Satellites plugin

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==Description==
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==Introduction==
 
+
 
The Satellites plugin simulates satellites in Earth orbit.  Satellite orbits are not very precisely predicted using the existing orbital models for the planets, as there are other factor involved - irregularities in the Earth's gravitational field, lunar interactions, atmospheric drag and so on.   
 
The Satellites plugin simulates satellites in Earth orbit.  Satellite orbits are not very precisely predicted using the existing orbital models for the planets, as there are other factor involved - irregularities in the Earth's gravitational field, lunar interactions, atmospheric drag and so on.   
  
 
This plugin implements the SGP4 and SDP4 models, and takes as it's input data NORAD TLEs (two line elements).  TLEs for hundreds of satellites are available online and are regularly updated.  
 
This plugin implements the SGP4 and SDP4 models, and takes as it's input data NORAD TLEs (two line elements).  TLEs for hundreds of satellites are available online and are regularly updated.  
  
http://porpoisehead.net/images/plugin-satellites.jpg
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==Usage==
 +
===Enabling the Satellites plugin===
 +
This plugin comes bundled with Stellarium version 0.10.3, although it is not enabled by default.  To enable the plugin, open the configuration dialog and go to the plugins tab.  Click '''Satellites''' from the list of available plugins and check the '''load at startup''' checkbox.  You will need to re-start Stellarium for changes to take effect.
 +
 
 +
===Using the Satellites plugin===
 +
To see the position of artificial satellites, you must have the observer location set to Earth.  You must also turn on Satellite indicators on the main tool bar as shown in the image below:
 +
 
 +
http://stellarium.org/wikiimg/sat_howto_02.jpg
 +
 
 +
====Searching for satellites====
 +
It should now be possible to search for artificial satellites using the regular search dialog (F3).  Note that at any given time, most Satellites will be below the horizon.
 +
 
 +
http://stellarium.org/wikiimg/sat_howto_03.jpg
 +
 
 +
====Diaplaying satellite data====
 +
When you have selected a Satellite, information about it will be shown just as for any other object which is selected.  This includes:
 +
 
 +
* Normal '''positional data''' (RA/Dec, Alt/Azi and so on)
 +
* '''Range''' in kilometers.  This is the line-of-sight distance between the observer and the selected satellite
 +
* '''Range Rate''' in kilometers per second.  This is the closing/parting speed of the satellite.  It is useful when calculating doppler shift necessary for communications (and is also just nice to know)
 +
* '''Altitude''' of the satellite above the ground in kilometers
 +
* '''Comms''' data.  Some satellites broadcast on frequencies which can be received by the general public or used by amateur radio operators.  Where such data is known about a satellite Stellarium will show it.
 +
 
 +
 
 +
http://stellarium.org/wikiimg/sat_howto_04.jpg
 +
 
 +
====Configuration====
 +
When the satellites plugin is loaded, the configuration button in the plugins tab of the configuration dialog will be enabled.  Clicking this button (or pressing Control+Shift+Z) will open the configuration dialog for the satellites plugin.
 +
 
 +
=====Settings tab=====
 +
In the settings tab you can control how often the Satellites plugin downloads updates for the TLE elements of known satellites.  The default is every 72 hours.  If an update is due when Stellarium is started, it will commence 30 seconds or so after the plugin is loaded.
 +
 
 +
http://stellarium.org/wikiimg/sat_howto_05.jpg
 +
 
 +
=====Satellites tab=====
 +
The Satellites tab shows data on known satellites and lets you choose which ones are visible.  Note that for each satellite which is visible, Stellarium must do extra work to calculate and show the position of the satellite.  If Stellarium is running very slowly with the Satellites plugin enabled, try reducing the number of satellites which are visible.
 +
 
 +
You can select and go to a satellite by double clicking it in the list.
 +
 
 +
At time of writing, this dialog is only doe display information about satellites and changing their visibility.  In future it will be possible to edit descriptions, comms data and so on, but this is not yet implements.
 +
 
 +
http://stellarium.org/wikiimg/sat_howto_06.jpg
 +
 
 +
=====Sources tab=====
 +
The Sources tab lets you see (and modify) where Stellarium is getting its TLE data from.  The default is a list of sources from [http://celestrak.com celestrak.com].
 +
 
 +
http://stellarium.org/wikiimg/sat_howto_07.jpg
  
==Using the Satellites plugin==
+
==Adding new Satellites==
Note that this plugin is still in the early stages of development, and may change quite a lot in the near futureThis description apples to version 0.1.1 of the plugin.
+
At time of writing, there is no simple way to add and remove satellites using the GUIHowever, you can modify the satellites.json file manually using a text editor.
  
#There is a tool bar button which can be used to toggle the display of satellites.
+
This this method you can edit the tags for a satellite, modify the description and comms data, and even add new satellites.
  
==How you can help==
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TODO: PLEASE SOMEONE WRITE A NICE GUIDE FOR THIS
Some specific things for non-programmers:
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*Create a really complete module.ini file. 
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**All the amateur satellites should have all their comms channels listed for all active satellites.  Also include modulation information, which is currently missing for most spacecraft.
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***[http://www.amsat.org/amsat-new/satellites/status.php Amsat.org Sat Status]
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**All scientific craft should be added
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**Please no military spacecraft
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*Find a list of URLs which link to TLE data for all satellites in the new module.ini file.  Please verify that the owners of the sites are OK with re-distribution of their data under open source licenses.
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**[http://www.amsat.org/amsat-new/tools/keps.php AMSAT Keplerian Elements]
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*Someone draw a nice icon for the left menu (for a GUI dialog).
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*Suggestions and so on.
+
  
For development tasks, see the TODO list, which is maintained in the [http://stellarium.svn.sourceforge.net/viewvc/stellarium/trunk/extmodules/Satellites/README?view=markup README] file for the plugin. If you are able to help with any item in this list, please contact the Stellarium developer team via the stellarium-pubdevel mailing list.
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TODO: Provide download links for alternative satellites.json files which include specialist lists of satellites.
  
We also welcome bug reports, feature requests and feedback through the usual channels (trackers, forums and so on).
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TODO: Find alternative Sources lists.
  
 
[[Category:Plugins]]
 
[[Category:Plugins]]

Revision as of 08:07, 29 January 2010

Contents

Introduction

The Satellites plugin simulates satellites in Earth orbit. Satellite orbits are not very precisely predicted using the existing orbital models for the planets, as there are other factor involved - irregularities in the Earth's gravitational field, lunar interactions, atmospheric drag and so on.

This plugin implements the SGP4 and SDP4 models, and takes as it's input data NORAD TLEs (two line elements). TLEs for hundreds of satellites are available online and are regularly updated.

Usage

Enabling the Satellites plugin

This plugin comes bundled with Stellarium version 0.10.3, although it is not enabled by default. To enable the plugin, open the configuration dialog and go to the plugins tab. Click Satellites from the list of available plugins and check the load at startup checkbox. You will need to re-start Stellarium for changes to take effect.

Using the Satellites plugin

To see the position of artificial satellites, you must have the observer location set to Earth. You must also turn on Satellite indicators on the main tool bar as shown in the image below:

sat_howto_02.jpg

Searching for satellites

It should now be possible to search for artificial satellites using the regular search dialog (F3). Note that at any given time, most Satellites will be below the horizon.

sat_howto_03.jpg

Diaplaying satellite data

When you have selected a Satellite, information about it will be shown just as for any other object which is selected. This includes:

  • Normal positional data (RA/Dec, Alt/Azi and so on)
  • Range in kilometers. This is the line-of-sight distance between the observer and the selected satellite
  • Range Rate in kilometers per second. This is the closing/parting speed of the satellite. It is useful when calculating doppler shift necessary for communications (and is also just nice to know)
  • Altitude of the satellite above the ground in kilometers
  • Comms data. Some satellites broadcast on frequencies which can be received by the general public or used by amateur radio operators. Where such data is known about a satellite Stellarium will show it.


sat_howto_04.jpg

Configuration

When the satellites plugin is loaded, the configuration button in the plugins tab of the configuration dialog will be enabled. Clicking this button (or pressing Control+Shift+Z) will open the configuration dialog for the satellites plugin.

Settings tab

In the settings tab you can control how often the Satellites plugin downloads updates for the TLE elements of known satellites. The default is every 72 hours. If an update is due when Stellarium is started, it will commence 30 seconds or so after the plugin is loaded.

sat_howto_05.jpg

Satellites tab

The Satellites tab shows data on known satellites and lets you choose which ones are visible. Note that for each satellite which is visible, Stellarium must do extra work to calculate and show the position of the satellite. If Stellarium is running very slowly with the Satellites plugin enabled, try reducing the number of satellites which are visible.

You can select and go to a satellite by double clicking it in the list.

At time of writing, this dialog is only doe display information about satellites and changing their visibility. In future it will be possible to edit descriptions, comms data and so on, but this is not yet implements.

sat_howto_06.jpg

Sources tab

The Sources tab lets you see (and modify) where Stellarium is getting its TLE data from. The default is a list of sources from celestrak.com.

sat_howto_07.jpg

Adding new Satellites

At time of writing, there is no simple way to add and remove satellites using the GUI. However, you can modify the satellites.json file manually using a text editor.

This this method you can edit the tags for a satellite, modify the description and comms data, and even add new satellites.

TODO: PLEASE SOMEONE WRITE A NICE GUIDE FOR THIS

TODO: Provide download links for alternative satellites.json files which include specialist lists of satellites.

TODO: Find alternative Sources lists.

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