Probably because Common Lisp has a bad rap at NASA.

http://www.flownet.com/ron/jpl-lisp.html

So why was lisp bad other than some bureaucrat saying it's bad.

Lisp isn't bad. Technically it was an unqualified success (and still is). It died at NASA simply because of politics.

Thanks for posting this interesting read.

Not that it answers your question, but JS dialects can be found in other strange embedded places such as Cognex's DataMan industrial barcode readers.

probably so astronomers can easily focus on their work - pointing the 'scope at stuff - and not worry about writing elegant/concise/reusable/succinct/$(feelgood adjective) code. I could understand it being used that way if it were for a limited scope (no pun intended) of operations, such as direction, focus, camera/sensor settings, etc. I'm sure they're not using JS to control thrusters or calculate trajectories.

Actually, us astronomers will never have to script anything with JS. They'll give us a GUI which will limit what we can do to strictly valid commands: e.g. point the telescope at this position in the sky and observe using this instrument for this much time.

There are plenty of languages that provide that same benefit of straightforwardness while also lacking warts and being even easier to embed; for example Lua, which was designed with express purpose of simplicity and ease of embedding.

The real answer is probably that in 2003 JS looked more interesting/good enough that it was chosen in this case.

So the Russians can hack it to self-destruct, obviously.