Exploring the Lunar Environment
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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

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

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Exploring the Lunar Environment

Brian DayLADEE 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


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 t+8s through t+42s, before cloud dropped below sensitivity range).

5


What did we see?

What did we see?

6


Centaur Impact Crater

7


Water Signatures Detected!

8


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 vapor+ice

      • OH emission strength at 308-310nm indicate 110 kg H2O vapor+ice

      • “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”


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

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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 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.

16

Deep Impact

Cassini

Chandrayaan-1


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

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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!

21


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.

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 2011.

  • Studying the solar wind and its interaction with the lunar surface, the Moon’s plasma wake, and the Earth’s 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.

24


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.

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

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

29


Lunar Exosphere

Cold-trapping in

Polar regions

Formation of

Lunar volatiles

Vondrak and Crider, 2003

Mendillo et al, 1997

Stern, 1999;Smyth

and Marconi, 1995

30


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

31

  • Eros

Delory, American Geophysical Union Fall Meeting 12-16-09


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


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

33

M. Horányi, LASP

51-622 Mbps


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


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.

37


  • Phase Matters

  • Impact flashes are observed in the unilluminated area of the Moon.

  • Near 1st Qtr, the Moon’s leading hemisphere faces Earth – generally best for observing impact flashes.

  • Near 3rd 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 (http://imo.net/)

  • American Meteor Society (http://www.amsmeteors.org/)

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Image credit:NASA/ISAS/Shinsuke Abe and Hajime Yano


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


Questions

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