Summer Afternoon Space Shuttle Launches
It's launch day for STS-127. Again. It was launch day on Monday, and it was launch day on Sunday before that, but both launches were scrubbed for weather. Lightning, high winds, clouds, and precipitation all have to be considered before a "go" is given for the launch. Since Space Shuttle launches are manned, the weather at the backup landing facilities must also be considered in the event of a failure that prevents the orbiter from reaching orbit. I found this 16-page document which seems to lay out all of the weather-specific requirements for launch. Feel free to peruse it.
So why would mission managers and rocket scientists, presumably some of the smartest people on this planet, decide to set a launch window right smack dab in the middle of a thunderstorm-infested summer afternoon? Sounds like a pretty simple decision, right?
Not so much.
See, there's no weather in space. The targets that we are trying to hit in space, such as the International Space Station in STS-127, don't exactly care what the weather is like in Florida when they are passing overhead. Consider a hunter trying to shoot a duck while it is flying. The hunter has to lead the flying duck so that his bullet meets the duck mid-flight. If that duck's flight path takes it behind a tree, the hunter won't have a clear shot and may miss the target. The hunter only has a narrow "window" of opportunity in which to hit his target.
When the NASA engineers select the time for each mission's launch window, it has very little, if anything, to do with the general weather pattern at the launch facility, and everything to do with hitting the target in space. If weather gets in the way, they can't just wait until it clears. Instead, they have to wait until the next time the target is in the appropriate position relative to the launch site.
It's all about tragectory, not Florida's summer afternoon climate.
So why would mission managers and rocket scientists, presumably some of the smartest people on this planet, decide to set a launch window right smack dab in the middle of a thunderstorm-infested summer afternoon? Sounds like a pretty simple decision, right?
Not so much.
See, there's no weather in space. The targets that we are trying to hit in space, such as the International Space Station in STS-127, don't exactly care what the weather is like in Florida when they are passing overhead. Consider a hunter trying to shoot a duck while it is flying. The hunter has to lead the flying duck so that his bullet meets the duck mid-flight. If that duck's flight path takes it behind a tree, the hunter won't have a clear shot and may miss the target. The hunter only has a narrow "window" of opportunity in which to hit his target.
When the NASA engineers select the time for each mission's launch window, it has very little, if anything, to do with the general weather pattern at the launch facility, and everything to do with hitting the target in space. If weather gets in the way, they can't just wait until it clears. Instead, they have to wait until the next time the target is in the appropriate position relative to the launch site.
It's all about tragectory, not Florida's summer afternoon climate.
posted by DaveFlys at
12:18 PM
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