WASHINGTON (Reuters) -Elon Musk's SpaceX and United Launch Alliance are expected to each win a U.S. Space Force rocket launch contract on Friday worth billions of dollars to send some of the Pentagon's most sensitive satellites into space over the next several years, according to two people familiar with the procurement decision.

The Space Force's flagship National Security Space Launch procurement program, which is poised to assign roughly 50 missions through 2029 in incremental task orders, is expected to announce its selection decision on Friday, with SpaceX and ULA among the winners, the sources said.

Space Force's Space Systems Command office did not immediately respond to a request seeking comment.

(Reporting by Joey Roulette and Marisa Taylor; Editing by Leslie Adler and Franklin Pauil)