text: or where:  is the standard gravitational parameter and  is characteristic energy, commonly used in planning interplanetary missions
  Note that the total energy is positive in the case of a hyperbolic trajectory (whereas it is negative for an elliptical orbit).
  Eccentricity and angle between approach and departure
  With a hyperbolic trajectory the orbital eccentricity () is greater than 1. The eccentricity is directly related to the angle between the asymptotes. With eccentricity just over 1 the hyperbola is a sharp "v" shape. At  the asymptotes are at right angles. With   the asymptotes are more than 120° apart, and the periapsis distance is greater than the semi major axis. As eccentricity increases further the motion approaches a straight line.
  The angle between the direction of periapsis and an asymptote from the central body is the true anomaly as distance tends to infinity (), so  is the external angle between approach and departure directions (between asymptotes). Then
  or
  Impact parameter and the distance of closest approach
  The impact parameter is the distance by which a body, if it continued on an unperturbed path, would miss the central body at its closest approach. With bodies experiencing gravitational forces and following hyperbolic trajectories it is equal to the semi-minor axis of the hyperbola.