CHAPTER 2
"7...6...main engine start."
The three liquid-fueled engines ignite and there's a deafening noise in the cockpit.  A growling, wrenching vibration shakes us.  I have to force myself to keep watching the instruments.  It's like trying to read a book on a theme park ride.  The noise and vibration and the thrill and fear makes it impossible to concentrate.
"...5....4....3...."
The countdown continues while Atlantis' computers check that the liquid-fueled engines are working okay.  The three liquid-fueled engines are started early because they can be turned off if something is wrong, like a car engine can be turned off.   But the solid-fueled boosters on the sides of the shuttle are like 4th of July bottle rockets.  Once they're started, they cannot be turned off.  Only at the very last moment, when the countdown reaches zero, will they be ignited.
"....2....1...Liftoff!"
The solid-fueled rocket boosters start, the threaded nuts holding them to the pad are exploded into pieces and the giant machine blasts from the launch pad.  The noise is incredible!  Only because I'm wearing a helmet can I hear Mission Control talking to us.  The engines are so powerful that I'm shoved backwards into my seat by a force one and half times as strong as gravity.  It makes my body and everything I'm wearing seem to weigh an extra hundred pounds.
"Roll program!"  The Commander shouts into his microphone.  Atlantis is rolling to the right to aim its trajectory over the ocean.
"Throttle down!"  The Commander sees that our engines are automatically reducing power.  Atlantis is accelerating too fast and there's a danger that the thick atmosphere will tear her apart.  The computers prevent this from happening by commanding the engines to pull back their power. 
Shock waves form on the nose and wings and add to the shaking.  Atlantis is going through the sound barrier.  In just 40 seconds the huge engines and solid-fueled rocket boosters have pushed a 4 1/2 million pound machine straight up to the speed of sound!  Just imagine the incredible power needed to do that.    The rushing sound of supersonic air howls around the machine.  It's louder than any airplane you've ever heard.  The vibrations increase.  My eyes skip from instrument to instrument.  Is everything still okay?  Will all this shaking damage something?  Will our air leak out?  Will the engines quit?  Will they explode?  I worry about everything.  But the instruments tell me that Atlantis is "nominal", that everything is okay.
A cloud zooms into our windshield and disappears behind us. Once again, I can feel my body being squeezed backwards.  It's from the engines returning to full power.  We're above the thick atmosphere and don't have to worry any more about the air pressure tearing Atlantis apart.  The ride is smoothing out.
There's no line that you pass where all the air is below and space is above.  The atmosphere just keeps getting thinner and thinner and, as it does, the sky changes from blue to black.  It becomes as black as night.  Sirius, the brightest star, appears.  It's so strange to see a black sky and a bright star while sunlight is filling the cockpit, but that's what I see from the shuttle windows.
"PC less than fifty!"  The numbers are flashing on our computer and the Commander calls them to Mission Control.  The pressure inside the solid-fueled rocket motors has decreased to 50 pounds per square inch.  That means the boosters are nearly out of fuel. 
BANG!!!!  WHOOSH!!!!
A loud bang shakes the cockpit and a flash of yellow fire covers the windshield.
Has something exploded?!  Is there an emergency?!