Astronaut Stephen Robinson is to attempt to fix the heat shield of the Discovery Space Shuttle today by first trying to pull out two ceramic strips that are sticking out from between the heat shield tiles and if that fails he will try to cut the strips off.
I am reminded of a little tile accident that occurred when I was in my final year in college. The house we had rented was badly built and one of the flaws was the fact that the splash back tiles over the cooker had come loose from the steam and were bulging out one day when we got back to the house. I had decided to fix the problem later that evening after I had some food. I warned all the others in the house at the time not to touch the tiles. However as I was sitting there another housemate came into the kitchen. She walked straight over to the tiles and said, "oh look at this". Before she could be warned she tried to push the bulge back in. Like a set of dominos half the tiles on the wall fell onto the counter. Luckily the tiles didn't break and I was able to put them back on the wall with proper tile cement and grouting.
Hopefully something similar will not happen when the astronaut tugs on the strips. It would be the end of Discovery if half her heat shield tiles broke loose and floated away and the crew would be stranded on the International Space Station until another shuttle could be sent to collect them. However it would be very very funny to watch.