The Space Shuttle hasn’t had the best track record of late. Right now, they are doing a visible inspection of the tiles that allow for proper re-entry, protecting the Shuttle from burn up when encountering the atmosphere. If you recall, these tiles fell off the wing of the Columbia when hit by foam on liftoff, ending in disaster.
When comparing the shuttle pictures to those 3 weeks prior to take off, they found white spots on the wing. Presumably in a similar place to where the aforementioned tile problem occurred. Upon closer inspection, it turns out to be bird poop. Having fished next to the shuttle recently, I can verify that there are many birds in this area as it is millions of acres of undisturbed land purchased in the 60’s.
So, the bird poop can survive vicious Florida thunderstorms that delayed the launch numerous times, thrust that can launch the bulk of the shuttle from zero to 17,500 MPH in minutes and make it into space. Maybe they should use bird poop instead of tiles to cover the Shuttle.