Atlas first stage burned just under 6 seconds short. That left a delta-V deficit that Centaur needed to make up. Centaur made up that difference by burning about a minute long, delivering Cygnus into a precise orbit, far better that the accuracy requirement (as is usual). However, this consumed propellant, so Centaur's planned de-orbit burn was shorter. Consequently, Centaur impacted in the ocean a little further downrange than the original plan. While this highlights the robustness of the system, we don't like anything happening that was not expected and are investigating this thoroughly. That's one of the reasons we have the mission success record we enjoy: Thoroughness. Every bit of data and every feature gets ground to dust by our engineers after every flight. (which is paid for on USAF missions by their ELC contract, BTW...) In this case, because we consider it an anomaly, a very specific and structured set of investigation protocols is followed with a dedicated team. We have a pretty good idea about the cause, but won't share until we are sure. That is another important discipline. We avoid jumping to the answer until the investigation is complete. That prevents us from narrowing in on a tempting answer too quickly before all the possibilities have been thoroughly investigated. By approaching investigations in this disciplined manner, you have the highest confidence of arriving at a complete, global, and permanent corrective action. Over the years, I've found that its poor practice and bad luck to jump to the easy answer before doing the homework. At present, I am not concerned about impacts to the manifest.
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timeasmymeasure
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Date: 2016-03-28 09:32 am (UTC)Atlas first stage burned just under 6 seconds short. That left a delta-V deficit that Centaur needed to make up. Centaur made up that difference by burning about a minute long, delivering Cygnus into a precise orbit, far better that the accuracy requirement (as is usual). However, this consumed propellant, so Centaur's planned de-orbit burn was shorter. Consequently, Centaur impacted in the ocean a little further downrange than the original plan.
While this highlights the robustness of the system, we don't like anything happening that was not expected and are investigating this thoroughly. That's one of the reasons we have the mission success record we enjoy: Thoroughness. Every bit of data and every feature gets ground to dust by our engineers after every flight. (which is paid for on USAF missions by their ELC contract, BTW...)
In this case, because we consider it an anomaly, a very specific and structured set of investigation protocols is followed with a dedicated team.
We have a pretty good idea about the cause, but won't share until we are sure. That is another important discipline. We avoid jumping to the answer until the investigation is complete. That prevents us from narrowing in on a tempting answer too quickly before all the possibilities have been thoroughly investigated. By approaching investigations in this disciplined manner, you have the highest confidence of arriving at a complete, global, and permanent corrective action.
Over the years, I've found that its poor practice and bad luck to jump to the easy answer before doing the homework.
At present, I am not concerned about impacts to the manifest.