Excitement before launch of overhauled space shuttle
Shortly before 10 p.m. CEST on Wednesday, the first launch of a space shuttle after the Columbia crash two and a half years ago is to take place. The team of seven astronauts, led by Commander Eileen Collins, will primarily put to the test the vastly increased security measures that have been implemented since the tragic end of the last mission.
The initially feared weather-related problems for the start have now been resolved, according to NASA meteorologists: The countdown has been running unhindered since hurricane "Dennis" weakened in western Florida. At most, isolated summer thunderstorms are predicted for the launch date, which should not pose a problem for the space shuttle. Those responsible now estimate the probability of a scheduled start at over 70 percent. If everything goes as hoped, the eastbound shuttle will be visible in the night sky over Germany from 10:10 p.m. for almost five minutes.
Nasa believes that it has gotten a grip on the danger points of a technical nature, which led to the loss of the Columbia and the death of seven astronauts two and a half years ago, with different approaches. The catastrophe occurred when a foam part of the tank insulation weighing almost one kilogram came loose during take-off and crashed into the heat shield insulation of the wing. The resulting leak in the shield was neither recognizable during the stay in space, nor could it have been repaired with on-board equipment. When re-entering the atmosphere, hot gas flowed in at the damaged area and destroyed the shuttle at an altitude of 70 kilometers.
In order to prevent a similar scenario with the current launch, the American space agency, in addition to minor modifications to the ferry, is relying on significantly increased monitoring of the launch process, various approaches for any space repair work and a revised evacuation concept for the crew in the event that re-entry of the shuttle is considered too dangerous.
Complete start monitoring
The actual problem, that parts of the material can always rain down on the fragile protective skin when the shuttle is launched, cannot be avoided due to the necessary insulation of the main tank. After all, the fragments should now be smaller overall than on previous missions, the Nasa engineers hope after their conversions. Analyzes of earlier launches had shown that catastrophic leaks had apparently not occurred before the Columbia accident only through fortunate circumstances. At the current launch of the Discovery, a total of 107 cameras on the ground and two aircraft are to monitor the launch phase and register potential leaking collisions with insulating material raining down. In earth orbit, a camera-equipped robotic arm can then seamlessly check all areas of the space shuttle for any signs of a collision. However, some analysts now fear that the meticulous monitoring could lead to excessive measures being taken even for scratches that are actually harmless.
Orbital Repairs
In the event of damage, the astronauts can now react with five experimental repair kits - their effectiveness has not yet been tested in space. The astronauts of the Discovery should now make up for this under operating conditions in the field, not only in the case of actual damage. The Nasa developers hope to be able to manually close cracks of up to ten centimeters in the hardened carbon covers on the shuttle nose and wing tips, which are particularly at risk, with a ceramic-polymer or carbon-silicone paste, for example. The heat shield tiles on the underside of the space shuttle are more difficult to repair, according to NASA. While shallow scratches could possibly be successfully painted over with a gray vulcanizing compound, deeper damage should be filled with some kind of insulating material and stabilized with a cover that is screwed on.
Evacuation to Space Station
If the damage found is judged to be too serious, the Discovery crew can be evacuated to the International Space Station. The shuttle should then be brought to a controlled crash. The station, on which a Russian and an American astronaut are currently staying, would then have to be evacuated within a good 50 days. The second of three still existing space shuttles is ready for this - the third, Endeavor, is currently being overhauled and is not operational.
Consequences of Failure
Another shuttle failure would mean the end not only of NASA's space shuttle program, but likely also of the International Space Station, the Hubble Telescope and the European research laboratory Columbus, all of which depend on missions currently planned. More than twenty flights would have to start to the ISS alone to keep the program alive, but only 15 are currently planned in the Nasa budget, even in the event that the current mission runs smoothly and fulfills its mission goals. In addition to the repair experiments, this also includes the assembly of an ISS stabilization unit, stocking up on supplies on board the space station and a garbage disposal service.
