T-minus 15 seconds and the sound suppression water system has been activated. We have a go for main change start. Three engines up and ready. Three, two, one. Z-Roll, booster ignition. And lift off of discovery. Blazing a trail to scientific discoveries aboard space station. I'm covering your roll program. By your roll discovery. This is the decision to control the system's visual discovery. It's rolling into a head-stamp position, putting it on force, for 21.6 degree, 136 by 36 statute-line orbit, and eventually the International Space Station. Discovery's three liquid fuel main engines are now rattling down to reduce stress. On the shuttle is it travels through the area of maximum dynamic pressure. Discovery is already at an altitude of 4.7 miles or 26,500 feet. Traveling. Discovery, go at throttle up. Roger, go at throttle up. Traveling 1,000 miles per hour. Discovery's engines are now throttle back up and performing at full capability. At lift off the shuttle weighed more than 4.5 million pounds. And now, one minute and 27 seconds into the flight, the main engines and solid rocket boosters have reduced that weight by about half. Solid rocket boosters alone are burning 11,000 pounds of propellant per second. And the external tank is now 3,000 pounds louder than when it began. Discovery's now 21 miles away from its launch pad and 22 miles an altitude, traveling 2700 miles per hour. All three main engines are working just as expected. The three fuel cells are generating power and three auxiliary power units are producing pressure. In short, everything performing well. Two minutes and seven seconds into the STS-131 mission. The booster officer in the mission control center has confirmed solid rocket booster separation. Our system's continuing to function well.