2009-05-20 16:33 BJT

Larger rockets are normally launched from a launch pad which serves as stable support until a few seconds after ignition. Due to their high exhaust velocity (Mach ~10+), big rockets are particularly useful when very high speeds are required, such as orbital speed (Mach 25+).

Atlantis during launch phase, showing both solid (SRBs) and liquid fueled (Shuttle) rocket engines in use.
Atlantis during launch phase, showing both solid (SRBs) and
liquid fueled (Shuttle) rocket engines in use.

Spacecraft delivered into orbital trajectories become artificial satellites which are used for many commercial purposes. Indeed, rockets remain the only way to launch spacecraft into orbit and beyond.

They are also used to rapidly accelerate spacecraft when they change orbits or de-orbit for landing. Also, a rocket may be used to soften a hard parachute landing immediately before touchdown

Editor: Yang Jie | Source: