ULA confirms Atlas V first stage malfunction

[DocM]

Oops.... It'll be interesting to see what the telemetry review turns up.

 

http://spacenews.com/ula-confirms-engine-issue-on-latest-atlas-launch/

 

ULA confirms engine issue on latest Atlas launch

 

WASHINGTON — The upper stage of the Atlas 5 that launched a Cygnus cargo spacecraft March 22 fired for more than a minute longer than planned, apparently to compensate for the premature shut down of the rocket’s first stage engine.

 

United Launch Alliance confirmed March 24 that the Centaur upper stage used on the launch of the Cygnus OA-6 mission burned for longer than scheduled, although the company did not provide a reason for the extended engine firing.

“The Centaur burned for longer than planned,” ULA spokeswoman Lyn Chassagne said in a statement provided to SpaceNews. “The team is evaluating the occurrence as part of the standard post-flight data analysis.” She later said that burn lasted about 60 seconds longer than planned.
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But in addition to the extended burn of the Centaur, launch telemetry broadcast on NASA TV indicates that the RD-180 engine in the first stage of the Atlas 5 shut down prematurely. That telemetry shows booster engine cutoff taking place about 4 minutes and 10 seconds into the mission, about five seconds before the scheduled cutoff time according to the ULA mission summary. Chassagne confirmed that the first stage burn was six seconds shorter than planned, but did not provide any details about what may have caused the stage to shut down early. Industry sources suggest that the Centaur burn may have extended to make up for any underperformance by the first stage, such as a premature shutdown. 
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[DocM]

Centaur and its debris did not land in the NOTAM area, and while it made the correct orbit Centaurs position relative to ISS is off target, meaning modifications to its flight path.

[Jim K Global Moderator]

Watching the launch the other day ... I thought the announcer was wrong ... because at one point he said 30 seconds to engine cutoff ... but it went on for another minute and a half.  Guess this explains why!

 

 

 

17:55 into the video

[DocM]

Yup. If S1 had stopped much sooner they may well have lost this one. AIUI Cygnus is in the proper orbit but out of position relative to ISS, so it's approach trajectory has be be modified.

[Draggendrop Veteran]

Hopefully we will find out later, how far off it was prior to corrections. Could have been a lot worse. 

[BetaguyGZT]

Yep, I was watching those numbers when he said "30 seconds to Centaur shutdown", and I was like "there's no way they can do that and expect Cygnus to make it". So yeah, they had to burn longer, but that left it out of position. Whoops. Hope they can get Cygnus there on an alternate intercept; but that'll be zero margin of error.

[flyingskippy]

What?!?!?  You mean a corporate partnership that gets paid $1B a year to "maintain its launch capability", and brags about its "100% success rate"  can have anomalies with its rocket?  That's unheard of!  And they don't even use super chilled prop for its "marginal performance benefits."

 

....i think I got the quotations in the right place. 

[DocM]

In their minds that 100% success rate only applies to not having a payload lost totally but placed in a sketchy orbit. In reality you have this and Centaur upper stage miscues that should apply as partial failures.

[chrisj1968]

Hmm, seems like they are having some minor issues with the development. Does this mean a delay of the overall program? they deemed it a success

[chrisj1968]

1 hour ago, flyingskippy said:

What?!?!?  You mean a corporate partnership that gets paid $1B a year to "maintain its launch capability", and brags about its "100% success rate"  can have anomalies with its rocket?  That's unheard of!  And they don't even use super chilled prop for its "marginal performance benefits."

 

....i think I got the quotations in the right place. 

and their parts aren't probably made by the lowest bidder

 

 

[DocM]

4 hours ago, chrisj1968 said:

Hmm, seems like they are having some minor issues with the development. Does this mean a delay of the overall program? they deemed it a success

 

'data anomaly' is ULA-speak for 'oops, that was close'

 

ULA: 

 

Cape Canaveral Air Force Station, Fla. (March 25, 2016) The Atlas V carrying the MUOS-5  mission for the U.S. Navy and the U.S. Air Force has been delayed to no earlier than May 12 to further review the data anomaly experienced during the OA-6 mission. The delay will allow additional time to review the data and to confirm readiness for the MUOS-5 mission. The MUOS-5 spacecraft is secure at the payload processing facility. ULA successfully delivered the OA-6 Cygnus spacecraft to the International Space Station (ISS) on March 22.

[flyingskippy]

11 hours ago, DocM said:

In their minds that 100% success rate only applies to not having a payload lost totally but placed in a sketchy orbit. In reality you have this and Centaur upper stage miscues that should apply as partial failures.

If it had been one of those beefy Spy sats this could have been a completely different outcome. Centaur  wouldn't have been able to handle the extra mass.  ULA is up S**t Creek without a paddle. 

[BetaguyGZT]

Darn right they wanna review it. Cygnus was close to not making it to the needed "ISS Intercept" orbit.

 

For those not aware, getting a payload up to the ISS isn't only about getting something up into space. Things have to happen at the right time and in the right sequence. Too early and you risk not making your orbit. Too late and you've overcooked your target orbit by tens of kilometers because once you hit orbital velocity things happen very quickly unless you throttle down to 10% or even 2% to fine-tune your altitude.

 

Having the Centaur correct the orbit because the Atlas' S1 cut out too soon, even by 5 seconds, meant that the Centaur had to burn its' much less powerful engine for another 45-60 seconds to compensate; and by then Cygnus was "out of position" relative to where it needed to be for its' ISS Intercept Burn -- and that's a big problem.

 

Now the Mil/Gov people are concerned about this kind of thing happening again to one of their birds ... and the Centaur most certainly won't be able to fix it like with Cygnus.

[Draggendrop Veteran]

Here is an article with a lot of info on the discrepancy of the launch profile,compared to media program. Lots of images as well.

 

Potential Performance Hit suffered by Atlas V ? – A closer Look at the Data

http://spaceflight101.com/potential-performance-hit-suffered-by-atlas-v-a-closer-look-at-the-data/

 

[DocM]

Makes a good case for an S1 burn that was 5.4s short, and also explains why the next MUOS launch has been delayed to mid-May.

[DocM]

ULA's Lyn Chassagne confirms telemetry shows  the RD-180 shut down 6 seconds early. Still no stated cause.

[Draggendrop Veteran]

United Launch Alliance narrowing lists of suspects in rocket anomaly

 

Quote

CAPE CANAVERAL — The detective work into the Atlas 5 rocket’s first stage performance trouble during the Cygnus cargo ship launch a week ago has implicated the fuel system as the likely culprit for using up the liquid oxygen supply too quickly.

 

That is what United Launch Alliance engineers report as the post-flight analysis continues into the first stage anomaly that shut down the main engine prematurely and required the Centaur upper stage to compensate for the shortfall.

 

“The team has been successful in isolating the anomaly to the first stage fuel system and its associated components,” the company said in a statement today.

 

The payload was delivered into the proper orbit for its journey to the International Space Station and launch success was achieved, but it was a breathtakingly close call.

 

The RD-180 engine propelling the rocket off the launch pad was supposed to burn for four minutes and 16 seconds. The problem, however, led to engine cutoff about six seconds too soon.

 

The first stage is loaded with 48,800 gallons of supercold liquid oxygen during the countdown and 25,000 gallons of a highly-refined kerosene fuel the day before flight.

 

After staging, the Centaur’s RL10C engine then ignited to put the 16,500-pound Cygnus freighter into orbit. In climbing to that 143-mile-high perch, however, the upper stage had to improvise by using up most of its propellant reserves in burning more than a minute longer than envisioned.

 

Quote

But ULA is working to avoid a repeat occurrence in the future. The engineering anomaly review team developed a cause-and-effect chart, often known as a fishbone diagram in investigations, to analyze the data and considere all components within the first stage.

 

To give the team ample time to figure out what went wrong and implement any corrective actions, the next Atlas 5 launch has been rescheduled from May 5 to May 12.

 

That flight will use the most-powerful Atlas 5 configuration with five side-mounted solid motors to lift the 15,000-pound Mobile User Objective System satellite No. 5 into a highly elliptical geosynchronous transfer orbit stretching 22,300 miles high.

http://spaceflightnow.com/2016/03/31/united-launch-alliance-narrowing-lists-of-suspects-in-rocket-anomaly/

[BetaguyGZT]

Fuel system, huh.

....

Bullocks.

 

Short of debris (quite unlikely, in the 0.5% range) or a vapor lock in the fuel lines (0.75% likelihood), or running out of one of the propellants because the mix was slightly off (most likely scenario, 98.75% chance), nothing else could cause a 6-second early cutoff except a deliberate action either by the on-board computer or human controller -- or an actual hardware failure.

 

So which scenario is it, ULA? Time to fess up.

[DocM]

"Fuel system" covers a helluva lot of territory, everything from tanks to the nozzles and all that controls them. Was there a leaky valve, a leak in the nozzle regeneration system, a leaky pump, a bad computer or programming or ?????? Clear as Mississippi mud.

 

Yeah, 'fess up indeed. 

[BetaguyGZT]

No kidding. If there was a leak somewhere in an RP-based fuel system that's bad. BAD bad. That purified and highly combustible stuff is known for going up simply out of spite. "No smoking within 50 feet" signs were all over the place pretty much anywhere that various Fuels were (RP-12/20/40 and JP-12/20/40, take your pick and it was there); and RP-1 is way, way more refined and "boomy" than that.

 

ULA got LUCKY, if there was indeed a leak. 

[DocM]

Given the Russian quality control issues, which they've admitted to and have caused problems with their own launchers and spacecraft, assuming RD-180 (Atlas V) and RD-181 (Antares 200 series) are unaffected is IMO a risky bet.

[BetaguyGZT]

7 hours ago, DocM said:

Given the Russian quality control issues, which they've admitted to and have caused problems with their own launchers and spacecraft, assuming RD-180 (Atlas V) and RD-181 (Antares 200 series) are unaffected is IMO a risky bet.

Yeah. And add to that the engines that were sold Stateside had been sitting for an indeterminate length of time in equally indeterminate conditions .. no amount of rehabbing is going to "turn back the clock" on those factors entirely.

 

I appreciate Russian engineering and ingenuity, and their dedication to what they do. I'll be the first one to say it. BUT. They aren't above taking shortcuts to make money. The RD-180 and 181 sales were shortcuts to make money; and they were smart for doing it.

 

Now what needs to happen is we either need to build those engines ourselves to ensure quality control (since we have the designs) OR we need better alternatives (which we should have already had).

[Draggendrop Veteran]

A day later and.....

 

ULA narrows cause of Atlas 5 launch anomaly

 

Quote

“The team has been successful in isolating the anomaly to the first stage fuel system and its associated components,” the company said in the statement, but offered no additional details on what caused the anomaly.

http://spacenews.com/ula-narrows-cause-of-atlas-5-launch-anomaly/

 

Not exactly confidence inspiring.

 

As far as the engines go (relying on my aircraft background for reference), regardless of condition, when installed, I imagine leaks checks will be performed and engine general health checked. It would be utterly silly to bolt in an unknown engine condition and send it out for launch. With this in mind, I would tend to think ancillary controls...if the engine health was indeed checked prior to launch and/or at stage assembly. Most professionals that I know, regardless of employer, have a conscience and do strive to do things right. I'll wait this one out for an answer, and I don't think it's the RD-180's, it's an ancillary component and/or control system (including software) glitch that just popped up under certain conditions that were met.  

[BetaguyGZT]

That's true also. I'm absolutely certain that they don't just get them out of the warehouse, ship them over, let 'em sit in another warehouse and strap 'em in a Atlas V to launch. They all go through a vetting, rehabbing and careful checking process to re-qualify and re-certify them for flight -- none of us have any doubts of that. And this could have been one of those instances where it's a genuine, unforeseen gremlin that "just happens". The engine in question had just been used, and it shut down five or six seconds early. It's not the end of the world, and the mission it was launching did get where it was supposed to go.

 

You're probably right, DD. It's as likely to be something else as the engine. Software glitch, slightly O2-rich fuel mixture, anything really. Long as ULA is on it and is taking steps to address it for future flights, that's all they really have to tell the public. *shrug*

[Draggendrop Veteran]

Being a SpaceX fan, I still can't deny ULA of one heck of a good launch record (regardless of expense), and these were done with RD-180's (Atlas 5).

The RD-180 has proven itself in ULA employ...no questions asked. Time for people to move on and recognize the ULA success with these engines. It will be nice to have all launchers on North American engines, and we are almost there. This whole scenario should be an example of what happens with procrastination and going for the quick buck. The North American launcher future is bright and it will be powered by American technology very soon.