#5

Abstract for Meteoroids 2007 - Barcelona, SpareJune 11-15, 2007

NASA's Lunar Impact Monitorin§ Program

Rob Suggs/NASA/MSFC EV13Bill Cooke/NASA/MSFC/EV13Wes Swift/RaytheonNick Hollen/Jacebs Sverdrup

NASA's Meteoroid Environment Office nas implemented a program to monitor the Moon formeteoroid impacts from the Marshall Space Flight Center. Using off-the-shelf telescopes andvideo equipment, the moon is monitored for as many as 10 nights per month, aepending onweather. Custom software automatically detects flashes which are confirmed by a secondtelescope, photometrically calibrated using background stars, anc published on a weDsite forcorrelation with other observations, Hypervelocity _mpact tests at the Ames Vertical Gun Facilityhave been performed to determine the luminous efficiency ana ejecta characteristics. Thepurpose of this researcn is to define the imoact ejecta environment for use by lunar spacecraftdesigners of the Constellatbn manned unar) Program. The observational techniaues andpreliminary results will be discussed.

https://ntrs.nasa.gov/search.jsp?R=20070032706 2018-05-28T12:26:01+00:00Z

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Automated Lunar and MeteorObservatory

• Telescopes• 2 Meade RCX400 14"(355 mm)• Meade or Optec O.33xfocal reducer giving -f2.6

• Recording Devices• Astrovid Stellacam EX• Sony Digital 8 recorderas digitizer• Firewire to PC harddisk

Observing the Moon• Dark (not sunlit) side only

• Earthshine illuminates lunar features• FOV is approximately 20 arcmin - covering 4.5

to 5 million square kIn - 12% of the lunarsurface

• 12th magnitude background stars are easilyvisible at video rates

• Crescent and quarter phases - 0.1 to 0.5solar illumination

• 5 nights waxing (evening)

• 5 nights waning (morning)

• Have taken data on about 55% of thepossible nights. > 190 hours in the past year.Cirrus is our enemy.

• Observing procedure

• Aim scope at Moon

• Record video from StellaCam EX to hard drive

• Wait and reposition - working on software toimprove tracking of Meade scopes

Probable Leonid ImpactNovember 17, 2006

Video is slowed by a factor of 7

Impact Candidates

Yellow are sporadic background meteoroidsWhite is likely Taurid, green Geminids, blue Leonids, red Lyrids

The Usual Suspects

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• Noise/cosmic rays

• Boundaries

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• Establishing 2nd siteto discriminate faintglints from orbitaldebris

• Impacts!

LunarScan (Gural)

Impact 15 Dec 2006

Photometric analysis is performed by LunaCon (Swift, poster paper)Currently adding collecting area and "limiting magnitude" determination toLunaCon

Probable Sporadic Impacts

Lunar Viewing and Impact Geometryfrom 3 Strongest Sporadic Sources

Implies an average of more than3 kilogram-class impacts per hoursomewhere on the moon duringnon-shower periods

First Quarter

56.8% of observing time

0.19 sporadic impacts/hour

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Last Quarter

Example of a Moderate-SizedImpactor - May 2, 2006

Duration of flash: -500 ms

Estimated peak magnitude: 6.86

Peak power flux reaching detector: 4.94 * 10-11 W/m2

Total energy flux reaching detector: 4.58 * 10-12 J/m2

Detected energy generated by impact: 3.394 * 107 J

Estimated kinetic energy of impactor: 1.6974 * 1010 J (4.06 tons of TNT)

Estimated mass of impactor: 17.5 kg

Estimated diameter of impactor: 32 cm (p =1 g/cm3)

Estimated crater diameter: 13.5 m

Ames Hypervelocity Impact Testing

• Purposes- Determine impact luminous efficiency (in our camera passband) - fraction

of kinetic energy converted to light- Determine size and velocity distributions of ejecta produced in cratering

process• These parameters are essential in defining the lunar design

environment• Fired IA inch pyrex projectiles into pulverized pumice at various speeds

and angles (2 - 6 km/sec)• Preliminary testing completed in October '06 - funded exclusively by

Meteoroid Environment Office (HQ OSMA sponsored)- Recorded impacts with our video cameras and Schultz's high speed

photometer

Ames Vertical Gun Range

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Preliminary Results

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Ejecta Flight ModelVery Preliminary Model Test Results

Simple assumed ejecta distribution

Vertical Impact

OBLIQUE VIEWS OF THREE-COMPONENT VEC'rOR PLOTSObfique impact captured at three different times. Vector colors iodate absolute magnitude ofvelocity

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From Schultz et al. (2000)

•

Summary• We have a fruitful observing program underway which has

significantly increased the number of lunar impacts observed. We planto continue for the foreseeable future.- Improving photometric analysis software- Adding 2nd site to discriminate geosynchronous orbital debris- Engaging amateur community by porting LunarScan to PC platform

• Already have one confirmed impact observed by amateur with 8 inchtelescope

- Websitewww.nasa.gov/centers/marshall/news/lunar/index.html

• We have done initial test shots at the Ames Vertical Gun Range ­obtained preliminary luminous efficiency values- More shots and better diagnostics are needed to determine ejecta velocity

distributions• Development has begun on a model to lash together the primary

impactor flux and ejecta distribution models to give the ejecta flux andsize/velocity distributions at any landing site

• We are working to have a more accurate ejecta environment definitionto support lunar lander, habitat, and EVA design

1) Bellot Rubio, L. R., Ortiz, J. L., and Sada, "Observation And Interpretation Of Meteoroid ImpactFlashes On The Moon", Astron. Astrophys. 542, L65-L68.

2) Cooke, W.J. Suggs, R.M. and Swift, W.R. "A Probable Taurid Impact On The Moon", Lunar andPlanetary Science XXXVII (2006», Houston, Texas, LPI, paper 1731

3) Cooke, W.J. Suggs, R.M. Suggs, R.J. Swift, W.R. and Hollon, N.P. ,"Rate And Distribution OfKilogram Lunar Impactors", Lunar and Planetary Science XXXVIII (2007», Houston, Texas, LPI,Paper 1986

4) Dunham, D. W. et ai, ''The First Confirmed Video recordings Of Lunar Meteor Impacts.", Lunar andPlanetary Science Conference XXXI ( 2000), Houston, Texas, LPI, Paper 1547

5) Gural, Peter, "Automated Detection of Lunar Impact Flashes", 2007 Meteoroid EnvironmentsWorkshop, MSFC, Huntsville, Alabama, January 2007

6) Ortiz, J.L. et aI., "Detection of sporadic impact flashes on the Moon: Implications for the luminousefficiency of hypervelocity impacts and derived terrestrial impact rates", Icarus 184 (2006) 319-326

7) Swift, W. R. "LunaCon - Software to detect lunar impacts" ,2007 Meteoroid Environments Workshop,MSFC, Huntsville, Alabama, January 2007

8) McNamara, H. et aI., "Meteoroid Engineering Model (MEM): A Meteoroid Model for the Inner SolarSystem", Earth, Moon, and Planets (2004), 95: 123-139.

www.nasa.gov/centers/marshall/news/lunar/index.html