Journal of Geophysical Research: Planets
Supporting Information for
NOx Production and Rainout from Chicxulub Impact Ejecta Reentry
Devon Parkos,a Alina Alexeenko,a Marat Kulakhmetov,a
Brandon C. Johnson,b,c H. Jay Melosha,b,d
aSchool of
Aeronautics and Astronautics, Purdue University,
701 W. Stadium Avenue, West Lafayette, IN 47907, USA
bDepartment
of Physics, Purdue University,
525 Northwestern Avenue, West Lafayette, IN 47907, USA
cDepartment
of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA
02139, USA
dDepartment of Earth, Atmospheric, and Planetary Sciences, Purdue University,
550 Stadium Mall Drive, West Lafayette, IN 47907, USA
Contents of this file
Text S1 to S4
Figures S1 to S2
Tables S1 to S7
Additional Supporting Information
Captions for Figures S1 to S2
Captions for Tables S1 to S7
Introduction
The supporting information is divided into four sections. The first examines the assumption of
quasi steady-state bulk atmospheric properties during the spherule reentry event. The second
tabulates section the parameters and reactions used for the direct simulation Monte Carlo
(DSMC) method. The third section tabulates the resulting coefficient values and production
rates extracted from the DSMC flow fields. The last section lists the parameters used in the
Gibbs method.
1
Text S1.
Our work assumes that the spherules reenter into an atmosphere with quasi-steady bulk
properties, namely time-constant bulk temperature and bulk density profiles. However, this is
not precisely what will occur. The spherules at the beginning of the event will encounter an
unsteady atmosphere that is gradually compressed and heated. Furthermore, the spherules at
the conclusion of the event will encounter an expanding and cooling atmosphere. However,
results from existing work [Goldin and Melosh, 2009] suggest that the majority of the
spherules, over ~85%, will experience near steady-state conditions (Fig. S1).
Next, we examined the sensitivity of NO production to the ambient bulk temperature and
found that the NO rate changes by less than 20% when the temperature is perturbed by 30%
from our chosen value (Fig. S2). Figure S1B indicates that roughly 5 minutes after the start of
the reentry event the ambient temperature reaches within 30% of its final value. Additionally,
the mass flux profile in Fig. S1A shows that less than 4% of the ejecta mass reenters within the
first 5 minutes of the event. Therefore, we conclude that approximately 85% of the spherules
will produce steady-state NO emissions, and an additional 11% of the spherules will experience
near steady-state emissions. For the sake of simplicity in our analysis, we neglect the effect of
a transient atmosphere. It is worth noting that the DSMC cases will also be sensitive to ambient
bulk density, however, decreases in ambient density would merely shift our predicted NO
production to lower altitudes. The spherules would retaining their velocity until reaching lower
altitudes due to the reduced drag force.
2
Max Temperature [K]
2
Spherule Mass Flux [kg/m /min]
5000
0.2
0.1
0
0
10
20
30
40
50
60
4000
3000
2000
1000
0
0
5
Time [minutes]
10
15
20
Time [minutes]
NO Production Rate [molecules/s]
Figure S1. (A) Approximated globally averaged flux of spherules determined using existing data
[Melosh et al., 1990] compared to the flux assumed by Goldin and Melosh [2009]. (B) Maximum
temperature in the atmosphere during the spherule reentry event reaches steady-state within
10 minutes and ~70% of its final value within 5 minutes.
1013
10
12
10
11
1010
109
10
8
0
0.2
0.4
0.6
0.8
1
1.2
1.4
Tambient/Tnominal
Figure S2. NO production rate sensitivity to ambient bulk temperature at the 113.6 km altitude,
7.3 km/s spherule velocity DSMC. All temperature modes are assumed to be in thermochemical
equilibrium in the freestream.
3
Text S2.
Spherule reentry is calculated at 16 conditions, where altitudes ranged between 66 and 134 km
and spherule velocities ranged between 5.5 and 11.5 km/s. The simulated velocities are 5.5, 7.3,
9.7, and 11.5 km/s are chosen as collocation points for the 5 to 12 km/s range. Spherules above
the 12 km/s ejection velocity will escape Earth’s gravity. Spherules entering below 5 km/s do
not cause significant N2 dissociation, which is essential for NO formation. At the free-stream
velocities of 5 km/s, less than 0.1% of particle collisions near the flow stagnation point have
energies above 10 eV.
The incoming flow is in thermochemical equilibrium at the elevated temperature conditions
specified in the main document.
Altitude
[km]
Temperature
[K]
Number Density
[molecules/m3 ]
134.45
3698
113.60
Mole Fractions
N2
O2
NO
N
O
5.00E+19
0.526
4.15E-6
3.86E-4
0.100
0.374
3285
8.30E+19
0.641
6.86E-5
1.14E-3
9.39E-3
0.348
86.40
2225
3.17E+20
0.741
0.132
1.14E-2
1.52E-6
0.116
65.56
534
4.85E+21
0.789
0.211
2.53E-9
3.59E-42
8.96E-21
Table S1. Free-stream temperature and density information for each altitude used for generating
the drag and production response surfaces.
Mole Fractions
Altitude
[km]
Temperature
[K]
Number Density
[molecules/m3 ]
134.45
464
1.14E+17
0.617
113.60
252
1.10E+18
86.40
208
65.56
233
N2
O2
NO
N
O
0.383
1.45E-10
4.80E-47
3.06E-22
0.727
0.273
0.00E-0
4.11E-92
2.69E-46
1.11E+20
0.784
0.206
4.44E-19
9.49E-114
3.36E-58
2.26E+21
0.781
0.209
1.34E-20
9.83E-102
3.63E-52
Table S2. Free-stream temperature and density information for the modern day atmosphere,
based on the MSIS-E-90 Atmosphere Model.
4
Reaction
Ea
A
b
Ea,r
Ar
br
O + N2  O + N + N
1.56E-18
4.09E-11
-1
5.24E-19
2.49E-12
-1
N + N2  N + N + N
1.56E-18
4.09E-11
-1
1.56E-18
2.49E-12
-1
O2 + N2  O2 + N + N
1.56E-18
4.09E-11
-1
1.56E-18
2.49E-12
-1
N2 + N2  N2 + N + N
1.56E-18
4.09E-11
-1
1.56E-18
2.49E-12
-1
NO + N2  NO + N + N
1.56E-18
4.09E-11
-1
1.56E-18
2.49E-12
-1
O + NO  O + N + O
1.04E-18
6.79E-12
-1
2.69E-19
5.81E-12
-1
N + NO  N + N + O
1.04E-18
6.79E-12
-1
1.00E-27
5.81E-12
-1
O2 +NOO2 +N +O
1.04E-18
6.79E-12
-1
1.04E-18
5.81E-12
-1
N2 +NON2 +N +O
1.04E-18
6.79E-12
-1
1.04E-18
5.81E-12
-1
NO+NONO+N +O
1.04E-18
6.79E-12
-1
1.04E-18
5.81E-12
-1
O+O2 O+O+O
8.20E-19
1.50E-11
-1
8.20E-19
1.49E-14
-0.5
N + O2  N + O + O
8.20E-19
1.50E-11
-1
1.00E-27
1.49E-14
-0.5
O2 +O2 O2 +O+O
8.20E-19
1.50E-11
-1
8.20E-19
1.49E-14
-0.5
N2 +O2 N2 +O+O
8.20E-19
1.50E-11
-1
8.20E-19
1.49E-14
-0.5
NO+O2 NO+O+O
8.20E-19
1.50E-11
-1
8.20E-19
1.49E-14
-0.5
O+N2 NO+N
5.24E-19
1.22E-18
0.5
5.24E-19
0.00E+00
0
O+NOO2 +N
2.69E-19
4.95E-19
0.5
2.69E-19
0.00E+00
0
N+NON2 +O
0.00E+00
2.66E-19
0.5
0.00E+00
0.00E+00
0
N+O2 NO+O
0.00E+00
1.58E-20
1
0.00E+00
0.00E+00
0
Table S3. Reaction rate coefficients for the modified Arrhenius equation [Hassan and Hash, 1993;
Hash et al., 1994].
5
Altitude
[km]
Particles
Per Cell
Time Step
[s]
Sampled
Steps
Samples
Per Cell
134.45
12.9
1.00E-09
1,500,000
5.956E6
113.60
10.7
1.00E-09
1,500,000
8.978E6
86.40
7.30
1.00E-10
1,500,000
1.153E7
65.56
6.51
4.00E-11
1,500,000
1.649E7
Table S4. Simulated particles per cell and sampling information for each altitude used for
generating the drag and production response surfaces.
Text S3.
The following section details the values extracted from the DSMC flow fields. The drag
coefficient was obtained by integration of surface pressure normal and shear forces acting
on the spherule geometry. The production rate is obtained by integration of chemical
fluxes at the domain boundary.
Spherule Drag Coefficient
Altitude
[km]
5.5 km/s
Velocity
7.3 km/s
Velocity
9.7 km/s
Velocity
11.5 km/s
Velocity
134.45
1.81
1.71
1.65
1.62
113.60
1.57
1.49
1.44
1.42
86.40
1.83
1.76
1.71
1.70
65.56
1.69
1.72
1.77
1.75
Table S5. Drag coefficient determined from integration of surface pressure extracted from DSMC
simulations.
6
NO Production Rate [molecules/s]
Altitude
[km]
5.5 km/s
Velocity
7.3 km/s
Velocity
9.7 km/s
Velocity
11.5 km/s
Velocity
134.45
2.57E+10
4.67E+11
1.27E+12
1.74E+12
113.60
8.65E+10
1.49E+12
1.26E+13
2.86E+13
86.40
1.96E+11
9.37E+12
9.63E+13
2.51E+14
65.56
7.43E+10
2.25E+13
1.26E+15
1.31E+16
Table S6. NO production rate determined from integration of flow field fluxes extracted from
DSMC simulations.
Text S4.
The following section details the parameters used in the Gibbs method, which allows
calculation of the atmospheric composition assuming equilibrium is reached.
Species
M
r
[g/mol]
[K]

v
e
Electronic
Heat of Formation
[K]
[K]
Degeneracies
[kJ/mol]
5, 3, 1, 5
246.79
4, 6, 4, 6
470.82
1, 2
0
2, 2, 2
89.775
3, 2
0
228
O
15.9994
-
-
-
326
22850
27659
N
14.0067
-
-
-
27672
41492
N2
28.0134
2.90
2
3390
NO
30.0061
2.44
1
2740
O2
31.9988
2.10
2
2270
99600
174
63300
11400
Table S7. Parameters used for Gibbs method to find equilibrium atmospheric composition.
7