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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.

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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

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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

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Build the A Train Constellation using STK

Select Insert>Facility From Facility Database

Then selectAdvanced>Network>USAF AFSCN

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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

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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.

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Build the A Train Constellation using STK

We want the Access for CloudSat to the 8 ground stations.

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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

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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.

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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.

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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.

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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.