CATO when used in context with rockets stands for Catastrophie At Take Off. This when the rocket motor fails at launch, usually exploding because of intense pressure. The rocket motor can ether split in half (as they usually do), or the top or bottom cap will blow of, whichever is the weakest point.

CATO can be caused by the following:

1. Propellant grain splits, producing too much pressure for the motor casing to handle, due to the increased surface area.
2. A small chuck of propellent breaks of and blocks the nozzle, causing pressure to build up and then explosion.
3. A defect in the casing, nozzle, or propellant.