|MadSci Network: Biophysics|
During ascent the Shuttle accelerates from a standing start on the surface of the Earth (which is rotating at about 1.6 miles per second at Kennedy Space Center) to an orbital speed of about 5 miles per second in 8.5 to 9 minutes.
During this time the Space Shuttle Main Engines (SSMEs) are throttled so that the astronauts and the vehicle experience about three times the force of Earth's gravity (3 gs). In comparison, many roller coasters can have short durations of force equivalent to 4 to 5 gs and a fighter pilot risks blackout around 9 gs even with a G Suit. So during the ascent the engines exert a strong but fairly steady force upon the astronauts.
In addition to the engine exhaust forces, the sound from the engines imparts a large vibrational force upon the vehicle and the astronauts. A jet engine generates sound pressure levels between 120 and 160 dB. The Space Shuttle generates sound pressure levels around 215 db or 324 times as great as a jet engine. This is sufficient to actually cause damage to the Shuttle and launch pad which is why a sound suppression system was installed.
For extremely detailed information on the Shuttle operation, NASA publishes the checklists and mission information which include reams of information on the actual operation of the Shuttle.
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