Table of Contents

Phase 1 - Liftoff

Teacher Backgrounder

Launching Rockets

There are two types of launching vehicles: Expendable Launch Vehicles and Reusable Launch Vehicles.

Expendable Launch Vehicles, or ELV's, are vehicles designed to propel a payload into space. They are also commonly known as rockets. A payload is a load carried by a spacecraft consisting of crew, instruments, and equipment necessary for the purpose of the flight. The payload can be weather or remote observation satellites or other types of space hardware.

An ELV consists of many rocket stages. After launch, each rocket stage burns propellant and is jettisoned from the vehicle back to Earth. Examples of expendable launch vehicles include the Russian Soyuz and Proton rockets and the European Ariane rocket series.

Reusable Launch Vehicles, or RLV's, are vehicles that are re-used for multiple missions. Over time the costs of reusing the launch vehicle are reduced. The most famous example of a RLV is the Space Shuttle.

The Count Down Procedure

The final countdown before a launch takes about three days to complete. During this time, detailed checks are made, fuel is loaded and the crew boards the spacecraft. If a problem is spotted that cannot be fixed by the scheduled time for liftoff, the mission is postponed.

Click here to learn more about the countdown procedure.

The Liftoff Procedure

An altitude of 185 kilometres is required to orbit the earth. To get to this altitude, the shuttle must accelerate from zero to about 29,000 kilometres per hour (18,000 miles per hour) in eight and a half minutes. The shuttle's three engines and two rockets provide the power to do this. To keep the shuttle on course, corrections are made by the shuttle's onboard computer.

Launch Windows

The range of time during which a shuttle can launch and eventually meet up with its intended destination is called the launch window.

Triangulation

Triangulation is the process of locating a position using triangles. Spacecraft use triangulation to locate their position in space, based on information provided by ground-based and other sensors.

Sensors

A sensor is a device that receives and responds to a signal.

To locate and track spacecraft, sensors on Earth provide information which is compared with information collected from aircraft or satellite sensors. This data is used to identify the spacecraft's location and to make any necessary corrections.

On spacecraft launches from Florida, sensors located along the eastern coast and in Bermuda are used to track the location of the spacecraft.

Orbit

An orbit is the path of an object, typically called a satellite, as it moves around a second object or point. For example, the Moon is a satellite of the Earth and the Earth is a satellite of the Sun.