1. The rate of descent.

2. Aerodynamic heating.

3. Decreasing forward velocity.

Fig. A1 to the left depicts a typical Space Shuttle reentry.  The area inside the red rectangle represents the final approach and landing phase shown in Fig. A3.  If Columbia had made it to this part of reentry it would have had to make a 270˚ right hand turn in order to land on Kennedy Space Center's runway 33 at 9:16 EST. as was anticipated.

Fig. A2

Fig. A2 shows the two typical flight paths across the United States for landing at Kennedy Space Center (KSC) depending on the shuttle's orbital inclination.  For STS-107 the orbital inclination was 39˚ and the associated flight path would have been the Maximum Westerly Approach.

Based only on this diagram, it would appear that the Columbia was significantly off course during the STS-107 reentry when compared to what is considered to be the typical nominal Maximum Westerly Approach flight path.  However, it is unknown if the Space Shuttle follows the exact same flight path every time or if the path is dependent on the particular circumstances of the flight.  Therefore the Columbia may not have been off course at all but the possibility is presented here only for discussion purposes.

Fig. A3 shows how the Space Shuttle makes its final approach to land at KSC on runway 33 which was the designated runway for STS-107.  What is most notable is the 270˚ right turn the shuttle needs to make in order to land.

Fig. A2 & A3 are from NASA document FS-2000-05-30-KSC
(Landing the Space Shuttle Orbiter at KSC)

Detailed Description of Flight Maneuvers in the Entry Subphase of Space Shuttle Reentry
Taken from the NASA Space Shuttle reference manual section on reentry.
Also available here Space Shuttle Reentry.

Guidance performs different tasks during the ¹Entry, ²TAEM and ³Approach and Landing subphases.  During the ¹Entry subphase, guidance attempts to keep the orbiter on a trajectory that provides  protection against overheating, overdynamic pressure and excessive normal acceleration limits.  To do this, it sends commands to flight control to guide the orbiter through a tight corridor limited on one side by altitude and velocity requirements for ⁴Ranging (in order to make the runway) and orbiter control and on the other side by thermal constraints. ⁴Ranging is accomplished by adjusting ⁵Drag Acceleration to velocity so that the orbiter stays in that corridor. ⁵Drag Acceleration can be adjusted primarily in two ways: by modifying the ⁶Angle of Attack, which changes the orbiter's cross-sectional area with respect to the airstream, or by adjusting the orbiter's ⁷Bank Angle, which affects lift and thus the orbiter's ⁸Sink Rate into denser atmosphere, which in turn affects drag. Using ⁶Angle of Attack as the primary means of controlling drag results in faster energy dissipation with a steeper trajectory but violates the thermal constraint on the orbiter's surfaces. For this reason, the orbiter's ⁷Bank Angle (Roll control) is used as the primary method of controlling drag, and thus ⁴Ranging, during this phase. Increasing the ⁹Roll Angle decreases the vertical component of lift, causing a higher ⁸Sink Rate. Increasing the ¹⁰Roll Rate raises the surface temperature of the orbiter, but not nearly as drastically as does an equal ⁶Angle of Attack command. The orbiter's ⁶Angle of Attack is kept at a high value (40°) during most of this phase to protect the upper surfaces from extreme heat. It is modulated at certain times to ''tweak'' the system and is ramped down to a new value at the end of this phase for orbiter controllability. Using bank angle to adjust ⁵Drag Acceleration causes the orbiter to turn off course. Therefore, at times, the orbiter must be rolled back toward the runway. This is called a ¹¹Roll Reversal and is commanded as a function of azimuth error from the runway. The ground track during this phase, then, results in a series of S-turns.

UPDATE: 12/20/2003

A transcript of voice communication during reentry between the shuttle crew and Mission Control Huston is in the document STS-107_Reentry_Text_J.pdf.  In this transcript at 13:41:35 Commander Rick Husband states' "Two minutes to entry interface.", to the other crew members.  Then again at 13:43:42 Commander Husband says, "OK. We're just past EI.".  If an official time for entry interface is not given then we know that it occurred somewhere in the 7 seconds between 13:43:35/42, the time 13:43:37 could be picked arbitrarily and made the official time of EI for use on this site.  The problem is that an official time for EI is given and it's 13:44:09, 32 seconds after the point where Commander Husband tells his crew that they just passed EI.

It could simply be assumed that Commander Husband checked his watch for the time not realizing it was off by 32 seconds or that Commander Husband was simply in error.  However several of the astronauts, Husband, McCool and Clark who are all veterans of at least one other shuttle mission, make statements about seeing plasma out of the front and side windows after 13:43:37 and well before 13:44:09.  If the time at which Columbia reached EI was changed after the loss of the shuttle as an effort to cover up something that happened to Columbia during reentry, the reason for the change cannot be found.  Since the Columbia was traveling at Mach 25 before EI the 32 seconds translates into 217 miles of travel over open empty ocean with no discernable observations or data points which may have required the 32 seconds to prove their legitimacy.

After looking at Fig. A10 and the STS-107 Ground Track documents, it does not appear that a 32 second shift would have significantly changed any of the data that creates the chart, (any changes in velocity, altitude or angle of attack would be negligible to nonexistent).  Based on the analysis done on Chris Valentine's visual data, the shuttle was where it was supposed to be when it was supposed to be there much later in reentry showing that other location data was not affected by a 32 second time shift.  EI may have been moved to accommodate the substitution of STS-5 telemetry data for STS-107 data as an early step in a cover up process when little to nothing was know about the shuttle data.  Because many of the data analysis posted on this site were done assuming that EI occurred at 13:44:09, that value will be maintained for the time being.

Any place where a total time after EI is referred to such as EI+500, 32 seconds can be added to give the time after EI per the cockpit intercom transcript  (EI+532).

---

Theory Under Consideration:

If a cover up exists within the Columbia investigation, then the 32 second shift in EI time may be connected to the additional 32 seconds of data taken from the ¹OEX data recorder after LOS occurred at 13:59:32.  Most likely all of the error messages and aerosurface position data were shifted 32 seconds forward along with the time of EI so that there would be 32 seconds of data available after LOS.  However, this has not been proven.

1. It has been shown that the OEX recorder was removed from Columbia before STS-107 and was then planted in the debris field after the exterior was made to appear heat damaged.

Fig. A4

If we had to state a time and location where Columbia's fate was sealed for the STS-107 mission, it would not be somewhere over the Atlantic shortly after launch on January 16, 2003.  It would instead be at 13:47:32 (EI+203) over the middle of the Pacific Ocean at an altitude of 298,446 Feet during her reentry, see Fig. A4.

What makes this location so suspect is that it was the end of both Laurel Clark's crew cabin video and marked the end of any and all significant voice communications with Mission Control Houston.  The Space Shuttle had not lost voice contact with Mission Control to such an extent since the Tracking and Data Relay Satellite TDRS system was put in place in the early nineties.  Typically the shuttle's avionics system would find a suitable backup for the voice transmitter and bring it on line, but that didn't happen during STS-107.

By 13:50:00 data transmissions from the shuttle were being affected as well.  Within two minutes after that the bits of data that were getting through indicated off nominal aero increments that were not being corrected by Columbia's avionics systems.

Fig. A5A

Fig. A5B

UPDATE: 12/21/2003

After once again closely scrutinizing the transcript of verbal communications during reentry that has been carefully reconstructed in the document, STS-107_Reentry_Text_J.pdf, a fact not previously noticed is a complete lack of voice communication between the shuttle crew and Mission Control Houston after 13:47:32 (EI+203).  Although Mission Control personnel are buzzing with the many strange and random anomalous events that begin some time after 13:51:00, there are no conversations with the crew about the failures.  The transcript contains some verbal ques from Mission Control personnel that may be attempts the contact the crew, but with the exception of Commander Rick Husbands two different moments when he is able to broadcast some cryptic syllables such as, "Bu" or "Uh", the loss of verbal communication continues to the end.

The STS-107 GTrack Rev 15.pdf and STS-107-Timeline-Rev15.xls documents only list brief communication blackouts that result in loss of data but do not indicate a total loss of air to ground verbal communication.  An interesting note is that 13:47:32 is also the exact time that Laurel Clark's camcorder failed marking the end of the crew cabin video released by NASA.  Because the camcorder failed completely at the exact same time that verbal communications were lost, the two events may be related.

1

Upper Left S-Band PM Antenna (S-Band Ant. No. 1).

LOS

Data taken from STS-107-Timeline-Rev15.xls and STS-107 GTrack Rev 15.pdf

These breaks in the communications between the Columbia and Mission Control are all listed as anomalous events for reentry.  However, the communications systems including the transmitting and receiving hardware as well as all of the antennas are all located well away from the left wing and do not have any associated cable harnesses that run through that general area.  Therefore a breach in the left wing does not explain any of the anomalies that occurred with the shuttle communications system that morning.

Fig. A6

Fig. A6 is from STS-107_ Event_Sequence.pdf released by the C.A.I.B. on 03/14/2003.  The image has been modified slightly to provide more information in a compact format.

Fig. A6 is a modified version of the image that is published with STS-107_Event_Sequence.pdf.  The diagram graphically shows the approximate X - Y location of all the affected sensors grouped and color coded by their associated wiring cable harnesses.

Table A2 is a summary of sensor activity from EI to LOS (Los Of Signal) that is taken from the same document as the image.  The numbers on the sensors in the image correspond to the numbers in the column labeled Sensor Ref. No.  and are the same as used in, STS-107_Event_Sequence.pdf.  The numbers do not correspond to the order of events.

The most puzzling of the sensor anomalies were those monitoring the supply water dump nozzles and the vacuum vent near the forward fuselage.  The suspected breach in either RCC panels 8 or 9 is too far from these to have effected the units or their sensors and wiring.

1

V62T0439A
V62T0440A