around (see Figs 2.2a and 2.2b). This point has been chosen so that reversal of the spacecraft and reignition of the main drive will result in arrival at the target at proper insertion speed. When the turn around point is reached, the drive will be shut down, and the probe rotated 180 degrees with respect to its velocity vector using the attitude control system. Following the turn around maneuver, the fission reactor will again be used to provide power to restart the drive. These activities will occur at the 71.27 year point in the mission (see Figs. 2.2c and 2.2d for graphs and appendix for calculations).
Throughout this phase of the flight, data from experiments on interstellar space will be returned to earth at low data rates. This will serve two purposes, providing scientific data, and ensuring that contact will be maintained with the probe. Since the probe will be fully autonomous, any problems with the communications system, due to degradation of the transmitting equipment or faulty link analysis will have to be corrected by making improvements to the receiving equipment. Maintaining constant contact will allow the required lead time to implement any necessary corrective measures in the receiving equipment.
After deceleration is completed, the two remaining fuel tanks and the fusion drive will be discarded and the instruments deployed. The attitude control system which was used to rotate the entire spacecraft will be used as necessary to place the
