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AGBell -1-
Build the A Train Constellation using STK
To build the “ideal” A Train constellation we will use STK - Satellite Tool Kit by AGI
We would like to add the 8 AFSCN Ground Stations that support CloudSat.
AGBell -2-
Build the A Train Constellation using STK
This diagram shows how ground command and telemetry are handled for CloudSat
As can be seen the AFSCN – Air Force Space Control Network is used.
We want to add Ground Stations for command and control of CloudSat
AGBell -3-
Build the A Train Constellation using STK
http://www.responsivespace.com/Papers/RS6/SESSIONS/SESSION%20I/1006_HODGES/1006P.pdf
CloudSat uses eight ground stations located around the world to collect telemetry and upload commands to the satellite.
The 8 Ground Stations are:
CTSDGSGTSHTSNHSTCSTTSVTS
AGBell -4-
Build the A Train Constellation using STK
Select Insert>Facility From Facility Database
Then selectAdvanced>Network>USAF AFSCN
AGBell -5-
Build the A Train Constellation using STK
The 24 USAF AFSCN Ground Stations are shown below
and then select the “Insert” button
Select the 8 Ground Stations
that CloudSat uses:
CTSADGSAGTSAHTSA NHSATCSATTSAVTSA
AGBell -6-
Build the A Train Constellation using STK
The 8 Ground Stations are then displayed in yellow on the globe. These Ground Stations are distributed around the world to minimize the amount of information that must be stored by the satellites.
AGBell -7-
Build the A Train Constellation using STK
We want the Access for CloudSat to the 8 ground stations.
AGBell -8-
Build the A Train Constellation using STK
Select all the Ground Stations and SelectCompute
Then select the 8 Ground Stations
Next, lets “compute” the Access time from CloudSat to the eight Ground Stations
AGBell -9-
Build the A Train Constellation using STK
In the 3D view a link between GTSA and CloudSat is shown. As the satellites orbit the Earth other Ground Station will be linked as CloudSat moves through its orbit.
Click on the picture to see the scenario.
AGBell -10-
Build the A Train Constellation using STK
We can also generate a report to show when and how long each Ground Station has access to CloudSat.
AGBell -11-
Build the A Train Constellation using STK
We can also view the Access time in a graphical view. CloudSat orbits the Earth about 14 times per day.
AGBell -12-
Build the A Train Constellation using STK
The combined access time for a 1 day scenario can be created using the access data which can be captured as a CSV file.
Max Access Time = 75 min Min Access Time = 5 min Ave Access Time = 34 minStDev Access Time = 25 min
Minutes starting from 18 March 2010 12:00 AM
No Access
Access
This type of information can be used to determine the amount of on-orbit storage needed and download data rates required.