  There are many different phenomenological models describing the cosmological
dark energy and accelerating Universe by choosing adjustable functions. In this
paper we consider a specific model of scalar tachyon field which is derived
from the NSR string field theory and study its cosmological applications. We
find that in the effective field theory approximation the equation of state
parameter w<-1, i.e. one has a phantom Universe. It is shown that due to
nonlocal effects there is no quantum instability that the usual phantom models
suffer from. Moreover due to a flip effect of the potential the Universe does
not enter to a future singularity.
