Fastest Space Transport: 42,000 Miles per Hour

While much of our discussion involves space transportation in Earth suborbital, Earth orbital and Cislunar space, it is worth considering how the current state-of-the-art scales to other destinations in space.

The fastest spacecraft flying today is NASA's New Horizon mission which is racing to Pluto at ~42,000 miles per hour. It was launched on an Atlas V on January 19, 2006 and accelerated to heliocentric escape velocity by a Boeing Star 48 upper stage. It should reach Pluto by July 2015.

Looking out further, the distance from the Sun to Alpha Centauri, in the next nearest star system, is 25.7 x 10^12 miles; approximately 276,000 times farther away than from Earth to the Sun. Transport to Alpha Centauri, traveling at the same Atlas V + Star 48 + gravity assist velocity of 368.2 x 10^6 miles in a year, would require a one-way trip of ~700,000 years.

If New Horizons had the stamina to continue and traverse the entire Milky Way galaxy (100,000 light years across) it would take
approximately 1.6 billion years to go from one side of the spiral galaxy to the other.

Consider the unfathomable: the comoving distance from Earth to the edge of the observable universe is 46.5 billion light-years. If cosmic expansion froze, New Horizons could travel across today's observable universe in 742 trillion years - or 54 thousands times older than the age of universe.

Space transport technology has quite a ways to go! I'll stick with the barely imaginable cislunar transport market.