On 10/1/2013 12:19 PM, Rand Simberg wrote:
Here's Dan Leone's story at Space News: http://www.spacenews.com/article/launch-report/37498no-upper-stage-explosion-after-falcon-9-v11-launch-spacex-says SpaceX continues to say it didn't happen.
More specifically, SpaceX says ".. our data confirms there was no rupture of any kind on the second stage." Also, "Following separation of the satellites to their correct orbit, the Falcon 9 second stage underwent a controlled venting of propellants ... and the stage was successfully safed."
If that's what their 2nd stage telemetry is showing, that's what it's showing. Any significant tank rupture would be screamingly obvious on the tank pressure traces.
Controlled upper-stage tank venting, FWIW, is a routine part of orbital debris-generation mitigation these days
Regarding the apparently spherical vented-propellant cloud imaged around the stage, it occurs to me that if the venting was non-propulsive (EG, use of a T-fitting or equivalent on the exit to balance thrusts) and relatively low-pressure, low-velocity, it might also produce that result, rather than the directional plumes imaged in some failed missile tests in recent years. That one could turn out to be a case of post in haste, repent at leisure.
They also say "During this process, it is possible insulation came off the fuel dome on the second stage and is the source of what some observers incorrectly interpreted as a rupture in the second stage." If orbits of the extra bits - "the U.S Air Force-run Space Surveillance System was tracking 20 objects associated with the launch in low Earth orbit. Experts were expecting to see 11 objects, including Cassiope; the three secondary payloads, one of which released seven independently flying objects; and the upper stage" - decay quickly relative to the at-some-point identified upper stage, that would tend to confirm this interpretation.
We'll see. Henry
On 10/01/2013 10:17 AM, Henry Spencer wrote:On Tue, 1 Oct 2013, 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.Doesn't have to be hypergolics -- any form of stored energy will suffice. Something like an engine hard start is plausible, given that SpaceX has admitted that there was a problem with the restart experiment. There may be hypergolics in the RCS. An overpressurized tank can explode. So can a shorted battery (yes, battery explosions can be quite violent). Henry Spencer henry@xxxxxxxxxxxxxxx (hspencer@xxxxxxxxxxxxx) (regexpguy@xxxxxxxxx)
