Newly re-elected New Orleans Mayor Ray Nagin has just signed himself up for what will probably be the hardest mayoral term of the near future. Honestly, the job of rebuilding seems so daunting it is difficult to reason where to start.After cleanup (read: bulldozing), I suppose the first thing to do is to make sure that this kind of structural failure won’t happen again. That means more than simply rebuilding the levees, but spending some of that $3 billion on research and engineering to improve the system.Generally, the problem with disasters of this magnitude is the very fact that they are so rare and therefore so difficult to foresee and plan ahead for. The lessons of September 11 and Katrina pushed us to take a long hard look at the safety of our airlines and of New Orleans’s levee system. Great: it’s unlikely either will give us problems in the future the same way they did in the past. But that is not enough. It still remains that the next national disaster will occur somewhere else and by some other means, and that is the lesson to be learned here. We need to approach nature’s ability to find and exploit our infrastructural weaknesses. We need to find them and we need to fix them.