The next task was to remove and replace the telescope's Science Instrument Command and Data Handling Unit, or SIC&DH, a computer that sends commands to Hubble's science instruments, and formats science data for transmission to the ground. This was the item that failed in September 2008, delaying STS-125 while engineers prepared a replacement part for the mission, and the crew trained for the new task. While the failure of the SIC&DH did not disable the telescope, replacing the unit restores the redundancies. The final major task was to install the Soft-Capture Mechanism (SCM), which includes the Low Impact Docking System (LIDS) that will allow spacecraft in the future to dock with the telescope, and to safely de-orbit the telescope at the end of its life. Feustel also installed two of four Latch Over Center Kits, or LOCKs, that make opening and closing Hubble's large access doors easier for the remaining spacewalks. The spacewalk officially ended at 20:12 UTC, for a time of seven hours and twenty minutes. It was the nineteenth spacewalk devoted to servicing the telescope, and brought the total time in servicing Hubble to one hundred thirty-six hours, thirty minutes. Due to the length of the spacewalk, and the delay in beginning, the crew was over an hour behind their scheduled timeline for the day, but worked through the post-EVA activities and evening activities without problems, and got to sleep only slightly behind their scheduled time. During the mission status briefing, David Leckrone, Hubble Project Senior Scientist, noted he was very relieved that the camera was replaced successfully, and noted that the problems with the bolt caused some concern, "I don't normally reveal my age and I'm not going to here, but I can tell you I'm five years older now than I was when I came to work this morning, we can sleep pretty well tonight, knowing that's been accomplished."
