We're scheduled to depart from the Kennedy Space Center at 7:55 p.m. this Friday (6:55 p.m. Central). Today's Q&A is about what it feels like to blast off.

Can you describe the launch into space?
-- Nate (Team Space Shuttle)

MAGNUS: It only takes about 8.5 minutes to get into our initial orbit, but it is an exciting 8.5 minutes. We get out to the launch pad several hours early so that there is time to get us in strapped down in our seats, and all of the final launch checks are completed. We basically lay there for about an hour to an hour and a half and time seems to move very slowly. Then, with 10 minutes to go before liftoff, things start moving very fast. We take control of the on-board systems and the shuttle computer starts the countdown to launch. At 6 seconds before liftoff, the shuttle's main engines light. When the main engines activate, you can feel the shuttle sway slightly on the pad (remember it is still bolted down at this point) and you feel some faint vibration and hear some white noise. At liftoff (T=0), the solid rocket boosters light, and at that exact moment some pyrotechnics blow the bolts holding the orbiter to the launch pad in half and the shuttle slowly lifts off of the launch pad. When the solid rocket boosters light you hear very loud noises and there is lots of vibration and you feel kind of a "kick in your seat" as the shuttle jolts off of the launch pad. It is a slow acceleration, not a quick one, and you can feel the increasing g-force through your chest as you lay there shaking and rattling in your seat. It is challenging to keep track of the small numbers on the computer screen while everything is bouncing around due to the vibration. In two minutes, we have used up the solid rocket boosters (6 million pounds of thrust) and with another loud bang of pyrotechnics going off, accompanied by a flash of light, you can see in the shuttle windows, the boosters separate from the vehicle and fall away. At this moment, the orbiter becomes relatively quiet and the vibrations are noticeably less. Finally, there is time to look out the windows and see the horizon drop away. But about a minute or so before main engine cut off, we go through a time period where we feel 3g's through our chests. This is the maximum g-force that we experience. It seems to last forever and it is hard to talk; you feel like there is a 200 lb gorilla sitting on your chest. The greatest thing is that right after you feel this very strong force holding you down in your seat, the main engines cut off and you are in orbit and immediately start floating in your seat, only held down by your seat belt. It is quite a contrast!