Note: To obtain the STK software go to http://stk.com and click on Educational  Partners to fill out an application to receive the STK CD ROM. Unfortunately you may have trouble running this program on older computers. Minimum recommended Windows workstation requirements are: Windows 95, 200 MB hard disk, 64 MB of  memory, color display, 1280 x 1024 resolution, CPU Pentium, Alpha, PowerPC.

Software Instructions

1. Open STKVO

2. In “Start Up for Applications – STK” window, click on the “Create New Scenario “ button.

3. Three windows will open: the browser window (Satellite Tool Kit) and two map windows.

4. Click in a blank space in the browser window. “Scenario1” is highlighted.

5. Enter FUSE. With “Scenario1” highlighted, click on the satellite on the left side toolbar. If the Orbit Wizard is displayed, click on “cancel”. Click once on the word “satellite1” and type FUSE. Choose “basic” from the pull down “Properties” menu. In the “Basic Properties window that appears, on the “Orbit” tab change the “Propagator” entry to MSGP4. Change the “SSC Number” to “25791”. (This number identifies the FUSE satellite.) Then, in the lower left part of the screen, press the “load” button in the “TLE Options” box. In the “TLE Selection” box that appears, choose “Online Load” as the “Load Method”, click the box to the left of “Load Newest”, and then click the “Go Online” button. Finally, click “OK” to close the “TLE Selection” box. Then click “OK” to close the “Basic Properties” window. If you now press the left arrow tip button on the tool bar in either map, you will see FUSE orbit. The lines on the two-dimensional display show the path of FUSE traced on the surface of Earth for one day.

6. Enter the Ground Station  The ground station available to receive FUSE data and transmit operating instructions to the satellite is located in Mayaguez, Puerto Rico.

7. Click on “Scenario1” in the browser window. Click on the second button on the left side tool bar to create a “new facility”. Name it Mayaguez by clicking once on “Facility 1”, typing “Mayaguez”, and pressing return.

8. To set the longitude and latitude of Mayaguez, be sure its name is highlighted and in the Properties menu, choose basic. On the position tab, set Type to Geodetic. Click in the Latitude box and enter “18.21 deg”. Click in the Longitude box and enter –67.14 deg. Click in the “Altitude” box and enter “0.006 km.” Click on the OK button. Note that Mayaguez is now located on both maps. Note that you can change your view in the 3D, “VO” map using a two- or three- button mouse. Position the mouse at the center of Earth. Move the mouse with the left button is depressed to change the view. Move the mouse up or down while the right or center button is depressed to zoom in or out.

9. Enter the Sensor Properties at Mayaguez. In the browser window, with “Mayaguez” illuminated, press the sensor button. Choose basic from the properties pull down menu.  In the “Sensor1-Basic Properties” box that appears, under the “Definition” tab, enter “85 deg” for “Cone Angle” and click ”OK.” Under the “Pointing” tab, enter “Targeted “ for Pointing Type. Illuminate FUSE in the Available Targets box and press the right arrow to make FUSE an assigned target. Finally click “OK” to close the “Sensor1-Basic Properties” box.

10. Calculate Contact Time. With Sensor1 illuminated in the browser box, choose “Access” from the “Tools” pull down menu. Highlight Fuse in the “Access for Sensor” window that appears. Click the “Compute” button and then click the “Access” button in the “Reports” box in the lower right. The report that appears gives you all contact times in one day plus minimum, maximum, mean, and total contact times. Note that these times are important because it is only during contact time that instructions can be transmitted to the satellite and data can be received from the satellite.
 
 

Extensions

This exercise led you through a very small part of the Satellite Tool Kit capability and showed only one aspect of mission control. To get a better feel for missions operations, try the following.

Training Exercises

In the opening window of STK or STK/VO, choose the training exercises instead of clicking the new scenario button. Start with the basic exercises and then go to an exercise in the science category. After highlighting your choices, click ”OK.” This will give you insight into the complexities of mission planning.
 

Plan an Orbit

Plan your own orbit for FUSE using STK/VO and compare it to the orbit chosen by mission planners. Take the following constraints into account:

1. Because cost increases with orbit height, plan an altitude of less than 800 km. Keep the altitude above 750 km to avoid a highly populated communications satellite altitude. The cost increases with height because the launch is more expensive and the signal gets fainter so you need more power on the space craft.

2. Use a nearly circular orbit to keep the atmospheric density the same throughout the orbit.

3. You must be able to make contact with Mayaguez and backup ground stations in Hawaii (latitude = 21^o N , longitude = 158^o W) and in Goldstone, CA (latitude = 35.3^o N, longitude 116.9^o W ).

4. Radiation damage to sensitive equipment is a concern for all space satellites. FUSE should spend the minimum possible amount of time in regions of space that contain a great many charged particles because FUSE detectors must be turned off in such regions to avoid damage. High energy particles are part of the solar wind and their distribution is shaped by Earth's magnetic field. Avoid a concentrated zone of radiation called the South American Anomaly. This region will be shown on the two dimensional map if you highlight FUSE in the browser window, choose graphics from the properties pull down menu, click the contours tab, click in the box to the left of “show”, and click OK. To show the region on the three dimensional map, highlight FUSE in the browser window, choose “VO” from the properties pull down menu, click on the box to the left of “show” under the “contours” tab, and click OK to close the window, Also, the orbit should be as close as possible to the equator because within the limits of altitude you are considering, this is a region of low radiation.