There's a new space race afoot -- and the International Space Station is just one part of it. Photo: Wikimedia Commons.

"Recent events in the Ukraine and our dependency on the Russians for transportation to the space station [make it] even more important to reignite our space program."

So argued Gene Grush, former head of the propulsion and power group at NASA's Johnson Space Center, in a series of articles published by Fox News earlier this year. But why is it so "important" that the U.S. "reignite" its space program? What sparked this sense of urgency, and what are America's space exploration companies doing to fix it?

The major impetus behind NASA's desire to free itself of Russian "dependency" was the threat leveled at Washington earlier this year by Russian Deputy Prime Ministry Dmitry Rogozin. Responding to sanctions that Washington imposed on Russia in the wake of the latter's invasion of Crimea, Rogozin promised Moscow would cut off the sale of its "RD-180" rocket engines for use by the American military (Russia may be rethinking that position -- or it may not).

This still leaves the question of why the RD-180 rocket engine is such a big deal. In the following slideshow, we'll try to lay out the dilemma for you -- and point out the companies that investors should be watching as we try to resolve the impasse. Take a quick look, and make sure to tune back in at the end for our special free report.