If aliens are close by and listening in on our spacecraft command indicators, we might hear again from them as early as 2029.
Since 1972, NASA has used a system of radio antennae known as the Deep Space Network (DSN) to trace spacecraft and ship highly effective radio indicators in the direction of them.
Howard Isaacson on the University of California, Berkeley, and Reilly Derrick on the University of California, Los Angeles, labored out which stars these radio indicators might have reached and when …
Source: www.newscientist.com