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Eclipse Shadow Model (Dual Cone)

Calculate fraction of solar disk visible at inertial positions

Since R2023b

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  • Eclipse Shadow (Dual Cone) block

Libraries:
Aerospace Blockset / Environment / Celestial Phenomena

Alternative Configurations of Eclipse Shadow Model (Dual Cone) Block:
Eclipse Shadow Model (Cylindrical)

Description

The Eclipse Shadow Model (Dual Cone) block calculates the fraction of the solar disk that is visible from the provided inertial positions, assuming that the occulted bodies and the Sun are spherical. The block operates with two shadow models:

Dual cone model — The block differentiates between partial, annular, and total eclipse, which means the spacecraft can be in sunlight, penumbra, antumbra, or umbra. The eclipse is partial in penumbra, annular in antumbra, and total in umbra. In summary:

  • Umbra, no sunlight — 0

  • Penumbra or Antumbra, partial sunlight — 0 to 1

  • Full sunlight — 1

Cylindrical model — The block differentiates only between total eclipse (umbra) and full sunlight. For more information, see Alternative Configurations section.

  • Umbra, no sunlight — 0

  • Full sunlight — 1

Ports

Input

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Position of the spacecraft with respect to ICRF coordinate system, specified as a 3-element vector or M-by-3 array, where M is the number of spacecraft. The Units parameter controls the units designation.

Data Types: double

Julian date specified as a scalar.

Dependencies

To enable this port, set Dialog to Port (Julian date).

Data Types: double

Julian date epoch from which to base elapsed Julian time, specified as a scalar.

Dependencies

To enable this port, set Dialog to Port (T0 and elapsed Julian time).

Data Types: double

Elapsed Julian time with respect to ΔTJD, specified as a scalar elapsed time.

Dependencies

To enable this port, set Dialog to Port (Julian date).

Data Types: double

Custom central body position with respect to the solar system barycenter, in the ICRF coordinate frame.

Dependencies

To enable this port, set Central body to Custom.

Data Types: double

Output

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Fraction of visible Sun (eclipse), returned as a scalar or vector of size M. M is the number of input spacecraft.

Dependencies

  • When the Shadow model parameter is set to Dual cone, the values are 0 (Umbra), between 0 and 1 (Penumbra or Antumbra), or 1 (Sunlight).

  • When the Shadow model parameter is set to Cylindrical, the values are 0 (Umbra) or 1 (Sunlight).

Data Types: double

Region depending on Shadow model value, returned as a scalar or M-element vector of integers. M is the number of spacecraft.

  • When the Shadow model parameter is set to Dual cone, region can be 0 (Umbra), between 0 and 1 (Penumbra or Antumbra), or 1 (Sunlight).

  • When the Shadow model parameter is set to Cylindrical, region can be 0 (Umbra) or 1 (Sunlight).

Dependencies

To enable this port:

  • Select the Output index of shadow region check box.

Data Types: int32

Region depending on Shadow model value, returned as a scalar or M-element vector of integers. M is the number of spacecraft.

  • When the Shadow model parameter is set to Dual cone, region can be 0 (Umbra), between 0 and 1 (Penumbra or Antumbra), or 1 (Sunlight).

  • When the Shadow model parameter is set to Cylindrical, region can be 0 (Umbra) or 1 (Sunlight).

Dependencies

To enable this port, select the Output index of shadow region check box and one of these settings:

    • Set Central body to Earth.

    • Select Include Moon.

or:

    • Set Central body to Moon.

    • Select Include Earth.

Data Types: int32

Parameters

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Position port units, specified as one of these values:

UnitsDistance
Metric (m)meters
Metric (km)kilometers
English (ft)feet
English (M)miles

Programmatic Use

Block Parameter: units
Type: character vector
Values: 'Metric (m)' | 'Metric (km)' | 'English (ft)' | 'English (M)'
Default: 'Metric (m)'

Shadow model for eclipse calculations, specified as one of these values.

  • Cylindrical — Fraction can be 0.0 (Umbra) or 1.0 (Sunlight).

  • Dual cone — Fraction can be 0.0 (Umbra), between 0.0 and 1.0 (Penumbra or Antumbra), or 1.0 (Sunlight).

Programmatic Use

Block Parameter: shadowModel
Type: character vector
Values: 'Dual cone' | 'Cylindrical'
Default: 'Dual cone'

To enable the port for the index of the shadow region, select this check box. Otherwise, clear this check box.

Programmatic Use

Block Parameter: outputShadowRegion
Type: character vector
Values: 'off' | 'on'
Default: 'on'

Time source method, specified as one of these values:

  • Dialog — Block dialog parameter.

  • Port (Julian date) — TJD port.

  • Port (T0 and elapsed Julian time) — TJD and ΔTJD ports.

Programmatic Use

Block Parameter: timeSource
Type: character vector
Values:'Dialog' | 'Port (Julian date)' | 'Port (T0 and elapsed Julian time)'
Default: 'Dialog'

Initial start date and time of simulation, specified as a valid scalar Julian date. To determine the current time at each simulation timestep, the block adds elapsed simulation time to this value.

Tip

To calculate the Julian date, use the juliandate function.

Dependencies

To enable this parameter, set Time source to Dialog.

Programmatic Use

Block Parameter: startDate
Type: character vector
Values:'juliandate(2020, 1, 1)' | valid scalar Julian date
Default: 'juliandate(2020, 1, 1)'

Occulting celestial body for eclipse calculations, specified as Earth, Moon, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, or Custom.

Position inputs are referenced with respect to the origin of the central body.

Programmatic Use

Block Parameter: centralBody
Type: character vector
Values: 'Earth' | 'Moon' |'Mercury' | 'Venus' | 'Mars' | 'Jupiter' | 'Saturn' | 'Uranus' | 'Neptune' | 'Custom' |
Default: 'Earth'

Equatorial radius for a custom central body, specified as a double scalar in the units specified in the Units parameter..

Dependencies

To enable this parameter, set Central body to Custom.

Programmatic Use

Block Parameter: customR
Type: character vector
Values: '3396200' | double scalar
Default: '3396200'

Option to include Moon as a secondary occulting body in eclipse calculations when central body is Earth.

Dependencies

Set the Central body parameter to Earth.

Programmatic Use

Block Parameter: includeMoon
Type: character vector
Values: 'off' | 'on'
Default: 'on'

Option to include Earth as a secondary occulting body in eclipse calculations when central body is Moon.

Dependencies

Set the Central body parameter to Moon.

Programmatic Use

Block Parameter: includeEarth
Type: character vector
Values: 'off' | 'on'
Default: 'on'

Select one of these ephemerides models defined by the Jet Propulsion Laboratory.

Ephemeris Model Description

DE405

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.

DE421

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.

DE423

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.

DE430

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.

DE432t

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'

Control how much data is loaded into memory during simulation and how much data is included in generated code for the block:

  • Clear this check box to include data for the complete date range defined in the Ephemeris model table.

  • Select this check box to limit the loading of ephemeris data to a specified date range.

Programmatic Use

Block Parameter: useDateRange
Type: character vector
Values: 'off' | 'on' |
Default: 'on'

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 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)'

Out-of-range block behavior, specified as one of these values:

ActionDescription
None No action.
Warning

Warning in the Diagnostic Viewer, model simulation continues.

Error (default)

Error in the Diagnostic Viewer, model simulation stops.

Programmatic Use

Block Parameter: action
Type: character vector
Values: 'None' | 'Warning' | 'Error'
Default: 'Error'

Alternative Configurations

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The Eclipse Shadow Model (Cylindrical) block calculates a fraction of the solar disk visible at inertial positions while assuming that:

  • The Sun is infinitely far from the occulting bodies and the spacecraft.

  • All rays of sunlight are parallel.

The block cannot differentiate between partial, annular, and total eclipse, which means the that the eclipse is either full sunlight or umbra only.

Differences between this block and the Eclipse Shadow Model (Cylindrical) include:

  • Shadow model is Cylindrical by default.

  • Output index of shadow region is cleared by default, resulting in only the output Fraction port appearing by default.

Libraries:
Aerospace Blockset / Environment / Celestial Phenomena

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2023b

See Also

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