This analysis is intended to resolve a possible return to flight issue for the space shuttle due to my review of the February 1, 2003 Columbia Accident. One item of concern was the left MLG up-lock roller recovered near Chireno, Texas implying possibility of premature deployment of the left main landing gear. I addressed this concern to the CAIB on March 30, 2003 with a calculation based on various assumptions. NASA have labeled this left MLG up-lock roller debris as item # 9618.

The design for the left MLG up-lock roller is significantly different from the original estimate conducted on March 30, 2003. A major influence was the mass difference since the hollow cores were not visible in the original analysis. However, the original estimate was actually a fairly good attempt given that the only available data was derived from a few photographs, discussion during CAIB press and public briefings, and experience on possible design.

COLUMBIA DEBRIS ITEM# 9618 LH MLG UP-LOCK ROLLER PHOTOS:

NOTE: Fitting mass loss at flange corner was estimated and subtracted from pristine condition mass total

TOTAL MASS: 0.1098 slugs

COLUMBIA DEBRIS ITEM# 9618 LH MLG UP-LOCK ROLLER DIMENSIONS:

Translating physical dimensions into an equivalent rectangular prism model for the trajectory program:

X-Z PLANE REFERENCE DIMENSION: 10.005 inches

X-Y PLANE REFERENCE DIMENSION: 4.059 inches

Y-Z PLANE REFERENCE DIMENSION: 2.900 inches

X-Z PLANE PROJECTED AREA: 19.791 in²

X-Y PLANE PROJECTED AREA: 17.787 in²

Y-Z PLANE PROJECTED AREA: 8.918 in²

SPAN = X-Z PLANE PROJECTED AREA / Y-Z PLANE REFERENCE DIMENSION

CHORD = X-Y PLANE PROJECTED AREA / X-Z PLANE REFERENCE DIMENSION

THICKNESS = Y-Z PLANE PROJECTED AREA / X-Y PLANE REFERENCE DIMENSION

SPAN: 0.569 ft CHORD: 0.148 ft THICKNESS: 0.183 ft

EVENT: LMG DOWNLOCK INDICATION

TIME: 13:59:06 GMT (EI + 897)

ALTITUDE: 204336 FT

LATITUDE: 33.36957 W

LONGITUDE: 100.3839 N

VELOCITY: MACH 18.68

EVENT: START OF YAW FIRING – LAST PULSE BEFORE LOS

TIME: 13:59:31 GMT (EI + 922)

ALTITUDE: 200767 FT

LATITUDE: 32.95608 W

LONGITUDE: 99.04132 N

VELOCITY: MACH 18.16

EVENT: DISCOVERY LOCATION FOR LMG UP-LOCK ROLLER

ALTITUDE: ESTIMATED BETWEEN 130 FT AND 725 FEET

LATITUDE: 31.46585 W

LONGITUDE: 94.34621 N

Great Circle Distance Formula( assuming R = 3960 miles for earth’s radius between conditions A & B):

D_AB = R * arccos( sin(latB) *sin(latA) + cos(latB) * cos(latA) * cos( lonA – lonB ) ) * ( p / 180 ) * 5280 = 437015 ft

Altitude change between conditions A & B = 204336-200767 = 3569

Trajectory angle @ Condition B = arctan( 3569 / 437015 ) = 0.468 degrees

Great Circle Distance Formula( assuming R = 3960 miles for earth’s radius between conditions B & FINAL):

D_BFINAL = R * arccos( sin(latFINAL) *sin(latB) + cos(latFINAL) * cos(latB) * cos( lonB – lonFINAL ) ) * ( p / 180 )= 293 miles

AVERAGE DISTANCE ( RUNS 1 à 6 ) = 218 MILES FOR NON-OSCILLATING MOTION

DISTANCE ( RUN 7 ) = 180 MILES FOR MAXIMUM OSCILLATING MOTION

ACTUAL DISTANCE BETWEEN LOCATION OF ROLLER AND INITIAL ALTITUDE WAS 293 MILES

DISTANCE DEVIATION = 293 – 180 = 113 MILES

Now let’s assume Condition C as a careful guess at a trajectory projection:

EVENT: 113 miles from Final Condition

TIME: 13:59:57 GMT (EI + 948 ) minimum

ALTITUDE: 195000 FT

VELOCITY: MACH 16.2 ( 4.73 miles per second )

TRAJECTORY ANGLE = 2.75 degrees

AVERAGE DISTANCE ( RUNS 1 à 6 ) = 140 MILES FOR NON-OSCILLATING MOTION

DISTANCE ( RUN 7 ) = 113 MILES FOR MAXIMUM OSCILLATING MOTION

ACTUAL DISTANCE BETWEEN LOCATION OF ROLLER AND INITIAL ALTITUDE WAS 113 MILES

DISTANCE DEVIATION = 113 – 113 = 0 MILES

Significant differences exist when comparing the March 30, 2003 estimate of the physical parameters to the actual pristine parameters. However, these differences neither negate the analysis procedure nor the need thereof.

The MLG up-lock roller center of gravity is not very close to any extremity defined as a reference dimension. The assumption of equally likely orientation combinations could be valid and the distance calculation of run 7 would be more viable as a solution unless the center of gravity calculation changes due to changes in dimensions or mass. Therefore, the solution approach by using selected results from runs 1 through 6, as well as the average result for runs 1 through 6, would have low probability for accuracy.

Geometry is a complex configuration of flanges and cylinders so the drag force has significant non-uniformity. The calculation method uses a computer program based on drag coefficients and geometry similar to flat plates in concert with aerodynamic drag theory, but attempts to model the MLG up-lock roller as a rectangular prism based on projected areas and this factor causes error relating to integration of the cylindrical sections of the MLG up-lock roller. Error is attributed to the MLG up-lock roller having some changes in mass and geometry when compared to pristine condition. The trajectory program has not yet been refined to factor hypersonic drag coefficients although supersonic drag coefficient theory is utilized. The trajectory program also has some inaccuracy due to the earth’s curvature, but this error is considered minor for relatively short distances of a few hundred miles with the velocity and altitude parameters. However, the results for run 7 offer the best available accuracy when these factors are considered.

Very little debris was found pertaining to the left wheel well door in comparison to the right wheel well door. The aluminum alloy apparently disintegrated with frictional heating at a high altitude and fast velocity. The corner of the nut-side flange had significantly more mass loss than the bolt-side flange. I theorize this damage occurred while the MLG up-lock roller remained attached to the door. This theory is based on the probability that aluminum alloy materials relatively close to the bolt-side flange provided temporary insulation or disturbance to the high temperature gases entering the wheel well while the nut-side flange was more exposed to these gases. I doubt any of this material seeped into the 1-inch diameter bore, cooled and solidified since the gases were probably high velocity streams directed away from the bore opening. No test data are currently available on item # 9618 to determine these amounts, if any. Therefore, I have subtracted this mass loss from the total mass calculation.

It is possible that some molten aluminum alloy materials seeped into the 1-inch diameter bore, cooled and solidified. Again, no test data are currently available on item # 9618 to determine these amounts, if any. Therefore, it is possible that the mass could have increased by additional 0.007slugs or about 6 percent with the bore completely filled. However, I believe the resulting error to the trajectory calculation would be minor.

The slag locations indicate the MLG up-lock roller probably slipped from the door frame as the door frame melted. This begs the question as to how could the object remain attached to the door frame remainder at lower altitudes ( below 190,000 feet ) if the majority of the door frame disintegrated at the higher altitudes and the all debris found relating to this door was at least ten miles west of the discovery location for item # 9618. The drag force on the MLG up-lock roller when still attached to a piece of the door frame could have caused a very short trajectory distance. Another curiosity is why haven’t the other three left side up-lock rollers been recovered. Unfortunately, insufficient data are available to provide better answers.

The Orbiter probably had an average velocity of at least 4.73 miles per second for the next 23.9 seconds from start of condition B; this Orbiter distance would equal the distance deviation of 113 miles and position the Orbiter somewhere south of Fort Worth at about EI + 948. Accuracy can be enhanced if available data from the MADS has specific velocity and altitude data for the Orbiter between EI + 948 and EI + 970. However, it is possible item # 9618 became completely separated from the Orbiter’s MLG door at an altitude of 195000 feet and 113 miles from the final location given the careful guess.

• Obtain more physical and dimensional data on actual condition of object
• Obtain altitude and velocity data for Orbiter trajectory between EI 948 and EI 970
• Obtain additional aerodynamic theory for trajectory program refinement

It is unlikely that premature deployment of the landing gear occurred prior to EI + 948 since the MLG up-lock roller would have remained inside the wheel well with a closed-door position. Too many variables limit further trajectory analysis of the MLG up-lock roller other than to indicate it became completely separated from all door frame components at some time beyond EI + 948. My best guess is that this separation occurred at an altitude of 195000 feet and 113 miles from the final location.

1. CAIB Final Report

2. STS-107 Accident Investigation Ground Track and Events Summary,Based on the Rev 13 Master Time

Line(Baselined, 02/15/03, 07:00 a.m.)February 18, 2003

3. March 30, 2003 letter from Weldon K. Chafin, Jr. to Gehman, CAIB

4. Trajectory Program by Weldon K. Chafin, Jr.

5. E-Mail with attachments from Les J. Boatright to Weldon K. Chafin, Jr. October 9, 2003

6. E-Mail with attachments from Les J. Boatright to Weldon K. Chafin, Jr. October 10, 2003

7. E-Mail from Les J. Boatright to Weldon K. Chafin, Jr. October 14, 2003 3:14 PM

8. E-Mail with attachments from Les J. Boatright to Weldon K. Chafin, Jr. October 24, 2003 3:17 PM

9. E-Mail with attachments from Les J. Boatright to Weldon K. Chafin, Jr. October 27, 2003 7:48 PM

10. E-Mail with attachments from Les J. Boatright to Weldon K. Chafin, Jr. October 27, 2003 7:54 PM

11. E-Mail with attachments from Les J. Boatright to Weldon K. Chafin, Jr. October 27, 2003 8:01 PM

12. E-Mail from Les J. Boatright to Weldon K. Chafin, Jr. October 29, 2003

This supplement to the Final Report documents the effects due to accuracy and functionality improvements for the Trajectory Program. The new data reflected only a few miles and a few seconds difference. No submittals of this supplement to NASA were implemented since the differences did not significantly influence the conclusions of the October 29, 2003 trajectory analysis.

The previous version of the trajectory program established altitude of zero for the end altitude in all calculations. One feature enhancement to the program was the addition of user input data for end altitude. A value of 283 feet was assumed since it is the average altitude for Nacogdoches County. However, the following tabulations show only the start altitudes.

The following tabulation of trajectory analysis simulations can be reproduced from data input into

either the C++ version or the Java applet version of my trajectory program provided at the following link:

Computer Programs

AVERAGE DISTANCE ( RUNS 1 à 6 ) = 217 MILES FOR NON-OSCILLATING MOTION

DISTANCE ( RUN 7 ) = 179 MILES FOR MAXIMUM OSCILLATING MOTION FOR ELAPSED TIME = 369 SECONDS

ACTUAL DISTANCE BETWEEN LOCATION OF ROLLER AND INITIAL ALTITUDE WAS 293 MILES

DISTANCE DEVIATION = 293 – 179 = 114 MILES IN RELATION TO RUN 7

EVENT: 114 miles from Final Condition

TIME: 13:59:56 GMT (EI + 947 ) minimum

ALTITUDE: 195000 FT

VELOCITY: MACH 16.2 ( 4.73 miles per second )

TRAJECTORY ANGLE = 2.75 degrees

The following tabulation of trajectory analysis simulations can be reproduced from data input into

either the C++ version or the Java applet version of my trajectory program provided at the following link:

Computer Programs

AVERAGE DISTANCE ( RUNS 1 à 6 ) = 139 MILES FOR NON-OSCILLATING MOTION

DISTANCE ( RUN 7 ) = 112 MILES FOR MAXIMUM OSCILLATING MOTION FOR ELAPSED TIME = 343 SECONDS

ACTUAL DISTANCE BETWEEN LOCATION OF ROLLER AND INITIAL ALTITUDE WAS 114 MILES

DISTANCE DEVIATION = 114 – 112 = 2 MILES