CHAPTER 19 SYSTEMS: ENVIRONMENTAL CONTROL AND LIFE SUPPORT SYSTEM—SUPPORTING THE HUMAN ELEMENT OF THE ISS 348 Emergency Response The previous sections outlined the basic equipment available to detect or respond directly to one of the three emergencies on the ISS—fire, rapid depress, or toxic chemical spill. However, these emergencies require time-critical responses from the entire crew and ground, and are heavily practiced by both. The initial response is similar for all three: warn others, gather in a safe haven, and work the emergency response. To warn others means to push the appropriate caution and warning alarm if an automated one has not been initiated. This process is critical to alert other crew members, but it also allows automated software to stop fans and close the IMV system, thereby reducing smoke or toxic gas from spreading throughout the ISS. Communication is also critical between the crew and ground. In the case of an emergency, both the Russian and NASA mission control centers spring into action. The crew is primed for responding to these emergencies, but the ground helps the crew as much as possible. Usually, the crew selects the location of the central post computer in the RS as the safe haven muster point. This is chosen because it is near the Soyuz vehicles, which might be needed for a quick evacuation if the situation is serious and cannot be resolved. If there are flames in the cabin between the crew and the Soyuz, the crew will create a safe haven away from the fire and then fight the fire as quickly and safely as possible. Crew members never want to be cut off from their escape vehicle. Once assembled, the crew will execute the appropriate response procedures, under the guidance of the commander. Generally, astronauts on the USOS use electronic procedures in English to perform their tasks, whereas cosmonauts use Russian procedures. However, emergency procedures are printed on paper—in what is called “the red book”—in case of computer or power problems. One page of the red book is in English and the facing page is in Russian so that any crew member can execute the steps under stress. One section of the red book is devoted each to fire, rapid depress, and toxic chemical spills. In the case of fire, the crew will begin by taking samples of the air in the safe haven with the CSA-CP to ensure the area is safe. Once safety is established, a team will usually go toward the fire, taking air samples along the way as the team prepares to identify and fight the fire. Crew members will don a mask if dangerous combustion products are detected. The crew will then try to locate the fire. This can be easy if smoke is visible otherwise, the crew will have to look on the Portable Computer System Caution and Warning display for help (see also Chapter 5). Such help can include indications of an alarm from a smoke detector or from a system, such as a failed piece of equipment or a power trip. Power is shut down in order to remove the ignition source or in case the event is caused by an electrical short or a smoldering wire. Simultaneously, the ground controllers look at the same data to help vector the crew to a likely location. Once the location is identified, the crew will use a PFE to extinguish the fire, whether in a rack or in the cabin area. Using a PFE in an open cabin is a little more challenging in microgravity than on Earth: the spraying of the CO 2 will act as a jet engine, propelling the crew member in the opposite direction if his or her feet are not anchored. The crew will close the hatches and seal the module while the ground figures out how best to clean up the smoke in cases where the heavy smoke will put the crew at elevated risk. The response to a possible depressurization event is initially the same. Once at the safe haven, crew members will estimate how much atmosphere is available. The US flight controllers have tools that tell them how quickly the air is escaping. The crew has access to a manovacumeter—i.e., a handheld device that shows the pressure in real time—that can be used by timing how quickly the pressure is decreasing. For holes so large that only minutes are available, crew members will evacuate to their Soyuz and prepare to depart. The ISS is about the size of a six-bedroom house, thus the hole would have to be very large to necessitate a departure by the crew. A hole that measures 0.6 cm (0.25 in.) in diameter will cause the ISS to depressurize to the minimal atmospheric level for supporting human life (490 mm Hg, 9.5 psi) in about 14 hours, whereas a 20 cm (8 in.) hole will reach that level in about 50 seconds. If enough time is available, crew members will look for the source of the leak. First, they will enter the docking