Moser, D. E.

Suggs, R. J.

Suggs, R. M.

NASA Technical Reports Server

Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Case Study:
Large Meteoroid Impact on the Moon
on 17 March 2013
D. E. Moser
Jacobs, ESSSA Group, Meteoroid Environment Office, NASA Marshall Space Flight Center
R. M. Suggs, R. J. Suggs
NASA, Meteoroid Environment Office, NASA Marshall Space Flight Center
https://ntrs.nasa.gov/search.jsp?R=20150016231 2019-08-31T06:59:52+00:00Z
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Overview
On 17 March 2013 at 03:50:54 UTC, NASA detected a bright impact 
flash on the Moon caused by a meteoroid impacting the lunar surface.
There was enhanced meteor activity in Earth’s atmosphere the same 
night from the Virginid Meteor Complex.
The impact crater associated with the impact flash was found and 
imaged by Lunar Reconnaissance Orbiter (LRO). 
Luminous efficiency estimates can be made by combining flash and 
crater measurements.  A sanity check of photometric procedures and 
crater scaling relations is also possible.
2
A known crater location provides “ground truth” for testing the 
geolocation technique.
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Typical impact flashes
15 Dec 2006
09:17:39.336 
33 ms
mR = 7.4
0.09 kg
Geminid (35 km/s)
22 Apr 2007
03:12:24.372
133 ms
mR = 6.7
0.08 kg
Lyrid (49 km/s)
3 Nov 2008
00:11:06.144
100 ms
mR = 7.7
0.1 kg
S. Taurid (27 km/s)
17 Nov 2006
10:56:34.820
66 ms
mR = 7.0
0.03 kg
Leonid (71 km/s)
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3
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Atypical flash on 17 March 2013
17 Mar 2013
03:50:54.312
1.03 s
mR = 3.0
16 kg
Virginid
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Detected with two  
0.35 m telescopes
Watec 209H2 Ult
monochrome CCD 
cameras
– Manual gain control
– No integration
– Γ = 0.45
Interlaced 30 fps video
Saturated → needed 
saturation correction!
Flash  info
4
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Peak R magnitude
saturation correction
Saturated
2D elliptical Gaussian fit 
to the unsaturated wings
(Similar results for  2D elliptical Moffat fit)
Peak mR = 3.0  0.4
Photometry 
performed using 
comparison stars
Peak mR = 4.9
Luminous energy = 7.1     106 J
+3.9
2.4
(see Suggs et al. 2014)
UNDERESTIMATED!
CORRECTION:
5
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Increased lunar activity
on 17 Mar 2013
6
02:17:00
33 ms
02:33:18
33 ms
03:50:54
1.03 s
03:14:21
66 ms
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Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Meteor activity on 17 Mar 2013
NASA network
SOMN
7
19 fireballs were observed by NASA & SOMN
all-sky meteor cameras on 17 Mar 2013
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Geocentric meteor radiants color-coded by 
speed with a tight cluster of 5 with:
19 fireballs seen on 17 Mar 2013 Cluster of 5 seen on 17 Mar 2013
meteoroids NVI EVI
a (AU) 2.25 ± 0.17 1.69 2.82
e 0.79 ± 0.02 0.71 0.86
i (°) 5.26 ± 1.02 3.7 5.2
ω (°) 280.32 ± 2.11 282.4 285.8
Ω (°) 356.65 ± 0.07 358.0 355.1
q (AU) 0.48 ± 0.02 0.496 0.40
Q (AU) 4.0 ± 0.3 2.89 5.25
Tj 3.1 ± 0.2
meteors NVI1 EVI2
αg (°) 184.1 ± 1.0 183.1 181.0
δg (°) 4.4 ± 0.9 2.3 4.7
vg (km/s) 25.6 ± 0.8 23.0 28.9
λsun (°) 356.6 356.6 356.6
Orbits of the cluster of 5 were very similar 
with the following average orbital elements:
Indicates ~asteroidal body
Virginid Complex
at λ=356.6
RA (J2000.0, deg)
D
ec
 (
d
eg
)
1Sekanina (1973), 2Whipple (1957)
8
Meteor shower activity
on 17 Mar 2013
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Favorable Virginid
radiant geometry
9
Pink indicates the portion of the moon visible to the radiant.
Impact angle ~56° from horizontal.
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Putting it all together
All-sky meteor cameras detected a deeply 
penetrating cluster of 5 fireballs on 17 March.
Radiant and orbital elements consistent with the 
Virginid Meteor Complex (EVI/NVI).
Assume impact flash was part of 
Virginid Meteor Complex 
vg = 25.6 km/s
θh = 56
Asteroidal? (Tj = 3.1 ± 0.2)
Masses 3-100 g
Pink = moon visible to the radiant
10
Impact Constraints
Impact flash rate increased to 1 every 0.87 hours 
on 17 March. (4 impacts in 3.5 hours)
RA (J2000.0, deg)
D
ec
 (
d
eg
)
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Mapping the impact location
“Rough workflow”
ArcMap was used to georeference the 
lunar impact 3 times, at peak brightness 
and late impact.
50 km
MARE IMBRIUM
Euler
Pytheas
Draper
Peak brightness
Late
impact
Rough workflow
Avg late impact
Average predicted crater position 
20.60  0.17 N, 23.92  0.30 W
was sent to LRO.
11
Clementine basemap
Using the geometric center of the flash
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Mapping the impact location
“Refined workflow”
Nominal predicted crater position 
20.6644 N, 24.1566 W
12
LRO basemap
Using the intensity-weighted center of the flash
Euler
Pytheas
Draper
Refined
workflow
Refined:
Refrac corr: Final predicted crater position 
Refrac corr
MARE IMBRIUM
20°. 6842−0.2581
+0.2585 N, 24°. 2277−0.2887
+0.2881 W
ArcMap was used to georeference the 
lunar impact following the geolocation
workflow.
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Impact crater found by LRO!
Robinson et al. (2014)
Crater info
• Rim-to-rim diameter = 18 m
• Inner diameter = 15 m
• Depth ≈ 5 m
NASA/GSFC/Arizona State University
Features
• Fresh, bright ejecta
• Circular crater
•Asymmetrical ray pattern
Actual crater location
• 20.7135°N, 24.3302°W
13
Image from Robinson (2013)
Circular crater, impact 
angle constrained h >15°
Ejecta gives no azimuth 
constraint
Impact Constraints
(Robinson, personal comm.)
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Comparison of geolocation
results to obs crater location
14
Method
Longitude
( W)
Latitude
( N)
Angular distance
from observed ()
Surface distance
from observed (km)
Rough workflow 23.922 20.599 0.39875 12.096
Refined workflow 24.1566 20.6644 0.169665 5.1469
Refined, with refraction correction 24.2277 20.6842 0.100261 3.0415
LRO observed 24.3302 20.7135 - -
+0.2881
−0.2887 −0.2581
+0.2585
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Crater scaling laws
15
Gault’s scaling law (Gault 1974) for D < 100 m
𝐷 = 0.25𝜌𝑝
0.167𝜌𝑡
−0.5𝐸0.29 sin 𝜃ℎ
 1 3
Holsapple crater calculator
(http://keith.aa.washington.edu/craterdata/scaling/index.htm)
ρt = target density
ρp = projectile density
h = impact angle measured wrt horizontal
E = kinetic energy of projectile
ρt
ρp
h
Moon
meteoroidE
D = transient crater diameter
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Crater scaling laws
16
http://keith.aa.washington.edu/craterdata/scaling/index.htm
D
• Transient crater diameter
• Measured at the height of the 
pre-existing surface
• Aka inner diameter, apparent 
diameter
Drim
• Crater rim diameter
• Measured from rim to rim
• Aka outer diameter
𝐷𝑟𝑖𝑚 = 1.3𝐷Holsapple assumes similar to Melosh (1989)
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Transient crater diameter estimates
Assumptions: Virginid vgfoc=25.7 km/s, θh = 56°; t = 1500 kg/m
3 (regolith)
Model Lum eff. 
KE
×109 (J)
Mass
(kg)
p
(kg/m3)
Dcalc
(m)
Dobs
(m)
% Err
Gault’s crater 
scaling law
(Gault 1974)
5×10-4
14
[9.4,22]
42
[28,66]
1800 18.5  [16.5,21.1] 15 23%
3000 20.2 [18.0,23.0] 15 35%
1.3×10-3
5.4 
[3.6,8.4]
16
[11,26]
1800 14.1  [12.5,16.0] 15 6%
3000 15.3  [13.6,17.4] 15 2%
Holsapple’s
online
calculator
(Holsapple 1993)
5×10-4
14
[9.4,22]
42
[28,66]
1800 12.2  [10.9,13.8] 15 19%
3000 12.5  [11.1,14.2] 15 17%
1.3×10-3
5.4 
[3.6,8.4]
16
[11,26]
1800 9.3  [8.3,10.5] 15 38%
3000 9.5  [8.5,10.8] 15 37%
Assuming a velocity dependent  = 1.310-3, these model
results are consistent with the observed crater diameters.
Dcalc =   8-18 m transient crater Dobs = 15 m inner (‘transient’)
Dcalc = 10-23 m rim-to-rim Dobs = 18 m rim-to-rim
Two example values of  from the literature yield large ranges for KE and mass.
Consequently, model results are highly dependent on luminous efficiency .
(Moser et al. 2011)
(Bouley et al. 2012)
17
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Luminous efficiency:  LEλ= ηλ KE
Dt = 15 m from crater measurements
LE = 7.1  10
6 J from flash measurements
Projectile densities
Regolith
t = 1500 kg/m
3
Hard soil / soft rock
t = 2100 kg/m
3
Typical values of  derived from lunar regolith range from 2 ± 1  10
-4 to 2 ± 1  10-3.
Assuming association with the Virginids, h = 56 and  7.5      10
-4 <  < 1.5      10
-3.
Gault’s crater scaling law (Gault 1974) rearranges to give 
 vs h without assuming impact speed.
 = LE / KE = LE / (4.0 Dt ρp
-0.167 ρt
0.5 sin-1/3θh)
1/0.29
+0.8
0.5
+4.5
2.5
18
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Date of impact:
Duration of impact:
Corrected flash peak R magnitude:
Luminous energy generated by impact:
Estimated kinetic energy of impactor:
Estimated mass of impactor:
Estimated diameter of impactor:
Crater diameter:
Crater location:
Possible meteor shower association:
17 March 2013  3:50:54 UTC 
1.03 s
3.0 ± 0.4 
7.1    × 106 J
5.4    × 109 J = 1.3 tons of TNT   (assuming η = 1.3 × 10-3 )
16     kg   (assuming v = 25.7 km/s)
22 ± 3 cm   (assuming ρp = 3000 kg/m3)
18 m rim-to-rim, 15 m inner (‘transient’)
20.7135° N, 24.3302° W 
Virginid Meteor Complex
Impact summary
+3.9
2.4
+3.0
1.8
+10
5
19
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
Backup Slides
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
References
Bouley et al. (2012) “Power and duration of impact flashes on the moon: implication for the cause of 
radiation.”  Icarus 218, 115-124.
Gault, D.E. (1974)  “Impact cratering.” In: A Primer on Lunar Geology, eds. R. Greely and P. Schultz, 
NASA TM-X-62359, 137-176.
Holsapple, K.A. “Crater sizes from explosions or impacts.” 
http://keith.aa.washington.edu/craterdata/scaling/index.htm. Accessed 2013.
Holsapple, K.A. (1993) “The scaling of impact processes in planetary sciences.” Annu. Rev. Earth 
Planet. Sci. 21, 333-373.
Melosh, H.J. (1989) “Impact cratering: a geologic process.” New York: Oxford University Press, p.112.
Moser, D.E. et al. (2011) “Luminous efficiency of hypervelocity meteoroid impacts on the moon derived 
from the 2006 Geminids, 2007 Lyrids, and 2008 Taurids.”  NASA/CP-2011-216469, 142-154.
Robinson, M. (2013) LROC Featured Image, posted 14 Dec 2013. 
http://lroc.sese.asu.edu/news/index.php?/archives/843-New-Crater!.html.  Accessed 2013.
Robinson, M.S. et al. (2014) “New crater on the Moon and a field of secondaries.” 45th LPSC, 2164.
Robinson, M.S. (2014)  Personal communication.
Robinson, M.S. et al. (2015) “New crater on the Moon and a swarm of secondaries.” Icarus 252, 229-
235.
Sekanina, Z. (1973) “Statistical model of meteor streams III. Stream search among 19303 radio meteors.”  
Icarus 18, 253-284.
Suggs, R. M. et al. (2014) “The flux of kilogram-sized meteoroids from lunar impact monitoring.”  
Icarus 238, 23-36.
Whipple, F.L. (1957)  “Some problems of meteor astronomy.”  In Radio Astronomy, Proc. IAU Symp. 
No. 4, ed. H.C. van de Hulst.
21
Lunar Impact Workshop, 2-3 June 2015Jacobs, ESSSA Group/MEO/D.E. Moser
High reflectance zone 10-20 m SW,  <10 m NE
Low reflectance zone 50 m WSW, 80 m ENE
1000 m
Ejecta distribution
after Robinson et al. (2014)
Low reflectance zone ~1 km centered in NE
248 circ/irreg splotches within 30 km
North
High reflectance zone  ~300 m rough semicircle
R
o
b
in
s
o
n
 e
t 
a
l.
 (
2
0
1
4
)
Temporal Ratio
22
Ejecta in multiple reflectance “zones”
Impact Constraints
Circular crater, impact angle constrained >15°
HRZ – impact possible from SE or NW
LRZ – impact possible from SW
 no azimuth constraint (Robinson, personal comm.)
See Robinson et al. (2014)
for more details
An impact from the SW is consistent with an 
impactor from the Virginid Meteor Complex.
100  m
North


Case Study: Large Meteoroid Impact on the Moon on 17 March 2013

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