Planetary Ephemeris
Implement position and velocity of astronomical objects
Libraries:
Aerospace Blockset /
Environment /
Celestial Phenomena
Description
The Planetary Ephemeris block uses Chebyshev coefficients to implement the position and velocity of the target object relative to the specified center object for a given Julian date. The Target parameter specifies an astronomical object. The block implements the ephemerides using the Center parameter for an astronomical object as the reference.
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.
This block implements the position and velocity using the International Celestial Reference Frame. If you require the planetary ephemeris position value relative to Earth in Earth-fixed (ECEF) coordinates, use the Direction Cosine Matrix ECI to ECEF 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.
Specify the Julian dates in Barycentric Dynamical Time (TDB).
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 date.
Specify the Julian dates in Barycentric Dynamical Time (TDB).
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
Xicrf1 — Barycenter position
vector
Barycenter position (Xicrf1) of the Target object relative to the barycenter of the Center object, output as a vector, in km or astronomical units (AU).
Tip
This block outputs the barycenter position in International Celestial Reference Frame (ICRF) coordinates. To convert these coordinates to Earth-centered Earth-fixed (ECEF), use the Direction Cosine Matrix ECI to ECEF block.
Data Types: double
Vicrf — Velocity
vector
Velocity (Vicrf) of the barycenter of the Target object relative to the barycenter of the Center object, specified as a vector, in km/s or astronomical units (AU)/day.
Data Types: double
Parameters
Units — Output units
km,km/s
(default) | AU,AU/day
Output units, specified as km,km/s
or
AU,AU/day
.
Units | Position | Velocity |
---|---|---|
| m | m/s |
| km | km/s |
| astronomical units (AU) | AU/day |
Programmatic Use
Block Parameter: units |
Type: character vector |
Values: m,m/s |
km,km/s |
AU,AU/day |
Default:
'km,km/s' |
Epoch — Epoch
Julian date
(default) | T0 and elapsed Julian time
Epoch, specified as:
Julian date
Julian date to implement the position and velocity of the Target object.. 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 date.
Programmatic Use
Block Parameter:
epochFormat |
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' |
Ephemeris model — Ephemeris model
DE405
(default) | DE421
| DE423
| DE430
| DE432t
Select one of these ephemerides models defined by the Jet Propulsion Laboratory.
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.
Programmatic Use
Block Parameter: ephemerisModel |
Type: character vector |
Values: DE405 | DE421 | DE423 | DE430 |
Default: 'DE405' |
Center — Center body
Sun
(default) | Mercury
| Venus
| Earth
| Moon
| Mars
| Jupiter
| Saturn
| Uranus
| Neptune
| Pluto
| Solar system barycenter
| Earth-Moon barycenter
Center body (astronomical object) or reference body, specified as a point of reference for the Target barycenter position and velocity measurement.
Programmatic Use
Block Parameter: center |
Type: character vector |
Values: Sun
| Mercury | Venus |
Earth | Moon |
Mars | Jupiter |
Saturn | Uranus |
Neptune | Pluto |
Solar system barycenter | Earth-Moon
barycenter |
Default:
'Sun' |
Target — Target body
Sun
(default) | Mercury
| Venus
| Earth
| Moon
| Mars
| Jupiter
| Saturn
| Uranus
| Neptune
| Pluto
| Solar system barycenter
| Earth-Moon barycenter
Target body (astronomical object) or reference body, specified as a point of reference for the barycenter position and velocity measurement.
Programmatic Use
Block Parameter: target |
Type: character vector |
Values: Sun
| Mercury | Venus |
Earth | Moon |
Mars | Jupiter |
Saturn | Uranus |
Neptune | Pluto |
Solar system barycenter | Earth-Moon
barycenter |
Default:
'Moon' |
Limit ephemerides date range — Option to enable start and end of range of ephemeris data
off
(default) | on
Control how much data is loaded into memory during simulation and how much data is included in generated code for the block:
Select this check box to limit the loading of ephemeris data to a specified date range.
Clear this check box to include data for the complete date range defined in the Ephemeris model table.
Dependencies
To enable this parameter:
Set the Propagation method parameter to
Numerical (high precision)
.
Programmatic Use
Block Parameter:
useDateRange |
Type: character vector |
Values: 'off' |
'on'
|
Default: 'off' |
Start date (JD) — Start date of ephemerides date range
juliandate(2020, 1, 1)
(default) | Julian date
Start date of ephemerides date range, specified as a Julian date.
Dependencies
To enable this parameter:
Set the Propagation method parameter to
Numerical (high precision)
.Select the Limit ephemerides date range parameter.
Programmatic Use
Block Parameter: startDate |
Type: character vector |
Values: 'juliandate(2020, 1, 1)' | Julian date |
Default: 'juliandate(2020, 1, 1)' |
End date (JD) — End date of ephemerides date range
juliandate(2050, 1, 1)
(default) | Julian date
End date of ephemerides date range, specified as a Julian date.
Dependencies
To enable this parameter, select the Limit ephemerides date range check box.
Dependencies
To enable this parameter:
Set the Propagation method parameter to
Numerical (high precision)
.Set the Limit ephemerides date range parameter to
on
.
Programmatic Use
Block Parameter: endDate |
Type: character vector |
Values: 'juliandate(2050, 1, 1)' | Julian format date |
Default: 'juliandate(2050, 1, 1)' |
Action for out-of-range input — Out-of-range block behavior
None
(default) | Warning
| Error
Out-of-range block behavior, specified as:
Action | Description |
---|---|
| No action. |
| Warning in the Diagnostic Viewer, model simulation continues. |
| Error in the Diagnostic Viewer, model simulation stops. |
Programmatic Use
Block Parameter: action |
Type: character vector |
Values: 'None' | 'Warning' | 'Error' |
Default: 'Warning' |
Calculate velocity — Calculate rate of target barycenter
on
(default) | off
Select this check box to calculate the velocity of the Target barycenter relative to the Center barycenter.
Programmatic Use
Block Parameter:
outputVelocity |
Type: character vector |
Values:
'off' | 'on' | |
Default:
'on' |
References
[1] Folkner, W. M., J. G. Williams, and D. H. Boggs. "The Planetary and Lunar Ephemeris DE 421." IPN Progress Report 42-178, 2009.
[2] Ma, C. et al. "The International Celestial Reference Frame as Realized by Very Long Baseline Interferometry." Astronomical Journal, Vol. 116, 516–546, 1998.
[3] 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 R2013aR2023a: Planetary Ephemeris Block Controls Range of Ephemeris Data
You can now control the range of ephemeris data for the Planetary Ephemeris using these new parameters:
Limit ephemerides date range — Select this check box to enable the start and end of the range of ephemeris data.
Start data — Enter the start date of the range of ephemeris data. The Epoch parameter affects this date format.
End data — Enter the end date of the range of ephemeris data. The Epoch parameter affects this date format.
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