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

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

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

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

PHYSICAL LAWS Is this orbit possible? 12 12

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

PERTURBATIONS Atmospheric Drag Perigee remains same, Apogee decreases 31 31

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

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

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

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

PLACING SATELLITES IN ORBIT Boosters DELTA IV 5 5

PLACING SATELLITES IN ORBIT Boosters ATLAS V 6 6

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

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

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

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

Civil Air Patrol Please complete the 2015 survey online for a chance to have your conference registration fee refunded https://www.surveymonkey.com/r/15NatCon Citizens Serving Communities 39