[meteorite-list] Space Shuttle Atlantis Suffered Major Micrometeorid/Orbiting Debris Hit

[Ron Baalke]

http://www.nasaspaceflight.com/content/?cid=4848  

Atlantis suffered major MMOD hit
By Chris Bergin
nasaspaceflightnow.com
October 4, 2006

Shuttle orbiter Atlantis was hit by a MMOD (micrometeoroid/orbiting
debris) event during STS-115, which NASA is describing as the "first or
second largest hit" in the history of the Shuttle program.

While the debris hit a radiator panel on the cargo bay doors, NASA are
concerned, given the size of the MMOD, which they claim was large enough
to have penetrated - possibly critically - Atlantis' heatshield.

MMOD hits are common for Shuttle missions, but are usually too small to
be of any concern. This event, however, raises questions, especially
when it is currently unclear if the damage was spotted on orbit.

'Radiator panel on STS-115 took MMOD hit. This is first or second
largest hit in history of SSP (Space Shuttle Program), noted a NASA
report, updated today, and acquired by this site. '0.108 inch diameter
at entry point. One-half inch thick honeycomb damaged.

'If hit were on RCC, it would have penetrated, but criticality of
resulting damage is not known.'

NASA is investigating how serious the damage to the RCC (Reinforced
Carbon Carbon) panels - located along the leading edge of each wing -
would have been, with sources reporting that previous MMOD hits to RCC
panels are being used for analysis.

While the very nature of a penetrating hit to RCC panels brings back
haunting memories of the damage sustained by Columbia on STS-107, it
needs to be stated that there is a huge difference between a MMOD hit
and the large chunk of foam that caused the fatal damage to Columbia.

What would have been a concern is the potential of a near miss on the 
MMOD hitting any of the Freon-22 coolant plumbing in the radiator panel. 
This could have caused an entire coolant loop to be shut down and 
declared 'failed'. This would have forced an immediate landing on the 
earliest US landing opportunity.

On STS-109, a small piece of debris was lodged stuck in Columbia's
coolant loop 2 and restricted the flow of Freon-22 in that coolant loop.
The amount of Freon-22 in the coolant loop was slightly below the flight
rule red-limit, but after exhaustive analysis by the engineers on the
ground, they decided to press on with the mission.

[snip]