WSF_PIECEWISE_EXPONENTIAL_ATMOSPHERE

Script Type: WsfPiecewiseExponentialAtmosphere.

atmosphere_model WSF_PIECEWISE_EXPONENTIAL_ATMOSPHERE
atmosphere_model <name> WSF_PIECEWISE_EXPONENTIAL_ATMOSPHERE
   ... Common Atmosphere Commands ...
end_atmosphere_model

Overview

The WSF_PIECEWISE_EXPONENTIAL_ATMOSPHERE models the atmospheric density using a series of exponential profiles for different altitude ranges. In each range the profile takes the form:

\rho(h) = \rho_0 \exp{\left[-\frac{h - h_0}{H}\right]},

where H is a scale height, h_0 is the altitude at which the segment begins, and \rho_0 is the density of the model at that altitude. The values of these constants can be found in Vallado’s Fundamentals of Astrodynamics and Application, Fourth Edition, in Table 8-4 on page 567, and are reproduced below. The values are chosen so that the resulting density is continuous at the segment boundaries.

h_0 [\rm{km}]

H [\rm{km}]

\rho_0 [\rm{kg} \cdot \rm{m}^3]

0.0

7.294

1.225e0

25.0

6.349

3.899e-2

30.0

6.682

1.774e-2

40.0

7.554

3.972e-3

50.0

8.382

1.057e-3

60.0

7.714

3.206e-4

70.0

6.549

8.770e-5

80.0

5.799

1.905e-5

90.0

5.382

3.396e-6

100.0

5.877

5.297e-7

110.0

7.263

9.661e-8

120.0

9.473

2.438e-8

130.0

12.636

8.484e-9

140.0

16.149

3.845e-9

150.0

22.523

2.070e-9

180.0

29.740

5.464e-10

200.0

37.105

2.789e-10

250.0

45.546

7.248e-11

300.0

53.628

2.418e-11

350.0

53.298

9.518e-12

400.0

58.515

3.725e-12

450.0

60.828

1.585e-12

500.0

63.822

6.967e-13

600.0

71.835

1.454e-13

700.0

88.667

3.614e-14

800.0

124.64

1.170e-14

900.0

181.05

5.245e-15

1000.0

268.00

3.019e-15

Common Atmosphere Commands

central_body … end_central_body
central_body <central-body-type>
   polar_offset_angles
end_central_body

Specify the central body and related ellipsoid model to be used by simulation platforms. Options for <central body type> are the following:

  • earth_wgs72 (Earth World Geodetic System 1972): The central body ellipsoid is defined according to the WGS-72 standard.

  • earth_wgs84 (Earth World Geodetic System 1984): The central body ellipsoid is defined according to the WGS-84 standard.

  • earth_egm96 (Earth Gravity Model 1996): The central body ellipsoid is defined according to the EGM-96 standard.

  • moon: The central body ellipsoid is defined according to published lunar parameters.

  • sun: The central body ellipsoid is defined according to published solar parameters.

  • jupiter: The central body ellipsoid is defined according to published Jovian parameters.

Default earth_wgs84

polar_offset_angles <angle-value> <angle-value>

Specify the central_body’s polar offset angles (x_p and y_p, respectively) of the Celestial Intermediate Pole (CIP) with respect to the WCS (ITRS) coordinate system. Providing these values (of the order of tenths of arc-seconds) enables very highly accurate conversions between ECI and WCS coordinates.

Default 0.0 rad 0.0 rad

Note

WCS->LLA conversions are affected by central body choice, as well as sidereal motion transforms calculated in inertial (ECI) coordinate conversions.