Exploring the Lunar Environment

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Exploring the Lunar Environment Brian DayLADEE
Mission NASA Lunar Science Institute
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A new generation of robotic lunar explorers is
revolutionizing our understanding of the Moon.
We now recognize the Moon as a dynamic world with
surficial and internal volatiles, active
geology, and complex interactions with space
weather. All of these could contribute to a
fascinating lunar atmospheric environment.
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LCROSS Mission Concept

• Impact the Moon at 2.5 km/sec with a Centaur
  upper stage and create an ejecta cloud that may
  reach over 10 km about the surface
• Observe the impact and ejecta with instruments
  that can detect water

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What did we see?
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What did we see?
What did we see?
Schultz, et al (2010)
Cam1_W0000_T3460421m473
(Observed expanded ejecta cloud 10-12 km in
diameter at 20s after impact. Visible camera
imaged curtain at t8s through t42s, before
cloud dropped below sensitivity range).
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What did we see?
What did we see?
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Centaur Impact Crater
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Water Signatures Detected!
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So... How Much Water?

• We sampled only one area, created a 20-30m
  diameter crater, at few meters depth.
• We excavated 250,000 kg (250 metric tons)
  regolith
• Of that only 2200-4400 kg material got into
  sunlight.
• Of that only 1300-2500 kg were within the 1 FOV
  of the spectrometers
• Band depths of H2O 1.4 1.8um features indicate
  145 kg H2O vaporice
• OH emission strength at 308-310nm indicate 110 kg
  H2O vaporice
• 29-38 gallons of water
• mean water concentration 5.6 wt 2.9 wt (by
  mass)

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M3 0.25 gal H2O/1 ton soil LCROSS 10 gal
H2O/1 ton soil
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Lunar Reconnaissance Orbiter (LRO)

• LROC image and map the lunar surface in
  unprecedented detail
• LOLA provide precise global lunar topographic
  data through laser altimetry
• LAMP remotely probe the Moons permanently
  shadowed regions
• CRaTER - characterize the global lunar radiation
  environment
• DIVINER measure lunar surface temperatures
  map compositional variations
• LEND measure neutron flux to study hydrogen
  concentrations in lunar soil

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Apollo 14 Landing Site Imaged by LRO
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You Can Help Explore the Moon!
Visit http//www.moonzoo.org/ to see how you can
help explore the images from LRO.
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The Moons Permanently Shadowed Craters are the
Coldest Places We have Found in the Solar System

• LRO has measured temperatures as low as -248
  degrees Celsius, or -415 degrees Fahrenheit
• This is colder than the daytime surface of Pluto!
  (-230 Celsius)

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LROs DIVINER Indicates Widespread Ice at Lunar
Poles

• In South Pole permanently-shadowed craters,
  surface deposits of water ice would almost
  certainly be stable.
• These areas are surrounded by much larger
  permafrost regions where ice could be stable just
  beneath the surface.

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Water at the North Pole Too!

• On March 1, 2010, NASA scientists announced that
  they have detected water ice deposits at the
  Moons North Pole.
• Discovery was made with the NASA Mini-SAR
  instrument aboard Indias Chandrayaan-1.
• More than 40 permanently shadowed craters were
  estimated to contain a total of at least 600
  million metric tons of water ice!

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Water in the Soil

• Chandrayann-1 and two other robot explorers found
  small amounts of water away from the poles.

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Deep Impact
Cassini
Chandrayaan-1
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Where Did the Water Come From?

• Were not sure, but we have some clues.

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Giant Impactor Formation of the Moon 4.5
billion years ago.The reason for a dry Moon?
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Lunar melt inclusion evidence of a wet Moon?
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Lobate Scarps The Shrinking Moon
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Moonquakes A Whole Lot of Shaking Going On

• Deep moonquakes about 700 km below the surface,
  probably caused by tides.
• Vibrations from the impact of meteorites.
• Thermal quakes caused by the expansion of the
  frigid crust when first illuminated.
• Shallow moonquakes 20 or 30 kilometers below the
  surface. Up to magnitude 5.5 and over 10
  minutes duration!

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Gravity Recovery and Interior LaboratoryGRAIL

• Launched Sept 10, 2011.
• Microwave ranging system will precisely measure
  the distance between the two satellites.
• Use high-quality gravity field mapping to
  determine the Moon's interior structure.
• Determine the structure of the lunar interior,
  from crust to core and to advance understanding
  of the thermal evolution of the Moon.

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ARTEMIS

• Acceleration, Reconnection, Turbulence and
  Electrodynamics of the Moons Interaction with
  the Sun
• Consists of two orbiters, ARTEMIS-P1 ARTEMIS
  P2, formerly part of the THEMIS mission.
• Moved to lunar L1 and L2 points in 2010 and
  lunar orbit in 2011.
• Studying the solar wind and its interaction with
  the lunar surface, the Moons plasma wake, and
  the Earths magnetotail.

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• Mission will study how solar wind electrifies,
  alters and erodes the Moon's surface.
• Could provide valuable clues to the origin of the
  lunar atmosphere.

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Lunar Atmosphere?

• Yes, but very thin! A cubic centimeter of Earth's
  atmosphere at sea level contains about 1019
  molecules. That same volume just above the Moon's
  surface contains only about 100,000 molecules.
• It glows most strongly from atoms of sodium.
  However, that is probably a minor constituent. We
  still do not know its composition.

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Lunar Exosphere

• An exosphere is a tenuous, collisionless
  atmosphere.
• The lunar exosphere is bounded by the lunar
  surface a surface boundary exosphere.
• Consists of a variety of atomic and molecular
  species indicative of conditions at the Moon
  (surface, subsurface).
• Wide variety of processes contribute to sources,
  variability, losses.

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A Dusty Lunar Sky?
In 1968, NASA's Surveyor 7 moon lander
photographed a strange "horizon glow" looking
toward the daylight terminator. Observations are
consistent with sunlight scattered from
electrically-charged moondust floating just above
the lunar surface.
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A Dusty Lunar Sky?
More possible evidence for dust came from the
Apollo missions.
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The Lunar Exosphere and Dust Sources Sinks
Inputs Solar photons Solar Energetic
Particles Solar wind Meteoric influx Large
impacts
Dayside UV-driven photoemission, 10s
V Nightside electron-driven negative
charging -1000s V
Processes Impact vaporization Interior
outgassing Chemical/thermal release
Photon-stimulated desorption Sputtering
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Lunar Exosphere
Cold-trapping in Polar regions
Formation of Lunar volatiles
Vondrak and Crider, 2003
Mendillo et al, 1997
Stern, 1999Smyth and Marconi, 1995
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Exospheres and Dust
Surface Boundary Exospheres (SBEs) may be the
most common type of atmosphere in the solar
system
Large Asteroids KBOs
Mercury
Moon
Evidence of dust motion on Eros and the Moon....
Europa other Icy satellites
Io
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Eros
Delory, American Geophysical Union Fall Meeting
12-16-09
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LADEE
The Lunar Atmosphere and Dust Environment Explorer

• Determine the global density, composition, and
  time variability of the fragile lunar atmosphere
  before it is perturbed by further human
  activity.
• Determine the size, charge, and spatial
  distribution of electrostatically transported
  dust grains.
• Test laser communication capabilities.
• Demonstrate a low-cost lunar mission
• Simple multi-mission modular bus design
• Low-cost launch vehicle

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Neutral Mass Spectrometer (NMS) MSL/SAM Heritage
UV Spectrometer (UVS) LCROSS heritage
SMD - directed instrument
SMD - directed instrument
In situ measurement of exospheric species P.
Mahaffy NASA GSFC
Dust and exosphere measurements A.
Colaprete NASA ARC
150 Dalton range/unit mass resolution
Lunar Dust EXperiment (LDEX) HEOS 2, Galileo,
Ulysses and Cassini Heritage
Lunar Laser Com Demo (LLCD) Technology
demonstration
SOMD - directed instrument
SMD - Competed instrument
High Data Rate Optical Comm D. Boroson MIT-LL
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M. Horányi, LASP
51-622 Mbps
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Spacecraft Configuration

• 330 kg spacecraft mass
• 53 kg payload mass

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Modular Common Spacecraft Bus

• LADEE is NASAs first mission using the MCSB.
• Usually space missions require unique spacecraft
  that are custom built for hundreds of
  millions of dollars.
• By using a modular platform NASA will no longer
  need to reinvent the wheel for each mission
  and leveraging previous RD further reduces
  design cost.
• Could be used to land on the Moon, orbit Earth,
  or rendezvous with asteroids.

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LADEE Mission Profile

• Launch in 2013 from Wallops using a Minotaur
  launch vehicle.
• 2-3 phasing orbits to get to Moon.
• Insertion into retrograde orbit around Moon.
• Checkout orbit (initially 250km) for 30
  days.
• 100-day science mission at 20-75km.

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Provide Background Science Data LADEE and Lunar
Impacts

• NASA Meteoroid Environment Office
• Lunar Impact Monitoring Program
• Help lunar scientists determine the rate of
  meteoroid impacts on the Moon.
• Meteoroid impacts are an important source for
  the lunar exosphere and dust.
• Can be done with a telescope as small as 8
  inches of aperture.
• Also planning to work with AAVSO Lunar
  Meteoritic Impact Search Section.

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• Phase Matters
• Impact flashes are observed in the unilluminated
  area of the Moon.
• Near 1st Qtr, the Moons leading hemisphere faces
  Earth generally best for observing impact
  flashes.
• Near 3rd Qtr, the Moons trailing hemisphere
  faces Earth generally less favorable for
  observing impact flashes.
• A large gibbous phase results in lots of glare
  from illuminated lunar surface, small
  unilluminated area for observing flashes, and
  diminished Earth shine on unilluminated area
  making localizing impacts difficult.
• Thin crescent phase results in restricted
  observing time in dark sky.

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• Lunar Meteoroid Impact Monitoring
• Minimum System Requirements
• 8" telescope
• 1m effective focal length
• Equatorial mount or derotator
• Tracking at lunar rate
• Astronomical video camera with adapter to fit
  telescope
• NTSC or PAL
• 1/2" detector
• Digitizer - for digitizing video and creating a
  720x480 .avi
• Segment .avi to files less than 1GB (8000 frames)
• Time encoder/signal
• GPS timestamp or WWV audio
• PC compatible computer
• 500GB free disk space
• Software for detecting flashes
• LunarScan software available as a free download

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• Meteor Counting
• The vast majority of meteoroids impacting the
  Moon are too small to be observable from
  Earth.
• Small meteoroids encountering the Earths
  atmosphere can result in readily-observable
  meteors.
• Conducting counts of meteors during the LADEE
  mission will allow us to make inferences as to
  what is happening on the Moon at that time.
• Much more simple requirements a dark sky, your
  eyes, and log sheet. (a reclining lawn chair
  is very nice too!)
• International Meteor Organization
  (http//imo.net/)
• American Meteor Society (http//www.amsmeteors.org
  /)

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Image creditNASA/ISAS/Shinsuke Abe and Hajime
Yano
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Lunar Phases for Major Meteor Showers in
2013 Jan 3 Quadrantids Last Qtr 61 Apr 22
Lyrids Waxing Gibbous 90 May 5 Eta Aquariids
Waning Crescent 15 July 27 Delta Aquariids
Waning Gibbous 66 Aug 12 Perseids Waxing
Crescent 35 Oct 21 Orionids Waning Gibbous
90 Nov 19 Leonids Waning Gibbous 94 Dec 14
Geminids Waxing Gibbous 95 Dec 22 Ursids
Waning Gibbous 73
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Lunar Phase Aug 12, 2013
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Questions
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