SpaceX Falcon 9 v1.1 - CASSIOPE - September, 2013 - GENERAL DISCUSSION THREAD

[Robotbeat]

I don't think they have done a particular analysis on the F9R. The 50% number was probably based on all new rockets historically.

Even so, to be fair:  F1 first flight = extra exciting.  F9 first flight = exciting, but nominal(ish).      A case can be made across the industry or specific to SpaceX.  Though I suspect the odds are a bit better than 50%.  A more relevant statistic might be comparing first launch of 3rd new launcher success rates per entity/company. 

Filet this red herring however you want; approval has been granted. 

If they went conservative, and it still approved, then no problem.

Cheers, Martin

Agreed.

The Air Force's assumption of risk may be conservative, but because it just considers historical vehicles, it is somewhat independent.

[douglas100]

...Just getting the first stage down in one piece is going to be a great leap forward.

That's the icing on the cake. The most important thing is that the vehicle performs properly and places the payloads in the correct orbit.

[king1999]

I don't think they have done a particular analysis on the F9R. The 50% number was probably based on all new rockets historically.

Even so, to be fair:  F1 first flight = extra exciting.  F9 first flight = exciting, but nominal(ish).      A case can be made across the industry or specific to SpaceX.  Though I suspect the odds are a bit better than 50%.  A more relevant statistic might be comparing first launch of 3rd new launcher success rates per entity/company. 

Filet this red herring however you want; approval has been granted. 

I think they made a correct decision denying SpaceX's request for launching Falcon 1 first flight from Vandenberg. SpaceX wouldn't be here today if they had allowed it.

Why? Had that first Falcon 1 failed out of VAFB, it certainly would not have been the first time a rocket launch out of VAFB failed. Also, correct me if I misremember - but didn't the environment at Kwajalein contribute an element to the failure?

Yes, the defective part was caused by the tropical climate. So it is not fair to assume it would fail the same way in VAFB.

But if it did, it would fall on the ULA pad next to it. Anyway, this is way OT.

[Chris Bergin]

Hey Chris is this launch going ahead as planned for sep. 5 still?

No, it's not. But September still looks good.

Sorry for being a bit vague. It's not for us to declare SpaceX's launch dates. A launch date will be known, via them, probably tomorrow....however, per L2 coverage, we know it slipped from September 5.

[mgrusin]

BTW, I also noted this:

"The launch vehicle will also carry five secondary payloads to the same orbit."

Is this news? Or just new to me?

I worked on one of the secondaries, DANDE https://directory.eoportal.org/web/eoportal/satellite-missions/d/dande. I just wanted to say I've been monitoring this thread closely to help me plan my travel to the launch, and I greatly appreciate all of your informed intrigue and expert speculation.

[Nickolai]

Hey Chris is this launch going ahead as planned for sep. 5 still?

No, it's not. But September still looks good.

Sorry for being a bit vague. It's not for us to declare SpaceX's launch dates. A launch date will be known, via them, probably tomorrow....however, per L2 coverage, we know it slipped from September 5.

Any idea what the orbital constraints are? i.e. do they get a launch window every day? once every 2 weeks? weekly until mid-october or something?

[Kabloona]

Any idea what the orbital constraints are? i.e. do they get a launch window every day? once every 2 weeks? weekly until mid-october or something?

Don't know about payload constraints, but the bigger constraint could be atmospheric conditions at VAFB. If I read the FAA wiaver that AJW posted upthread correctly, FAA will not allow launch on days when there is an atmospheric inversion over VAFB, and statistically speaking that condition is absent only 40% of the time in September, resulting in only 40% probability that the weather on any given day will be acceptable.

Another way to interpret that: on any given day in September, there's a 60% chance of violating the FAA launch constraint.

Someone correct me if I'm wrong, but that's how I read the waiver.

[dglow]

Wasn't the waiver about recognizing the unlikelihood of SpaceX finding a launch window without an inversion layer present?
(combined with assumptions around new LV first-launch woes)

[Vultur]

Why does an atmospheric inversion affect rocket launches? I know it traps pollutants...

[ChrisWilson68]

Why does an atmospheric inversion affect rocket launches? I know it traps pollutants...

According to the waver document, it's all about what happens if the rocket explodes in a giant ball of flames.  If that happens, the pressure wave bounces off the inversion layer and most of the overpressure stays close to the surface.  So the overpressure blast wave is more powerful for a longer distance.  That means more of a chance of killing innocent bystanders far away just from the blast.

[mlindner]

Why does an atmospheric inversion affect rocket launches? I know it traps pollutants...

http://en.wikipedia.org/wiki/Atmospheric_inversion#Shock_waves

[joek]

Here is something new to chew on while we wait....
https://s3.amazonaws.com/public-inspection.federalregister.gov/2013-20726.pdf

Also see the launch license which recently showed up on the FAA site.  Interestingly, it was issued 2-Aug-2013 and (among other things):

SpaceX is authorized to conduct pre-flight ground operations at VAFB associated with the launch of primary and secondary payload satellites on a Falcon 9 Version 1.1 launch vehicle.

[Lars_J]

Yes, the document states that there will be 5 secondary payloads.

[kevin-rf]

Do all large vehicles out of Vandenberg need a waiver to launch during inversions?

I would assume the Delta IV and Atlas V can produce an equally large "bang".

[ugordan]

I would assume only the first couple of launches of a vehicle require it. The expected failure rate would drop after that, keeping the expected casualty rate under the allowable limit.

[Antares]

Someone correct me if I'm wrong, but that's how I read the waiver.

No: that's why the waiver is needed.  The commonly present inversion would reduce launch availability so drastically that the 3e-5 E_c for overpressure is waived in favor of the total 1e-4 E_c for overpressure, toxics and debris, on the rationale that the specific E_cs for toxics and debris are low enough that the total E_c is less than 1e-4.

[kevin-rf]

Does the location of pad and flight path relative to other structures and populations factor into this calculation?

I am just wondering if choosing a different pad location would have led to a lower, or higher number...

[Antares]

Yes.  Here's a good summary.
http://kscsma.ksc.nasa.gov/Range_Safety/Annual_Report/2006/Printpages/SII-Distant-Focusing-Overpressure-images.pdf

[Chris Bergin]

Just so everyone is aware, this is now our general discussion thread for the launch. I'll set up a update thread (which will be strictly updates only - thus not very busy each day, but a good one stop area to catch up etc) and the Party thread (heh) later.

I'll take Party Thread Title suggestions to my PM - private message - (so as not to clog up the thread) - So PM me, and I'll remove this note from the thread when I pick one.

[Kabloona]

Someone correct me if I'm wrong, but that's how I read the waiver.

No: that's why the waiver is needed.  The commonly present inversion would reduce launch availability so drastically that the 3e-5 E_c for overpressure is waived in favor of the total 1e-4 E_c for overpressure, toxics and debris, on the rationale that the specific E_cs for toxics and debris are low enough that the total E_c is less than 1e-4.

My comment on the waiver was in response to the question "will there be a launch opportunity every day?" And the waiver, as I understand it, says no, the revised E_c will allow a launch only 40% of the time in September, statistically speaking.

From page 7: " Granting a limited risk waiver...increases launch availability...to approximately forty percent in September."

And from page 4: "Based on preliminary calculations...the collective risk...will be less than 0.0001 approximately forty percent of the time in September."

Since the only variable here is atmospheric conditions, I take that to mean atmospheric conditions that allow the revised E_c to be met will occur only forty percent of the time in September.

So what is the atmospheric condition that determines whether or not any given day will be "green" for launch? Since the E_c takes into consideration debris impact and toxic cloud effects, perhaps the determining factor is wind direction/strength, and not the inversion. Apologies for muddying the waters about the inversion.

Does that make more sense, that the 40% probability of meeting the E_c is dependent on wind direction/strength for debris impact and toxicity?

(edit for corrections)