"It was determined that during the ascent, the foam separation from the external tank was carried by the aerodynamic flow and pelted the nose of the orbiter and cascaded aft from that point. Once again, this foam was carried in a relative air-stream between MACH 2 and MACH 4!"
Reading the article further, I was then really astounded when I read this:
"POSSIBILITY 3
The STS-86 mission revealed a similar damage pattern but to a much lesser degree than STS-87. The STS-86 tile damage was accepted ruled as an unexplained anomaly because it was a night launch and did not provide the opportunity for the photographic evidence the STS-87 mission did. A review of the records of the STS-86 records revealed that a change to the type of foam was used on the external tank. This event is significant because the pattern of damage on this flight was similar to STS-87 but to a much lesser degree. The reason for the change in the type of foam is due to the desire of NASA to use "environmentally friendly" materials in the space program. Freon was used in the production of the previous foam. This method was eliminated in favor of foam that did not require freon for its production. MSFC is investigating the consideration that some characteristics of the new foam may not be known for the ascent environment."
Read the whole article, by Greg Katnik, a mechanical systems engineer at the Kennedy Space Center, here:
I hope this event didn't happen just so NASA could be politically correct.
I think I'm going to be ill....