  A fundamental problem in spacecraft mission design is to find a free flight
path from one place to another with a given transfer time. This problem for
paths in a central force field is known as Lambert's problem. Although this is
an old problem, we take a new approach. Given two points in the plane, we
produce the conic parameters for all conic paths between these points. For a
given central force gravitational parameter, the travel time between the launch
and destination points is computed along with the initial and final velocities
for each transfer conic. For a given travel time, we calculate the parameters
for a transfer conic having that travel time.
