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Build the A Train Constellation using STK

Next we will use global information about the Earth to help define and understand how the A-Train orbits the Earth.

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Build the A Train Constellation using STK

First, lets add some information to our simulation so we can look more closely at the satellites. Select “properties”

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Build the A Train Constellation using STK

In the “Details” form we want to add Longitude and Latitude lines every 15 degrees.

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Build the A Train Constellation using STK

Also show the Equator and Prime Meridian

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Build the A Train Constellation using STK

Now we have a grid reference we can use to better understand how the satellites orbits the earth.

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Build the A Train Constellation using STK

For more spacial references add an Earth Sun Vector with an equatorial plane with a 100km grid spacing.

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Build the A Train Constellation using STK

Then add Earth Equator Plane with a 100km grid. (You can also select an 80% Translucent Plan to match the following slides).

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Build the A Train Constellation using STK

The “ascending node” is where the satellites crosses from south to north across this place. This is one of the primary COEs for the satellites.

The addition of the Equatorial Plane will allow us to see where the satellites cross the equator.

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Build the A Train Constellation using STK

To get a better view of the relationship between the satellites and the Equatorial Plane we will change our viewpoint to one of the satellites, Aqua.

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Build the A Train Constellation using STK

Select Satellite>AQUA as your new viewpoint.

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Build the A Train Constellation using STK

You then can move to see Aqua crossing the Equatorial Plane at about 700km. Remember each grid line is equal to 100km.

~700 km

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Build the A Train Constellation using STK

We can also run a report to determine the time Aqua and Aura crossed the ascending mode. Then compare the difference in time to what we previously entered.

Click on the picture to see the scenario.

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Build the A Train Constellation using STK

Select Aqua>Ascending Mode then select the “Generate” button.

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Build the A Train Constellation using STK

All the times that Aqua crosses the Ascending Node are then displayed in the report. For our calculation we will use the 1st time value.

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Build the A Train Constellation using STK

Likewise we will run a report on Aura and capture the 1st time value.

Aqua Aura Dtime DtimeAscending Node Time 17:46:48 17:54:05 0:07:18 7.30

time D time D degrees Mean Anomaly

OCO 3.00 3.00 10.93 276.564Aqua 0.00 0.00 0.00 265.636Cloudsat 1.00 -1.00 -3.64 261.993Calipso 0.29 -1.29 -4.71 260.931Parasol 1.00 -2.29 -8.35 257.288Glory 1.00 -3.29 -11.99 253.645Aura 4.00 -7.29 -26.56 239.074

Aqua lead Aura by ~ 7.3 minutes. This is pretty close to what we expected.

embedded spreadsheet