  We present spectra of the optical transient of GRB021004 obtained with the
Hobby-Eberly telescope starting 15.48, 20.31 hours, and 4.84 days after the
burst and a spectrum obtained with the H. J. Smith 2.7 m Telescope starting
14.31 hours after the burst. GRB021004 is the first afterglow whose spectrum is
dominated by absorption lines from high ionization species with multiple
velocity components separated by up to 3000 km/s. We argue that these lines are
likely to come from shells around a massive progenitor star. The high
velocities and high ionizations arise from a combination of acceleration and
flash-ionization by the burst photons and the wind velocity and steady
ionization by the progenitor. We also analyze the broad-band spectrum and the
light curve. We distinguish six components along the line of sight: (1) The
z~2.293 absorption lines arise from the wind of a massive star. For a mass loss
rate of ~6 x 10^{-5} solar masses per year, this component also provides the
external medium to create the afterglow light. (2) A second shell produces
absorption lines with a relative velocity of 560 km/s, and this is associated
with the shell created by the fast massive star wind blowing a bubble in the
preceding slow wind at a radial distance of order 10 pc. (3) More distant
clouds within the host galaxy lie between 30-2500 pc, where they have been
ionized by the burst. (4-6) The massive star wind has clumps with radii and
over-densities of 0.022, 0.063, and 0.12 parsecs and 50%, 10%, and 10%
respectively. The immediate progenitor of the burster could either be a WC-type
Wolf-Rayet star or a highly evolved star whose original mass was just too small
for it to become a WN-type Wolf-Rayet star.
