This class on the space environment and its effects on space systems is for technical and management personnel who wish to gain an understanding of the important issues that must be addressed in the development of space instrumentation, subsystems, and systems. The goal is to assist students to achieve their professional potential by endowing them with an understanding of the fundamentals of the space environment and its effects. The class is designed for participants who expect to either, plan, design, build, integrate, test, launch, operate or manage payloads, subsystems, launch vehicles, spacecraft, or ground systems. Each participant will receive a copy of the reference textbook: Pisacane, VL. The Space Environment and its Effects on Space Systems. AIAA Education Series, 2008.

1. Space Environment & It's Effects On Space Systems
Instructor:
V. L. Pisacane
ATI Schedule: http://www.ATIcourses.com/schedule.htm
http://www.aticourses.com/Space_Environment_And_Effects_On_Space_Systems.htm
ATI's Space Environment:

2. www.ATIcourses.com
Boost Your Skills 349 Berkshire Drive
Riva, Maryland 21140
with On-Site Courses Telephone 1-888-501-2100 / (410) 965-8805
Tailored to Your Needs
Fax (410) 956-5785
Email: ATI@ATIcourses.com
The Applied Technology Institute specializes in training programs for technical professionals. Our courses keep you
current in the state-of-the-art technology that is essential to keep your company on the cutting edge in today’s highly
competitive marketplace. Since 1984, ATI has earned the trust of training departments nationwide, and has presented
on-site training at the major Navy, Air Force and NASA centers, and for a large number of contractors. Our training
increases effectiveness and productivity. Learn from the proven best.
For a Free On-Site Quote Visit Us At: http://www.ATIcourses.com/free_onsite_quote.asp
For Our Current Public Course Schedule Go To: http://www.ATIcourses.com/schedule.htm

3. Chapter 7
Neutral
Environment
SPACE ENVIRONMENT AND ITS EFFECTS ON
SPACE SYSTEMS
Chapter 7
Neutral Environment
by
V. L. Pisacane
Space Environment and its Effects on Space Systems ©VLPisacane,2012

4. Chapter 7
Neutral
TOPICS Environment
 Introduction
 Earth Atmosphere
 Atmospheric Models
 Planetary Atmospheres
 Propagation
 Atomic Oxygen
 Aerodynamic Forces
 Effusion
Space Environment and its Effects on Space Systems 7–2 ©VLPisacane,2012

5. Chapter 7
INTRODUCTION 1/2 Neutral
Environment
 An atmosphere is the layer of gas that surrounds a celestial body
 The planets were formed with atmospheres primarily of hydrogen and helium
 On the terrestrial planets (Mercury, Venus, Earth, and Mars) the thermal
velocities of the atmosphere due to the solar wind was greater than the escape
velocity of the gravitational field so the lighter constituents were loss
 Mercury has essentially no atmosphere while the other terrestrial planets have
retained the heavier molecular constituents such as carbon dioxide, nitrogen,
oxygen, ozone, and argon
 The outer or gaseous planets (Jupiter, Saturn, Uranus, and Neptune) being
farther from the Sun and more massive were able to retain much of their the
lighter molecular constituents such as hydrogen and helium
Space Environment and its Effects on Space Systems 7–3 ©VLPisacane,2012

6. Chapter 7
INTRODUCTION 2/2 Neutral
Environment
 Over time, the atmospheres of the terrestrial planets evolved, primarily by
release of trapped volatiles by outgassing through bombardment of the
surface by particulates and volcanic actions
 As the distance from the center of a planet increases, the atmospheric
pressure and density decrease approaching the interplanetary environment
without a sharp discontinuity
 In the case of the Earth, 50% of the mass of the atmosphere is below 5 km
altitude and 75% is below 11 km
 Planetary atmospheres absorb energy from the Sun, redistribute atmospheric
constituents, and together with any electrical and magnetic forces present
produce the planet’s climate
Space Environment and its Effects on Space Systems 7–4 ©VLPisacane,2012

7. EARTH ATMOSPHERE Chapter 7
Neutral
Lower Atmosphere 1/2 Environment
 Earth atmosphere divided into 5 distinct layers
 Troposphere
– Extend 9 km at poles to 17 km at equator
– Heated by Earth so temperature decreases
– Temperature decrease ~6.5 K/km
– Contains 90% of the total atmosphere mass
– Upper boundary is tropopause
 Stratosphere
– Extends from tropopause to ~ 50 km
– Temp increases by UV absorption in Ozone layer
– 99% of total mass in Stratosphere and
Troposphere
– Upper boundary is stratopause
 Mesosphere
– Extends from stratopause to 80-85 km
– Temperature decreases with altitude
– Most meteoroids burn up in Mesosphere
– Constituents in an excited state from solar
radiation causing ionosphere
http://en.wikipedia.org/wiki/Atmosphere_of_Earth
– Upper boundary is mesopause
Space Environment and its Effects on Space Systems 7–5 ©VLPisacane,2012

8. EARTH ATMOSPHERE Chapter 7
Neutral
Lower Atmosphere 2/2 Environment
 Thermosphere
– Extends from mesopause to 200-300 km
– Temperature increases to 1800 K
– Small change in solar activity can cause large
change in temperature
– Upper boundary is thermopause or exobase
 Exosphere
– Extends from thermopause/exobase upwards
– Sometimes considered outer layer of
thermosphere
– Temperature is essentially constant
– Density so low particles travel ballistic paths
and may escape
http://en.wikipedia.org/wiki/Atmosphere_of_Earth
Space Environment and its Effects on Space Systems 7–6 ©VLPisacane,2012

9. EARTH ATMOSPHERE Chapter 7
Neutral
Upper Atmosphere Environment
 Thermosphere extends from 80-85 km to
altitude where temperature is constant
typically 200-500 km
 Exosphere extends from thermopause to
outer space Thermopause
 In lower thermosphere temperatures rise
rapidly with altitude
 Above 200 300 km temperature remains
relatively constant
 Temperature varies significantly between
day and night and between the minimum
and maximum solar activity
Thermopause
http://www.windows2universe.org/earth/Atmosph
ere/thermosphere_temperature.html&edu=high
Space Environment and its Effects on Space Systems 7–7 ©VLPisacane,2012

10. EARTH ATMOSPHERE Chapter 7
Neutral
Homosphere and Heterosphere Environment
 It is possible to stratified the
atmosphere by composition into two
regions: the homosphere and the
heterosphere separated by the
turbopause or homopause
 Turbopause/homeopause ~80-100 km
 Homosphere is the well-mixed region
of the atmosphere lying below the
turbopause that has constant
constituents
 Heterosphere is the region above the
homopause or turbopause with
significantly variation in composition
as a function of altitude
 Hydrogen and helium, being lighter,
are found in the upper heterosphere
while nitrogen and oxygen, being
heavier are found in the lower
heterosphere
Figure 7.6 Vertical structure of the atmosphere
Source unknown
Space Environment and its Effects on Space Systems 7–8 ©VLPisacane,2012

11. EARTH ATMOSPHERE Chapter 7
Neutral
Composition Homosphere Environment
 Lower atmosphere (< 80 km) constituents are constant due to turbulent mixing
 Region from 0-~80 km is known as the homosphere
Gas Volume Molecular Mass
Nitrogen (N2) 780,840 ppmv (78.084%) 0.78084x2x14.007 = 21.8745
Oxygen (O2) 209,460 ppmv (20.946%) 0.20946x2x15.999 = 6.7023
Argon (Ar) 9,340 ppmv (0.9340%) 0.009340x39.948 = 0.3734
Carbon dioxide (CO2) 390 ppmv (0.039%) Total = 28.9502 ≈ 29 kg kmol-1
Neon (Ne) 18.18 ppmv (0.001818%)
Helium (He) 5.24 ppmv (0.000524%)
Methane (CH4) 1.79 ppmv (0.000179%)
Krypton (Kr) 1.14 ppmv (0.000114%)
Hydrogen (H2) 0.55 ppmv (0.000055%)
Nitrous oxide (N2O) 0.3 ppmv (0.00003%)
Carbon monoxide (CO) 0.1 ppmv (0.00001%)
Xenon (Xe) 0.09 ppmv (9×10−6%) (0.000009%)
Ozone (O3) 0.0 to 0.07 ppmv (0 to 7×10−6%)
Nitrogen dioxide (NO2) 0.02 ppmv (2×10−6%) (0.000002%)
Iodine (I2) 0.01 ppmv (1×10−6%) (0.000001%)
Ammonia (NH3) Trace
Not included in above dry atmosphere:
Water vapor (H2O) ~0.40% over full atmosphere, typically 1%-4% at surface
Space Environment and its Effects on Space Systems 7–9 ©VLPisacane,2012

12. EARTH ATMOSPHERE Chapter 7
Neutral
Composition of Heterosphere Environment
Maximum solar
activity
Note: Different r
scale length for
each species
Minimum solar
activity
Turbopause
From Pisacane Ed
Fundamental of space
systems, Oxford Press,
2005 Source unknown
Space Environment and its Effects on Space Systems 7 – 10 ©VLPisacane,2012

13. EARTH ATMOSPHERE Chapter 7
Neutral
Pressure and Density Equations Environment
 Assume hydrostatic equilibrium
  p  dh A  pA  rg(Adh)  0
dp dp  rg dh
 
 dh 
 From the perfect gas law
RT Mg
pr dp  p dh
M RT
 Integration with H defined as the scale height
RT
p  p0 exp
Mg
 RT h  h0   p0 exp  h  h0 
  
H
Mg
   H 
 Density follows as
r
pM p0M
 exp
Mg
 RT h  h0   r0 exp  h  h0 
  
RT RT    H 
where T = temperature constant with height h, K
g = acceleration of gravity assumed constant, m s-2
M = molecular mass, kg-kmol-1
` p = pressure at height h
po = pressure at height ho
R = universal gas constant, J kmol-1 kg-1
r = density at height h
ro = density at height h0
H ≡ RT/Mg, scale height
h = height
Space Environment and its Effects on Space Systems 7 – 11 ©VLPisacane,2012

14. EARTH ATMOSPHERE Chapter 7
Neutral
Earth Scale Height Environment
 Problem: Determine the scale height of
the Earth’s atmosphere
 Solution: Scale height is given by Eq. 7.47
as
RT
H
Mg
where at the surface of the Earth
M = 29 kg kmol-1
T = 273.15 K (0oC)
g = 9.8 0665 m s-2
R = 8314.472 J kmol-1 K-1
 Consequently
8314.472  273.15
H  8.0 km
29  9.80665
 Since temperature decreases fater than
the decrease in g in the stratosphere the
scale height decreases from the value at
the Earth’s surface
Source unknown
Space Environment and its Effects on Space Systems 7 – 12 ©VLPisacane,2012

15. EARTH ATMOSPHERE Chapter 7
Neutral
Pressure and Density with Lapse Rate Environment
 If the temperature as a function of altitude is approximated by
T  T0  Lh  h0 
the pressure and density is given by

Mg 
 
 L   RL 
p  p0  1  h  h0 
 T   p0eh / H L0
 0 

Mg 
 1 
 L   RL 
r  r0  1  h  h0 
 T   r0eh / H L0
 0 
where L = lapse rate, K m-1
T0 = temperature at height h0, K
T = temperature at height h, K
g = acceleration of gravity, m s-2
M = molecular mass, kg-kmol-1
` p = pressure at height h
po = pressure at height ho
R = universal gas constant, J kmol-1 kg-1
r = density at height h
ro = density at height h0
H ≡ RT/Mg, scale height
Space Environment and its Effects on Space Systems 7 – 13 ©VLPisacane,2012

16. EARTH ATMOSPHERE Chapter 7
Neutral
Lapse Rate Environment
 Several lapse Rates are employed
 Dry Adiabatic Lapse rate (DALR) 10 K km-1
– Adiabatic process ─ no transfer of heat or mass across
the boundaries
– Temperature changes within air parcel only caused by
increases or decreases of internal molecular activity
– Dry air parcel rising cools at rate of 10 k km-1
– Dry air parcel sinking cools at rate of 10 k km-1
 Saturated Adiabatic Lapse Rate (SALR) 5.5 K km-1
– Rising air parcel containing water vapor will cool at dry
adiabatic lapse rate until it reaches condensation
temperature, or dew point
– Condensation releases latent heat in parcel and thus
cooling rate of the parcel reduces
– SALR depends on temperature and pressure but in
middle troposphere is between 5 and 6 K km-1
 Environmental Adiabatic Lapse Rate (EALR) 6.5 K km-1
– Actual lapse rate is function of actual temperature
– Standard model temperature gives ~ 6.5 K km-1
http://www.ux1.eiu.edu/~cfjps/1400/atmos_struct.html
Space Environment and its Effects on Space Systems 7 – 14 ©VLPisacane,2012

17. ATMOSPHERIC MODELS Chapter 7
Neutral
Selected Available Models Environment
 US Standard Atmosphere
 Harris–Priester Model
 Jacchia Reference Atmosphere 1977
 Atmospheric Handbook
 COSPAR international Reference Atmosphere (CIRA) Model
 Mass-Spectrometer-Incoherent-Scatter (MSIS)-90 Model
 NRL Mass-Spectrometer-Incoherent-Scatter Empirical (MSISE)-00 Model
Just a few of the models that are available
Space Environment and its Effects on Space Systems 7 – 15 ©VLPisacane,2012

18. Chapter 7
ATMOSPHERIC MODELS Neutral
Model Input Parameters Environment
Source unknown
Space Environment and its Effects on Space Systems 7 – 16 ©VLPisacane,2012

19. ATMOSPHERIC MODELS Chapter 7
Neutral
U. S. Standard Atmosphere Environment
 The standard atmosphere gives the average pressure, temperature, and air density
as a function of altitudes
 It is a piece-wise continuous with 7 regions
– Sea level pressure = 101,325 N/m2 (1 bar = 100,000 N/m2)
– Sea level temperature = 288.15 K
– Sea level density =1.225 kg/m3
– M = molecular mass of air = 28.9644 kg kmol-1
– Geometric height, z, actual physical height above mean sea level
– Geopotential height, h, where g0h = ∫gdz = potential energy, g0=9.8 m s-2 in MKS
Space Environment and its Effects on Space Systems 7 – 17 ©VLPisacane,2012

20. Chapter 7
ATMOSPHERIC MODELS Neutral
Environment
Jacchia Reference Atmosphere Model
 Jacchia Reference Atmospheres were published in 1970, 1971, and 1977
 Density, temperature, and composition are given for altitudes 90 ─ 2500 km
 Effects include
– season
– latitude
– local time (diurnal bulge)
– solar activity
– geomagnetic activity
– atmospheric rotation
– atmospheric tides
– Earth oblateness on altitude
– semi-annual and seasonal-latitudinal effects
 Model are based mostly on satellite drag data
 Assuming diffusive equilibrium, the atmospheric profiles are defined by the
exospheric temperature
 Outputs
– Temperature,
– Mean molecular mass
– Density
– Number densities of the major gas constituents (N2, O, O2, Ar, He, and H)
Space Environment and its Effects on Space Systems 7 – 18 ©VLPisacane,2012

21. ATMOSPHERIC MODELS Chapter 7
Neutral
COSPAR international Reference Atmosphere CIRA-86 Model Environment
Source unknown
Space Environment and its Effects on Space Systems 7 – 19 ©VLPisacane,2012

22. ATMOSPHERIC MODELS Chapter 7
Neutral
NRL-MSISE Reference Atmosphere Environment
INPUTS OUTPUTS
 Mass-Spectrometer- Year, day, UT sec He number density
Incoherent-Scatter models: Altitude O number density
– MSIS-86 Geodetic latitude O2 number density
– MSISE-90 Geodetic longitude N number density
Local apparent solar time N2 number density
– NRLMSISE-00 F10.7 81 day average Ar number density
F10.7 prior day daily value H number density
 NRLMSISE-00 represents
AP magnetic index day
Anomalous oxygen
improvements over the number density
earlier MSISE-90 model by AP magnetic index 3 h before current
Total mass density
time
including additional drag
AP magnetic index 6 h before current
and accelerometer data time
Exospheric temperature
from spacecraft AP magnetic index 9 h before current
Temperature at altitude
time
 Inputs and outputs of the AP magnetic index average of eight 3
hours indices from 12 to 33 h before
NRLMSISE-00 model are current time
given AP magnetic index average of eight 3
hours indices from 36 to 57 h before
current time
Space Environment and its Effects on Space Systems 7 – 20 ©VLPisacane,2012

23. ATMOSPHERIC MODELS Chapter 7
Neutral
NRL-MSISE Sample Result ─ Lower Atmosphere Environment
Source unknown
Day = 172 UT(Sec) = 29000
Geodetic Latitude(Deg) = 60 Geodetic Longitude(Deg) = 120
Local Apparent Solar Time(Hrs) = 16 81 day Average of F10.7 Flux = 150
Daily F10.7 Flux for Previous Day = 150 AP=Magnetic Index (Daily) = 4
Space Environment and its Effects on Space Systems 7 – 21 ©VLPisacane,2012

24. Chapter 7
ATMOSPHERIC MODELS Neutral
MSIS-90e Density Distribution Environment
Source unknown
Space Environment and its Effects on Space Systems 7 – 22 ©VLPisacane,2012

25. ATMOSPHERIC MODELS Chapter 7
Neutral
NRLMSISE-00 Model Example 1 Environment
 Model Average Density (cm-3)
Average Front Flux (cm-2 s-1)
2.8822E+05
2.1229E+11
– NRLMSISE-00 Average Back Flux (cm-2 s-1) 1.5933E+04
– F10,7 prev day 70.0 10-22 W m-2 Hz-1 Front Fluence (cm-2) 6.6948E+18
– F10.7 81 day average 60.0 10-22 W m-2 Hz-1 Back Fluence (cm-2) 5.0246E+11
– Daily Ap 15.0
 Conditions
– Sun at equator
– Sun in orbital plane
 Orbit
– Altitude: 1000 km circular
– Inclination: polar
– Epoch: 0h UT 21 Mar 2014 (Vernal Equinox)
– Period: 1.75 h r
– Rev per day: 13.72 1 revolution
Space Environment and its Effects on Space Systems 7 – 23 ©VLPisacane,2012

26. ATMOSPHERIC MODELS Chapter 7
Neutral
NRLMSISE-00 Model Example 2 Environment
 Model Average Density (cm-3)
Average Front Flux (cm-2 s-1)
2.6291E+05
1.9362E+11
– NRLMSISE-00 Average Back Flux (cm-2 s-1) 1.9209E+04
– F10,7 prev day 70.0 10-22 W m-2 Hz-1 Front Fluence (cm-2) 6.1061E+18
– F10.7 81 day average 60.0 10-22 W m-2 Hz-1 Back Fluence (cm-2) 6.0576E+11
– Daily Ap 15.0
 Conditions
– Sun at Tropic of Cancer, 23.44 deg North
– Sun orthogonal to orbital plan
 Orbit
– Altitude: 1000 km circular
– Inclination: polar
– Epoch: 0h UT 21 June 2014
– Period: 1.75 h r
– Rev per day 13.72
Space Environment and its Effects on Space Systems 7 – 24 ©VLPisacane,2012

27. PLANETARY ATMOSPHERES Chapter 7
Neutral
Planetary Scale Heights Environment
 Recall
h  h0 
r  r0 exp 
 
 H 
* Surface defined by pressure of 1 bar = 100 kPa where 1.01325 bar = 1 atm pressure
Space Environment and its Effects on Space Systems 7 – 25 ©VLPisacane,2012

28. PLANETARY ATMOSPHERES Chapter 7
Neutral
Planetary Compositions Environment
Planet Surface Pressure (bars) Surface temperature (K) Major Constituents
42% Oxygen
29% Sodium
22% Hydrogen
Mercury 10-15 440 6% Helium
0,5% Potassium
< 1% Trace elements
96.5% Carbon Dioxide
Venus 92 737 3.5% Nitrogen
Trace elements
78.08% Nitrogen
20.95% Oxygen
Earth 1 288 0.9% Argon
Trace elements
95% Carbon Dioxide
3% Nitrogen
Mars .01 210 1 % Argon
1 % Oxygen
<1% Trace elements
89.8% Hydrogen
Jupiter Unknown 165 @ 1 bar 10.2% Helium
Trace elements
96.3% Hydrogen
Saturn Unknown 134 @ 1 bar 3.25% Helium
Trace elements
82.5% Hydrogen Source:
15.2% Helium http://nssdc.gsfc.nasa.gov/pl
Uranus Unknown 76 @ 1 bar 2.3% Methane anetary/factsheet/
Trace elements
1 bar = 100 kPa where
80.9% Hydrogen
19.0% Helium
1.01325 bar = 1 atm
Neptune Unknown 72 @t 1 bar 1.5% Methane pressure
Trace elements
Space Environment and its Effects on Space Systems 7 – 26 ©VLPisacane,2012

29. To learn more please attend this ATI course
Please post your comments and questions to our blog:
http://www.aticourses.com/blog/
Sign-up for ATI's monthly Course Schedule Updates :
http://www.aticourses.com/email_signup_page.html