Hail damage to Atlantis and ET – ROLLBACK

by Chris Bergin

Engineers are evaluating observed damage to the top of the External Tank (ET-124) – which is set to fly with Atlantis on STS-117 – caused by a hail storm late on Monday.

The damage is visible to the SOFI foam on the top of the LOX tank and an Ice Frost Ramp (IFR), and with up to 7000 areas of damage, rollback of the STS-117 stack into the Vehicle Assembly Building (VAB) for repairs has now been confirmed.

Atlantis herself also suffered 27 dings on her left wing. New launch date is NET April 22.

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With rollback, the new dates that can be aimed for will depend on the extent of the repaires required, with the worst case scenario based on requiring the changeout of the External Tank (ET-124) to ET-117 – due to arrive at KSC in April.

‘This evening, around 1700, Pad A experienced hail up to golf ball size. Damage to the ET was visible on OTV. OTV recorded multiple views of the damage prior to darkness,’ noted a NASA e-mail sent around this morning. ‘An ET Team (USA/NASA ET Mechanical and Lockheed ET TPS) reviewed the video imaging of the damage on the external tank.

‘At a glance, the damage is worst than ET-100 (previous rollback with about 700 areas of damage). Damage is at least 1000 and is in the no-debris zone. It also looks like there is damage on at least one Ice Frost Ramp. Visible damage appears to be on the southwest of the tank. However, the north side of the tank was not imaged……’

That last time a stack was rolled back to the VAB for ET SOFI repairs due to hail was on STS-96 in 1999. However, a clue to how long such repairs could take can be drawn from that incident, which only led to a seven day delay. STS-96 was originally scheduled for May 20 1999, launch occurred as planned on the new launch date of May 27 1999.

To aid the inspections, the GVA was extended and hood lowered on the ET for close-up inspections of the damage, which is on-going, as one engineer walks around the hood for a closer look at the damage.

‘There has been a great deal of speculation in the last 12 hours regarding the severe weather damage to the ET caused by a line of storm that moved through the KSC area yesterday afternoon,’ noted another NASA e-mail.

‘The plan is for inspections of the tank to pick up this morning in order to ascertain the damage. We thought it was valuable to pass along the details as we know them so here is the KSC report from the on-console OPE and a few pictures from the OTV system.’

NASA managers are currently starting STS-117’s FRR (Flight Readiness Review), which has opened with discussions on the seriousness of the ET damage.

‘Norm Knight is in attendance at the STS-117 Level I FRR and this is the first topic that will be discussed this morning,’ added an e-mail sent on his behalf. ‘If there are launch date impacts, those will become more clear in the next 24-48 hours. We will pass on any additional details as soon as they become available so that you may plan accordingly.’

This article will be updated as new information arrives – due to the high volume of information arriving, please refer to the live update pages on L2 and Atlantis’ section.

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