Reliability model of tracking

telemetry and command (TT&C) and communication task was constructed based on task arc division.According to time sequence of TT&C and communication resources

and the resources taking part in task and task success criterion

the TT&C and communication task can be divided into several successive task arcs.General task arc and idle task arc were defined

and their reliability modeling methods were proposed by using Markov approach.Moreover

the modeling methods considering the preparation time after resource opening and the resource close time were proposed.In these cases

task arcs were re-divided

and each of them was modeled according to the corresponding methods discussed.The task reliability can be obtained by solving these task arc models one by one.Finally

examples with numerical results under several cases show efficiency of the modeling methods.