4 Navigation of the Pioneer Spacecraft

Modern radio tracking techniques made it possible to explore the gravitational environment in the solar system up to a level of accuracy never before possible. The two principal forms of celestial mechanics experiments that were used involve planets (e.g., passive radar ranging) and Doppler and range measurements with interplanetary spacecraft [19Jump To The Next Citation Point29]. This work was motivated by the desire to improve the ephemerides of solar system bodies and knowledge of solar system dynamics.

The main objective of spacecraft navigation is to determine the present position and velocity of a spacecraft and to predict its future trajectory. This is usually done by measuring changes in the spacecraft’s radio signal and then, using those measurements, correcting (fitting and adjusting) the predicted spacecraft trajectory.

In this section we discuss the theoretical foundations that are used for the analysis of tracking data from interplanetary spacecraft. We describe the basic physical models used to determine a trajectory.

 4.1 Models for gravitational forces acting on a spacecraft
  4.1.1 The parametrized post-Newtonian formalism
  4.1.2 Relativistic equations of motion
 4.2 Light times and time scales
  4.2.1 Light time solution
  4.2.2 Standard time scales
 4.3 Nongravitational forces external to the spacecraft
  4.3.1 Solar radiation pressure
  4.3.2 Solar wind
  4.3.3 Interaction with planetary environments
  4.3.4 Interplanetary magnetic fields
  4.3.5 Drag forces
 4.4 Nongravitational forces of on-board origin
  4.4.1 Modeling of maneuvers
  4.4.2 Other sources of outgassing
  4.4.3 Thermal recoil forces
  4.4.4 The radio beam recoil force
 4.5 Effects on the radio signal
  4.5.1 Plasma in the solar corona and weighting
  4.5.2 Effects of the ionosphere
  4.5.3 Effects of the troposphere
  4.5.4 The effect of spin
  4.5.5 Station locations
 4.6 Modeling the radiometric Doppler observable
 4.7 Orbit determination and parameter estimation

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