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Comment by cmrx64 | Hacker News Reader

One of my friends works at the STSCI on various visualization and simulation tools (all web-based, written in a modern stack!) for planning missions for this thing. It's a really really neat project.

The telescope itself is "scriptable" using a (truly ancient) version of JS via a really old implementation that I've seen referenced but can't find right now. There's a lot of open information about the JWST, but it's not widely reported on. Definitely worth checking out if you're interested in space, technology, and the systems we actually deploy into the void!

Some papers: http://www.stsci.edu/~idash/pub/dashevsky0607rcsgso.pdf

http://arc-test.aiaa.org/doi/pdfplus/10.2514/6.2006-5747

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Oh lord, JavaScript goes to space. You thought losing the MCO because of Imperial units was embarrassing? Just wait until this $9 billion telescope explodes because [] == ![] or something.

(This was supposed to be humorous, just making sure)

Or just can't do a calculation right because single precision floats lack the granularity for it.

JavasScript uses double precision floats, unless you're working with float32 typed arrays.

Seriously though, considering how deeply every other aspect of this project was deliberated (presumably, given the cost involved) - how they could possibly end up going with Javascript is bizarre. You'd think there would be a preference for arbitrary precision and against undefined behavior.

I can't find the evaluation paper they cited in the second linked paper, but it looks like it's using Javascript because they wanted a COTS script engine (as opposed to running compiled code) that was compatible with VxWorks, and the particular Javascript engine they selected (ScriptEase) was presumably the best option they found back in 2003. I'm not really sure what all options they would have had in 2003 though.

They should have hired Erann Gat to do it in Lisp.

Th spacesuit software runs on Node. The NASA guys are quite active on the conference circuit

What is the MCO?

This, I assume: https://en.wikipedia.org/wiki/Mars_Climate_Orbiter

Looks like it's worth the read.

Thank you.

Where does it say that the planning component is going to space? The web stuff seems to be for UI and is all ground based. i think that most Gui work these days is web based as we have forgotten how to do it in any other way.

Its like this: programmers who do ui move on to other things (mostly into stuff that gets you a higher sallary) and the new ones are left with the latest and greatest toolkits - all with their own set of weak points.

In both of the papers I reference, there is a javascript component running on the JWST.

Of course the mission planning stuff is all groundside.

In fact, one of the major reasons for the $4B+ budget overage was the rewrite from plain Javascript to Backbone in 2012, again to Angular in 2014, and to React last year.

Why Javascript?

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

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 because Common Lisp has a bad rap at NASA.

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

Thanks for posting this interesting read.

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.

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.

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.

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.

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