Meetings have already begun – as early as 5am Central time – to build a rationale to present to the midday Management Mission Team (MMT), in the hope that Shuttle Atlantis will be cleared to fly on Friday.
NASA is looking at data from the infamous STS-93 launch, which is believed to show data that relates to the failure of one phase (of three) in Fuel Cell 1, which caused the scrub of Wednesday’s launch attempt.
**L2 STS-115 Coverage: L-2 and L-1 MMT Notes. ALL related handbooks, from Final Flight Plan to EVA Presentations (550mb of 115 presentations downloadable)**.
**STS-115: MMT Troubleshooting Update Page** – One stop LIVE updates.
KEY EVENTS: (Colour code: Red ‘No Go’ – Green: ‘Go’)
External Tank Weather Orbiter Range.
Update: 22 PDFs from Wednesday’s MMT available to download on L2. Full MMT overview following the conclusion of last night’s meeting also available. UPDATE: 32 more presentations for today’s MMT now available, plus 10 new images of FC1, plus the ‘engineering-ly brilliant’ e-mail from STS-93 EGIL Tim North and OVERVIEW FOR MMT.
Key Points/Newsflashes: Meetings taking place (Central Time): Decision pending. Early source information favouring GO for launch.
Yesterday’s meetings were a fascinating insight into the ‘open forum’ NASA and its contractors now appear to have, with every single department and manager, from NASA administrator Mike Griffin, down to contractor level, being able to give their input on the correct approach to either flying ‘as-is’ or replacing the Fuel Cell (FC).
Columbia’s launch on STS-93 was a multi-event launch, with the loss of engine controllers on two different engines due to a short circuit – one failure away from losing either of those engines. This flight also that had a slightly early Main Engine Cut Off (MECO) due to a fuel leak.
**Click the image to view the video of STS-93’s launch – including transcript of the Air-to-Ground loop (free to view for forum members)**
However, this launch also saw what is being called a related event with the Fuel Cell, noted as ‘At approximately 5 seconds into the launch of STS-93, a momentary short occurred on AC1 phase A.’
This made up the basis of the key question that was polled to all managers at the MMT, worded: ‘Question – STS-93 event and this event are related in some respects. The Fuel Cell was cleared, but did we have some reverse voltage into the pump that is now manifesting itself.
’21 hrs of ATP for other work, but no dielectric test since 1981 delivery. Was the 1970â€™s manufacturing with thinner coating that between the 93 short and lightning strike degraded to the point that caused the short we saw now?’
One document (of over 20) acquired by NASASpaceflight.com shows all the poll answers that came back to that question, showing a broad range of opinion throughout the agency on whether to go launch, or stand-down and replace the Fuel Cell.
A selection of answers follow:
‘OPO – This morning position was that it would be prudent to change the fuel cell out given the lack of data on collateral damage and uncertainties. But now some more data can be collected on damage to motor and harness before tonightâ€™s tanking meeting. Still not seeing a common cause safety of flight issue, just mission success. There is rational here to go fly.
‘JSC Engineering – Trying to generate flight rationale by isolating any future shorts on Phase A by pulling cb. Also if can isolate shorts on Phase B & C to ensure fuel cell and SSME controller health. Donâ€™t have a good story on the STS-93, and subsequent work to feel you have isolated it to the phase. No GO from engineering point of view. From a program point of view want this crew to perform the mission than do MDF and have the station stage perform the EVAs. Should R&R the FC, and trade the risk of night launch.
‘MOD – Open questions of propagation of the short to phase B & C and is this potentially common cause. Donâ€™t see we have the flight rational to be go for launch. Need positive rule out propagation and common cause before can be go for launch.
‘Flight Ops Integration – think common cause is unlikely based on fuel cell performance. Havenâ€™t seen the two phase pump under ascent or zero-g environment. Rather trade risk of fly as is vs R&R to get off the ground in Oct. Stand down and fix it, then challenge the night launch rules.
‘Flight launch manager – agrees with Flight Ops & Int SE&I – is the risk increased? Donâ€™t know because they donâ€™t know what the failure is yet. Maybe wire harness, maybe in the pump, maybe due to lightning, maybe not aging issue. Probably not safety of flight concern, even though SSME shutdown is handle. Launching doesnâ€™t get as many points as assembling the mission does. Starting off with a failure, not how we want to be. Donâ€™t feel we have flight rationale data, can go into tanking to wait for data. Need to see that data before go for launch Thursday or Friday. Is this isolated to phase A or something from STS-93. squeeze data out to get flight rationale, but not there yet.
‘Flight Crew Ops – havenâ€™t heard enough to be safe to go fly, but could get there. Want to hear about physical damage, (burned wires, arc tracking). If we lose 2nd phase what happens, what is the signature. Take time to get more data. Willing to trade MDF, R&R, night launch.
‘Range – based on ELV experience, need some more time to figure out the unknowns.
‘ISS – if you believe reasonable chance of not launching into MDF then get the hardware to orbit. Been a lot of talk that this wont affect the other phases, but if you get comfortable with the isolation then take the risk to launch. Hardware on the ground doesnâ€™t do much for us, and willing to take risk of MDF. Tanking meeting good point to decide if have enough data to be go.
‘USA – not pessimistic as some as common cause. Probably good explanation that it happened this time and after such a long down time on this fuel cell. Is a programmatic risk discussion. Ascent increase in risk to additional phase problems. There is no impact only if engine redundancy is effected. Orbit donâ€™t think there is increase in risk. The longer the fuel cell is running, the more confident you become in fuel cell performance. Proceed to tanking with intention of launching tomorrow unless eureka data points out something.
‘Lockheed Martin – opportunity to launch, but common cause and root cause data should be gotten. Look through fault tree with probabilities of risk.
‘ET – still concern with phase B & C. may not have enough data that it will be isolated even tomorrow. Can you programmatically clear the tower with 2 fuel cells. Do you do whole mission or MDF.
‘Poulos – nothing we are going to do to identify root cause until R&R, assume FC1 short out at tower clear. Do you do the mission on the 2 fuel cells.
‘ATK – seems like understanding cause or consequence which you can get comfortable to go fly. On the consequence side.
‘RSRM – what we know or donâ€™t know and what is positive or negatives. Donâ€™t have enough positives to quantify a go. Another 24 hours might find with vendor, drawings etc to preserve launch.
‘SRB – if this failure doesnâ€™t lead us to effect main buses then SRB is fine. Data set is imperfect and doesnâ€™t seem to meet standards of rational. People struggling with the fact the fault tree isnâ€™t shaking out a probable cause. STS-93 might give us some history or cause. Consequence side is not as crisp as needs to be. What are the level of redundancy, performance margin (3 sigma, ICD). Not now but maybe tonight or 24 hours to crisp rational up. If this could be common cause, we need to exonerate the other fuel cells. Pile of imperfect data that could be woven into rational.
‘SSME – assess common cause or collateral damage. Assuming pump operates without issue on two phases. If we lose fuel cell and safe engine shutdown. STS-93 scenario demonstrated risk and capability. Pump appears operating nominally. Bring more data to tanking meeting. If history shows no collateral damage and not indict the other phases of this pump.
‘MSFC Engineering – donâ€™t have anything to cling to that this is stable, this is okay. Keep working, keep supporting and get more data.
‘Deputy MSFC – rational is pretty weak if you look just at fuel cell. How much more load is going to be put on unit. But from programmatic view, it is what it is. Accept risk from SSME and orbit has options. Be in the probably alright mode, given more time orbiter could get more data. R&R vs daylight launch. Give Orbiter 24 more hours.
‘Shuttle Processing – program management can accept risk of MDF and fly with cb out. Wavering on where the failure is (in pump, in harness). More time to look at data on STS-93, vendor insight, wire harness, energy absorption. Donâ€™t work the team to get data or launch. If there is a reasonable chance of not launching into MDF, then give team rest and launch tomorrow. Spend 24 hours getting more data.
‘SM&A – thinks this is a safety issue since cant rule out common cause or root cause. Just because hasnâ€™t happened before doesnâ€™t mean could be common cause (APU issue from STS-79). Usually donâ€™t fly with unknown conditions. Risk trade of manifest if R&R vs MDF risk. Have 3 weeks of manifest margin, where as MDF gets us into posture of needing another mission possibly. PAD abort gets us into SSME units availability. Safest and best thing to do is to R&R.
‘Shannon – have shown this is not a crew safety issue. Sufficient redundancy in fuel cell to get to orbit. Potentially drop controllers offline, but not an abort. Program needs to weigh if canâ€™t complete mission or push to stage. Team needs to keep working. The programmatic risk of delay is not worth it for this issue. Negative reporting basis into tanking meeting. If pump is still performing well then go for launch.
‘Vendor – looked at past performance data from 3 years ago. Donâ€™t know what happened since then to pump, to harness. Not comfortable with the fuel cell.
‘LeRoy (Cain) – no violation of LCC, launching with full SSME controllers. Risks to transients on Phase B & C is incremental increase. Program risk not safety of flight risk. No impact to mission for loss of single phase. Fuel cell performance has been very good since start up. Flying with phase A cb open makes sense. Risk to R&R at the PAD is unknown and a concern. Should be mindful of vertical R&R. Rolling back is even more risk to both programs because of the October launch. Can fly safe and not get much more data anytime soon. We have never had perfect data. Continue with the launch countdown with a T-0 on Thursday. If we get negative data to consider common cause then we will talk about not launching.
‘Crew – full confidence in the team to make the right decision. Going to sleep expecting to launch. Thanks to the team for the work they have done on lighting strike and this issue.
‘Wayne Hale – Decided to take a day to look at the data to review that there isnâ€™t an issue with other fuel cells. Hate to waste a good weather day, but its wise to take the time to review the data.
(Bill) Gerst – pushing a little too hard and need to take the day to look at the data some more.
‘Griffin – suspicious of coincidence. Not put enough emphasis of this unit on the same phase had issue previously. Phase might be no good, but may be no impact to phase B & C and thus go for launch. Opportunity to look at the data and say yes Phase A sucks, but the other two are fine.’
Back-up plans are already in place, ranging from a mission duration reduction to seven days – likely to be in a scenario where one FC fails during the mission, and – as exclusively reported by NASASpaceflight – launching on Saturday, to allow more time to evaluate data, should today’s meetings fail to find a conclusive answer to the FC question. Saturday’s launch attempt is now officially listed on NASA documentation as an option.
The Seven Day mission profile would run as follows: ‘STS-115 Minimum Duration Flight: FD-1 Launch. FD-2 RCC inspection. FD-3 RNDZ with ISS, P3/P4 unberth/Handoff. FD-4 P3/P4 Install, EVA-1 connect umbilicals for survival power. FD-5 transfer mandatory/critical items. FD-6 undock, stow, FCS C/O and RCS Hot Fire. FD-7 Deorbit.’
Other options include the possibility of replacing the FC at the pad, dropping lighting requirements, and allowing for a launch in a window that opens on September 24, as favoured by a number of managers who wish to see the FC replaced. (New manifest for a slip to Sept. 24 on L2).
Today, like yesterday, will prove once again to be a fascinating insight into how NASA approach such issues, as they attempt to Return To Assembly.
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