如何从python调用程序而不等待它返回

is there a way to call a program from python without waiting for it to return? i created a script which copies a program to a directory and runs that program. but when i call the program from python, the python script does not exit until the program i launched exits. i have tried os.system and Popen. is there another way to do this?is there a way to call a program from python wi