AE1601_StandardAtmosphereActivity_Fall 2020
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School
Georgia Institute Of Technology *
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Course
1601
Subject
Astronomy
Date
Apr 3, 2024
Type
Pages
4
Uploaded by junsu607
AE 1601 – Standard Atmosphere Activity Turn in on Canvas (Individual) Background Information The purpose of this exercise is to gain an understanding of planetary atmospheres by comparing the atmospheres of Venus and Mars to the Earth standard atmosphere. Atmosphere profiles for Venus and Mars will be constructed based upon published data obtained by space flight entry probe observations. There are several handy equations and constants used in this exercise. They are listed below.
a.
Relation between geometric altitude (
h
G
), geopotential altitude (
h
), and planet radius (
r
0
) ℎ
=
𝑟𝑟
0
𝑟𝑟
0
+
ℎ
𝐺𝐺
ℎ
𝐺𝐺
b.
Hydrostatic Equation for Isothermal Layer, or constant temperature (note in lecture p=p
2
, p
b
=p
1
) 𝑝𝑝
2
=
𝑝𝑝
1
𝑒𝑒
−
[
𝑔𝑔
0
/(
𝑅𝑅𝑅𝑅
)](
ℎ
2
−ℎ
1
)
c.
Hydrostatic Equation for Gradient Layer, or variable temperature (note in lecture T=T
2
, T
b
=T
1
) 𝑝𝑝
2
=
𝑝𝑝
1
�
𝑇𝑇
2
𝑇𝑇
1
�
−𝑔𝑔
0
/(
𝑎𝑎𝑅𝑅
)
Note: a
is the temperature lapse rate with altitude. d.
Equation of State (Ideal Gas Law) 𝑝𝑝
=
𝜌𝜌𝜌𝜌𝑇𝑇
e.
Specific Gas Constants (R): Earth = 287 J/(kg K), Mars = 188.92 J/(kg K), Venus = 188.92 J/(kg K) f.
Planet Radii: Earth = 6,378.14 km, Mars = 3,397.2 km, Venus = 6,051.8 km g.
Gravitational Acceleration at Planet Surface: Earth = 9.8 m/s
2
, Mars = 3.8 m/s
2
, Venus = 8.9 m/s
2
1.
The figure below shows the measured temperature profiles for the Mars atmosphere recorded by the Viking landers. A linear fit (shown in red) has been made to the Viking Lander 1 data, with a single gradient layer from 0 to 40 km, and a single isothermal layer from 40 to 80 km. Note that the altitudes (z) are geometric altitudes. Fill in the missing values from the table. NOTE: You may use Excel for these calculations. h
G
(km) h (km) T (K) p (N/m
2
) ρ
(kg/m
3
) 0 0 230 7.5E02 20 40 150 60 80 150
2.
The figure below shows the measured temperature profiles for the Venus atmosphere recorded Pioneer Venus probes. A single linear gradient layer (shown in red) provides a very good fit to the measured data. Again, the altitudes are geometric altitudes. Fill in the missing values from the table. NOTE: You may use Excel for these calculations. h
G
(km) h (km) T (K) p (N/m
2
) ρ
(kg/m
3
) 0 0 735 9.5E06 20 40 60 255
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3.
Use the 1976 Standard Atmosphere Tables (can be found online) to fill in the table below for Earth. Discuss briefly how the atmosphere of earth compares to that of Mars and Venus. h
G
(km) T (K)
p (N/m
2
) ρ
(kg/m
3
) 0 20 40 60