The USSR's discovery of life on Mars, using low temperature Water/Hydrogen Peroxide as a solvent, made 1997 one of the pivotal years not just for the sciences but for human history in general. The resiliency of life even on the dying Mars propelled hopes for widespread life in the universe and further invigorated the space programs of the world.
What if this discovery were delayed? The Aelita program essentially stumbled upon the Lobachevsky Cave Complex's opening on the edge of the Argyre Basin after a landslide exposed it, and the manned Mars mission almost never got off the ground in the first place.