EVA 3 mission for Gap Filler removal

by Chris Bergin

NASA manager Wayne Hale has announced that one astronaut will be tasked with the removal of two protruding “gap fillers” from Discovery’s Thermal Protection System.

The 90 minute repair will be conducted on Wednesday as the second part of EVA 3 – with Steve Robinson tasked with the mission, following concerns of the protruding material effects on the Orbiter during the Boundary Level Transition section of re-entry.

Robinson will be guided out for a first-of-its-kind mission to the belly of Discovery to pull out the two slices of material out of the TPS. Should that fail, sawing and cutting the material will be open options to the Astronaut.

The “very simple plane,” Hale noted it as, will eliminate the slight danger the protrudances would disturb the air flow over the TPS of Discovery on re-entry, even though some engineers claim it is very unlikely – and would usually burn up or bend back during the return to Earth.

However, NASA is taking no chances.

“At the end of the day, the bottom line is that there is large uncertainty,” Hale said. “Therefore, mission managers decided to go ahead with the operation to set everyone’s minds at ease.

“It could end up with bad things, so we don’t want sleepless nights about these bad things.”

EVA managers have been working on a plan that will guide the movement of the Space Station’s Robotic Arm – with Robinson attached to the end – with the main concern centring around the need to ensure the Astronaut doesn’t hit the TPS – damaging areas that are currently unaffected.

On the ground, United Space Alliance officials and engineers will be closely looking at the reason the protrudances have occurred. STS-73 landed with such Gap Fillers sticking out of the belly of the Orbiter – and while proving to be no threat to the spaceship, in works discussions are taking place on looking at the adhesives and bondings used on the TPS.

Should a new process be called for, engineers may have to give a timeline for such a change in process on NASA’s three remaining Orbiters.

However, that is still at the discussion stage, given Hale’s comments that Atlantis is still very much in her process flow – with rollout to the pad still set for August 6.

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