Apollo 11's objective was to land safely on the Moon, rather than to touch down at a precise location. Three minutes into the lunar descent, Armstrong noted that craters were passing about two seconds too early, which meant the Lunar Module "Eagle" would probably touch down several miles (kilometres) beyond the planned landing zone. As the "Eagle"s landing radar acquired the surface, several computer error alarms sounded. The first was a code 1202 alarm, and even with their extensive training, neither Armstrong nor Aldrin knew what this code meant. They promptly received word from CAPCOM Charles Duke in Houston that the alarms were not a concern; the 1202 and 1201 alarms were caused by executive overflows in the lunar module guidance computer. In 2007, Aldrin said the overflows were caused by his own counter-checklist choice of leaving the docking radar on during the landing process, causing the computer to process unnecessary radar data. When it did not have enough time to execute all tasks, the computer dropped the lower-priority ones, triggering the alarms. Aldrin said he decided to leave the radar on in case an abort was necessary when re-docking with the Apollo command module; he did not realize it would cause the processing overflows.