Jim Oberg emails:

ALERT: Tomorrow may be ‘Eureka Day’ — the solution to the Columbia catastrophe.

At a one-hour briefing this morning by Columbia Accident Investigation Board (CAIB) member Scott Hubbard, the results of last week’s air-gun-fired foam impact test were summarized.

Basically, the investigators were astonished at the amount of damage when a fiberglass panel was used as a target, and they expect a better-than-even chance that tomorrow, using an actual shuttle leading edge panel (‘RCC’), they will break a hole in it.

The test will take place, weather permitting, in San Antonio. If the impact is as powerful as expected — like getting hit with a 500-mph basketball is how Hubbard described it — the ‘missing link’ in the causal chain that doomed Columbia Feb 1 may finally be on hand.

The experiment was surprising, Hubbard said, because the investigators (and NASA, which never even thought to perform such a test in the 25 years before this disaster) didn’t appreciate how an entire mechanism of thermal protection hardware bolted together could flex and vibrate under the impact, suffering much more stress than just one piece of the system held firmly in place on a test stand. This ‘missing link’ has frustrated investigators for months.

Last week’s test was using fiberglass, to verify the aiming of the air-gun. tomorrow’s test will use an actual RCC panel from a flown shuttle. The RCC material is stiffer than fiberglass but four times weaker. If a piece breaks loose, it could be the explanation for the mystery orbiting object that was tracked falling away from the shuttle in orbit.

If a piece breaks loose tomorrow, ‘pieces will fall INTO place’ on the investigation.

The full presentation and dramatic photos are now on-line.

Further impact tests are planned through the end of June, but if the impact tomorrow shatters the leading edge panel, it will be THE most important day since the spaceship and crew were lost, more than four months ago.

So they may finally have the smoking gun. It’s been pretty clear for weeks what happened. What remains unclear is what we do about it.