Given an initial configuration of satellites specified for time 
,
it is possible to start the
satellite configuration from any arbitrary point in time through the use of the
time_advance_ parameter (this is really only useful for LEO
simulations). During the simulation run, this will set the position of
the object to the position at time
Scheduler::instance().clock + time_advance_ seconds.
Position/Sat set time_advance_ 0; # seconds