EEEN 567-Satellite Launching Study Guide

Satellite launching involves placing artificial satellites into specific orbits around Earth or other celestial bodies. This process requires careful planning of trajectories, orbital mechanics, and propulsion systems.

For electrical engineering students, understanding satellite launching is crucial as it involves:

• Power systems for launch vehicles and satellites
• Communication systems for tracking and control
• Electronic guidance and navigation systems
• Remote sensing and data transmission

A parking orbit is a temporary orbit used by a spacecraft during a portion of its mission. It serves as a "waiting area" before the spacecraft moves to its final orbit or trajectory.

Characteristics of Parking Orbits

• Altitude: Typically low Earth orbit (LEO) between 160-2,000 km
• Orbital Period: About 90 minutes for LEO parking orbits
• Purpose: To verify spacecraft systems, wait for optimal launch windows, or prepare for orbital maneuvers

Electrical Engineering Considerations

During the parking orbit phase, electrical systems are thoroughly tested:

• Power generation and storage systems
• Communication subsystems
• Attitude control systems
• Thermal management systems

Transfer orbits are intermediate trajectories used to move a spacecraft from one orbit to another. The most common is the Hohmann transfer orbit, which is energy-efficient for changing between circular orbits.

Hohmann Transfer Orbit

A Hohmann transfer uses two engine burns:

1. First burn: Transfers spacecraft from initial circular orbit to elliptical transfer orbit
2. Second burn: Circularizes the orbit at the target altitude

Bi-Elliptic Transfer

This transfer uses three burns and can be more efficient than Hohmann for certain orbital changes, especially when the ratio of final to initial orbit radius is large.

Electrical Engineering Applications

• Precise timing of propulsion system activation
• Navigation and guidance during orbital changes
• Power management during high-energy maneuvers
• Communication during critical orbital transitions

Lunar missions involve sending spacecraft to orbit or land on the Moon. These missions require complex orbital mechanics and precise navigation.

Lunar Transfer Trajectories

There are several approaches to reach the Moon:

• Direct Transfer: A single burn places the spacecraft on a trajectory to the Moon
• Phasing Orbits: Using Earth orbits to time the lunar encounter
• Weak Stability Boundary: Low-energy transfers that take longer but require less fuel

Lunar Orbit Insertion

Once the spacecraft reaches the Moon, it must perform a lunar orbit insertion (LOI) burn to be captured by the Moon's gravity and enter lunar orbit.

Electrical Systems in Lunar Missions

• Radiation-hardened electronics for space environment
• Solar power systems optimized for lunar conditions
• Communication systems for Earth-Moon distance
• Navigation systems for precise landing

Various methods are used to launch satellites into space, each with advantages and limitations.