switch and the contact, closing the circuit. The immediate solution – tapping on the panel next to the switch – did work briefly, but the circuit soon closed again. If the problem recurred after the descent engine fired, the computer would think the signal was real and would initiate an auto-abort, causing the ascent stage to separate from the descent stage and climb back into orbit. NASA and the software teams at the Massachusetts Institute of Technology scrambled to find a solution. The software was hard-wired, preventing it from being updated from the ground. The fix made it appear to the system that an abort had already happened, and it would ignore incoming automated signals to abort. This would not prevent the astronauts from piloting the ship, though if an abort became necessary, they might have to initiate it manually. Mitchell entered the changes with minutes to go until planned ignition. A second problem occurred during the powered descent, when the LM landing radar failed to lock automatically onto the Moon's surface, depriving the navigation computer of vital information on the vehicle's altitude and vertical descent speed. After the astronauts cycled the landing radar breaker, the unit successfully acquired a signal near . Mission rules required an abort if the landing radar was out at , though Shepard might have tried to land without it. With the landing radar, Shepard steered the LM to a landing which was the closest to the intended target of the six missions that landed on the Moon. Lunar surface operations Shepard stated, after stepping onto the lunar surface, "And it's been a long way, but we're here." The first EVA began at 9:42 am EST (14:42 UTC) on February 5, 1971, having been delayed by a problem with the communications system which set back the start of the first EVA to five hours after landing. The astronauts devoted much of the first EVA to equipment offloading, deployment of the ALSEP and the US flag, as well as setting up and loading the MET. These activities were televised back to Earth, though the picture tended to degenerate during the latter portion of the EVA. Mitchell deployed the ASE's geophone lines, unreeling and emplacing the two lines leading out from the ALSEP's Central Station. He then fired the thumper explosives, vibrations from which would give scientists back on Earth information about the depth and composition of