No! One can't speak of a social mission in that sense!

Heidegger (1969) critiques Marx's contention that: "Philosophers have only interpreted the world differently; what matters is to change it."

http://www.youtube.com/watch?v=jQsQOqa0UVc

(Translation is in the info box to the side of the video.)

This point came up in the seminar and Heidegger's response may be of interest.