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« on: February 26, 2011, 04:17:45 PM »
Well, it seems that another foam strike incident was barely avoided during the last shuttle launch. Fortunately, the pieces came off at a high enough altitude where they are less likely to damage the tiles.(?) But that tank had problems from the time that they filled it and emptied it the first time. The insulation is exposed to such drastic temperature differences that it can not adhere properly to the tank. Also, the tanks have cracked on a couple of occasions, which was only detected by examining the foam.
If the U. S. does go forward with some kind of launch vehicle which is man-rated, the only thing that we will be able to orbit will be a small capsule, holding at most 5 people, and more likely 4. With one person being the pilot, that means that only three or four people will be rotated on each launch. To support a large station, or allow more frequent crew rotations, we will have to launch quite often. The shuttle can carry 7 people, in addition to the pilot and commander. If the cargo bay were devoted to passenger accommodations, the shuttle could probably carry 20 passengers in comfort.
We don't seem to have any problem launching rockets which just carry cargo, it is the manned ones that give us so much grief. That is because the thing has to work absolutely perfectly. When you are going straight up, you can't pull over to check under the hood! Which brings me to one of my pet rants: Taking off straight up is no longer necessary, if we go about it right. Up until the last few years, we could not build an aircraft big enough to carry a spacecraft capable of reaching orbit, which will probably weigh around 1.5 million pounds. But the advances in carbon composite construction, as well as developments in engine technology, have brought us to the point where we could conceivably build a huge wing which could lift a spaceplane to a high enough altitude that it could use all of its propellant to gain speed, instead of fighting gravity.
Many people do not realize that getting into orbit is not a process of going straight up, but of going FAST in regards to the surface of the planet. The only reason that rockets launch straight up is so that they can get out of the thickest part of the atmosphere as quickly as possible, because they cannot use their power to go fast until they are above most of the atmosphere. By the time one reaches 50,000 feet, over three-quarters of the atmosphere is below you, so you can go fast. And the faster you go, the higher you climb, as the velocity throws you away from the center of the planet.
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