  Based on the VLBI Space Observatory Programme (VSOP) observations at 1.6 and
5 GHz, we find that the luminous high-redshift (z=3.215) quasar PKS 1402+044
(J1405+0415) has a pronounced 'core--jet' structure. The jet shows a steeper
spectral index and lower brightness temperature with the increase of the
distance from the core. The variation of brightness temperature is basically
consistent with the shock-in-jet model. Assuming that the jet is collimated by
the ambient magnetic field, we estimate the mass of the central object as ~10^9
M_sun. The upper limit of the jet proper motion of PKS 1402+044 is 0.03 mas/yr
(~3c) in the east-west direction.

Astrophysics