CHAPTER 6 DAY IN THE LIFE: “BRAIN TRANSPLANTS” ON THE INTERNATIONAL SPACE STATION 112 without requiring an actual Thermal Control System to be connected. Note that this sort of testing has to be integrated with all the systems. The Command and Control System (CCS) software interfaces with the Internal, External, and Guidance, Navigation, and Control (GNC) software, to name a few, as well as the Russian, European, Japanese, and commercial partner systems. Code changes in the CCS have to be tested with the latest code in all these systems to ensure compatibility. Testing between the CCS and the Russian computers is some of the most complicated owing to the critical functions that both segments control, and because the systems are very different. This is called “four- box testing” since it uses flight-like items for the four key computers (Command and Control [C&C] MDM, GNC MDM, Service Module Central Computer, and the Service Module Terminal Computer) on both sides of the interface. Flight controllers and engineers from multiple countries spend months testing the four-box configuration. Once the software has passed the flight qualification test, it is ready to be loaded on the space station computers. Preparing for the Transition Once the software is ready for uplink, the operations team—consisting of the key personnel from the various disciplines along with the flight director—begins the process of preparing for the actual installation. As with a Space Shuttle mission (see Chapter 4) or a spacewalk (see Chapter 17), a lead team is assigned to the project. The process of a software upgrade is fairly complicated. The first thing the team needs is to figure out is the strategy—i.e., which computers are to be updated and in which order. Changes to the CCS will affect other Tier 2 computers as well as the crew’s PCS and perhaps the robotics software. Therefore, changes to those computers are usually updated around the same time. For example, the 14th release of the CCS, called Release 14 (R14), was combined with seven other operating systems on 11 MDMs and PCS laptops. Although several computers are being upgraded, by convention the entire set of transitions is labeled according to the CCS software being uploaded. The upgrade is summarized in Table 1 and represents updates to nearly 1.5 million lines of software code. Table 1. Summary of software systems upgraded in the R14 group transition. See Chapter 5 for more details on the different MDMs and software systems. This is the software transition shown in the flowchart at the beginning of this chapter. Software System Old Release g New Release Number of and Computers Affected Command and Control Software (CCS) Release (R)13 g CCS R14 3 – Command and Control Multiplexer/DeMultiplexers (MDMs) Portable Computer System (PCS) R16 g PCS R17 7 – PCSs Mobile Servicer System (MSS) 8.1 g MSS 8.2 3 - C&C MDMs Hub Control Software (HCS) R3 g HCS R4 2 – Hub Control Zone MDMs Starboard 3 (S3) Port 3 (P3) R4 g S3P3 R5 4 – S3 and P3 MDMs Laboratory System 3 R5 g LSYS3 R6 1 – LA-3 MDM Node 2 System (N2SYS)2 R3 g N2SYS2 R4 1 – N2-2 MDM The transition to the new software has to be seamless since the software is still controlling the vital functions of the space station. Therefore, the new software is loaded to the backup computer for those systems that have a backup. The primary and backup computers are swapped when the team is ready, during a time in which there are no major activities such as a visiting vehicle docking or a spacewalk. Usually, this is accomplished by telling the primary to mode itself to a standby or diagnostic safe state (see Chapter 5). Seeing no primary, the backup MDM will transition to that role, but will be operating on the new software. If a backup MDM does not exist, as is the case with the Tier 3 MDMs (see Chapter 5), the sole computer is loaded in a diagnostic state and then transitioned to operational when ready. Whenever the CCS is upgraded, the PCS software is also upgraded since both work hand in hand. Unlike the MDMs, this can be done via CD-ROM (as can be done via laptop on Earth) or by sending up a new hard drive with the software already loaded. Half the PCS laptops are converted to the new software prior to the transition. Only half are loaded to allow for a possible