In my previous article on the history of nuclear pulse propulsion, I outlined three research programs in nuclear propulsion systems for space travel.  The first of these, Project Orion, was investigated in the 1950s and 1960s as a very serious and practical option for space travel.  Its only limiting factor was the signing of the International Test Ban Treaty in 1963 that barred the detonation of nuclear weapons in space.

In this first of a series of articles on nuclear propulsion for space travel, allow me to enlighten each of you about the fascinating history of this technology. This post will cover three early projects, with posts to follow that will explore other technologies along with an assessment of future prospects.

Cassini-Huygens is a Flagship-class NASA-ESA-ASI robotic spacecraft sent to the Saturn system. It has studied the planet and its many natural satellites since its arrival there in 2004, as well as observing Jupiter and the Heliosphere, and testing the theory of relativity. Launched in 1997 after nearly two decades of gestation, it includes a Saturn orbiter Cassini and an atmospheric probe/lander Huygens that landed in 2005 on the moon Titan. Cassini is the fourth space probe to visit Saturn and the first to enter orbit, and its mission is ongoing as of 2013.  It is powered by a plutonium power source, and has facilitated many landmark scientific discoveries in its mission to the stars.