Aldrin saw a broken-off circuit breaker switch lying on the floor of the lunar module and "gulped hard." Following the Apollo 11 historic July 20, 1969, moonwalk, Aldrin and Neil Armstrong were preparing to return to command from their lunar module when they discovered that a 1-inch engine arm circuit breaker switch had broken off the instrument panel. Buzz Aldrin's ingenuity averted disaster with a simple felt-tip pen.