Root cause breakthrough during Luca’s leaky EMU investigation
The International Space Station (ISS) crew have managed to recreate the substantial water leak in Luca Parmitano’s faulty spacesuit, the cause of the premature end to EVA-23 last month. The crew are expected to removed and replace faulty components from the suit, for return to Earth on board the soon-to-depart Soyuz TMA-08M (34S).
EMU 3011 Investigation:
Diligent root cause investigations into the failure of Luca’s suit have been ongoing since the EVA was ended when water started to collate inside the Italian’s helmet during EVA-23 on July 16.
Although the well-practiced procedures to safely return Luca to the safety of the Quest Airlock were successful, a blog post by the ESA astronaut portrayed just how serious the situation was when Mission Control in Houston ordered the EVA to end around one hour into the spacewalk tasks.
A large amount of work has taken place on finding a root cause for the fault, with the initial theory pointing towards a vent loop water leak caused by either a blocked or clogged Water Separator Pilot Tube, a blocked condensate water relief valve, or a blocked condensate water line – causing the water separator loop to allow excessive amounts of water to enter the ventilation loop.
The investigation is being conducted by NASA’s Anomaly Resolution Team (ART) at the Johnson Space Center (JSC) in Houston, in tandem with hands on work by the ISS crewmembers on orbit.
A breakthrough in finding the root cause was made on Tuesday, when the crew successfully recreated a substantial water leak during a troubleshooting procedure.
“Extravehicular Mobility Unit (EMU) 3011 Trouble Shooting Status: The crew performed a water recharge on EMU 3011 in preparation for a EMU screening test scheduled for August 27,” pre-empted noted ISS notes (L2).
“This upcoming test is designed to detect internal water leakage from the EMU Condensate Water Transport Loop into the EMU vent loop.
“The team expects the proposed EMU 3011 test will result in similar internal water leakage signature as seen during US EVA 23.”
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As the suit was tested, engineers on the ground watched recorded video of the leak developing during the test – as they had predicted – with liquid collecting in in the helmet, as was the case during the EVA.
Controllers jokingly told Luca not to taste the water during the cleanup process, a reference to when the Italian had to swallow some of the strange tasting liquid during his attempts to return to the Quest Airlock..
On a more serious note, the cleanup was carefully monitored, as the team looked to gauge the amount of water leaked into the helmet during the troubleshooting test.
With confidence raised on the specific hardware at fault inside the EMU, the NASA ART will meet again on Wednesday to review the procedures for removing and replacing the components.
The R&R effort is expected to take place on orbit on Saturday, August 31, with the faulty components set to return to Earth on board the Soyuz TMA-08M (34S), which is currently scheduled to depart from the ISS on September 11.
ISS managers will continue to discuss the status of the EMUs on the ISS, per any requirement to conduct a contingency EVA.
At present, an immediate risk discussion would be held with ISS senior management to discuss the residual risk, should an EVA be required, per the “Big 12” problems that could occur on the Station.
Managers had already decided that some EMU elements – namely ground-built Helmet Absorption Pads (HAPs) – will ride uphill on an upcoming Soyuz and on Orbital’s Cygnus vehicle, the latter scheduled to make its debut trip to the ISS during the ORB-D mission in September.
SpaceX’s next Dragon mission to the ISS – CRS-3 (SpX-3) – also holds the option to utilize a specially made rack, allowing for EMU hardware to be launched to the ISS, and possibly for the faulty EMU 3011 to then head back to Earth.
However, based on the breakthrough with the root cause, it may be possible to return EMU 3011 to service, after replacement parts check out in the suit.
(Images: L2’s ISS Section and NASA – L2 Members, click this link for rolling updates into this investigation)
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