Wednesday, November 07, 2007

Ready Houston, here we come!

Discovery is getting ready for re-entry burn. Weather is clear enough at KSC to land. I will be live blogging as much as I can.

Discovery will be coming over British Columbia, Flying over the heartland of America! And landing at KSC.

-- 9:00 AM PST Good Burn No trim required

-- 9:30 AM PST Discovery is near atmosphere re-entry. It's about a half hour to touch down at the cape.
Discovery is beginning to encounter the effects of the atmosphere, a point called "entry interface." Now flying at about 16,000 miles per hour, the orbiter is angled upward with wings level. The shuttle is set to touch down in just over 30 minutes.
HT from NASA Landing Blog here.

-- 9:36 AM PST Discovery is closing in on the coast of Canada. They will be the first to hear the double sonic booms.
What causes the booms?
Air pressure. As the shuttle cuts through the atmosphere flying faster than the speed of sound, air molecules get pushed aisde (like water around a fast-moving boat). The air molecules form a shock wave around the nose and the tail of an aircraft. The rapidly increasing air pressure can be heard as a loud boom.

Why two sonic booms?
The space shuttle is big for a supersonic aircraft. A typical aircraft capable of this kind of speed would be a fighter jet, something about 50 feet or so long. For those small fighters, the shock waves generated at the nose and the tail of the aircraft happen less than one-tenth of a second apart. On the ground, people would hear what sounds like one boom. The orbiter is 122 feet long. The time between the nose and tail shock waves is half of a second, just long enough for us to hear both of the booms.
HT from Flame Trench here
-- 9:40 AM PST Right over Montana. 22 minutes to Florida coast!
-- 9:42 AM PST Right over Nebraska with 18 minutes to go to landing.
-- 9:44 AM PST Right over Kansas TODO! 16 minutes to go.
-- 9:46 AM PST Right over Missuiori with 14 minutes to go.
-- 9:47 AM PST Right over Mississippi and Alabama! 13 minutes to go.
-- 9:49 AM PST Right over Alabama toward Georgia. Florida here we come! 12 Minutes.
-- 9:50 AM PST Merrius Island tracking station has Discovery on site. Less then 11 minutes to go. GPS and tracking a-go.
-- 10:01 AM PST TOUCH DOWN! Great landing! Photos of banking and landing were fantastic! Good Job Pam!

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