ISS problems raise STS-116 CSCS concerns

by Chris Bergin

The troublesome Elektron Oxygen Generating system is once again broken – and requires a new part to be delivered to the International Space Station (ISS) on the next Russian Progress re-supply ship (M-58).

The long-term oxygen supply status on the Station is now starting to become the cause of concern NASA, given its relation to the amount of CSCS (Crew Shuttle Contingency Support) days available, should a “safe haven” contingency be required for STS-116.

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Currently, LON (Launch On Need) requirements call for Atlantis (STS-317) to be ready to launch within around two months of Discovery’s lift off in December. That length of time, known as the CSCS timeline, is determined by the amount of time the International Space Station (ISS) can comfortably accommodate both the ISS crew and a stranded STS-116 crew before Atlantis arrives as the rescue shuttle.

One of the defining factors of the ISS’ consumables is the level of oxygen supplies, which are plentiful. However, those levels are currently being depleted due to another failure of the Elektron, which in turn reduces the CSCS timeline, something NASA would wish to avoid given the
lack of contingency days remaining in Discovery – and more so – Atlantis’ processing flows.

‘Due to Wednesday’s failure of an Elektron control panel (blown fuse), the scheduled troubleshooting could not be completed. Preliminary data seems to implicate a valve solenoid (coil), but a formal determination will not be available until Friday,’ noted Thursday’s On Orbit report.

‘Necessary replacement hardware would be delivered on 23P (Progress re-supply ship). Meanwhile, MCC-H has made the decision to use oxygen from US Airlock HPGT (High Pressure Gas Tank) storage for the first time until 23P arrives. First US O2 repress occurred on Thursday.’

That replacement part won’t arrive at the ISS until the end of October, with the Russian Progress M-58 not due to launch until the 24th of October, docking three days later.

Due to this scenario, NASA managers will have to continually evaluate the accurate CSCS timeline, based on ISS consumables. This was acknowledged in a NASA memo this week, acquired by this site, noting the Elektron situation is the ISS’ ‘biggest challenge’ for the NET (No Earlier Than) December 7 launch of Discovery.

Discovery can’t launch unless NASA is comfortable that there is enough contingency for Atlantis to launch in time to rescue the crew of Discovery, in the event of a Safe Haven scenario being called.

‘The ISS Program can support a December 7 launch date for STS-116. The biggest challenge will be supporting CSCS; capabilities will be reduced from previous missions,’ noted the memo. ‘The Elektron needs to be recovered and there is no spare available. OGS (Oxygen Generating System) hardware is being expedited for flight on STS-116.’

Interestingly, the same memo notes that NASA is in talks with the Russians in relation to supporting CSCS requirements, potentially in relation to previous offers of Soyuz support made by RSC Energia president Nikolay Sevastyanov, who claimed they could support an expedited turnaround of Soyuz vehicles for aiding the rescue of crewmembers, should a ‘safe haven’ event be called.

‘Negotiations are on-going with the Russians on crew rescue and crew rotation,’ added the memo. ‘International Partner flight opportunities are being worked among the partners.’

A solution to the Elecktron issue would certainly ease the concerns, although that will have to wait until the system is hopefully fixed after the replacement hardware arrives in the latter part of this month.

This still leaves plenty of time for NASA to make an accurate CSCS evaluation, in time for the FRR (Flight Readiness Review) for STS-116.

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