69 DAY IN THE LIFE: THE MAKING OF A MISSION CHAPTER 4 The second spacewalk primarily focused on installing the ammonia jumpers along with the main power and data connections that had been previously installed on the outside of the ISS and routed. The ammonia lines had to be installed first for two reasons: it was the main objective of the spacewalk for that day and ammonia could leak out when integrating the ammonia hoses with those already in use on the ISS. Ammonia is highly toxic and can be tricky to see. Just a little on one of the suits could kill the entire crew once the crew members got back inside. The EVA team developed complicated procedures to detect ammonia and clean the crew before opening the hatch. Among other things, the affected crew member had to sublimate the crystals off the suit using a warm metal tool. Then, he or she would float to a sunny spot in space and hang out for a while to allow any possible remaining ice crystals to evaporate. Once in the airlock after repressurization to 259 mm Hg (5 psi), the crew member measured the amount of ammonia in the air before fully repressing and removing his or her helmet. If ammonia was detected, the contaminated atmosphere would be vented overboard and fresh air would be pumped in. Again, the check was performed and repeated until it was safe for the crew. Since the spacesuits only had a limited amount of consumables (e.g., battery power, oxygen), time for these cleanup procedures (~90 minutes) had to be planned for in the timeline. At that point, only one more spacewalk was planned. The intent was to prepare the Cupola for its later relocation from its launch position to its permanent nadir location (see Figure 1). This meant removing the insulation and locking bolts on the external shutters that were required to prevent launch vibrations from causing damage. Since the insulation was large and bulky, the team decided to jettison it (i.e., throw it away in space so it would reenter Earth’s atmosphere and burn) rather than return it to Earth inside the shuttle. Since there was a chance that the Cupola might need to be moved again in the future, the team later changed this decision and the insulation was taken inside and stored on the ISS. As team members better understood the time required to perform each activity, they saw several opportunities to get ahead. In particular, they concluded that there might be time to perform the Cupola relocation. This task would benefit from the extra available shuttle astronauts, and its completion during the shuttle mission would reduce the crew’s workload in the smaller increment. Therefore, in the spring of 2009, the team added the Cupola relocation to the end of the second EVA. This also meant a quick activation of the module because electronics were needed to operate the berthing mechanisms and cooling was needed to prevent the electronics from overheating. Choreography would be tight. Integrating Node 3 cooling lines into the existing ISS systems meant shutting down those systems. As discussed in Chapter 11, the external cooling system is broken into two functionally redundant, separate loops—A and B. Choreography would then look something similar to this: n Power down systems on loop A n Turn off loop A cooling n Astronauts to disconnect the hoses and integrate Node 3 lines on the A side n Turn on loop A cooling n Power up systems on loop A n Verify everything is working properly n Repeat for loop B This took a fair amount of time. Spacewalking astronauts had approximately 6.5 hours to conduct the EVA (see Chapter 17). Therefore, only one set of lines would be opened on this EVA. Next, the ground activated the key systems of Node 3. Once the module was basically working, the attachment mechanisms could be used to relocate the Cupola. Although this sounds straightforward, any glitch would derail the entire plan. The flight control team and training team began extensive work to refine the activation procedures and to train them very carefully. Remodeling With the current EVA timelines, some free time was still available during the mission. The ISS Program officials asked whether the team could move the PMA3 module from its current temporary position to its new home on the end of Node 3—i.e., the port end (Figure 5)—where the Cupola was located at the time of launch. After the robotics, EVA, and OSO teams assessed the proposal, a workable plan was developed however, the plan required adding another day to complete the mission. Adding days to a shuttle mission required substantial analysis to ensure the supplies required for the seven-member crew could fit on the already busy and heavy mission. With the Space Shuttle Program winding down, the ISS Program was looking to take up as much equipment and supplies as possible.