failing. and two -- >> looks like the hydraulic system on system two is only going to last another minute. you can expect to lose that. >> since they are practicing for worst case. >> looks like a leak in he yd system three now. >> houston, we simulated a problem and this shuttle must come home immediately. >> if you have never flown backward at mach 5, this is the time to to it. >> what is happening in the simulator today has never happened for real. >> felt like it was crashing around us. >> 12 years in training. in year two, year three we would feel the same waylike i don't know what is going on here. you do this day in and day out. >> shepard: and did dominica it for years. for these men and women, more than ten years each. and you are ready for whatever