Cuckoo was coming.
No one knew what is was - but everyone knew it was trouble.
Designated Object Lambda when it first appeared on the fringes of the galaxy, 20,000 light-years away, it was traveling at one-sixth the speed of light.
The astrophysicists said thet it was vast... light... and had the potential for utter destruction. So an exiting space probe was reoriented to intercept; it was staffed with replicates of both humans and aliens.
Then the space probe began to leak radiation...
Frederik George Pohl, Jr. (1919-2013) was an American science fiction writer, editor and fan, with a career spanning over seventy years. From about 1959 until 1969, Pohl edited Galaxy magazine and its sister magazine If, winning the Hugo for if three years in a row. His writing also won him three Hugos and multiple Nebula Awards. He became a Nebula Grand Master in 1993.
Frederik Pohl used these pseudonyms: Edson McCann, Jordan Park, Elton V. Andrews, Paul Fleur, Lee Gregor, Warren F. Howard, Scott Mariner, Ernst Mason, James McCreigh, Dirk Wilson, Donald Stacy and James MacCreigh.
Frederik Pohl. Wikipedia.