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Overview of Anomalous EventsDuring Columbia's Reentry 

Page A 

Updated 10/1/010 

 

Breakup and Debris Field

 

Page Notes:

Because this site may be considered controversial by some people, out of respect for the astronauts and their families nophotos of the astronauts or attempted memorials will be posted on this site. The names of the astronauts will only be usedwhen absolutely necessary to the investigation.

Columbia's Reentry During STS!"#

$eneral reentry e%planation&The simplest e%planation of what occurs during a Space Shuttle reentry is a careful balance of three things.

!. The rate of descent.

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. (erodynamic heating.

). Decreasing forward velocity.

*f the shuttle descends too +uicly through an increasingly dense atmosphere it will suffer e%tensive thermal damage that may burnthrough the sin of the orbiter resulting in its loss. *f its forward speed is not decreased sufficiently or if it has not descended to thecorrect altitude at the right time, it will not be in the proper position for landing and will either have to land at an alternate site or

crashed into an unpopulated area after the crew has escaped.

 

Eqn. A1Reentry !lig"t Control #arameters

1.) 1Heating Rate Equation

 

Qmax  < ! Btu " Ft.#$%e&.

k   ' (.(*+1**,1!$*

 

' $as Density -%lugs " Ft.)

V  % &eloity -Ft. " %e&.)

#.)  Nor/al A&&eleration Equation

an '  L cos α -  D sin α an max  < #.+ 0

 L  ' Aerodynami (ift) *ee E+n) A,-1

 D  ' Aerodynami Drag) *ee E+n) A,- 

α 

' Angle of Atta.  -Degrees)

.)  Dna/i& Pressure Equation

q ' 1 "# ρV  #qmax < !! ps2 

 

' $as Density -%lugs " Ft.)

V  % &eloity -Ft. " %e&.)

1. Deter/ined e/piri&all during %pa&e %3uttle 2lig3ts and is based on a one di/ensional adiabati& stead state 3eating /odel. 4t is t3e

3eating rate 2or stagnation regions o2 t3e s3uttles sur2a&e during 3ig3 5a&3 nu/ber reentr at/osp3eri& 2lig3t.

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Eqn. A#

*i Degrees of !reedom E+uations for *pae *"uttle Reentry 

 

r c  Distane from enter of 

Eart" to ve"ile C)$) !t)

Θ

€

$eodeti (ongitude)

 

€

$eodeti (atitude)

V r   2"e Eart"'s relativeveloity) !t)/*e)

γ

€

!lig"t pat"

angle) Deg)

Ψ

€

&eloity A3imut"

angle) Deg)ω

€

Eart"'s rotation

rate) Deg)/*e)

σ€ &e"ile ban. 

angle) Deg)

Eqn. A

(ift and Drag E+uations

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+.)  C  L0  ".!//0"

.)  C  L1  "."0/

.)  C  D0   "."#12/

6.)  C  D1  3.!20"4!"5$

*.)  C  D   3.!/"14!"5$(

 L   Aerodynami (ift) 

 D   Aerodynami Drag)

ρ

€

$as Density -%lugs " Ft.)

V    &eloity -Ft. " %e&.)

 S ref *"uttle referene surfae area -#7*! Ft.#)

m = 4ass of s"uttle -#!7!!! lbs.)

C  L  Coeffiient of (ift) -5a&3 8 #.+)

C  D  Coeffiient of Drag) -5a&3 8 #.+)

α  Angle o2 atta&k Degrees

 

To help eep the aerodynamic heating to a minimum the shuttle has an e%tremely shallow rate of descent. ( typical reentry startswith the shuttle at an altitude of #3 miles and a distance of 2,"3) miles from the landing site this is e+ual to a rate of descent of only!.26, see "Reentry Aerodynamics" , in the document, Shuttle78light79roperties.pdf . :owever, simply flying with a constant shallowrate of descent isn't enough due to changes in the properties of the atmosphere as you drop through it as well as local weatherconditions. To accomplish the feat of eeping temperature distance and velocity in perfect balance, the shuttle also has a suite ofcomple% guidance software that taes it through a few fairly simple flight maneuvers designed to eep all of those factors in perfect

balance. By taing sensor reading from different areas of the shuttle and the outside atmosphere for temperature and pressure, aswell as being fed other data such as current altitude and distance from the landing site, the shuttle's computers calculate the correcttime to perform the maneuvers. ( human pilot can not tae all this data and mae all the calculations fast enough to control theshuttle through the critical phases of reentry. *t has been estimated that increasing the rate of descent ;ust a few percent at thewrong time could lead to a worst case scenario. This is why the shuttle must be on auto pilot for most of reentry and also why the

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avionics system is so important that it has a total of five identical flight computers and no less than two bacup units for every otherflight critical system.

5ap o2 9.%. i/e ;ones.

2ime 5ones

Clicing on the image to the left will bring up anenlarged map of <.S. Time =ones with a table

defining how to calculate the times for the different>ones.

 ( similar map showing time >ones around the worldis also available.

orld i/e ;ones

8ebruary !, "") STS!"#&?yewitness accounts of the Columbia's last few minutes indicate that the shuttle was losing material from very early on during

reentry. Some initial accounts report debris shedding being spotted by ground observers at 2&/2 a.m. 9ST This was probably notpossible when the shuttle was high over the middle of the 9acific @cean. @ther accounts and at least one video tape made inCalifornia at 2&2) a.m. indicated that debris was coming off the shuttle at that point. Some witnesses said it looed lie the shuttlewas, Adropping flaresA, as it flew over California. (t this time the shuttle was at an altitude of )),/2" 8t. and had ;ust barely reachedits ma%imum temperature. This would tend to indicate that damage was being done to the shuttle well before 2&2) a.m. and wellbefore the ma%imum temperatures were reached. This is also the point where temperature anomalies and sensor problems startedto be noticed.

Deorbit burn& (t !6:1+:! a./. E% -1:1+:! 05) the Columbia initiated deorbit burn for minutes and )1 seconds to position itself for ?ntry*nterface 4?*5.

STS!"# Reentry Data

Pre De$orbit burn data

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• =rbit 4n&lination: *>

• ?o&ation -latitude"longitude in degrees): $+.!!!!! %. " 6+.!!!! E.

• i/e: 1:1+:!! 05

• Altitude: *#*7!1 Ft. 167)87 statute miles

• @elo&it: 17(* /p3 79::1 !t)/*e)

Post De$orbit burn data• =rbit 4n&lination: *>o ;o "ange

• ?o&ation -latitude"longitude in degrees): $.+6 %. " *6.1 E.o C"ange< 676),8 statute miles• i/e: 1:1:6 05o =urn duration< <,> 

• Altitude: *#*7!1 Ft. 167)87 statute mileso ;o "ange• @elo&it: 171*. /p3 79?01 !t)/*e)

o C"ange in veloity< - 16: mp" 

?ntry *nterface 4?*5&?ntry *nterface then began at 1:((:!* 05. ?ntry *nterface is defined as the point when the shuttle has attained, or descended to,an altitude of /"",""" 8t.  per t"e Reentry  doument on t"e ;A*A @uman *pae !lig"t ebsite)

STS!"# Reentry Data

Entr 4nter2a&e

• ?o&ation -latitude"longitude in degrees): !.61 N. " $1.++( .

o 3ange +6!.!! statute /iles

• i/e: 1:((:!* 05

o 3ange !!:#:1

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• Altitude: *+7!1! Ft. -(.61 statute /iles)

o 3ange +(!! Feet

• @elo&it: 5a&3 #(.+ , -speed o2 sound Alt. ' 17(1 Ft."%e&.)  ' +71(+ Ft."%e&. -#7* /p3)

o13ange C*7( Ft."%e&. -+ /p3)

• Reentr Angle setup beteen De$orbit Burn and E4 ' !.((>

o A2ter E4 t3e angle is tpi&all adusted to beteen 1 and 1.+.

1. 4t is unknon 3 t3e in&rease in Gelo&it beteen t3e end o2 t3e deorbit burn and E4 is so great. 42 it is not anerror it /a b a bprodu&t o2 t3e entr pro&ess. 3e Galue ill be &3e&ked 2urt3er until it is &on2ir/ed.

Reentry flight maneuvers&The shuttle crew initiated the @9S )"/ guidance program at 2 minutes prior to ?* per the STS!"# reentry instructions, see the flightdocuments ?ntry7chec7list7STS!"#7a.pdf  and ?ntry7chec7list7STS!"#7b.pdf . @9S )"/ is a closed loop guidance programdesigned specifically to control the shuttle through the pea heating phase of reentry from E4C(!! to E4C1#!!, see 8ig. (!" for thedefinition of the pea heating region. @9S )"/ uses closed loop feedbac to determine when and where to initiate the Roll banmaneuvers that reduce the rate of descent and bleed off the e%cessive forward speed. Because the RCS Roll ;ets are deactivated

at bar !" psf the shuttle uses the elevons and aw ;ets to perform maneuvers. The basic operation of the @rbital EaneuveringSystem 4@ES5 and RCS are described on page Technical @verview of the Space Shuttle @rbiter .

Fig. A1

8ig. (! to the left depicts a typical SpaceShuttle reentry. 2"e area inside t"e redretangle represents t"e final approa"and landing p"ase s"own in Fig. A.  *fColumbia had made it to this part of reentry itwould have had to mae a #"F right hand

turn in order to land on Gennedy SpaceCenter's runway )) at *:1 E%. as wasanticipated.

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Fig. A# 8ig. ( shows the two typical flight paths across the <nitedStates for landing at Gennedy Space Center 4GSC5 dependingon the shuttle's orbital inclination. 8or STS!"# the orbitalinclination was )0F and the associated flight path would havebeen the Ea%imum Hesterly (pproach.

Based only on this diagram, it would appear that the Columbia

was significantly off course during the STS!"# reentry whencompared to what is considered to be the typical nominalEa%imum Hesterly (pproach flight path. :owever, it is unnownif the Space Shuttle follows the e%act same flight path every time

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or if the path is dependent on the particular circumstances of theflight. Therefore the Columbia may not have been off course atall but the possibility is presented here only for discussionpurposes.

 

Fig. A

 

8ig. () shows how the Space Shuttle maes its final approach to

land at GSC on runway )) which was the designated runway forSTS!"#. Hhat is most notable is the #"F right turn the shuttleneeds to mae in order to land.

 

Fig. A#  A are 2ro/ NA%A do&u/ent F%$#!!!$!+$!$I%

(anding t"e *pae *"uttle Orbiter at B*C

 

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Detailed Des&ription o2 Flig3t 5aneuGers in t3e Entr %ubp3ase o2 %pa&e %3uttle Reentr2a.en from t"e ;A*A *pae *"uttle referene manual setion on reentry )

 Also available "ere *pae *"uttle Reentry ) 

$uidance performs different tass during the 1Entry , #2AE4  and  Approa" and (anding  subphases. During the 1Entry  subphase, guidanceattempts to eep the orbiter on a tra;ectory that provides protection against overheating, overdynamic pressure and e%cessive normalacceleration limits. To do this, it sends commands to flight control to guide the orbiter through a tight corridor limited on one side by altitude andvelocity re+uirements for (Ranging  (in order to make the runway) and orbiter control and on the other side by thermal constraints. (Ranging  is

accomplished by ad;usting +Drag Aeleration to velocity so that the orbiter stays in that corridor. +Drag Aeleration can be ad;usted primarilyin two ways& by modifying the  Angle of Atta. 9 which changes the orbiter's crosssectional area with respect to the airstream, or by ad;usting theorbiter's =an. Angle9 which affects lift and thus the orbiter's 6*in. Rate into denser atmosphere, which in turn affects drag. <sing  Angle of Atta.  as the primary means of controlling drag results in faster energy dissipation with a steeper tra;ectory but violates the thermal constraint onthe orbiter's surfaces. 8or this reason, the orbiter's =an. Angle Roll ontrol is used as the primary method of controlling drag, and thus(Ranging 9 during this phase. *ncreasing the *Roll Angle decreases the vertical component of lift, causing a higher 6*in. Rate. *ncreasing the1!Roll Rate raises the surface temperature of the orbiter, but not nearly as drastically as does an e+ual  Angle of Atta.  command. The orbiter's Angle of Atta.  is ept at a high value 4/"I5 during most of this phase to protect the upper surfaces from e%treme heat. *t is modulated at certaintimes to ''twea'' the system and is ramped down to a new value at the end of this phase for orbiter controllability. <sing ban angle to ad;ust+Drag Aeleration causes the orbiter to turn off course. Therefore, at times, the orbiter must be rolled bac toward the runway. This is called a11Roll Reversal  and is commanded as a function of a>imuth error from the runway. The ground trac during this phase, then, results in a series of Sturns. 

e&3ni&al Footnotes:

1. Entr:3e 2irst subp3ase o2 reentr 2ro/ E4$+ /in. to 3ere Ge3i&le is traGeling at #+!! Ft."%e&. -67!!! Ft. altitude).

#. AE5 -er/inal Area Energ 5anage/ent):3e se&ond subp3ase o2 reentr begins at #+!! Ft."%e&. to altitude under 1!7!!! Ft.

. Approa&3 and ?anding:3e t3ird subp3ase o2 reentr 2ro/ under 1!7!!! Ft. altitude and t3e s3uttle lined up it3 runa and ends it3 orbiterseig3t on nose gear a2ter tou&3don.

(. Ranging:3e pro&ess 3ere t3e s3uttleJs guidan&e sste/ &ontinuousl &al&ulate t3e required altitude and Gelo&it based ondistan&e to t3e runa.

+. Drag A&&eleration:3e p3si&al 2lig3t para/eter adusted to a&&o//odate t3e results o2 t3e Ranging &al&ulations7 Optimum value is,,!t)/*e) )

  Adusted using eit"er Angle of Atta. or =an. Angle.

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. Angle o2 Atta&k:Angle beteen an air&ra2ts longitudinal a,is and its dire&tion o2 traGel.

. Bank Angle:Rotation about Ge3i&le Gelo&it Ge&tor -dire&tion o2 traGel).

6. %ink Rate:An air&ra2t rate o2 des&ent into t3e at/osp3ere.

*. Roll Angle:

Rotation about Ge3i&le longitudinal K a,is.1!. Roll Rate:

3ange in Ge3i&le Roll angle it3 ti/e.

11. Roll ReGersal:urns s3uttle ba&k toards runa to &orre&t Bank Angle error.

 

Critical Systems 8ailures During ReentryJ(S('s STS!"#TimelineRev!2.%ls ?%cel file gives a detailed list of anomalous events as they occurred. That data was then usedto create a ground trac presentation in STS!"# $Trac Rev !2.pdf .

Fig. A( *f we had to state a time and location whereColumbia's fate was sealed for the STS!"#mission, it would not be somewhere over the (tlantic shortly after launch on Kanuary !3,""). *t would instead be at 1:(:# EF0, over the middle of the 9acific @ceanat an altitude of 01,//3 8eet during her

reentry, see 8ig. (/.

Hhat maes this location so suspect is that itwas the end of both Laurel Clar's crew cabinvideo and mared the end of any and all

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significant voice communications with EissionControl :ouston. The Space Shuttle had notlost voice contact with Eission Control to suchan e%tent since the Tracing and Data RelaySatellite TDRS system was put in place in theearly nineties. Typically the shuttle's avionicssystem would find a suitable bacup for the

voice transmitter and bring it on line, but thatdidn't happen during STS!"#.

By 1:+!:!! data transmissions from theshuttle were being affected as well. Hithintwo minutes after that the bits of data thatwere getting through indicated off nominalaero increments that were not being correctedby Columbia's avionics systems.

Communication failures&

The first events were loss of communication from the e%ternal SBand antennas. 8ig. (2( and (2B show the location of all e%ternal (ntennas on the Columbia. The purpose and operation of the SBand antennas is further e%plained in, ?ffects of hypersonic flowduring reentry of the Space Shuttle, Communications& and Technical @verview of the Space Shuttle @rbiter 4(vionics andCommunications Systems5, Communications Systems.

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Fig. A+A

 

Fig. A+B

 

Table (! lists all of the communication loss events between the shuttle and mission control which resulted in the missing data shownin the Time Line documents. ?ach event includes the time, duration and what hardware was involved. Hhat is not shown in the

chart is the omplete loss of voie ommuniation after 1,<?6<,)  (lthough this was the most significant anomalouscommunication failure none of the official investigation documents mention anything about it. *t is unnown why the shuttlecontinued to transmit telemetry data and not voice communications. ( possible reason is that voice communications are carried onthe SBand 9E two ways system while data is typically carried on the SBand 8E system which transmits only and cannot receive. (nother possibility is that what ever affected electronic systems onboard the orbiter had a much greater affect on microphonecomponents than other systems. See, Technical @verview of the Space Shuttle @rbiter 4(vionics and Communications Systems5 ,Communications Systems.

3is nes stor &on2ir/s 3o un&o//on su&3 a loss o2 &o//uni&ations is at t3is point in our spa&e progra/7  G 2"e *"uttle=la.out 4yt" #ersistsG .

The crew cabin video released by J(S( is said to have come from a video tape in a camcorder which survived breaup and was

found in the debris field. This video is available for viewing on various news sites, CBS news Space Shuttle reentry video. *t canalso be downloaded from *nside GSC.com here Crew Cabin &ideo 100 4=)

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Sensor failures&The ne%t events were the beginnings of sensor anomalies. The STS!"#7?vent7Se+uence.pdf   document from J(S( containsdiagrams that show the time and location of the various sensor failures and off nominal readings. The document STS!"#7Sensor78ailure.pdf  contains similar information but is an older version. Jote that both documents were released before the@?M data recorder was found and therefore neither contains the @?M data that has been determined to be +uestionable and mostliely fabricated. Because many of these events are mentioned during reentry by Eission Control personnel it may be possible toverify the data by comparing the events to the transcript of voice communications in the STS!"#7Reentry7Te%t7K.pdf  document.

Fig. A 8ig. (3 is a modified version of the imagethat is published with STS!"#7?vent7Se+uence.pdf . The diagramgraphically shows the appro%imate M location of all the affected sensors groupedand color coded by their associated wiringcable harnesses.

Table ( is a summary of sensor activity from?* to L@S 4Los @f Signal5 that is taen fromthe same document as the image. Thenumbers on the sensors in the imagecorrespond to the numbers in the columnlabeled %ensor Re2. No.  and are the sameas used in, STS!"#7?vent7Se+uence.pdf .The numbers do not correspond to the orderof events.

The most pu>>ling of the sensor anomalieswere those monitoring the supply water

dump no>>les and the vacuum vent near theforward fuselage. The suspected breach ineither RCC panels 1 or 0 is too far from theseto have effected the units or their sensors

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Fig. A is 2ro/ %%$1!L EGentL%equen&e.pd2  released b t3e .A.4.B. on !"1("#!!. 3ei/age 3as been /odi2ied slig3tl to proGide /ore in2or/ation in a &o/pa&t 2or/at.

and wiring.

8ig. (3 shows the temperature sensor cable harness for hydraulic systems !, and ) return lines as having a close pro%imity to theleft wing leading edge near RCC panels #, 1 and 0, the e%act location of the wing breach that e%ists in the C.(.*.B.'s failurescenario. This is why the investigators concluded that the wiring harness was attaced by heat which caused the anomalies that

were recorded, (see Table (N Events 1, 7, 8, 9, 10 and 1).

t "as been s"own on t"is site t"at t"e *pae *"uttle left wing wiring diagrams su" as t"at s"own above in Fig. A werereated after t"e Columbia disaster for use wit" t"e offiial investigation) 2"ese diagrams portray sensor able routingst"at are not aurate) 2"e sole purpose of t"ese diagrams is to furt"er legitimi3e t"e eistene of a brea" in t"e leading

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edge of t"e s"uttle's left wing and point diretly to it as t"e soure of reentry sensor eletrial anomalies) 2"e differenesbetween t"e wiring diagrams dotored by t"e C)A))=) and t"e atual wire and able routing used on all t"e s"uttles islarified in detail in one of t"e *pae *"uttle te"nial setions)  %ee7 Technical @verview of the Space Shuttle @rbiter 4Hings,Tail, Body 8lap and Control Surfaces5, Hiring harness routing.

 (vionics failures&Jothing is mentioned in either the STS!"# Timeline or STS!"# $round Trac documents about failures of the $eneral 9urposeComputers 4$9C's5 or any other of the flight control systems or avionics e+uipment onboard the Columbia. The space shuttle hasfive general purpose computers that are all identical. 8our of the computers are loaded with the same software for guidance,navigation and control which is produced by 9(SS. The 9(SS software is broen down into @9S programs that control everythingthe space shuttle does from launch to wheel stop. The fifth computer is loaded with Bacup 8light Software 4B8S5 that is producedby a different company. This software is only used in the event that the four main computers are off line. The B8S can be initiatedeither by another $9C or manually by the pilot.

8light Control and $uidance 8ailures During ReentryThe final report on the Columbia disaster produced by the C.(.*.B. traces all anomalous events during the reentry of STS!"# to abreach in one of the leading edge RCC panels of the left wing. This report states the breach as being in panels #, 1 or 0 andassumes that it is a ! to !/ inch wide hole in the top part of the panel, see 8ig. (3. *t has already been shown that the officialinvestigation altered the location of sensor wires to help legitimi>e the breached wing scenario, see the Sensor failure section aboveand the technical section on Hiring harness routing. The following detailed analysis of what was happening to Columbia's flightcontrol system between 1:(:!! and 1(:!!:!! also indicates e%tensive attempts to force the evidence to follow the breached wingscenario. This is done by ignoring important data or distorting other data as well as the results of technical analysis. Hhen all of thedata is considered and analy>ed from an ob;ective point of view, the cause of the Columbia disaster appears to lead in the directionof multiple system failure rather than e%ternal damage.

 (erodynamic events and attitude corrections&

An tele/etr data re2erred to in t3e 2olloing se&tion &an be re2eren&ed 2ro/ eit3er %%$1! i/eline-ReG1+) or %%$1! 0round ra&k -ReG1+).

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The earliest now Ao!! nomina A e%ternal event7 t"e nature of t"is event is never eplained7 during the STS!"# reentry occurredat 1:+1:1*. 9rior to this there was some type of multi system failure at 1:(:#, see 8ig. (/.  (fter this the reentry flight wasplagued by ever increasing off nominal aw and Roll aeromoments. (t 1:+1:( the Time Line and $round Trac documentscontain the following entry,

4nertial sideslip angle -Beta) goes and stas NegatiGe until ?=%

3ile t3e /agnitude o2 t3e obserGed Beta is not outside t3e 2lig3t 3istor -(10 (#)7 t3e al/ost linear negatiGe ra/p prior tot3e 2irst Roll reGersal is not &onsistent it3 ot3er 2lig3ts reGieed. 3is is &onsistent it3 a negatiGe rolling and aing torqueon t3e Ge3i&le.

The interpretation of the above statement is that the value of this sideslip angle is no better or worse than what has been measuredin previous flights and is therefore considered to be within the nominal range. :owever, the fact that this negative Beta or negativeaw continues with no attempt by the shuttle's Digital (uto 9ilot 4D(95 to correct the flight path is not normal. The C.(.*.B.'se%planation for the negative aw is that the breach on the leading edge of the left wing resulted in e%cessive aerodynamic drag onthe left side only, forcing the shuttle to turn in that direction. *f we continue to follow the C.(.*.B.'s scenario, we can assume that theonly thing wrong with the Columbia when she reentered the atmosphere was the wing breach. Therefore all of the orbiters othersystems should be without damage and functioning normally. @ne could then only assume that the drag force related to the wingbreach went beyond the ability of the shuttle's flight control system to compensate and reestablish the correct flight path. :owever,

the fact is that the D(9 itself made absolutely no attempt to reorient the shuttle. 

 (n analysis of the control surface motions and RCS ;et firings occurring between 1:+1:( and 1:+*:! listed in able A do notappear to be an attempt to correct the flight path.   (ll of the events that occurred during that period of # minutes and // seconds arebrief, random and unrelated. The only real attempt to correct Columbia's attitude did not occur until 1:+*:! when the shuttle'sautopilot suddenly shut down and the RCS aw ;ets fired for a full 1 seconds in an obvious attempt to correct the negative aw angleand bring the orbiter bac under control. <nfortunately the calculations done in e&3ni&al Arti&le A$A# shows that the 1 second ;et firing overcorrected the negative aw to a full 0"I positive aw placing the shuttle with the left wing facing fully windward. Theerror messages near the end of the Time Line referring to the Left RCS system, # R$% #EA&  and # R$% ' , would seem toindicate that there was no chance of using the Left RCS Kets to recorrect the positive aw. The result of this calculation would notbe provable e%cept for a close analysis of the olon @ideo seen in e&3ni&al Arti&le A$A which appears to show the Columbiafor the few seconds between the aw ;et firing and orbiter breaup flying sideways with the left wing still intact and facing windwardagainst the hypersonic flow.

2"e left wing disintegrated first beause it was eposed to t"e "ypersoni flow in a manner t"at eeeded its design limits9not beause a brea" in t"e leading edge reated a wea. spot t"at beame eploited) e also .now t"at t"e Haw and Roll

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trends did not ontinue until (O*9 and t"at t"e RC* ets were powerful enoug" to ounter a drag fore from t"e left wing ifit eisted)

The inability of a space shuttle to mae a simple course correction during any point in reentry is an indication that the full array of 2$eneral 9urpose Computers $9C's failed simultaneously. *t is also an indication of partial or full corruption of the main flightsoftware routines as well as the bacup flight software. The design incorporating 2 identical $9C's as well as bacup flight softwareis in place to negate the possibility that a space shuttle is ever left without flight critical avionics. Something completely une%pectedand unaccounted for attaced the hardware onboard the shuttle so +uicly and completely that not one of the astronauts or any ofthe flight engineers at Eission Control were aware of the conse+uences. By observation it appears that whatever happened to theColumbia began at appro%imately 1:(:!, see 8ig. (/, with the severest e%tent of the damage complete between 1:+!:!! and1:+1:!!.  That is the defining line between normal reentry flight operations and the complete breadown of critical avionicssystems.

Fig. A 8ig. (# is a visual definition of sideslip. (s the Space Shuttledescends through the atmosphere it reaches a point where significantincreases in atmospheric density result in a much greater rate ofaerodynamic heating. This heating effect is controlled by slowingdown the rate of descent and bleeding forward speed as possible.This is accomplished through the use of flight maneuvers.

The typical shuttle reentry involves / Roll maneuvers and / RollReversals. The Roll maneuvers causes sideslip which results in theorbiter being off course. The Roll reversal maneuvers are performedto put the shuttle bac on its proper flight path.

Fig. A6 8ig. (1 describes how the negative Beta is controlled and used to rollinto the first flight maneuver. (nother method for slowing down theshuttle's rate of descent and airspeed is by flying with a very large (ngle of (ttac 4(@(5. The (@( must be maintained at (!> from ?*through the pea heating region. This angle is difficult to hold and ispart of the Digital (utopilot 4D(95 reentry program. 42 t3e autopilot isdisabled t3e s3uttle ould leGel out Ger qui&kl resulting in a2aster des&ent.

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Because of this e%treme (@( the lower surface of the orbiter taes thebrunt of the heat load during reentry. Therefore the entire bottom ofthe shuttle is covered with the heavy duty blac tiles.

There is also a more natural and provable e%planation for the negative aw trend which the official report attributes to the leadingedge wing breach. During reentry the Digital (uto 9ilot 4D(95 running the @9S)"/ reentry flight control and guidance programmaintains the (ngle of (ttac 4(@(5 at /"I and calculates the correct time to initiate the flight maneuvers. The first flight maneuverwhich is a Roll to the right was initiated at 1:(*:# and is started by lowering the left elevons a few degrees. Because the (@( isdifferent from any other aircraft, the result of this command to the aero surface is a negative aw rate and a positive Roll rate or aroll to the right. The maneuver was initiated ;ust after the multi system failure began at 1:(:!, and ;ust prior to what seems to be

its completion at 1:+!:!!.  Jormally the aw and Roll would be controlled so the maneuver could be completed but the flight controlsystems may have become too damaged. ( good indication that the maneuver was not completed is that the time of completion ismissing throughout the final report and all associated documents. (n incomplete Roll Eaneuver would have left the Columbia withthe left elevon e%tended downward by a few degrees resulting in a constant negative aw rate and positive Roll rate as shown in8ig. (0. Therefore it is a distinct possibility that the aw and Roll trends were the result of an uncompleted flight maneuver.

 (nother and far more serious problem resulting from the loss of flight control and especially the D(9 that early in reentry would bethe inability to maintain the (@( at /"I, see 8ig. (1 above. The shuttle's natural aerodynamic tendency is to level out flat if nothingis constantly maintaining the (@( at /"I. *f no flight maneuvers are performed during reentry and the shuttle flies with the (@( or9itch angle "I it will descend far too fast through the atmosphere and be sub;ect to e%treme thermal attac on the T9S. Thedescent flight path of the space shuttle should loo something lie the altitude curve of the chart in 8ig.(!". Hhen the space shuttlesets itself up for reentry it initially enters the atmosphere with an angle of descent that may seem very small but is essentially theangle that would cause the shuttle to intersect the ?arth at its landing location. The angle is usually around !I, STS2 happened tobe !./I. Hithout any additional input from the flight control system the shuttle will descend straight through the atmosphere withoutstopping the descent to bleed off some of its forward speed. This is what is happening in 8ig.(!" while the shuttle is passing

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through the pea heating region. The official investigation didn't say much about the (ngle of (ttac e%cept that it didn't seem lie aproblem for them.

Fig. A*

Fig. A* is 2ro/ a .A.4.B. press presentation on !("#"#!! pb$#!!!(!6$!1a.pg.

8ig. (0 is a graphic from one of the C.(.*.B.technical presentations that were held once ortwice a month to bring the press up to date onthe progress of the investigation. The graphic

has been altered slightly with the addition of thered lines and te%t indicating event times anddescriptions. Because the chart has no units andno detailed e%planation in the accompanyingreport te%t, its e%act meaning and relationship toColumbia's attitude are unnown. *ts only valueis in showing Roll and aw trends over thecourse of reentry.

Table () lists all of the RCS ;et firings duringreentry along with changes in position of the

control surfaces, left and right elevons, bodyflapand speedbrae, (*ue te+t reates to controsur!aces and R$% et !irin-s). (ll of the data inTable () comes from STS!"#TimelineRev!2.%ls which also lists times when certainflight maneuvers were made. These flightmaneuvers are also listed in the table forcomparison with other data.

The flight data used by the C.(.*.B. and which appears in the official final report also contains another glaring discrepancy. The TimeLine and $round Trac documents list a time that the first flight maneuver, a Roll to the right, was initiated as being 1:(*:#, but atime for the completion of the maneuver is not stated, see the preceding paragraph. The documents then list another flightmaneuver which is a Roll Reversal initiated at 1:+:! and completed at 1:+:++.  :owever, the chart in 8ig. (0 indicates that the

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off nominal aw and Roll trends continued throughout reentry including the period of time when the Roll reversal was performed.2"erefore t"ese two statements from t"e offiial final report are in star. ontradition to one anot"er) Eit"er t"e Columbia performed flig"t maneuvers during reentry9 or9 it ontinued yawing and rolling in t"e same diretions as t"e "art in !ig) A8below s"ows) =ot" statements annot be true) 2"e addition of t"e seond flig"t maneuver was probably an early attemptto ma.e t"e *2*-106 reentry appear more normal up to a point)

?yewitness (ccounts

Crossing over Jevada, <tah, (ri>ona and Jew Ee%ico&Chris Oalentine is another individual who has done a great deal of wor combining and overlaying images to get a better idea ofwhat happened to Columbia during reentry. Some graphics he has created such as a compilation of the many amateur videos ofColumbia's breaup have been featured on news reports and have been used for official training purposes. Some of his data maybe able to tell us how the Columbia was flying through that period of reentryN anaysis !oows.

Crossing into Te%as&Chris Oalentine's video tracs the Columbia through most of the shuttles travel across the <nited States from ;ust ?ast of the

California border to nearly where the orbiter enters Te%as. Jot only is this an important piece of evidence because he captured somany events of debris shedding, but it also maes the transition from observing the Columbia crossing the dar night sy into earlymorning light in Te%as where many of the videos that captured the final breaup were shot. <nfortunately there does not seem to beany video of Columbia from ;ust before she entered Te%as until ;ust after L@S where several different videos all seem to capture thesame events. (mong the many amateurs recording the Columbia's breaup after L@S that day were a pair of not so amateur Dutch (:3/ pilots training near 8ort :ood who ept the (paches gun site camera trained on the Columbia debris for as long as possible.*t is unnown if the pilots who were in (merica for training new what they were watching at the time. *t is possible they were waitingto catch the incoming shuttle on the attac choppers advanced 8L*R sensor.

Sonic booms& (ll eyewitness accounts of the shuttle disaster are virtually identical for those residents living within the area that maes up the last

)/ of the debris field. The first odd occurrence that caught the attention of many residents of Kacsonville, Jacogdoches Countyand :emphill Te%as very shortly after 1&"" a.m. CST on the morning of 8ebruary !, "") was a very loud twin sonic boom followedby a rumbling that many of them described as feeling as if they were standing ne%t to a freight train. The first person to produce awritten statement of what happened the morning of 8ebruary !st, "") lives in Ma&ksonGille e,as. The web page can be accessed

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at http&www.tyler.netbone;bafeb"!").html. This account states that the sonic booms started at e%actly 1&"! a.m. CST with thefollowing rumble lasting for at least )" seconds.

 (nother account written by Kohn 8rederic of Na&ogdo&3es e,as is very similar to the first e%cept he states that the sonic boomsbegan at 1&"/ a.m. :e described the sound as, a large =OO4 followed by a seond smaller =OO4 , which would indicate thatit was not the +uic succession of two booms about a half second apart. This could be taen to mean that something washappening to the shuttle at the moment the shocwave events occurred. The Space Shuttles twin sonic booms are similar to that of

any super sonic swept wing aircraft where the initial event is the shocwave from the nose of the shuttle and the second is from therear of the swept wings and or tail section. This is another personal account written by a Na&ogdo&3es resident, Sharon Gasper .

The booms were followed by a loud rumbling event that is not at all typical of a shuttle landing. (gain Kohn 8rederic's accountstates that it was, an etended rumble I roar t"at s"oo. our "ouse for at least 0-,0 seonds.  The time period of " to )"seconds is probably accurate based on statements by many people who said they had time to run to different rooms of the houseand outside while it was happening. @ne possibility for what caused the loud rumble is the many separate shocwave that werecreated as substantial pieces of debris broe away from the main body and passed overhead at supersonic speeds. 8rom the videocompilation on Chris Oalentine's website the three main engines can be seen +uite clearly separating from each other and continuingon to impact in Louisiana. The difference in the times when the sonic booms were heard can be accounted for based on the traveldistance from Kacsonville to Jacogdoches as well as a decrease in velocity of the debris itself. This is assuming that someone's

cloc was not off the correct time by more than a few seconds. (ll of the sonic boom witnesses also reported debris falling in theirareas immediately after the event, perhaps within a minute

NN ani/ation: olu/bia oGer e,as *oni booms during *pae *"uttle reentry 

3is te&3ni&al arti&le 2ro/ t3e NA%A ebsite7 %3uttleLReentr.pd2 7 e,plains 3o t3e %pa&e%3uttle tpi&all reenters Eart3s at/osp3ere listing t3e Garious p3ases o2 2lig3t et&. 3edo&u/ent states t3at t3e s3uttle does not enter subsoni& 2lig3t until it 3as rea&3ed analtitude o2 (*7!!! 2eet and is about #+ /iles 2ro/ t3e runa. 3en t3e s3uttle is aboGe+!7!!! 2eet Ger little o2 t3e soni& energ rea&3es t3e ground.

3ere2ore people on t3e ground usuall onl 3ear t3e soni& boo/s 3en t3e s3uttle isbeteen 6!7!!! and (*7!!! 2eet. EGen t3en ou ould onl re&ogniOe it as a soni& boo/

2ro/ t3e s3uttle i2 ou ere listening 2or it. 5u&3 o2 t3e ti/e at t3ose altitudes t3e soni&boo/s are barel audible and /ost people donJt 3ear t3e/ at all. 3e 2a&t t3at so /anpeople liGing near 3ere olu/bia broke up 3eard t3e soni& disturban&e so pro/inentlould al/ost &ertainl /ean t3at t3e olu/bia as /u&3 loer t3an #!!7 2eet 3ens3e broke up7 -see able A()7 and /a 3aGe eGen been belo +!7!!! 2eet.

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• A more omplete eplanation of s"o. wavesand soni boomse&3ni&al Arti&le: A$A( %3o&kaGe For/ation and %oni& Boo/s

L@S, @rbiter Breaup and Debris 8ield

L@S and breaup&

9PDAE: !#"1+"#!!(

*t has since been determined that the spread sheet and graph of Table (/ and 8ig. (!" do not accurately represent STS!"#. The true altitude data from STS!"# was replaced with either nominal data or data straight from another shuttle

mission such as STS2. This was part of an effort to maintain a cover story that Columbia was flying normally for most ofreentry.

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 (ll that can really be determined about the actions of the people involved in Columbia's reentry and breaup is that no one seemedto be alerted to the impending disaster. The document, STS!"#7Reentry7Te%t7K.pdf , is a transcription of all of the released verbalcommunications between the Columbia and Eission Control at :ouston Space Center as well as between the Columbia crewmembers. The official final report leads us to believe that the foam strie and the possibility that the T9S somewhere on the orbiterhad been severely breached was widely discussed with great concern among J(S( personnel as well as between flight engineersand the shuttle crew. This is at odds with the crew cabin video, Crew Cabin Oideo !"" EB, from the first half of reentry that showssmiling astronauts going through reentry checlists and commenting about the bright and colorful plasma forming outside the

windows. The transcribed communications between Eission Control personnel is also overly free of concern for the fate of theshuttle. (lthough some statements do acnowledge the relatively minor temperature increases seen in the telemetry datatransmitted to Eission Control, no mention is ever made that the cause could be a breach in the T9S. There was also no mention of the ever increasing aw anomaly depicted in the graphic from 8ig. (0

Fig. A11  (fter the complete loss of communications occurred withEission Control at 1:+*:#7 a contingency plan was put inplace for what actions to tae when the Columbia landed atits prescheduled time of 1(:1:!!.  *t ;ust didn't occur tothose tracing the shuttle that the worst had happened untilthe reports of multiple contrails and debris falling all overcentral Te%as began coming in. Jo one in Eission Control

:ouston ever used the words Gbrea"G  or Gburn t"roug"G  anytime during reentry. 8ortunately some of the bestaccounts of Columbia's final minutes come from theamateur videos that have been widely seen. *f anyoneobserving the events in Eission Control thought that a burnthrough was happening as some later stated on television,they didn't mention it at the time.

Page Notes:

Reference documents for this page are available in the Download page under STS!"# Time Line P Reentry.

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