did they say it lessened or increased?
If the lack of tiles caused it to heat up, the tire could have burst from the heat inside the wing.
As for the significance of the tire pressure (it could also have been overpressure) or the apparent contact with the wing by a piece of the external tank, that is all inferred at this point. More from Spaceflight Now's STS-107 mission status page
1404 GMT (9:04 a.m. EST)
We're getting reports from Texas of debris behind the shuttle's plasma trail during reentery.1401 GMT (9:01 a.m. EST)
Columbia is out of communications with flight controllers in Houston. Now 15 minutes from landing time.1359 GMT (8:59 a.m. EST)
At an altitude of 40 miles, shuttle Columbia has entered Texas.1357 GMT (8:57 a.m. EST)
The shuttle is now 43 miles over New Mexico. Columbia is now reversing its bank to the left to further reduce speed.1356 GMT (8:56 a.m. EST)
Columbia's speed is now about 15,000 miles per hour as it streaks over northern Arizona.1355 GMT (8:55 a.m. EST)
The shuttle is now soaring over the southern portion of Nevada. Columbia set for touchdown at Kennedy Space Center in Florida in about 20 minutes.SATURDAY, FEBRUARY 1, 2003
1353 GMT (8:53 a.m. EST)
Columbia is now crossing the California coastline.SATURDAY, FEBRUARY 1, 2003
1351 GMT (8:51 a.m. EST)
Altitude 47 miles. Speed 16,400 miles per hour.1349 GMT (8:49 a.m. EST)
Columbia is beginning the first in a series of banks to scrub off speed as it plunges into the atmosphere. These turns basically remove the energy Columbia built up during launch. This first bank is to the right.
From the landing videos I've seen, they lower the landing gear at pretty much the last possible second -- you can see them pop out when the shuttle is just a few hundred feet above the runway.
So yes, the landing gear is still retracted during re-entry and approach.
Or an increase of tire pressure due to increased heat?
DEORBITING THE SHUTTLE/LANDING SEQUENCE
To return to Earth the astronauts must perform a number of checklist items including cleaning up the crew cabin, reinstalling the mission and payload specialist seats, powering down scientific experiments or the Spacelab, and closing the payload bay door s. If the doors fail to close an astronaut must perform an EVA to remove four shear pins that allow the doors to be manually closed; the orbiter cannot reenter with the payload bay doors open. Next the astronauts don the pressure suits which they wore during ascent to prevent loss of oxygen and pressure during descent and to accomplish the contingency abort if it becomes necessary.
After the astronauts are suited and seated, the shuttle commander orients the shuttle using the RCS so that the OMS engines are pointing in the direction of the orbiter motion. An OMS burn performed in this position slows down the orbiter so that its new perigee point is about 6 miles or 36,000 feet above the Earth's surface. Another RCS maneuver points the nose forward and sets up a space-atmosphere interface attitude of about 30º nose up. This insures that the thermal energy is concentrated on t he heat tiles. From a point halfway around the world the shuttle begins its entry.
The orbiter enters the Earth's atmosphere as it travels toward its new perigee point. A spacecraft normally increases velocity as it travels from apogee to perigee, but the drag induced by the Earth's atmosphere begins to slow down the shuttle. This decrease in speed causes the orbiter to increase its descent rate as the perigee point changes due to the spacecraft slow down. The pilots continue to orient the spacecraft using the RCS so that its bottom surface faces down with the nose facing forward.
About 30 minutes after the deorbit burn the shuttle begins to penetrate the Earth's atmosphere in earnest. Tremendous heat builds up on the orbiter's underside until it reaches a maximum at 20 minutes before landing. Thermal protection of the spacecraft is vital to human survival; this protection depends upon 32,000 silica glass tiles. These tiles vary from a measurement of six inches by six inches to eight by eight inches. They range in thickness from one-half an inch to 3.5 inches and are the consistency of chalk. Twenty thousand of these tiles are called high temperature reusable surface insulation (HRSI) and cover the areas most likely to encounter intense heat such as the bottom of the orbiter and its nose. These tiles are painted black and resist temperatures up to 1300ºF by radiating 90% of the heat back into the Earth's atmosphere. Low temperature reusable surface insulation tiles are painted white and resist temperatures up to 1200ºF. These tiles cover the upper side of the or biter's wing and the sides closest to the nose.
Because of the intense heat generated on the orbiter's nose and leading edges of the wings, reinforced carbon-carbon with a temperature resistance of 2300ºF is used to cover these surfaces. The rest of the orbiter including the top of the wings and the payload bay only encounter mild heat effects so they are covered with a thin layer of white insulation called flexible reusable surface insulation (FRSI) which protects up to 700ºF.
The reentry heat also causes another phenomenon called ionized communications blackout. The energy causing the heating strips away the electrons from the nitrogen and oxygen molecules causing positive ions which ensheath the sides and bottom of the orbiter thus causing loss of communications from 25 minutes before landing until 12 minutes before landing.
During the last 16 minutes before landing the orbiter performs four S-turn maneuvers to slow it down. Each of these turns removes energy from the vehicle very much like that experienced by a giant slalom skier. At this time the flight control systems such as the elevons and the rudder have sufficient air pressure to accomplish the maneuvers and the RCS is turned off. The last S-turn is performed five minutes prior to landing while the orbiter's speed is still MACH 2. At 5 minutes before landing the shuttle is at 83,000 feet. Its target is a 15,000 foot runway which looks like a skinny postage stamp at this altitude. At 86 seconds prior to landing the orbiter is at 425 miles per hour and at 13,000 feet; at this point the autoland sequence begins. Approaching the runway from this altitude, the shuttle has a 22º glide slope and a rate of descent approaching 22,000 feet per minute. The average airliner uses three degrees and a rate of descent of 700 feet per minute. At 17 seconds prior to touch down the glideslope is changed from 22º to 1.5º. At 14 seconds prior to touchdown the landing gear is lowered and then touchdown occurs at 215 miles per hour. When all three gear are firmly on the runway a small drag chute is released to slow the orbiter further and expend less energy on the wheel brakes. The orbiter rolls to a stop and then a convoy comes out to safe the craft. The major fact to remember is that this entire landing sequence is done without any power and the astronauts are flying nothing more than a large glider.
}:-)4