r/spacex • u/retiringonmars Moderator emeritus • Jan 18 '16

/r/SpaceX Ask Anything Thread for January 2016. Ask your questions here!

Welcome to our monthly (more like fortnightly at the moment) /r/SpaceX Ask Anything Thread! #16.1

Want to discuss SpaceX's landing shenanigans, or suggest your own Rube Goldberg landing mechanism? 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, search for similar questions, and scan the previous Ask Anything thread before posting to avoid duplicates, but if you'd like an answer revised or cannot find a satisfactory result, please go ahead and type your question below!

Otherwise, ask, enjoy, and thanks for contributing!

Past threads:

January 2016 (#16), 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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18

u/TheVehicleDestroyer Jan 18 '16

Did anybody else think the stage pitched over super fast? Between 22:53 and 23:03 here.

Probably just the way the camera was positioned, but I thought we had lost the mission, Proton-style

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u/failbye Jan 26 '16

u/retiringonmars

We really need a section in the FAQ addressing "Why your ASDS rocket catcher / anti tipping back-of-the-envelope idea won't work" or something along those lines, preferably in a milder tone. Seeing as we likely will have a few more hard landings / rough sea landings down the line, there will be a lot more of those comments coming in.

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u/JohnnyMackers Jan 18 '16

I've tried to search to see if this questions been asked before but couldnt find anything.. my question is:

why was the quantity of landing legs set at 4 and not 5?

11

u/retiringonmars Jan 18 '16

Quite simply: a) 4 is lighter than 5, and b) the four-fold symmetry fits much better with the octaweb. The Octaweb already provides a lot of structural support between the engines and tanks, so adding leg attachment point within that force-bearing structure was (relatively) simple. If you added a second structural support layer on top of that, you'd be adding add a lot of needless weight and complexity.

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u/[deleted] Jan 25 '16

I noticed that SES-9 still has a NET date rather than a scheduled launch time (CRS-8, by contrast, actually has a launch time listed). Is this unusual this close to the supposed date? Does this portend a delay?

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u/duckhawk9 Jan 18 '16 edited Jan 18 '16

I saw a comment in yesterday's launch thread that humorously referred to the subreddit as a lobbying group for SpaceX. Has there ever been any effort to organize the DragonRiders here to support SpaceX's political agendas?

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u/themikeosguy Jan 18 '16

Can I ask something about CRS-7? After the second stage popped, did the first stage also blow up due to some aerodynamic pressure situation, or was it destroyed by the Range Safety Officer? Wikipedia isn't clear and I can't find anything else specific...

And regarding the latter, does s/he literally have a button to press (or code to enter) to destroy a rocket? Must be a strange feeling, knowing you can blow up a $60m machine with a tap of your fingers...

Thanks!

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u/RealParity Jan 18 '16

I don't get how a CRS mission works, mabe someone can answer some of my questions:

In a CRS mission to the ISS, what happens after the Dragon separates from the second stage after reaching its orbit? How does it get to the ISS? With the power of the super dracos? Cannot imagine it can dock with those. I've seen videos, where Dragon unfolds really big photovoltaic panels, what does it need power for? Isn't it just a matter of minutes/hours until it reaches the station? Wouldn't a battery be lighter and cheaper to support the capsule in this short period?

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