  We study in perturbative QCD the helicity ampltiudes of the process
$\gamma^{*} p \to \rho p $ at large virtualities $Q$ of the photon
$\gamma^{*}$. We estimate all spin flip amplitudes taking into account an
important effect of the scale behaviour of the gluon density. The transition of
a transverse virtual photon to a longitudinal vector meson is not small at
typical HERA conditions. This helicity non-conserving amplitude leads by
interference to a measurable effect in the distribution of the angle between
the electron scattering and the meson production planes.
