  The power spectrum of M-theory cascade inflation is derived. It possesses
three distinctive signatures: a decisive power suppression at small scales,
oscillations around the scales that cross the horizon when the inflaton
potential jumps and stepwise decrease in the scalar spectral index. All three
properties result from features in the inflaton potential. Cascade inflation
realizes assisted inflation in heterotic M-theory and is driven by
non-perturbative interactions of N M5-branes. The features in the inflaton
potential are generated whenever two M5-branes collide with the boundaries. The
derived small-scale power suppression serves as a possible explanation for the
dearth of observed dwarf galaxies in the Milky Way halo. The oscillations,
furthermore, allow to directly probe M-theory by measurements of the spectral
index and to distinguish cascade inflation observationally from other string
inflation models.
