There are more and less important things, you seem to be lumping them together. The space exploration is probably the most important thing for the future of our civilization unlike exploring Antarctica. The latter is certainly a noble thing to do as well, but not of the same magnitude of importance. Every tragedy is sad, but plain tragic traffic accidents have much less impact on grander things than a tragedy of truly cosmic proportions such as the one that happened over Texas today. To me this a tragedy of our civilization that has been trying to conquer the space and now is paying a heavy toll for that once again. It is more than just an American tragedy. 9/11 could be considered an American tragedy to a greater extent than this one.