3 SYSTEMS: INTERNATIONAL SPACE STATION PLANNING—A ROADMAP TO GETTING IT ALL DONE CHAPTER 1 physical space), or crew availability (e.g., a given crew member trained for a particular task). The focus of this chapter is on the increment, typically a 6-month stay for a crew, where multiple events—spacewalks, supply missions, scientific research— take place, whereas Chapter 4 details the planning process for a specific mission. The long- and short-range planning process will be discussed along with the specific products and groups involved. With assembly of the ISS complete, the ultimate goal in planning is to maximize the amount of research that will be performed by a well-resourced crew. Long-Range Planning— Building Up to the Increment Years in advance, ISS Program personnel lay out a high-level manifest. The focus of this manifest is primarily supply—i.e., when will cargo vehicles be available to transport critical food, water, oxygen, fuel, spare parts, clothing, and scientific payloads. Since supply vehicles can, and have, failed to reach the station (e.g., the Russian Progress and the American Orbital and SpaceX launch failures in 2014 and 2015), the program tries to allocate extras wherever possible. Another factor in this planning may be the availability of hardware. For example, an experiment might be planned for a particular increment however, if the hardware runs into unexpected issues during development, the schedule will slip, perhaps to an increment that does not have the necessary upmass capability or enough crew time available due to higher priorities. Approximately 2 years prior to a given increment, ISS Program personnel, with input from the operations team, begin detailed planning by establishing priorities for a given increment. These priorities are documented in an increment- unique requirements document called the Increment Definition and Requirements Document (IDRD). The IDRD contains specific categorical requirements for areas such as medical operations, science operations, photography, ISS maintenance, and equipment manifests. Unique to each increment, the IDRD is used in conjunction with a more-generic requirements document called the Generic Groundrules, Requirements, and Constraints (GGR&C), which applies to all increments. The GGR&C provides general requirements for all activities. For example, it dictates that the astronauts should normally plan for at least 8.5 hours of sleep per day, 2 hours of pre-sleep to unwind and prepare for bed, and 1.5 hours of post-sleep to wake up, perform hygiene duties, and prepare for the day. The execution planning teams use this document as the primary guidance for developing the plans that will be described in this chapter. The primary focus of the IDRD development phase is to define requirements for the increment (e.g., number of spacewalks or reboosts needed to maintain vehicle altitude). Since there is always more to do than available time or resources allow, the IDRD provides priorities to aid in decision making during execution, should trades need to be made. The IDRD also details the availability and expected use of key consumables that the ISS uses over the course of the increment. Managing consumables is also a complex process. Consumables include those needed for life support as well as for the spacecraft or experiments. Program personnel estimate how much oxygen, water, fuel, etc. are needed. This can be a tricky calculation because individual crew members consume oxygen and water at different rates. Even fuel can be difficult to manage because the altitude of the ISS is affected by a number of parameters, not the least being the irregular activity on the surface of the sun. Once the needs are identified, program personnel evaluate the available upmass—i.e., which launch vehicles have available space. Something big or heavy being launched on one vehicle means less available upmass for other items. Program personnel put forth considerable effort analyzing the stowage configuration throughout the increment based on the visiting vehicle traffic plan along with the expected trash generation and disposal plan. Development of the research plan—specifically, which experiments will fly, and when those experiments will fly—occurs in parallel with this planning. This intricate planning can be especially challenging when an experiment, new hardware, or even a replacement part is not ready as scheduled, due to unexpected challenges. Program requirements determine how much time is available for specific activities. Per the GGR&C, astronauts are required to have 8.5 hours a day allocated for sleep. Four hours a day are set aside for post-sleep and pre-sleep, 3 hours for meals, and approximately 2.5 hours for exercising. Daily planning conferences are scheduled twice a day to allow the ground and crew time to tag up on the activities about to be performed or completed. Time for other tag-ups are also allocated to discuss stowage and transfer, especially prior to and during cargo resupply missions or in preparation for spacewalks. Since the astronauts are typically on the ISS for 6 months, unlike a short Space Shuttle mission, they have a half day on Saturdays to perform weekly housecleaning, and a full day on Sundays to do whatever they please. Several major holidays