Calculating Risk

Shuttle launch debris risk uncertain but ‘acceptable’, Spaceflight Now

“The uncertainties in each of those areas are significant,” he said. “There are all sorts of numbers that are floating around. We have nine different estimates for ice on tile from one ice location. … It is a very complex problem.”

NASA Confident on Managing Shuttle Ice Problem, NY Times

“The NASA managers declined to release numbers to quantify the risk ice posed by hitting different parts of a shuttle, saying such numbers would confuse the public unless all assumptions behind them were also explained and understood.”