Exploring the Lunar Environment Brian Day LADEE Mission NASA Lunar Science Institute

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. 2

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 3

What did we see? 4

(Observed expanded ejecta cloud km in diameter at 20s after impact. Visible camera imaged curtain at t+8s through t+42s, before cloud dropped below sensitivity range). Schultz, et al (2010) Cam1_W0000_T m473 5

What did we see? 6

Centaur Impact Crater 7

Water Signatures Detected! 8

So... How Much Water? M3 “0.25 gal H2O/1 ton soil”; LCROSS “10 gal H2O/1 ton soil” 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 kg material got into sunlight. Of that only kg were within the 1° FOV of the spectrometers –Band depths of H 2 O 1.4 & 1.8um features indicate 145 kg H 2 O vapor+ice –OH emission strength at nm indicate 110 kg H 2 O vapor+ice –“29-38 gallons of water” »mean water concentration 5.6 wt% ± 2.9 wt% (by mass) 9

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 Moon’s 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 10

Apollo 14 Landing Site Imaged by LRO 11

You Can Help Explore the Moon! Visit to see how you can help explore the images from LRO. 12

The Moon’s 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) 13

LRO’s 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. 14

Water at the North Pole Too! On March 1, 2010, NASA scientists announced that they have detected water ice deposits at the Moon’s North Pole. Discovery was made with the NASA Mini-SAR instrument aboard India’s Chandrayaan-1. More than 40 permanently shadowed craters were estimated to contain a total of at least 600 million metric tons of water ice! 15

Water in the Soil Chandrayann-1 and two other robot explorers found small amounts of water away from the poles. Deep ImpactCassini Chandrayaan-1 16

Where Did the Water Come From? We’re not sure, but we have some clues. 17

Giant Impactor – Formation of the Moon 4.5 billion years ago. The reason for a dry Moon? 18

Lunar melt inclusion – evidence of a wet Moon? 19

Lobate Scarps – The Shrinking Moon 20

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! 21

Gravity Recovery and Interior Laboratory GRAIL Launched Sept 10, 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. 22

ARTEMIS Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s 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 Studying the solar wind and its interaction with the lunar surface, the Moon’s plasma wake, and the Earth’s magnetotail. 23

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. 24

Lunar Atmosphere? Yes, but very thin! A cubic centimeter of Earth's atmosphere at sea level contains about 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. 25

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. 26

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. 27

A Dusty Lunar Sky? More possible evidence for dust came from the Apollo missions. 28

The Lunar Exosphere and Dust: Sources & Sinks Inputs: Solar photons Solar Energetic Particles Solar wind Meteoric influx Large impacts Processes: Impact vaporization Interior outgassing Chemical/thermal release Photon-stimulated desorption Sputtering Dayside: UV-driven photoemission, +10s V Nightside: electron-driven negative charging -1000s V negative charging -1000s V 29

Lunar Exosphere Mendillo et al, 1997 Stern, 1999;Smyth and Marconi, 1995 Formation of Lunar volatiles Cold-trapping in Polar regions Vondrak and Crider,

Exospheres and Dust Io Europa & other Icy satellites Eros Large Asteroids & KBOs Moon Surface Boundary Exospheres (SBEs) may be the most common type of atmosphere in the solar system… Evidence of dust motion on Eros and the Moon.... Delory, American Geophysical Union Fall Meeting

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 32

Lunar Dust EXperiment (LDEX) HEOS 2, Galileo, Ulysses and Cassini Heritage Neutral Mass Spectrometer (NMS) MSL/SAM Heritage UV Spectrometer (UVS) LCROSS heritage Lunar Laser Com Demo (LLCD) Technology demonstration Dust and exosphere measurements A. Colaprete NASA ARC In situ measurement of exospheric species P. Mahaffy NASA GSFC Mbps 150 Dalton range/unit mass resolution M. Horányi, LASP High Data Rate Optical Comm D. Boroson MIT-LL SMD - directed instrument SMD - Competed instrument SOMD - directed instrument 33

Spacecraft Configuration 330 kg spacecraft mass 53 kg payload mass 34

Modular Common Spacecraft Bus LADEE is NASA’s 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 R&D further reduces design cost. Could be used to land on the Moon, orbit Earth, or rendezvous with asteroids. 35

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. 36

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. Provide Background Science Data: LADEE and Lunar Impacts 37

Phase Matters Impact flashes are observed in the unilluminated area of the Moon. Near 1 st Qtr, the Moon’s leading hemisphere faces Earth – generally best for observing impact flashes. Near 3 rd Qtr, the Moon’s 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. 38

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 39

Meteor Counting The vast majority of meteoroids impacting the Moon are too small to be observable from Earth. Small meteoroids encountering the Earth’s 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 ( American Meteor Society ( Image credit:NASA/ISAS/Shinsuke Abe and Hajime Yano 40

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% Lunar Phase Aug 12,

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