We Must Think Outside the Rocket Equation

The rocket equation contains three variables. Given any two of these, the third becomes cast in stone. Hope, wishing, or tantrums cannot alter this result. Although a momentum balance, these variables can be cast as energies. They are the energy expenditure against gravity (often called delta V or the change in rocket velocity), the energy available in your rocket propellant (often called exhaust velocity or specific impulse), and the propellant mass fraction (how much propellant you need com...

 Carl Sagan on the Audacity of John F. Kennedy's Moon Miss...

Once upon a time, we soared into the solar system, for a few years. Then we hurried back. why? What happened? What was Apollo really about? The scope and audacity of John Kennedy's May 25th 1961 message to a joint session of Congress on "Urgent National Needs" -- the speech that launched the Apollo program--dazzled me. We would use rockets not yet designed and alloys not yet conceived, navigation and docking shemes not yet devised, in order to send a man to an unknown world--a world not yet...