For a linear autonomous system, if a state is reachable from zero in s
ome time duration, then it is reachable within any positive time durat
ion. However, the norm of the control that steers the zero state to th
e given reachable state increases as the available control time shrink
s. This paper gives the asymptotics of minimal L-p-norm controls as th
e time duration goes to zero; there are also some further remarks for
other related norms.