1. CAP-STK Aerospace Program
CIVIL AIR PATROL
CAP-STK Aerospace Program
2015!!
Orbital Mechanics and other Space Operations Topics !!
Colorado Springs Cadet Squadron
Lt Col M. T. McNeely 1 1

2. ORBITAL MECHANICS Physical Laws Requirements for Injection
Classifications of Orbit
Six Orbital Elements
Ground Tracks 22 22

3. ORBITAL MECHANICS
Two men in history that were essential to formulating orbital mechanics:
Kepler and Newton!!
Kepler’s 3 Laws:
Law of Ellipses
Law of Equal areas
Law of Harmonics
Newton’s 3 Laws:
Law of Inertia
Law of Momentum
Law of Action -Reaction 22 22

4. PHYSICAL LAWS Kepler’s 1st Law: Law of Ellipses
The orbits of the planets are ellipses with the sun at one focus. Or, the orbits of satellites around the earth are ellipses with the earth at one focus….. 10 10

5. PHYSICAL LAWS
Is this orbit possible? 12 12

6. PHYSICAL LAWS Kepler’s 2nd Law: Law of Equal Areas
The line joining the planet to the center of the sun sweeps out equal areas in equal times T6 T5 T4 T3 T2 T1 A2 A3 A4 A5 A6 A1 13 13

7. PHYSICAL LAWS Kepler’s 2nd Law: Law of Equal Areas
Satellites travel at the same speed!! 14 14

8. PHYSICAL LAWS Sir Isaac Newton
Derived three laws of motion
Derived the Law of Universal Gravitation
Explained why Kepler’s laws worked 17 17

9. PHYSICAL LAWS Newton’s 3rd Law: Action - Reaction
For every action, there is an equal and opposite reaction
Hints at conservation of momentum 20 20

10. INJECTION REQUIREMENTS Speed
A satellite must be going 17,500 mph to stay in a low earth orbit
17,500 mi/hr
100 miles 25 25

11. INJECTION REQUIREMENTS Altitude
Are you moving FASTER or SLOWER the higher your altitude? 26 26

12. ORBITAL ELEMENTS or The Six Keplerian Elements
Size/Period
Shape (Circular or Ellipse)
Inclination
Right Ascension
Argument of Perigee
True Anomaly 31 31

13. ORBIT CLASSIFICATION Size/Period
Size is how big or small your satellite’s orbit is….
Defined by semi-major axis
There are basically 4 sizes of orbits satellites use:
Low Earth Orbit (LEO): approx 120 – 1200 miles above Earth
Medium Earth Orbit (MEO) or Semi-synchronous Orbit: approx 12,000 miles above Earth
Highly Elliptical Orbit (HEO): altitude varies greatly! From 100 miles to sometimes several hundred thousand miles
Geo-synchronous or Geo-stationary Orbit
(GEO): approx 22,300 miles from Earth 32 32

14. ORBIT CLASSIFICATION Shape
Orbit shapes are either
circular or not circular:
some sort of an
Ellipse!!
How elliptical an orbit, is called Eccentricity 34 34

15. ORBIT CLASSIFICATIONS Eccentricity
The closer your Eccentricity is to 1, the more elliptical your orbit is
Why could you never have an Eccentricity of 1?? 42 42

16. ORBITAL ELEMENTS Inclination
Inclination is the tilt of your orbit
At 0 degrees of inclination, you are orbiting the equator
At 90 degrees of inclination, you are in a polar orbit
Orbital Plane
Equatorial Plane
Inclination
Inclination: Is this angle, measured in degrees 62 62

17. ORBITAL ELEMENTS Right Ascension
Right Ascension is the swivel of your tilt, as measured from
a fixed point in space, called the First Point of Aries i
Line of Nodes
Right Ascension of the Ascending Node ()
First Point of Aries () 63 63

18. ORBITAL ELEMENTS Argument of Perigee
Argument of Perigee is a measurement from a fixed point
in space to where perigee occurs in the orbit
It is measured in degrees
Perigee
Argument of Perigee: Is this angle, measured in degrees
You will be able to much easily see what Argument of Perigee is when using STK!!
Inclination
Apogee
Line of Nodes   64 64

19. ORBITAL ELEMENTS True Anomaly
True Anomaly is a measurement from a fixed point in space to
the actual satellite location in the orbit
It is measured in degrees
True Anomaly: Is this angle, measured in degrees
Direction of satellite motion
You will be able to much easily see what True Anomaly is when using STK!!
Fixed point in space 65 65

20. Ground Tracks Westward Regression
- Earth rotates east under a satellite => satellite
appears to walk west
- Earth rotates 360 degrees in 24 hours
(15 degrees per hour) 5 5

21. Ground Tracks Westward RegressionB A
-120
-90
-60
-30 30 60
A - time zero
B - after one orbit
C - after two orbits 6 6

22. Ground Tracks Eccentricity
Ground Track for Molnyia orbit
eccentricity = .7252 8 8

23. Ground tracks Inclination60 30
45N 30 60
45S
Inclination = 45 degrees
Eccentricity ~ 0 16 16

24. Ground tracks Argument of Perigee
Argument of Perigee ~ 90 degrees (red)
argument of perigee ~ 270 degrees (white) 18 18

25. PERTURBATIONS Definition Types
A disturbance in the regular motion of a celestial body
Types
Gravitational
Atmospheric Drag
Third Body Effects
Solar Wind/Radiation Effects
Electro-magnetic 23 23

26. PERTURBATIONS Gravitational
Ellipticity of the Earth causes gravity wells and hills
Stable points: 75E and 105W
-- Himalayas and Rocky Mountains
Unstable points: 165E and 5W
-- Marshall Islands and Portugal
Drives the requirement for station keeping 29 29

27. PERTURBATIONS Atmospheric Drag
Friction caused by impact of satellite with particles in the Earth’s atmosphere
Reduces satellite’s energy
Changes the size (semi-major axis) and shape (eccentricity) 30 30

28. PERTURBATIONS Atmospheric Drag
Perigee remains same, Apogee decreases 31 31

29. PERTURBATIONS Electro-Magnetic
Interaction between the Earth’s magnetic field and the satellite’s electro-magnetic field results in magnetic drag 34 34

30. TYPES OF ORBITS - Uses of Satellites
Daily Uses of Satellites
Big Picture
Affects of Altitude 4 4

31. TYPES OF ORBITS - Uses of Satellites
Global Positioning System!! 5 5

32. TYPES OF ORBITS - Uses of Satellites
A Remote Sensing Satellite’s view of Earthquake Damage in Haiti 6 6

33. PLACING SATELLITES IN ORBIT
Boosters
DELTA IV 5 5

34. PLACING SATELLITES IN ORBIT
Boosters
ATLAS V 6 6

35. PLACING SATELLITES IN ORBIT
Boosters
Space –X!
- Falcon 9 Rocket
- Dragon Spacecraft 6 6

36. PLACING SATELLITES IN ORBIT
Spacecraft
NASA’s
- Orion
Spacecraft! 6 6

37. PLACING SATELLITES IN ORBIT
Boosters
NASA’s
New Space Launch System!
Mission to Mars?? 6 6

38. ORBITAL MECHANICS Classroom Presentations using Powerpoint
Demonstrate with STK
Let’s Demo !!
The world of Space Operations awaits you!! 5 5

39. Civil Air Patrol Please complete the 2015 survey online for a chance
to have your conference
registration fee refunded
Citizens Serving Communities 39