Summary: While the official word from NASA is that Space Shuttle Discovery will launch No Earlier Than November 30th, the chances of the agency actually making that particular window are dwindling. The last launch attempt of Space Shuttle Discovery on mission STS-133 was scrubbed and the orbiter grounded November 5th, 2010. The reason the vehicle couldn’t launch was a leak in the Ground Umbilical Carrier Plate or GUCP which allows the flow of super cooler liquid hydrogen to enter the orange external tank. Basically, Discovery had a fuel leak. As engineers were working on a solution another issue cropped up: the orange external tank had a crack filled with ice. This is bad because if a large chunk of the foam falls off during ascent it can cripple the black Thermal Protective System or heat shield thats on the under side of the orbiter. NASA called off the launch until No Earlier than November 30th. While repairing the initial crack in the external tank NASA decided to cut away some of the foam to do an inspection. It was found that there were two additional 9 inch cracks in a flat attachment plate for an underlying stringer. To repair this NASA decided to attach a ‘doubler’ plate on top of the stringer to give it more strength and we should be good to go. But NASA wanted to be sure and decided to cut away more foam, just to take a peek. On Friday, November 12th engineers found a third crack on another stringer directly to the left of the previous crack. Then over the weekend a forth crack was found on yet another stringer. As we sit right now it looks like the GUP issue may be repaired, so Discovery shouldn’t have any more leaks. NASA managers would like to run some tanking tests to make sure that when the final countdown does start we won’t have to abort for yet another leak. However we still have the issue of the cracks in the external tank, 4 of them now. Engineers will work on adding doubling plates to repair the problem, but we’re only 13 days away from the opening of this launch window and that’s not a lot of time to carry out all the required work, verify and start the countdown. NASA does not need to launch on November 30th, they just can’t launch before then. The available window is open from the 30th until December 5th and they can schedule T0 for any day within that window, so long as the launch pad is in the proper position under the space station. So basically 1 shot per day. Once we hit December 6th there will be a restriction called a Beta Angle Cutout. What is a beta angle cutout? When the International Space Station is at a certain beta angle, usually over 60 degrees it will cause a beta angle cutout. This is because the percent of time that the shuttle spends in sunlight will cause solar power generation and thermal control problems due to the fact that they can’t maneuver the orbiter when it is docked to the space station. So they can’t move it in or out of the sun as needed. The shuttle could overheat, underheat, not get enough power, or generally do really bad things. The beta angle needs to be acceptable for the entire duration of the mission, not just the launch or docking. And on December 6th the beta angle is no longer acceptable for this mission. Lets say we miss this window and can’t make the final available launch day of December 5th. What then? Well Discovery would get pushed back to a No Earlier Than February 2011 launch date and that would certainly impact the final launch of Space Shuttle Endeavour on STS-134. Additionally we would no longer have a night launch and the window would probably open up again around 3:30pm Eastern Standard Time. While we all want to see one final night launch of Discovery, and how cool would that be, more than that we want this to be a safe and successful flight. So if it takes NASA a few more weeks to get the kinks worked out, then it takes a few more weeks. But we can still hope for a late November launch. And to pass the time,
