[AR] Re: Falcon 9 flight today
- From: Jonathan Goff <jongoff@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Tue, 1 Oct 2013 10:44:04 -0600
Henry,
A few thoughts:
1- SpaceX is claiming that they've analyzed the data, and that there was no
explosion. Take that with the size of NaCl crystal you feel is most
appropriate.
2- Many of the secondary payloads were multi-piece. IIRC, there were
something like 12 pieces expected to be floating around there and only 13
of the 20 or 21 pieces had multiple sightings to very they weren't false
positives. So there's still a real chance that there weren't unexpected
pieces thrown off.
3- If there was some sort of unplanned disassembly, the biggest issue
SpaceX had been running into had been with the M1-Vac nozzle extension. If
something failed, it may have been the nozzle extension itself. If it
failed in some unsymmetrical way that might have made it impractical to try
relighting the engine.
It'll be interesting to see what we find out when we have more data to go
with our speculation. :-)
~Jon
On Tue, Oct 1, 2013 at 10:37 AM, Henry Vanderbilt <
hvanderbilt@xxxxxxxxxxxxxx> wrote:
> On 10/1/2013 8:42 AM, Rand Simberg wrote:
> > SpaceX is denying it, claiming that initial tracking data is always a
> > little flaky. And what could cause an explosion? It has no hypergolics
> > on it, AFAIK.
> >
>
> A quick search gives numerous references to the F9 second stage using four
> Draco hypergolic engines for reaction control. Said quick search showed
> nothing about that having been eliminated for this new version, FWIW.
>
> Regardless, an obvious non-RCS candidate for a second-stage explosion here
> would be a severe hard (re)start of the second-stage main engine. (Purely
> speculative at this point, but clean restarts of LOX-kero engines depend
> considerably on complete purging of kerosene from engine passages after the
> first run. There is a strong incentive to minimize use of purge gas in a
> flight vehicle in order to minimize the mass of pressure bottles carried
> along, and thus to implement the minimum purge that works reliably on a
> test stand. But kerosene is in general difficult to purge, and such
> purging quite plausibly may not work the same way in free-fall and vacuum
> as it does at 1 G on a test stand. As I said though, purely speculative at
> this point.)
>
> Another more generic possibility here is damage to the second stage
> occurring at payload separation - not of course then an issue for missions
> requiring a second burn before payload separation.
>
> I would only conclude at this point that the problem was not a subtle one,
> given SpaceX's statement that they already know what it is and don't expect
> any trouble fixing it.
>
> In general, I don't at all blame SpaceX for minimizing comment on the
> matter till more data is in. Rocket operators in general go a long way out
> of their way to avoid ever using the word "explosion" in connection with
> their operations, and for good reason. But in this case, between the new
> orbital object distribution spotted and the South African
> spherical-venting-cloud photos, I'd have to say a stage explosion is a
> distinct possibility.
>
> Henry V
>
>
> On 10/01/2013 07:41 AM, Henry Spencer wrote:
>>
>>> Another little fly in the ointment: <http://www.zarya.info/blog/?**
>>> p=1595 <http://www.zarya.info/blog/?p=1595>>
>>> reports indications that the Falcon 9 second stage may have exploded in
>>> orbit, although after payload separation. Which is not as bad as having
>>> it happen with payloads still on board, but certainly isn't good news.
>>>
>>> Henry Spencer
>>>
>>> henry@xxxxxxxxxxxxxxx
>>>
>>> (hspencer@xxxxxxxxxxxxx)
>>>
>>> (regexpguy@xxxxxxxxx)
>>>
>>>
>>>
>>
>>
>>
>
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