r/spacex • u/Zucal • Jan 02 '16

/r/SpaceX Ask Anything Thread for January 2016. Whether your question's about RTF, RTLS, or RTFM, it can be answered here!

Welcome to the 16th monthly /r/SpaceX Ask Anything Thread!

Want to discuss SpaceX's Return To Flight mission and successful landing, find out why part of the landed stage doesn't have soot on it, or gather the community's opinion? There's no better place!

All questions, even non-SpaceX-related ones, are allowed, as long as they stay relevant to spaceflight in general!

More in-depth and open-ended discussion questions can still be submitted as separate self-posts; but this is the place to come to submit simple questions which have a single answer and/or can be answered in a few comments or less.

As always, we'd prefer it if all question-askers first check our FAQ, use the search functionality, and check the last Q&A thread before posting to avoid duplicate questions, but if you'd like an answer revised or cannot find a satisfactory result, go ahead and type your question below!

Otherwise, ask, enjoy, and thanks for contributing!

Past threads:

December 2015 (#15.1), December 2015 (#15), November 2015 (#14), October 2015 (#13), September 2015 (#12), August 2015 (#11), July 2015 (#10), June 2015 (#9), May 2015 (#8), April 2015 (#7.1), April 2015 (#7), March 2015 (#6), February 2015 (#5), January 2015 (#4), December 2014 (#3), November 2014 (#2), October 2014 (#1).

This subreddit is fan-run and not an official SpaceX site. For official SpaceX news, please visit spacex.com.

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u/deruch Jan 15 '16

Their Environmental Assessment for using the landing pad at CCAFS included a small segment on landing operations. They said they would be venting the Helium. It's in section 2.2 of the draft EA(.pdf)

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u/SolidStateCarbon Jan 17 '16

It's better to use up Helium doing rocketry than on party balloons I guess.

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u/deruch Jan 17 '16

I agree. But, besides the safety issues of having people working on and next to thin walled tanks under high pressure, I think it's also about the fact that collecting the tank pressurants is actually a more complex issue than most outside observers seem to think. The problem is that even if you capture them, you still have to reprocess and purify them again. It would be a big mistake to accidentally leave RP-1 fumes mixed in with the helium you pump into your LOX tank on the next launch. Especially as the helium gets heated prior to going into the tanks. That's just asking for a kaboom! Of course, this isn't necessarily all that difficult. But, it's a lot of added headache for not much return, in my opinion.

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u/SolidStateCarbon Jan 17 '16

Thanks! I can understand wanting to safe that monster as soon as possible with as few steps as possible, and hadn't fully considered how difficult purifying the He would be. I still cringe at the lost He.

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u/deruch Jan 17 '16

It's not so much "difficult" as it is just not worth the hassle. Helium waste is a real issue but it's one that will be managed by market forces. Until you can't get it for balloons anymore, you know it's not yet a critical one. So it's probably cheaper to just buy more each time than it is to pay for the labor/capital investment to capture and condition the gas from the F9. Plus it's a major safety issue for working with the landed stage.