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.

We want to add Ground Stations for command and control of CloudSat 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.

The 8 Ground Stations are: CloudSat uses eight ground stations located around the world to collect telemetry and upload commands to the satellite. The 8 Ground Stations are: CTS DGS GTS HTS NHS TCS TTS VTS http://www.responsivespace.com/Papers/RS6/SESSIONS/SESSION%20I/1006_HODGES/1006P.pdf

Select Insert>Facility From Facility Database Then select Advanced>Network> USAF AFSCN

The 24 USAF AFSCN Ground Stations are shown below and then select the “Insert” button Select the 8 Ground Stations that CloudSat uses: CTSA DGSA GTSA HTSA NHSA TCSA TTSA VTSA

The 8 Ground Stations are then displayed in yellow on the globe 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.

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

Select all the Ground Stations and Select Compute Then select the 8 Ground Stations Next, lets “compute” the Access time from CloudSat to the eight Ground Stations

In the 3D view a link between GTSA and CloudSat is shown 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.

We can also generate a report to show when and how long each Ground Station has access to CloudSat.

We can also view the Access time in a graphical view We can also view the Access time in a graphical view. CloudSat orbits the Earth about 14 times per day.

Minutes starting from 18 March 2010 12:00 AM Max Access Time = 75 min Min Access Time = 5 min Ave Access Time = 34 min StDev Access Time = 25 min Access No Access Minutes starting from 18 March 2010 12:00 AM The combined access time for a 1 day scenario can be created using the access data which can be captured as a CSV file. This type of information can be used to determine the amount of on-orbit storage needed and download data rates required.