The Space Shuttle lifting off and headed for the nether regions of space, although a majestic sight, is one of the most grueling and critical parts of the space mission because of all the raw power and energy expended by the craft.
NASA astronaut John Mace Grunsfeld knows the experience well. He’s flown on five Shuttle missions between 1995 and 2009, including a 16-day mission of ultraviolet observations with the Astro observatory, in addition to the fifth mission to the Russian Mir space station, and three servicing missions to the Hubble Space Telescope (including the final Hubble servicing mission in 2009). John has logged more than 58 days in space, and 58 hours and 30 minutes of extravehicular activity in eight space walks.
“I absolutely love spaceflight,” says John, “but there is no escaping the fact that getting to space is physically demanding on both machine and astronaut.” He adds that the eight-and-a-half minute period between liftoff and getting into Earth’s orbit is particularly critical.
John explains what this thrilling, but important, part of a Space Shuttle mission is like:
“We train upwards to a year to be an astronaut and a lot of people are involved in getting us and the craft ready, so when launch day arrives, a lot of things are on the line.
The Shuttle crew, wearing space suits weighing about 85 pounds, climbs into the Shuttle two hours before liftoff. The ground crew then closes the door. We are lying on our backs in our seats, and our pre-flight checks begin. The Shuttle, loaded with 4.5 million pounds of explosive rocket fuel, is ready to go.
Everyone on the launch pad and in the immediate vicinity begins to get as far away as possible from the craft. The countdown begins. All this time we are flipping switches and thinking about our training and the jobs we have to do.
But it’s not until you get to the last 10 seconds in the countdown that you begin to think of
what’s going to happen.
The liftoff occurs…The Shuttle’s acceleration is so great, the force is so tremendous – the raw acceleration is so hard to describe! At the very least, you know you are going somewhere, and that somewhere is up, very quickly. In the few seconds it takes us to clear the launch pad’s 200 foot tower, we are already going about 100 mph. With such acceleration at this point we have difficulty moving any part of our body because of the extra G-force we are experiencing at this point.
Two-and-a-half minutes after liftoff the solid rocket motor, as it is designed to do, separates from the Space Shuttle, leaving the craft to be powered solely by the main engines. At about six minutes into the flight we feel like we weigh 700 pounds as the tremendous acceleration continues to push us, pin us, back in our seats.
Eight-and-a-half minutes following liftoff, we are outside the earth’s atmosphere that’s when the engines turn off, and instantaneously we go from feeling like we weigh 700 pounds to being totally weightless. The transition is so sudden, it almost makes you giddy. At this point the Shuttle is essentially in orbit, and that’s when you can really feel the joy of having survived the launch.
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