Level 2 FreeFlyer Certification Exam Part A

Coverage and Contact

1. A Sensor object can be attached to two object types. Which are they?

Spacecraft and GroundStation
Spacecraft and GroundVehicle
Spacecraft and Structure
GroundStation and GroundVehicle

2. Which of the following approaches for orienting a Sensor is not valid?

Using a unit vector
Using the SetOrientation method
Using manually set quaternions
Using a pair of Azimuth-Elevation angles

3. Which of the following is not a valid method of Sensor FOV definition?

Cylinder
Cone
Rectangle
Custom azimuth and elevation angles

4. Which Method returns the start time, end time, and duration of a Spacecraft Sensor's view of another Object?

Spacecraft.Access()
Spacecraft.InView()
Spacecraft.Contact()
Spacecraft.FOVInterface()

5. Which of the following is not configurable for a Sensor View?

Reference Object
FiniteBurn
Target Object
SpecificBurn

6. How can the pointing of a Sensor boresight be defined? (If applicable, select multiple answers to fulfill the correct response)

With a unit vector referenced to the Body Coordinate System of the Spacecraft
With 3 Euler Angles referenced to the Spacecraft Body Coordinate System
With a pair of Azimuth-Elevation angles referenced to the Spacecraft Body Coordinate System
By aligning the sensor boresight with the z-axis of a CoordinateSystem using the Sensor.SetOrientation() Method

7. What object is used to perform contact analysis?

VisibilityEvaluator
VisibilitySegment
VisibilityTimes
VisibilityVector

8. Which components are included in a VisibilitySegment?

Target
Occulting Bodies
Observer
All of the above

9. Why might you use a VisibilityCalculator instead of a VisibilitySegment?

To save on computational resources and improve performance
To perform occultation analyses using terrain data
To manage VisibilitySegment objects when calculating chain visibility
To incorporate effects due to refraction into the line of sight calculations

10. Which of the following can be set as the Target, but not the Observer, when defining a VisibilitySegment?

CelestialObject
PointGroup
Star
All of the above

11. Which of the following can impact line of sight visibility for a VisibilitySegment? (If applicable, select multiple answers to fulfill the correct response)

FOVInterference
Occulting Bodies
Occulting Terrain
Refraction Modeling

12. Which of the following are occultation objects that can be added to a Visibility Segment? (If applicable, select multiple answers to fulfill the correct response)

CelestialObject
Region
Spacecraft
Terrain

13. What happens if propagation begins or ends during an interval method event?

FreeFlyer will report the start/end time of propagation as the start/end time of the event
FreeFlyer will automatically step to the beginning of the next event/end of the current event
FreeFlyer calculates the actual start/end of the event and reports that as the event time
FreeFlyer does not process or report partial events

14. Which of the following is not calculated by Interval Methods in FreeFlyer?

Close Approach Times
Shadow Entry/Exit Times
Contact Start/End Times
Intersection Beginning/End Times

15. Where is the KA2S GroundStation located?
Hint: Build a GroundStation using the Station Geodetics File option

Wallops Island, VA
Edwards AFB, CA
Tokyo, Japan
Canberra, Austrailia

16. How would you define a GroundStation on Mars?

Station geodetics file
Custom latitude and longitude
Manual placement in the preview window
All of the above

17. Which method provides detailed information on the contact between a GroundStation and a Spacecraft?

Spacecraft.PassData()
Spacecraft.FlybyData()
Spacecraft.GSData()
Spacecraft.GetData()

18. Which types of sensor masks can be applied to a GroundStation? (If applicable, select multiple answers to fulfill the correct response)

Cone
Rectangular
Custom
All of the above

19. Which Property can be used to specify the number of points in a PointGroup?

PointGroup.GroupSize
PointGroup.Size
PointGroup.Count
PointGroup.PointSize

20. Which of the following objects' usage is unrelated to coverage and contact analysis?

PointGroup
FiniteBurn
Sensor
Region

21. To which objects can ProximityZone objects be attached?

CelestialObject
GroundStation
Spacecraft
All of the above

22. Which of the following is not a valid shape for a ProximityZone?

Cylinder
Spherical
Ellipsoid
Rectangular

23. Which of the following are valid ways to orient a Proximity Zone attached to a Spacecraft?

Define a Quaternion wrt a valid reference frame
Define a sequence of Euler Angles wrt a valid reference frame
Define a 3x3 Attitude Matrix wrt a valid attitude reference frame
All of the above

24. Which of the following Objects will act as a valid transmitter or receiver for the RFLink Object?

GroundStation
Sensor
Spacecraft
All of the above

25. What is the BlockageDiagram Object used for in FreeFlyer?

Evaluating blockage over a given timespan
Visualizing blockage over a given timespan
Visualizing blockage scenarios
All of the above

26. Which combination of objects can be used to compute and visualize viewshed analysis?

PointGroup, Vector
PointGroup, VisibilitySegment
Region, Vector
Region, VisibilitySegment

27. Using the FreeFlyer Terrain Index Generator, which vertical datum values are valid for creating terrain index files? (If applicable, select multiple answers to fulfill the correct response)

EGM96
MSL
NAVD88
WGS84

28. Which of the following commands would generate a single terrain index file for ‘MountEverest.tif’ using an EGM96 vertical datum in meters with a resolution of 10? (If applicable, select multiple answers to fulfill the correct response)
Assume you are already in the correct directory for the terrain index generator and the ‘MountEverest.tif’ file is stored in the same directory.

freeflyer_terrain_index_generator.exe -r 10 -d EGM96 -u meters “MountEverest.tif”
freeflyer_terrain_index_generator.exe -resolution 10 -datum EGM96 -units meters “MountEverest.tif”
freeflyer_terrain_index_generator.exe -d EGM96 -u meters “MountEverest.tif”
freeflyer_terrain_index_generator.exe --resolution 10 --vertical-datum EGM96 --height-units meters “MountEverest.tif”

GroundStation Short Mission Plan

Design a Mission Plan propagates the default Spacecraft Object for 1 day using the default propagation settings. Add the Canberra, Goldstone, Madrid, and Wallops GroundStation Presets to the Mission Plan. Use the Spacecraft.PassData() Method to answer the following:

1. Which GroundStation does the Spacecraft come into contact with the most?

Canberra
Goldstone
Madrid
Wallops

2. What is the MaxElevation (deg) angle of the longest duration pass for that GroundStation?

38.19
71.13
84.39
89.85

3. Which GroundStation does the Spacecraft come into contact with the least?

Canberra
Goldstone
Madrid
Wallops

4. What is the shortest Duration (min) pass for that GroundStation?

3.29
8.88
8.14
8.81

5. Which subsystems are available for both the Spacecraft and GroundVehicle Objects?

ProximityZones
Sensor
Tanks
All of the Above

6. How can GroundVehicle motion be controlled?

By specifying surface-velocity in the North and East directions
By defining a series of waypoints for the GroundVehicle to navigate to
By specifying both heading and speed
All of the above

7. Which two Methods can be used to identify when a Spacecraft is over a Region?

Spacecraft.InRegion() & Spacecraft.ExclusionZone()
Spacecraft.InView() & Spacecraft.Access()
Spacecraft.InRegion() & Spacecraft.Access()
Spacecraft.ExclusionZone() & Spacecraft.InView()

8. Which two Methods can be used to identify when a Spacecraft's Sensor can see a Region?

Spacecraft.InRegion() & Spacecraft.ExclusionZone()
Spacecraft.InView() & Spacecraft.Access()
Spacecraft.InRegion() & Spacecraft.Access()
Spacecraft.ExclusionZone() & Spacecraft.InView()

9. What is the minimum number of points needed to define a Region?

1
3
4
There is no minimum

Region Short Mission Plan

Design a Mission Plan that propagates the AQUA Spacecraft Object Preset for 1 day using the default propagation settings. Add the SAA_Med Region to the Mission Plan. Use the Spacecraft.ExclusionZone() Method to answer the following questions:

1. How many times does the AQUA Spacecraft pass over the SAA_Med Region?

5
6
7
8

2. What is the longest Duration (min) pass?

11.363
13.278
13.981
15.135

3. What is the shortest Duration (min) pass?

1.203
3.102
4.256
5.592

Design a Mission Plan that propagates the AQUA Spacecraft Object Preset for 1 day using the default propagation settings. Add a sensor to the AQUA Spacecraft and set the cone half angle to 45 deg. Add the SAA_Med Region to the Mission Plan. Use the Spacecraft.Access() Method to answer the following questions:

4. How many times does the SAA_Med Region come in view of the AQUA Spacecraft's sensor?

8
9
10
11

5. What is the longest Duration (min) pass?

13.747
14.182
14.268
15.172

Change the cone half angle on the AQUA Spacecraft to 60 degrees. Use the Spacecraft.Access() Method to answer the following questions:

6. How many times does the SAA_Med Region come in view of the AQUA Spacecraft's sensor?

8
9
10
11

7. What is the longest duration pass

18.334
18.431
19.391
20.154

ProximityZones Short Mission Plan

Create a Mission Plan that propagates the default Spacecraft and ISS Spacecraft Object Preset for 1 day using the default propagation settings. Set the default Spacecraft's epoch to "Jun 01 2016 00:00:00.000000000" to match the ISS. Add a default Ellipsoid ProximityZone to the ISS object. Set the default Spacecraft's semi-major axis to 6780.0 km. Use the Spacecraft.Intersects() Method to answer the following questions:

1. How many times does the default Spacecraft intersect the ISS's proximity zone?

5
6
7
8

2. What is the longest Duration (min) intersection?

0.769
1.105
1.13
1.345

Use the Spacecraft.CloseApproachRange() Method to answer the following questions:

3. What is the closest approach Range(km) reported?

284.944
307.851
319.155
366.749

4. Which three event types are reported by the Spacecraft.ShadowTimes() method?

Annular Shadow, Earth Shadow, Moon Shadow
Annular Shadow, Moon Shadow, Penumbral Shadow
Earth Shadow, Moon Shadow, Penumbral Shadow
Annular Shadow, Penumbral Shadow, Umbral Shadow

5. Which of the following are examples of Instantaneous Shadow Analysis Methods?

Spacecraft.ShadowTimes()
Spacecraft.InShadow()
Spacecraft.InView()
All of the above

6. Which of the following are examples of Interval Shadow Analysis Methods?

Spacecraft.InShadow()
Spacecraft.PercentShadow()
Spacecraft.ParticleFlux()
Spacecraft.ShadowTimes()

Shadow Analysis Short Mission Plan

Create a Mission Plan that propagates the ISS Spacecraft Object for 1 day using the default propagation settings. Using the Spacecraft.ShadowTimes() Method, answer the following:

1. How many Earth penumbral shadow events are reported?

13
14
15
16

2. How many Earth Umbral shadow events are reported?

13
14
15
16

3. Which type of shadow event has the longest Duration (min)?

Annular
Penumbral
Umbral
Annular & Penumbral

4. What is the Duration (min) of the longest reported shadow event?

15.653
22.6367
23.559
25.521

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