A satellite is an object in orbit around a celestial body. There are different types of orbits depending on factors like altitude and inclination. Low Earth orbit is commonly used for Earth observation, crewed spaceflight, and spy satellites due to being easy to reach. However, it has disadvantages like a small field of view and fast orbital decay. Polar and sun synchronous orbits are specifically designed for Earth observation as they maintain the same relationship with the sun, allowing comparable images over time. The future may involve large constellations of small satellites for various applications.

1. Satellites for
Dummies

2. What is a ?
Some Stuff
(the satellite)
Orbit
A satellite is
some stuff in
an orbit.
So what's an
orbit than?

3. Isaac Newton
“In physics, an
orbit is the
gravitationally
curved
trajectory of
an object.”
FZP = FG
v = √(G*M/r)
V1 = 7,9 km/s
High → Slow
Low → Fast

4. Orbital Elements

5. Earth Observation Orbits

6. Low Earth Orbit ( LEO ) - That’s us!
● Altitude up to 2000 km
● One orbit takes roundabout 100 min
Usage:
● Earth Observation (Sentinel 1&2, …)
● Crewed Spaceflight (ISS, MIR, …)
● Hubble
● Spy satellites
Advantage
● Easy to reach
● High bandwidth and low
communication latency
● Close to Earth
Disadvantage
● Small momentaryfield of view
● Fast orbital decay
● Space debris

7. Polar & Sun Synchronous Orbit - Orbits made for EO
- takes more energy ( ΔV ) to reach
+ always maintains the same relationship with the Sun
+ images of differenttime stamps get comparable
Sentinel 2

8. Satellite
BusMission System
Payload Communication Power Supply
Attitude and orbit
control system
Data handling
Thermal control
system
Satellite Subsystems

9. Sentinel
Flock ( Planet)

10. The Future: Huge constellations of
small satellites