Tcl is used on the International Space Station to control or provide a programmatic interface to experiments, as part of an experiment platform.
An excerpt from Declic: Linux 2.6 on the International Space Station ,Taco Walstra ,2004 :
"In an early stage of the Declic development, the French company EREMS, responsible for the PDHS development, came up with the idea to use Tcl for the interface. Scientists now are given a complete programming language to formulate the experiment. They can execute commands, store values from read commands in variables and make decisions using the Tcl language for configuring the next executed command."
... good decision EREMS!
RS: As the article is dated August 2004, I'm not sure whether Tcl is still "out there"... :^) But in an international environment, msgcat could be helpful: "Юстон, у нас проблема"
Bart van Deenen: I'm one of the developers, and we used some Tcl scripting in early 2010 to work around a sensor malfunction in a critical thermal control loop.
arjen 2010-07-06 02:23:55: ... but that would have been a much smaller one than without Tcl and msgcat ...
etdxc 2010-07-09:
The OLMSE (Online Mission Support and Evaluation) ground system for the European Robotic Arm (ERA), which will (eventually) go on the Russian Segment (RS) of the ISS, is a collection of starpacks developed to manage mission telemetry and perform performance analysis. All in 25k lines of code to ESA/Dutch Space/Spacebel standards.