On 10/1/2013 7:41 AM, Henry Spencer wrote:
Another little fly in the ointment: <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
Of note there is the chart of new objects more or less evenly
distributed around the nominal perigee & apogee - the obvious way of
producing such a distribution is the roughly symmetrical explosion of
an object at the target perigee & apogee.
Also pointing toward a second-stage explosion are the two photos of a
cloud of vented propellant spotted over South Africa some minutes
after the payloads separated from the second stage, at
http://www.avcom.co.za/phpBB3/viewtopic.php?f=1&t=122495.
Other ground photos of stage venting events I've seen tend to show
streamers (sometimes spiral if the stage is spinning) indicating the
venting is happening over time in a largely unidirectional jet or
jets. The two photos here both show an apparently spherical cloud,
indicating the propellant was released all at once, presumably from a
major rupture of the propellant tanks.
All SpaceX has said so far (that I've seen) is that the second-stage
relight test failed, that they think they know why, and they expect no
problem fixing it. The key for this mission was that the redesigned
second-stage problem happened after the payloads were safely
separated. The next F9 mk 2 mission, IIRC, is to GEO transfer orbit
and will require the second burn.
To put this in perspective, this was still an extraordinarily
successful first flight of what is (despite the similar appearance)
something close to a new expendable booster - both stages have
undergone significant redesigns, and the Merlin 1D engines of course
are a major redesign/upgrade of the Merlin 1C's previously flown.
Historically, first flights of new expendable booster designs are a
coin-flip, with a catastrophic failure rate of near 50%. Spacex has
been doing remarkably well so far with the F9.
Henry
