More Related Content Similar to Space Environment & It's Effects On Space Systems course sampler (20) More from Jim Jenkins (20) Space Environment & It's Effects On Space Systems course sampler1. Space Environment & It's Effects On Space Systems
Instructor:
V. L. Pisacane
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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
pr 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 Lh h0
the pressure and density is given by
Mg
L RL
p p0 1 h h0
T p0eh / H L0
0
Mg
1
L RL
r r0 1 h h0
T r0eh / H L0
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
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