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Mugge
Thunderbolt, fuck yeah!
 
Join Date: Jan 2005
Location: Denmark
 
2014-11-14, 11:22

Quote:
Originally Posted by Dorian Gray View Post
So why, then, does hardware so often fail? I mean, it doesn’t surprise me because I see it happening all the time – it seems most ambitious missions have some failure or another (often multiple failures!). To the uninitiated, the hard part would seem to be escaping earth’s gravity, navigating in massive arcs through the solar system with unbelievable precision, and transmitting info back and forth over billions of kilometres. After all that, to have the bloody harpoons fail is a bit of a downer.
The is an article in the Danish newspaper Ingeniøren (the Engineer) that reports that the harpoons on Philae used nitrocellulose as propellant and this substance has problems igniting in low pressure environments. Space is pretty much as low pressure as it gets, so that explanation seems fair enough.

Apparently an ESA scientist called up someone from Copenhagen Suborbitals and wanted to know about their experiences with nitrocellulose because CS also had suffered a failure with this at one of their rocket tests. The charge was supposed to deploy a parachute at 8 km altitude and apparently even that was too low pressure for it to ignite.

I'm kinda wondering why nobody knew about this beforehand as nitrocellulose is not exactly a new substance. But maybe using it in spacecrafts is?
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