153 DAY IN THE LIFE: DEBRIS AVOIDANCE—NAVIGATING THE OCCASIONALLY UNFRIENDLY SKIES OF LOW-EARTH ORBIT CHAPTER 8 of the conjunction meant it would have been impossible to push the ISS out of harm’s way. This has happened only four times during 18-year lifetime of the ISS. So, in this case, Houston gave us the order early morning Saturday to configure the ISS for possible impact and subsequent abandonment. We were told to power down all the nonessential equipment, close the hatches between the various modules, shut down the intramodule ventilation, and then take shelter in our respective Soyuz spacecraft. The TCA was 6:38 a.m. The ground uplinked a “late-notice conjunction/safe haven actions” procedure that would guide us through the power downs and module isolation and tuck us safely away in our Soyuz spacecraft, ready to abandon ship, if necessary. This was an all-hands-on-deck effort where all six of the ISS crew members worked in tight coordination with the MCC flight controllers to safe the ISS. By closing the hatches between the modules, we gave the crews and MCCs a fighting chance of recovering the ISS by isolating any breached modules from the rest of the ISS volume. Compartmentalization is how the sailors and submariners refer to this, where damage to one portion of a ship is prevented from threatening other portions by keeping water-tight hatches secured. In our case, we weren’t worried about water coming in, but rather air going out. By 5:00 a.m., we started working the isolation/safe haven procedures beginning at the forward-most part of the ISS, carefully working our way aft toward the Soyuz spacecraft. One of the last things we did before entering our respective spacecraft and closing the hatches was to configure the ISS communication system for emergency mode, which would enable communication between the ground and the two Soyuz spacecraft. By 6:00 a.m., Anton [Shkaplerov], Anatoly [Ivanishin], and I were in our Soyuz and Don [Pettit], Andre [Kuipers], and Oleg [Kononenko] were in their Soyuz. We partially closed (to soft dock) our Soyuz hatches and then all sat quietly and waited for either a loud boom or [hopefully] the “all clear” call from Houston. Thankfully, 6:38:33 a.m. passed uneventfully and the ISS and its menacing interloper passed each other at a comfortable 16.5 km (10.2 miles) miss distance. We all floated out of our spacecraft, reconfigured the ISS hatches and systems, and enjoyed many more weeks of life and work aboard the ISS. Conclusion Despite a debris environment that has become more hostile over the decade and a half that ISS has been in orbit, Mission Control, NASA researchers, and JSpOC have correspondingly improved tools to protect the ISS and its crew. They have crafted methods that better track debris and characterize the threat from an identified conjunction with debris, and developed operational responses to help the ISS move into a safer orbit, rapidly, and avoid maneuvers unless absolutely required. As the population of debris in low-Earth orbit continues to worsen, these tools will continue to be refined to keep the ISS a safe and operationally useful laboratory.