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 <mailto: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 <mailto:henry@xxxxxxxxxxxxxxx>
(hspencer@xxxxxxxxxxxxx <mailto:hspencer@xxxxxxxxxxxxx>)
(regexpguy@xxxxxxxxx <mailto:regexpguy@xxxxxxxxx>)
