UC Berkeley astronomers announce the hibernation of the networked citizen science project SETI@home after 21 years of operation. Since the 1999 launch of its iconic (net.art-y) screensaver software, more than 5.2 million participants have reportedly donated CPU time to help scan data from the Arecibo Telescope for signs of alien intelligence. Now, diminishing returns—“we analyzed all the data we need for now”—and administrative costs force a pause: On March 31, 2020, SETI@home will stop distributing work to volunteers.