1. Morehead State University
Understanding Orbits
Chapter 4-9
Morehead State University
Morehead, KY
Prof. Bob Twiggs
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2. SSE-120
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3. Understanding Orbits
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4. Understanding Orbits
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5. Understanding Orbits
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6. Understanding Orbits
Eccentricity
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9. Understanding Orbits
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10. Understanding Orbits
North Pole to the South Pole (the shortest diameter) is approximately 12,714 km.
The equatorial diameter (the longest diameter) is approximately 12,756 km.
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11. What about gravitational pull on the satellite in the orbit?
Understanding Orbits
What about gravitational pull on the satellite in the orbit?
Would it be uniform all around the orbit?
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15. Fc v Fg Understanding Orbits
What determines the velocity of spacecraft in a circular orbit? Fc
Altitude: given v
Velocity of spacecraft
Vcir = r-1/2 km/sec
r - is from center of the earth – 6378 km
Orbit
Vesc = r-1/2 km/sec Fg
Orbit Period
Circumference = 2pr
Time to orbit = distance/velocity
Orbit Period = Time to orbit (minutes)
What about gravitational pull on the satellite in the orbit?
Would it be uniform all around the orbit?
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16. What is ISS altitude? Understanding Orbits
Spacecraft Orbital Velocity and Orbit Period -2
What is ISS altitude?
= 17,142 mi/hour
h = (150) (1.852) = 278 km
LEO
convert
km/s mi/hour
X (km/s) x 60s/m x 60m/hour x (1/1.6) mi/km = X (km/s) x 2250 mi/hour
V = (7.739 km/s) x mi/hour
= 17,142 mi/hour
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17. Velocity of spacecraft
Understanding Orbits
Altitude: given
Velocity of spacecraft
Vcir = r-1/2 km/sec
r - is from center of the earth – 6378 km
Vesc = r-1/2 km/sec
Orbit Period
Circumference = 2pr
Time to orbit = distance/velocity
Orbit Period = Time to orbit (minutes)
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23. Sun-synchronous LEO orbit
Understanding Orbits
Sun-synchronous LEO orbit
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24. Understanding Orbits
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25. Perturbation Orbital Velocity Orbit period Ascending node
Understanding Orbits
Perturbation
Orbital Velocity
Orbit period
Ascending node
Plane changes
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32. Morehead State University
Understanding Orbits
Morehead State University
Morehead, KY
Prof. Bob Twiggs
SSE-120