Getting to Mars means stopping, landing

The Challenger and Columbia space shuttle disasters were perhaps two of the most prominent reminders of how crucial it is that everything work just right for a spacecraft to travel to space and successfully return back to Earth. Whether it was the failure of the seal used to stop hot gases from seeping through, or a piece of foam insulation that damaged the thermal protection system, scientists and engineers must make thousands of predictions of all the things that could go wrong during flight.