Moon Libration
Implement Moon librations
Libraries:
Aerospace Blockset /
Environment /
Celestial Phenomena
Description
The Moon Libration block implements the Moon librations using Chebyshev coefficients or a given Julian date. The block uses the Chebyshev coefficients that the NASA Jet Propulsion Laboratory provides.
Tip
For TJD
, Julian date input for the block:
Calculate the date using the Julian Date Conversion block or the Aerospace Toolbox
juliandate
function.Calculate the Julian date using some other means and input it using the Constant block.
Ports
Input
TJD — Julian date
scalar | positive | between minimum and maximum Julian dates
Julian date, specified as a positive scalar between minimum and maximum Julian dates.
See the Ephemeris model parameter for the minimum and maximum Julian dates.
Dependencies
This port displays if the Epoch parameter is
set to Julian date
.
Data Types: double
T0JD — Fixed Julian date
scalar | positive
Fixed Julian date for a specific epoch that is the most recent midnight at or before the interpolation epoch, specified as a positive scalar. The sum of T0JD and ΔTJD must fall between the minimum and maximum Julian dates.
See the Ephemeris model parameter for the minimum and maximum Julian dates.
Dependencies
This port displays if the Epoch parameter is
set to T0 and elapsed Julian time
.
Data Types: double
ΔTJD — Elapsed Julian time
scalar | positive
Elapsed Julian time between the fixed Julian date and the ephemeris time, specified as a positive scalar. The sum of T0JD and ΔTJD must fall between the minimum and maximum Julian date.
See the Ephemeris model parameter for the minimum and maximum Julian dates.
Dependencies
This port displays if the Epoch parameter is
set to T0 and elapsed Julian time
.
Data Types: double
Output
φ θ ψ (rad) — Euler angles
vector
Euler angles (φ θ ψ) for Moon attitude, in rad.
Data Types: double
ω (rad/day) — Moon libration Euler angular rate
vector
Moon libration Euler angular rates (ω), in rad/day.
Data Types: double
Parameters
Epoch — Epoch
Julian date
(default) | T0 and elapsed Julian time
Epoch, specified as:
Julian date
Julian date to calculate the Moon libration. When this option is selected, the block has one input port, TJD.
T0 and elapsed Julian time
Julian date, specified by two block inputs:
Fixed Julian date representing a starting epoch.
Elapsed Julian time between the fixed Julian date (T0JD) and the desired model simulation time. The sum of T0JD and ΔTJD must fall between the minimum and maximum Julian dates.
Programmatic Use
Block Parameter:
epochflag |
Type: character vector |
Values: Julian
date | T0 and elapsed Julian
time |
Default: 'Julian
date' |
Ephemeris model — Ephemeris model
DE405
(default) | DE421
| DE423
| DE430
| DE432t
Select one of these ephemerides models defined by the Jet Propulsion Laboratory. The block uses ephemeris data to calculate relative celestial positions required for third body point mass gravity and solar radiation pressure.
Ephemeris Model | Description |
---|---|
| Released in 1998. This ephemeris takes into account the Julian date range 2305424.50 (December 9, 1599) to 2525008.50 (February 20, 2201). This block implements these ephemerides with respect to the International Celestial Reference Frame version 1.0, adopted in 1998. |
| Released in 2008. This ephemeris takes into account the Julian date range 2414992.5 (December 4, 1899) to 2469808.5 (January 2, 2050). This block implements these ephemerides with respect to the International Celestial Reference Frame version 1.0, adopted in 1998. |
| Released in 2010. This ephemeris takes into account the Julian date range 2378480.5 (December 16, 1799) to 2524624.5 (February 1, 2200). This block implements these ephemerides with respect to the International Celestial Reference Frame version 2.0, adopted in 2010. |
| Released in 2013. This ephemeris takes into account the Julian date range 2287184.5 (December 21, 1549) to 2688976.5 (January 25, 2650). This block implements these ephemerides with respect to the International Celestial Reference Frame version 2.0, adopted in 2010. |
| Released in April 2014. This ephemeris takes into account the Julian date range 2287184.5, (December 21, 1549 ) to 2688976.5, (January 25, 2650). This block implements these ephemerides with respect to the International Celestial Reference Frame version 2.0, adopted in 2010. |
Note
This block requires that you download ephemeris data using the Add-On Explorer. To
start the Add-On Explorer, in the MATLAB® Command Window, type aeroDataPackage
. in the MATLAB desktop toolstrip, click Add-Ons .
Dependencies
To enable this parameter:
Set the Propagation method parameter to
Numerical (high precision)
.
Programmatic Use
Block Parameter: ephemerisModel |
Type: character vector |
Values: DE405 | DE421 | DE423 | DE430 |
Default: 'DE405' |
Action for out-of-range input — Out-of-range block behavior
None
(default) | Warning
| Error
Out-of-range block behavior, specified as follows.
Action | Description |
---|---|
| No action. |
| Warning in the Diagnostic Viewer, model simulation continues. |
| Error in the Diagnostic Viewer, model simulation stops. |
Programmatic Use
Block Parameter: errorflag |
Type: character vector |
Values: 'None' | 'Warning' | 'Error' |
Default: 'Error' |
Calculate rates — Calculate rate of Moon libration
on
(default) | off
Select to calculate the rate of the Moon libration.
Dependencies
Select this check box to display the ω port.
Programmatic Use
Block Parameter:
velflag |
Type: character vector |
Values:
'off' | 'on' | |
Default:
'on' |
References
[1] Folkner, W. M., J. G. Williams, D. H. Boggs. "The Planetary and Lunar Ephemeris DE 421." IPN Progress Report 42-178, 2009.
[2] Vallado, D. A. Fundamentals of Astrodynamics and Applications. New York: McGraw-Hill, 1997.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.
Version History
Introduced in R2013a
See Also
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