Did my research now and it was his first story "The Coldest Place".
"Larry comments on how his first story, The Coldest Place was obsolete almost before it was published when the first space probes approached Mercury and found that it was not a one face planet"
no subject
"Larry comments on how his first story, The Coldest Place was obsolete almost before it was published when the first space probes approached Mercury and found that it was not a one face planet"
Quote from http://www.larryniven.org/www.shtml