Escape velocity is the speed at which an object must be propelled in order not to return to another object under their mutual gravitational attraction. Alternatively, it is the speed required to propel the object into a orbit about that body. But that assumes a one time acceleration and then coast, with the gravitational attrition gradually eroding the speed. Too little, you stop and fall back. Enough, and you continue to coast, at a small speed, untill attracted to another body or Lagrange point.
However,assuming you have a variable thrust engine with enough impulse, you could balance your thrust against gravity and climb out of the gravity well at a foot a second if you wished, though it might take a while and be very inefficient. Similarily, a space elevator would allow slow climb out of the well.
The difference is in how the power is supplied. The same case can be made for the velocity required to fire an artillery shell 20 miles, but the same shell can be carried the same distance in the back of a truck at 20mph....
Last edited by ORAC; 29th June 2006 at 11:00.