1. Orbital Mechanics Basic Orbits Include:
Low Earth Orbit (LEO), including sun-synchronous
Medium Earth Orbit (MEO) Also called semi-synchronous
Geosynchronous Earth Orbit (GEO) including Geostationary.
Highly Elliptical Orbit (HEO) including Molniya
Spacecraft obey Kepler, not Bernoulli
Satellite manoeuvres require
Deliberate planning
Time
Fuel (limited)

2. Low-Earth Orbit (LEO) Altitude 160 – 2000 km
Show the satellite sweeping a different area every orbit, ideal for imagery.
Altitude 160 – 2000 km

3. LEO Orbit – 2D Ground Trace
This is where the fudge comes!
To maintain an orbit over the Poles we have to incline the orbit past the vertical due to a phenomenon known as Orbital Twist.
Key Point is that you can choose an orbital height whereby the satellite will cross the same point on the surface of the Earth every 12 hrs, once by day, once.
Mil App: ISR!

4. Sun-Synchronous Orbits
SunsychTerminator: Difficult (and boring) showing a video of a satellite going over the same location every 24 hours! This is a special case of a SunSych aligned with the Day/Night Terminator so is always in direct view of the sun. An advantage if you need to constantly generate power through solar panels.
Near-Polar, 97°-99° Inclination km

5. LEO Sun-Synchronous Orbit 2D Ground Trace
This is where the fudge comes!
To maintain an orbit over the Poles we have to incline the orbit past the vertical due to a phenomenon known as Orbital Twist.
Key Point is that you can choose an orbital height whereby the satellite will cross the same point on the surface of the Earth every 12 hrs, once by day, once.

6. Medium Earth Orbits (MEO) 2D Ground Trace
Not much to say about MEO. Sits between the Inner and Outer Van Allen Belts.
This type of orbit crosses the Equator 4x per day. So what?
Means with Grd Stns at or about the Equator you can update the satellites on a regular basis. V.useful for GPS. Will see later.
Also referred to as semi-synchronous. Reference only!
Period: 2 – 24hrs
Average = 12 hour period
Altitude: 2000 – km, Near Circular
Average 20,800 km

7. Geostationary
GEOSensor: Generic GEO orbit with a sensor showing almost semi-global coverage and tracks the same area constantly.

8. Highly Elliptical Orbits (HEO)
Apogee
High Altitude
Used to overcome the lack of coverage of the polar regions by GEO.
Perigee
Low Altitude

9. HEO
Actually the 'Michibiki' Japanese SatNav satellite in a HEO orbit. Like a Molinya with a long linger time over Japan

10. HEO 2D Ground Trace
Geostationary orbit v. advantageous in Direct Provision services. The grd segment can be set up and left pointing at the satellite. E.g Sky.
Cost though is in requirement to correct the satellite’s natural drift towards a geosynchronous orbit.
Geosynchronous negates this but requires an element of tracking of the satellite by the user segment on the grd.
Period equal to a Sidereal day 23 hrs, 56 mins, 4 secs. 24 hour period
Key Point: You can only achieve a Geo orbit by having the satellite in the Earth’s Equatorial plane, and at 36,200km. (Diffraction Limit of Optics)
Good Slide Link to HEO: You can see that at Geo it is diff to hold the Poles and the Satellite in view. We will look at a way to overcome this soon.

11. Orbital Example – Earth Fixed
Shows GEO MEO LEO HEO centered on the earth. All are generic except the HEO is a 'Molinya' orbit. It aways lingers over the same point over the ground at its apogee. Russia exploits this type of orbit as GEO signals are weak at high altitudes.