Lisping at JPL

Common Lisp was used for JPL's Remote Agent autonomous control system, which successfully operated NASA's Deep Space 1 mission in 1999. According to the project engineer, Lisp enabled in-flight debugging via a REPL, crucial for resolving a race condition undetected during ground tests. Despite this, political pressure and integration challenges with C led management to mandate a shift to C++ and later Java, citing industry best practices. Lisp was subsequently phased out at JPL, though the author notes the decision stemmed partly from unreliable C-based interprocess communication, not language deficiencies.