NASA pressing ahead with Shuttle flow

by Chris Bergin

NASA is moving forward with mitigation plans to help aid the next salvo of Shuttle missions, including issues relating to the International Space Station (ISS).

While processing both Discovery and Atlantis for missions STS-116 and STS-117 (LON-317 – rescue flight) continues to be tight on the timeline, the ISS’ role in supporting the upcoming missions is crucial.

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Processing flows for both Discovery and Atlantis are proceeding at a pace, with the STS-116 SRBs (Solid Rocket Boosters) and ET-123 now stacked in the VAB (Vehicle Assembly Building), in readiness for the arrival of Discovery – currently November 1.

One of the items of interest in Discovery’s processing flow was the need to replace the right hand ET door, which required replacement parts for R&R work. While that work was never deemed as a hit on the timeline, proceeding is going to plan, according to NASA memos thanking people involved for the movement towards striking the door off the problem list.

‘(Orbiter) thanked everyone who worked over the weekend and last week and a half or so doing analysis and NDE and getting equal parts to KSC for the ET door replacement parts. Parts got NDE’ed and got a good set of parts to floor early this week. Wanted to thank everybody all around the country for a very good effort.’

Meanwhile, the Flight Readiness Review for STS-116 has been confirmed to take place on November 28th and 29th.

Processing on Atlantis, with the aim on being ready for LON (Launch On Need) support mission STS-317 early in February, continues to go well, although she is still classed as ‘red’ on the lack of contingency days in the flow.

‘Post flight inspections are about 94 percent complete and tracking less PRACA than 103 (Discovery) saw,’ noted the in-depth Standup/Integrated Flow Status Report. ‘OMS Pod functional completed. MPS Repliset continues. Fuel Cell 3 R&R is in work. We have the old unit out and have a nutplate to changeout and will install the new unit on Saturday.’

The tank for STS-117 (ET-124) remains behind schedule, with an expected delivery date of December 17. ‘Bipod processing is critical path. Working through mechanical activities on the hardware’, continued the flow report. ‘Surface preps in order to get TPS (Thermal Protection System) Sprays started and proficiency sprays for the TPS workers.’

So far, the tank is proceeding through final processing without issue, with a couple of days taken out of the timeline.

The report didn’t state any major concerns with the tank delivery dates, as with previous reports, which made a point of emphasising the problems with the current NET (No Earlier Than) dates for the forthcoming missions. However, clarity is expected from Monday’s Shuttle Manifest Summit.

While the Shuttle Program get on with preparing the orbiters for flight, their destination continues to be troublesome.

Oxygen supplies on the ISS are a major determining factor for the CSCS (Crew Shuttle Contingency Support) timeline, and a successful repair of the Elektron system – via a spare part being delivered on the next Russian Progress flight – will help ease concerns over the length of time between Discovery launching and Atlantis being ready to launch on a potential rescue mission.

‘The Elektron unit, the one unit that right after we undocked, failed and is considered hard failed,’ noted Shuttle manager Wayne Hale on the Integration Flow report. ‘The replacement unit they put in has a valve problem and they hope to fly up a new solenoid valve on Progress in about two weeks and get that back on-line.

‘In meantime, they are having to use some of the candles and some of the high pressure gas which will affect our CSCS calculations. We are interested in how that is going to turn out. (ISS managers) do not think that was a huge problem and hopefully they can get this fixed.’

It appears NASA is favoring the return of faulty Elektron equipment with Discovery on STS-116, allowing for repairs to be carried out on Earth, before returning it to the ISS on a future mission.

‘We do have a big mission ahead of us and have to remain flexible,’ added Hale. ‘We are probably going to be bringing back one of those failed Elektron units because, like us, they do not have a lot of spares and they need to get their equipment back on the ground so that it can be refurbished. We have a lot of work ahead of us and I appreciate the attitude that everyone has.’

Also complicating matters is the failure of one of the Control Moment Gyroscopes on the ISS, which is likely to be replaced via an EVA, after delivery from a shuttle mission next year.

‘The ISS had a Control Moment Gyro that is currently offline because it was giving some interesting vibration signatures,’ Hale added. ‘It may be that a CMG replace is in the not too distant future for us. In the meantime, it does complicate operations significantly for the next couple of flights.’

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