Taurus XL (OCO- Orbiting Carbon Observatory) Launch Failure

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Lucas

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"John Brunschwyler, Taurus program manager from Orbital Sciences, explains what was supposed to happen during the nose cone separation and what actually occurred this morning:

"The fairing separates by a sequence of electrical pulses that drive ordnance. The clamshell fairing is a two-piece device and it's separated first with four pulses from an electronics box. These are two primary pulses and two redundant pulses, which separate along the fairing rails, which is the vertical part, if you will, of the fairing. About 80 milliseconds later, the base joint is severed in a similar fashion, that is with four pulses - two primary and two redundant.

"We have confirmation that the correct sequence was sent by the software. We had good power going into this event, and we also had healthy indications of our electronics box that sent the signal. Once that time had passed, which was about three minutes into the flight, we observed various pieces of telemetry that, of course, we then tried to correlate. Because at first, being humans, we don't necessarily believe one piece of data and we need to correlate the various pieces to kind of come to a conclusion. And indeed we did come to a conclusion later in the flight."

The pieces of the telemetry puzzle that showed the fairing had failed to separate included the breakwire signals not indicating a jettison, the fairing temperature sensors continuing to function later during ascent and engineers not seeing the jump in acceleration that was expected after fairing would have been shed.

"As a direct result of carrying that extra weight, we could not make orbit," Brunschwyler said."

Pictures I took from my house in San Diego.

ocolaunch1.jpg

ocolaunch2.jpg

ocolaunch3.jpg

ocolaunch4.jpg

LAW_0078.jpg
 
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Well...this just proves it...

If it had been a CAMRY launch instead of a Taurus, it would have been successful!

:p
 
Great photos! I'm amazed at how far away the vehicle was during those staging events... we saw them clearly up here in LA, too. I guess it helps that the vehicle was powered by big, bright solids :)
 
"As a direct result of carrying that extra weight, we could not make orbit," Brunschwyler said."

I've worked with Orbital in the past, they have a somewhat different approach to fairing seperation than our other launch contractors. Another point he could had made is the fact with out the fairing separation the spacecraft separation would not had occurred either by software inhibit or possible physical impact into the fairing. Mission failure even if it made orbit.

Again, this is one of the downsides to a solid motor upperstage. A liquid fueled upper stage can be burnt in such a way to control thrust and burn time to compensate whereas a solid offers no such flexibility.

Great photos Lucas!, yes solids do offer brighter flyouts.
 
Again, this is one of the downsides to a solid motor upperstage. A liquid fueled upper stage can be burnt in such a way to control thrust and burn time to compensate whereas a solid offers no such flexibility.
Hmmm. If a liquid fueled upper stage had just enough fuel to produce the same Newton-second total as a solid, I do not understand how the varying the burn of a liquid could compensate. Could you explain this?

Now I do see how on one of the Saturn-V launches, when one of 5 J-2 engines failed, they fired the other 4 J2’s for a longer burn time (using the unburned fuel from the 5th engine), and the loss of 20% of the intended thrust level was not critical to making the desired orbit. As well, the Saturn-V may have had somewhat more of a “margin” to it than with today’s launch vehicles, so it probably took a performance hit but the performance hit was within a wider performance envelope than something like the Taurus would have.

- George Gassaway
 
Hmmm. If a liquid fueled upper stage had just enough fuel to produce the same Newton-second total as a solid, I do not understand how the varying the burn of a liquid could compensate. Could you explain this?


- George Gassaway

No, not in the case of exactly the same newton-second total. What I didn't clearly state was with liquid fueled upper stages the flight design generally has postive margin such that there is remaining propellent once the spacecraft is separated. That could have been used in the Taurus scenario to allow it to reach orbit.

On our current rockets, we use that extra left over fuel for collision avoidance once we seperate and/or do a depletion burn.
 
Liquid or solid upper stage, it really didn't matter on this flight - they had large performance reserves, as the payload was originally slated to go on a standard Taurus, not a Taurus XL.

Solids work well as an upper stage - you just have to manage the energy differently. Each method has it's own advantages. Solids don't waste any fuel - they burn up everything. Liquids can be cut off at a precise point. It all depends on your mission requirements which way works best, and both can be made to work within acceptable limits.

Bottom line is, when it didn't sep the fairing, the mission was doomed, orbit or not orbit.

The overall system has a pretty good flight heritage, though most of it is on smaller fairings than the big one they were flying for OCO. It will be interesting to see what caused the failure. Fairings have a lot of "black magic" in them - they are hard to test in realistic flight conditions.

Matt
 

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