239 DAY IN THE LIFE: VITAL VISITING VEHICLES—KEEPING THE REMOTE OUTPOST CREWED AND OPERATING CHAPTER 14 control center of the visiting vehicle. These teams will spend months preparing procedures and flight rules to govern the real-time execution of the mission. The team will also simulate the operations multiple times to ensure the procedures and rules are correct, the timing and communication between the control centers is perfect, and the ground equipment that allows the control centers to share data and voice communication is operational (see Chapter 10). The simulations, conducted jointly between NASA and the home control center for the visiting vehicle, generally occur between launch minus 6 weeks and launch minus 2 weeks. When the approaching visiting vehicle enters the real-time phase of the mission known as Joint Operations, the mission authority transfers from the home control center of the vehicle to MCC-H, except in the case of Russian vehicles when the MCC-M is in charge. The home control center retains vehicle authority and is responsible for configuration and performance of the vehicle. NASA is responsible for the overall safety of the ISS crew, the safety of the ISS, and the mission objectives. Within Joint Operations, all decisions to proceed to the next phase of the mission (known as “go/no go” decisions) are made by the flight director in MCC-H after consultation with the mission director at the home control center. These roles and responsibilities are stressed during the training so that decisions can be made accurately and expeditiously during the real-time execution of the mission. Crew Training The crew on board the ISS has a critical role in the execution of a visiting vehicle mission. The crew will monitor the incoming vehicle, starting at a range of approximately 1000 m (3281 ft) relative to the ISS. The crew is given specific parameters to monitor and actions to take if the vehicle violates preset criteria. The crew monitors the vehicle range relative to the ISS, the range rate or speed, and the position of the vehicle relative to the space station. If precisely defined criteria using these parameters, previously worked out between the two flight control teams, are violated, the crew can issue a command to the incoming vehicle over the ship-to- ship link (see Chapter 13) to have it hold its current position, retreat to a preset previous position, or perform an abort and fly away from the ISS. This monitoring is critical to prevent a collision between the visiting vehicle and the ISS. For example, each visiting vehicle will move toward the ISS within the approach corridor, which is a cone with its apex centered on the destination point of the visiting vehicle. The ISS crew will issue a command for the visiting vehicle to abort its rendezvous and move away from the station if the spacecraft goes outside of this corridor, thus indicating that the control system is not working properly and the ISS is at risk of a collision if the trajectory worsens. The home control center of the vehicle is responsible for commanding the vehicle to advance toward the ISS after receiving the appropriate approval or “go” from the flight director at MCC-H. Once the incoming berthing vehicle reaches a predetermined position— about 11 m (36 ft) underneath the ISS—it will hold its position relative to the space station. At this point, the visiting vehicle and the ISS are flying in formation. The crew will use the SSRMS to grab the visiting vehicle. This is known as the capture operation. As they do with a module, the astronauts will maneuver the robotic arm end effector and capture a grappling pin on the hovering vehicle. The capture needs to be performed precisely so as to avoid knocking the vehicle and thereby causing it to spin and move uncontrolled in close vicinity of the ISS. Once captured by the arm, the vehicle automatically goes to what is known as free drift, which means it is no longer firing any of its thrusters. This allows the SSRMS to maneuver the vehicle to its berthing port without damaging it through an unexpected push or pull by a thruster. See also Chapter 15. The crew procedures, displays, data, and training need to be near perfect because of the close interaction between the crew and the flight control teams on the ground and the tight timeline choreography. Crew members are trained on the ground before they begin their mission on board the ISS. About a week prior to the arrival of the visiting vehicle, crew members conduct their refresher on-board training as it likely has been many months since they received training on the ground. The crew uses a robotic arm computer-based simulator to practice moving the SSRMS in and capturing the visiting vehicle. In the days leading up to the arrival of the vehicle, the crew will practice the capture operation over and over again on a laptop