector – Hydrogen 1998
Ref: Feldman, W.C. et al. Science 281, 1496-1500 (1998)
Map courtesy of D. Lawrence, Los Alamos National Laboratory.
• Neutron spectrometer maps of both lunar poles
• Low resolution data indicate elevated concentrations of hydrogen at
both poles
• It does not tell us the form of the hydrogen

8. The “Famous” LP maps
Feldman, W.C. et al. Science 281, 1496-1500 (1998)
Map courtesy of D. Lawrence, Los Alamos National Laboratory.
(dark blue/purple <-> low # neutrons <-> high hydrogen <-> water?)

9. Evidence against ice lakes at poles
Hi-Res Arecibo & Green Bank radar – 2005
Ref: Campbell, D.B. et al. Nature, 443, 835-837 (2006)
• Higher spatial res. (20 m) than 1994
Clementine & 1992 Arecibo data (125 m)
• Surveyed south pole and nearside to
latitude ~65° S
• Data indicate correlation between areas
of high CPR with walls and ejecta
deposits
– Shackleton had same CPR values as
Schomberger A&G, and many other
young craters
– High CPR areas in Shackleton are in
both permanent shadow and
seasonal illumination
• Conclude high CPR in Shackleton is not
due to ice deposits
– But they conclude they are open to
possibility very low abundance (1-2% Radar image Moon South Pole
by mass) mixed in grains from the (left) OC 100m; (right) CPR 500 m
Fig1 from Campbell, D.B. et al. Nature, 443, 835 (2006)
upper 1 m of regolith

10. Evidence against ice lakes at poles; temperature is cold enough to support ice
Selene (Kaguya) Terrain Camera – 2007
Ref: Haruyama, J. et al. Science, 322, 938-939 (2008)
• Terrain Camera (10 m res.) surveyed
inside Shackleton Crater
– Targeted during lunar mid-summer to
get max. illumination of the shadowed
regions by sunlight scattered off
nearby higher terrains
– Discovered small craters on inner wall
(100’s m dia.), mount-like features
(300-400m thick), & central hill (200m
height)
• Derived temperature measurement of
Shackleton floor ~88 K (max)
– Cold enough to retain water-ice
• Did not find bright areas in Shackleton that
could be due to pure water-ice
– Looking for albedo ~1.0
• They also conclude they are open to
possibility very low abundance (1-2% by
mass) mixed in grains from the upper 1 m
of regolith

11. How could there be water at
the lunar poles?
• The Sun never rises more
than a few degrees
above the polar horizon so
the crater floors are in
permanent shadow (PSR).
• The crater floors are very
cold with temperatures
< -200° C (70K, -328° F), so Many orbits Clementine data
water molecules move very South Pole (Ben Bussey, APL)
slowly and are trapped for
billions of years.
(On October 9, 2009, LCROSS performed the first “in-situ” study of a PSR.)

12. Where could water ice come from?
• Over the history of the Moon, when comets or • Water molecules at lower latitudes may form
asteroids impact the Moon's surface, they from interactions with hydrogen streaming out
briefly produce a very thin atmosphere that in the solar wind.
quickly escapes into space. • These water molecules may get baked out of
• Any water vapor that enters permanently the lunar soil and can then get trapped in polar
shadowed craters could condense and craters.
concentrate there.
(volatiles from comets, asteroids, IDPs, solar wind, GMCs, the Moon itself!)

13. How much water could there be?
• There is ~12,500 km2 of
permanently shadowed
terrain on the Moon.
• If the top 1 meter of this area
were to hold 1% water (by
mass)*, that would be
equivalent to about 4.1 x 1011
liters of water!
• This is approximately 2% the
volume of the Great Salt Lake
in Utah.
(*The Sahara desert is 1.2% water (by mass) in its top 20cm,
with 2.5-4.5% at 3m.)

14. Enter LCROSS-The pathfinder
LCROSS had a challenging set of
constraints:
• We had to fit within 1000Kg wet
mass…
• We had to design and build the
payload, spacecraft and
mission in only 30 months!
• We had a cost-cap of $79M,
including reserves…
• We couldn’t levy any
requirements on LRO…
• As a NASA Class D mission
some programmatic and
technical simplifications could
be leveraged

15. The LCROSS Experiment
Flash Curtain Crater
~0.1 min 3.0 min 1 min
• Impact the Moon at 2.5 km/sec (5,600 mph) with a ~2366 kg
(5216 lb) Centaur upper stage and create an ejecta cloud into
the sunlight for observation
• Observe the impact and ejecta with instruments that can
detect water
• Four minutes later the ~625 kg (1378 lb) LCROSS S/C itself
impacts at 2.5 km/s

16. Excavating with 6.5-7 billion Joules
• About equal to 1.5 tons of TNT
• Minimum of 200 tons lunar rock and soil expected to be
excavated
• New crater estimated to have ~20-25 m diameter and ~3m
depth
• Similar in size to East Crater at Apollo 11 landing site

17. Anatomy of an Impact –
flash, curtain, crater
ARC Vertical Gun Experiments
Step 1 Step 5
Impact flash
Nadir View of Impact and Ejecta Curtain
Step 2 Step 6 Incandescent particles
Crater rim
Time
Time
Step 3 Step 7
“Sunrise”
Reverse ejecta
Ejecta Step 4 Step 8
Curtain Into
sunlight
Scales to ~2 sec after
Pete Schultz
Centaur impact

18. Recent “Controlled” Lunar Impacts
S/C Impact Date S/C Mass S/C Velocity Impact angle Impact Location Observations
at impact from
horizon.
Hiten/ 10 Apr 1993 143 kg 2.33 km/s 42° 55°E, 32.4°S Flash
Muses (hydrazine)
LP 31 Jul 1999 161 kg 1.69 km/s 6.3° South pole area Null
SMART-1 3 Sep 2006 285 kg 2 km/s 1° 46.2°W, 34.4° S Flash, plume
Change’1 1 Mar 2009 2350 kg ? ? just south of the ?
lunar equator, at
52.36 degrees East
Longitude
Kaguya 10 Jun 2009 ~1800 kg 1.8 km/s 1° 80.4°E, 65.5°S Flash
(Selene)
LCROSS 09 Oct 2009 2366 kg 2.5 km/s >85 ° 48.703°W, 84.675°S; Flash, Plume,
Crater
LCROSS 09 Oct 2009 625 kg 2.5 km/s >85 ° 48.703°W, 84.675°S; Null (to date)
S-S/C

19. Why LCROSS would be different….
400
LCROSS
SMART-1 LCROSS Centaur
350
LP
300 LCROSS S-S/C
NOTE: LCROSS Predictions
shown. LP/SMART-1
250 actuals shown
200 LCROSS S-S/C
150
100
SMART-1 (hill side impact)
Ejecta Mass (Metric Tones)
50
0
0 LP 20 40 60 80
Impact Angle (degrees)
SMART-1 (grazing impact)

20. ARC Vertical Gun Experiments

21. LCROSS was an artificial impactor
(natural impacts* happen all the time)
Ref: Montañés-Rodríguez, Pallé, & Goode, AJ, 134, 1145-1149 (2007)
NASA Marshall Lunar Impact Monitoring Program http://www.nasa.gov/centers/marshall/news/lunar/
(*Natural impacts typically have much more energy than
LCROSS’s 6-7e9 Joules.)

22. The LCROSS Mission Recipe
• Step 1: Hitch a ride to the Moon
• (Thanks LRO)
• Step 2: Part with LRO, but hang onto that rocket!
• (we’ll use it later)
• Step 3: Tug it around the Earth
• Step 4: Point it toward our crater
• Step 5: Let go!
• Step 6: Slow-down & watch what kicks-up
• Step 7: Send pics & data back to Earth
• Step 8: Say good-bye
• (Taste regolith!)

23. The LCROSS Mission Concept
1. Launched stacked with LRO 2. After Lunar swing-by, enter a 4
June 18, 2009 month cruise around Earth
3. October 9, 4. S-S/C observes
2009, target the impact, ejecta
Centaur Upper cloud and
Stage and resulting crater,
position S-S/C making
to fly 4 minutes measurements
behind until impacting
itself

24. Spacecraft & Impactor

25. Secondary Payload Approach
Atlas V
LCROSS literally
hitched a ride to
the moon!
Delta II
When LRO
upgraded to a
larger launch
vehicle, there
was an extra
1kg launch
mass available.
(LCROSS was required to meet a 28 month, ATP to launch, schedule, and
to have minimal impact to LRO development and launch.)

26. Secondary Payload Approach
http://www.nasa.gov/mission_pages/LCROSS/multimedia/gallery/

27. Secondary Payload Approach
http://www.nasa.gov/mission_pages/LCROSS/multimedia/gallery/

28. “Creativity Loves Constraints”
LCROSS’ Innovative Approach
Re-use of upper-
Centaur stage as the
2300kg impactor
Turn the ESPA ring into
the actual spacecraft
mechanical structure
Spare Tracking
Data Relay
System satellite
propellant tank
Petal-like panels fold up and
down during I&T, eased access
http://lcross.arc.nasa.gov/spacecraft.htm

29. “Creativity Loves Constraints”
Leveraged Technology
Shares the same build-to-print Propulsion System uses all
avionics suite as LRO commercially available parts
Star Tracker & IRU & ACS FSW similar to
LRO’s arrangement
NG Flight Software
Heritage, using 10 year
old code, just updated
http://lcross.arc.nasa.gov/spacecraft.htm

30. “Creativity Loves Constraints”
COTS Payload

31. Kimberly Ennico & Mark
Shirley testing the LCROSS
payload at NASA ARC (left)
and NGST (right)

32. Mission Day 0 (09-169; Jun 18)
Launch! 5:32pm EDT
Mission Ops Center NASA Ames Launch from Cape Canaveral, FL
Fairing
Earth LCROSS star tracker
Fairing separation

33. Where’s LCROSS?

34. LCROSS taken through Liverpool 2-meter Telescope,
La Palma, Canary Islands – Robert Smith

35. LCROSS in flight taken through an amateur 16-inch telescope
– Paul Mortfield

36. Where’s LCROSS?
LCROSS in flight taken through an amateur 16-inch telescope
– Paul Mortfield

37. Where’s LCROSS?

38. Where’s LCROSS?
http://www.lewislearning.org/

39. Mission Day 4 (09-173; Jun 22)
Starfield Calibration
Angular distance between αAquila (Altair) and γAquila (Tarazed) on the sky is 1.86 degrees and was
measured to be 46 pixels (along the diagonal) on NIR2. This confirmed a platescale of ~1.89/46 = 0.04
degrees/pixel for NIR2 (at least within the central region of the array).

40. Mission Day 5 (09-174; Jun 23)
Lunar Swingby
Ennico, et al. (2009)

41. Mission Day 5 (09-174; Jun 23)
Lunar Swingby
(This was the scene of Lunar Swingby, June 23, ~2:30am.)
Tony Colaprete (maroon shirt), reviews live data, Kim Ennico (black shirt) in front compares live data to expected
performance using checklists. Jen Heldmann (in back) updates STK viewpoint for live streaming test.

42. Mission Day 44 (09-213; Aug 01)
Earth Calibration at 360,000 km
North
North
NIR1 MIR1*
NIR2
MIR2 Full Earth at 360,000km
O3 O2γ
CO2
H2O H2O
H2O
CO2 CH4
O3
Ennico, et al. in prep.

43. Mission Day 60 (09-229; Aug 17)
Earth Calibration at 520,000 km
Crescent Earth at 520,000km. Crescent Moon at 881,000 km.

44. Mission Day 92 (09-261; Sep 18)
Earth Calibration at 560,000 km
STK Boresight Map
NIR1 (1.4-1.7um) NIR2 (0.9-1.7um) MIR1 (6.0-10um) MIR2 (6.0-13.5um)
Quarter-Earth at
560,000 km
Ennico, et al. in prep.

45. Mission Day 113 (09-282; Oct 09)
Separation
MIR_S1_W0000_T3425736m453 MIR_S1_W0000_T3425953m305
d = 150 m d = 300 m
Cam6_W0000_T3425736m969 MIR_S1_W0000_T3426668m025
d = 150 m d = 800 m
Ennico, et al. (2009)

46. Mission Day 113 (09-282; Oct 09)
Separation
Centaur Light curves observed from Earth 3-5 hrs before impact Buie & Ryan, SWRI & Magdalena Ridge

47. Mission Day 113 (09-282; Oct 09)
Impact!
(This was the scene of Impact at the Science Ops Center, Oct 9, ~4:30am.)
Tony Colaprete (black shirt), reviews live data, Kim Ennico (maroon shirt) on voice command to MOS to command camera
change request based on live data analysis by Tony & Kim (on the fly).

48. Where did we go and why?
Target Selection
Criteria:
1. Ejecta Illumination
2. Association with
hydrogen •
3. Observable to Earth
4. “Smooth”, flat terrain
LCROSS Visible Camera
Image 2009-09-09 11:00 UTC
Cabeus Crater
Final decision considered available data, status of LCROSS
payload, ability of LRO to observe, and limits of Earth observing
for each site.

49. Where did we go?
X
Goldstone map
http://www.nasa.gov/mission_pages/LCROSS/main/candidate_craters_story.html

50. Where did we go?
X
Goldstone map
http://www.nasa.gov/mission_pages/LCROSS/main/candidate_craters_story.html

51. Where did we go?
Cabeus A:
• Best Earth observing (not
perfect since backdrop
would have been lit moon)
• Hydrogen association
was questionable
Cabeus B:
• No obvious
association
with hydrogen
Cabeus:
Obvious hydrogen, but
worst Earth observing
LCROSS Visible Camera Image 2009-09-09 11:30 UTC
(Viewpoint from LCROSS, Oct 9)

52. Where did we go?
Target Crater Cabeus
Target Crater Cabeus
Nancy Chanover, APO
(Viewpoint from Earth, Oct 9)

53. Where did we go?
Expected
Plume Area
Nancy Chanover, APO
(Viewpoint from Earth, Oct 9)

54. Where did we go?
(Target area with good elevation angles to Sun for ejecta illumination.
Source: LRO LOLA.)

55. How Close Did We Hit?
Marshall, W., Shirley, M. et al. in prep.
(We hit within 100 meters of our predicted target!)

56. So... Why no big plume?
Schultz, et al (2010)
Predicted What we think we did

57. What did we see?
Cam1_W0000_T3460421m473 Schultz, et al (2010)
(Observed expanded ejecta cloud 10-12km in diameter at 20s after impact. Visible camera
imaged curtain at t+8s through t+42s, before cloud dropped below sensitivity range).

58. What did we see?
Multi-pixel signature >1km structure
t+0s t+2s t+4s
MIR_S1_W0000_T3460402m651.png MIR_S1_W0000_T3460404m653.png MIR_S1_W0000_T3460406m655.png
t+6s t+8s t+10s
MIR_S1_W0000_T3460408m657.png MIR_S1_W0000_T3460410m659.png MIR_S1_W0000_T3460412m159.png
(Thermal signature seen in mid-IR cameras t+2-10s believed to be impact-heated ballistic ejecta
that did not get into sunlight (low-angle plume). Ejecta after 4s is within a single pixel,
~1km/pix at this altitude.)

59. Coordinating Observations
View of Moon from Earth on 9 October 2009, 4:30 a.m. PDT

60. Coordinating Observations
A Coordinated Professional Observation Campaign using Earth, Earth-Orbit
and LRO has been part of the mission from the start.

61. Coordinating Observations
Backyard astronomer observations are coordinated through the
LCROSS Google Group
http://groups.google.com/group/lcross_observation?hl=en

62. Other Eyes
Canada France Hawaii Telescope (Hawaii)
Apache Point Observatory (New Mexico)
Infrared Telescope Facility (IRTF, Hawaii)
MMT Observatory (Arizona)
Magdalena Ridge Observatory (New Mexico)
Keck (Hawaii)
Gemini North (Hawaii)
Subaru Telescope (Hawaii)
Korea Astronomy & Space Science Institute (Arizona & Korea)
Mount Wilson (California)
Air Force AEOS Telescope (Hawaii)
Allen Telescope Array (California)
Palomar Observatory (California)
Lick Observatory (California)
Hubble Space Telescope, Lunar Reconnaissance Orbiter
Odin, IKONOS, GeoEye-1
LCROS EBOC Campaign

63. Coordinating Observations
NASA GSFC

64. Coordinating Observations

65. Coordinating Observations
Apache Point Observatory (New Mexico)
Nancy Chanover, APO

66. Coordinating Observations
Keck guider image (Mauna Kea, Hawaii)
Wooden, et al.

67. Coordinating Observations
Canada France Hawaii Telescope
Christian Veillet, CFHT

68. Coordinating Observations
MMT Observatory, Arizona
BEFORE
AFTER
Faith Vilas, MMT

69. LCROSS Water Measurement

70. New Lunar Water Evidence (?)- 2009
Must
excavate
1 ton regolith
to get 32oz
(0.25 gal)
‘water.’
(1000 ppm)
Chandrayaan-1 Deep Impact Cassini
Data from these probes has shown that small amounts of water
are widespread across the upper millimeter surface of the Moon. The
amount of water may change during the course of the lunar day.
Clark, et al (2009), Pieters, et al (2009), Sunshine, et al (2009)

71. LCROSS’ (different) water measurement
The measurement...

72. LCROSS’ (different) water measurement
Model a 230°C (500K) greybody...

73. LCROSS’ (different) water measurement
H2O H2O
H2O
Add to it a water model...

74. LCROSS’ (different) water measurement
H2O H2O
Other
Other
H2O
Add in some other simple molecules...

75. So... How Much water?
• LCROSS (Colaprete, et al 2010)
– sampled one area, created a 20-30m diameter crater, excavated ~250 metric tons
(from model)
– only observed 2202-4382 kg sunlit material (above 833m alt) at impact+8s.
– two band depths measured
• H2O (1.4 & 1.8um) -> 145 kg H2O vapor+ice
• OH (308-310nm) -> 110 kg H2O vapor+ice
– model dependent (mixing) -> mean water concentration 7.4 wt% ± 5.4 wt%
– observed 688-1369 kg sunlit material at impact +30-200s
• LAMP/LRO (Hurley, et al. 2009)
– observed H2, peak column density ~158kg H2 released,
– fit models -> <400 kg H2O released,
– assumed 20,000kg was released -> <2% wt%
• LEND/LRO (Mitrofanov, et al. 2010)
– 2100-5400 ppm measurements -> 1.9-4.9 wt%
• Diviner/LRO (Hayne, et al. 2010)
– observed 760-1800 kg sunlit material at impact +90s
M3 “0.25 gal H2O/1 ton soil”; LCROSS “10 gal H2O/1 ton soil”

76. In Summary (1 of 3)
• LCROSS proved that a new class of mission (NASA Class D) high
science payoff at low cost/high risk is possible
• Tight schedule & budget constraints (or you would lose your ride)
forced proactive and rigorous project management with very visible
risk management
• Lifecycle of “cradle to grave” in <3 years excellent training
experience
• Design engineers used as part of ops team was essential in quick
turn-around response to anomalies and events
• Ruggedized-COTS instruments did perform well in space (~5-10 hrs
operation time), high performance at low cost
• Never underestimate the importance of on-orbit calibration data
(saved our bacon)

77. In Summary (2 of 3)
• Impact appears to have occurred in a volatile rich area:
• Water …and other stuff!! (e.g., CH4, CO2, SO2, NH3, Na, K, CO, NH2)
possibly observed…work occurring now to get unique identification
• Band depths and OH emission strengths indicate significant amounts of
water (>150 kg vapor and ice)
– Reported concentration: 7.4 wt% ± 5.4 wt% (Colaprete, et al. 2010)
– From LEND: ~ 1.9 - 4.9 wt% (for 3 cm dry layer) (Mitrofanov, et al. 2010)
– Remember, ESMD requirement for moon base was 1 wt%
• The amount and types of volatiles suggest:
– The very cold temperatures sequester all sorts of volatiles (see Zhang &
Paige, 2009)
– Need multiple source model (see Lucey, 2000)

78. In Summary (3 of 3)
Science can be surprising!
Updates on the LCROSS mission results are posted at
http://www.nasa.gov/LCROSS
http://lcross.arc.nasa.gov
Prediction What may have happened...

79. LCROSS Papers/Presentations
Lunar Exploration Analysis Group (LEAG), November 17-19, 2009, Houston, TX (Impact +1 m)
Colaprete et al.,
Schultz et al.,
Heldmann et al.,
Wooden et al.,
American Geophysical Union (AGU), December 12-16, 2009, San Francisco, CA (Impact +2 m)
Colaprete et al.,
Schultz et al.,
Chin et al.,
McClanahan et al.,
Hermalyn et al.,
Ennico et al.,
Heldmann et al.,
Wooden et al.,
Hurley et al.,
Submitted to Science, Jan 2010 (Impact + 3m)
Colaprete et al.,
Schultz et al.,
Hayne, et al.
Goldstone et al.
Mitrofanov, et al.
Lunar and Planetary Science Conference, March 1-5, 2010, Houston , TX (Impact +5 m)
Seven (7) oral and eleven (11) poster presentations in Special Session: “A New Moon: LCROSS,
Chandrayaan Chang'E-1 Results”