****Report of the PRESIDENTIAL COMMISSIONon the Space Shuttle Challenger Accident****
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****Chapter II: Events Leading Up tothe Challenger Mission****
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** **

[**10**] Preparations for thelaunch of mission 51-L were not unusual, though they were complicatedby changes in the launch schedule. The sequence of complex,interrelated steps involved in producing the detailed schedule andsupporting logistics necessary for a successful mission alwaysrequires intense effort and close coordination.

Flight 51-L of the Challenger was originallyscheduled for July, 1985, but by the time the crew was assigned inJanuary, 1985, launch had been postponed to late November toaccommodate changes in payloads. The launch was subsequently delayedfurther and finally rescheduled for late January, 1986.

After the series of payload changes, theChallenger cargo included two satellites in the cargo bay andequipment in the crew compartment for experiments that would becarried out during the mission. The payloads flown on mission 51-Lare listed in this table:

**Mission 51-L Payloads**

> - Tracking and Data Relay Satellite-B    Spartan-Halley Satellite
  - Comet Halley Active Monitoring   Program      Fluid Dynamics Experiment
    - Phase Partitioning Experiment        Teacher in Space Project
      - Shuttle Student Involvement Program          Radiation Monitoring Experiment

The primary payloads were the Tracking andData Relay Satellite (a NASA communications satellite) and theSpartan satellite that would be deployed into orbit carrying specialinstruments for the observation of Halley's Comet.

The NASA communications satellite was to havebeen placed in a geosynchronous orbit with the aid of a boostercalled the Inertial Upper Stage. The satellite would have supportedcommunications with the Space Shuttle and up to 23 otherspacecraft.

The Spartan satellite was to have beendeployed into low Earth orbit using the remote manipulator system.The Spartan instruments would have watched Halley's Comet when it wastoo close to the Sun for other observatories to do so. Subsequently,the satellite would have been retrieved and returned to Earth in theShuttle payload bay.

** **

**Crew Assignments**

On January 27, 1985, one year before launch,NASA announced the names of the astronauts assigned to mission51-L:

**
Commander

Francis R. Scobee

Pilot

Michael J. Smith

Mission Specialist One

Ellison S. Onizuka

Mission Specialist Two

Judith A. Resnik

Mission Specialist Three

Ronald E. McNair
**

The mission commander, Francis R. (Dick)Scobee, first flew on the Space Shuttle as the pilot of mission 41-Cin April, 1984. Mr. Scobee, a native of Auburn, Washington, receivedhis bachelor's degree in aerospace engineering from the University ofArizona. A former Air Force....

 

**[**11**]**
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**Space Shuttle 51-L on Pad 39-B ofKennedy Space Center's launch complex.**

 

[**12**] ...test pilot with7,000 hours in 45 aircraft types, he became an astronaut in1978.

The mission pilot, Captain Michael J. Smith,USN, was on his first Shuttle flight after being selected as anastronaut in 1980. A native of Beaufort, North Carolina, CaptainSmith, a 1967 graduate of the United States Naval Academy, received amaster's degree from the Naval Postgraduate School. He was a Navytest pilot with extensive experience in a variety of aircraft.

Mission specialist Lieutenant Colonel EllisonS. Onizuka, USAF, from Kealakekua, Kona, Hawaii, received hismaster's degree in aerospace engineering at the University ofColorado. A flight test engineer in the Air Force, he became anastronaut in 1978 and flew on the first military mission (51-C) inJanuary, 1985, aboard the Space Shuttle Discovery

Mission specialist Judith A. Resnik, Ph.D.,flew on the first flight of the Orbiter Discovery on mission 41-D inAugust, 1984. Born in Akron, Ohio, Dr. Resnik received her doctoratein electrical engineering from the University of Maryland in 1976.After working for several industrial firms, she became an astronautin 1978.

Mission specialist Ronald E. McNair, Ph.D., anative of Lake City, South Carolina, received his doctorate inphysics from the Massachusetts Institute of Technology in 1976. Afterworking as a research physicist in civilian industry, he...

 

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**Diagram shows the scheduling ofvarious preparatory milestones in the months that preceded thelaunching of the Mission 51-L Shuttle.**

 

[**13**] ....became anastronaut in 1978 and first flew on mission 41-B in February, 1984,aboard the Space Shuttle Challenger.

Payload specialists are members of a SpaceShuttle crew who are not career astronauts. Two such specialists,Christa McAuliffe and Gregory B. Jarvis, were added to the crew ofmission 51 -L.

Ms. McAuliffe was born in Boston and raised inFramingham, Massachusetts, where she graduated from Framingham StateCollege. After teaching a variety of junior high and high schoolsubjects in Maryland and New Hamphire, she was selected as theTeacher in Space. She was assigned to the 51-L crew in July,1985.

Mr. Jarvis was a former Air Force engineer whospecialized in satellite design. He was born in Detroit, Michigan,and received his master's degree in electrical engineering fromNortheastern University in Boston. He was assigned to the 51-L crewin October, 1985, as a representative of the Hughes AircraftCompany.

The payload specialists each hadresponsibilities for mission 51-L. Ms. McAuliffe was to conduct aseries of classroom lessons from orbit and conduct several basicclassroom experiments. Mr. Jarvis was to perform a series of fluiddynamics experiments that would support satellite redesign.

** **

**Preparations for Flight**

Planning for mission 51-L began in 1984, but10 major change documents adding or deleting payload items causedsome disruption in the preparation process. Because the 12- to18-month process is a series of repetitive cycles that define aflight design in progressively more specific detail, significantchanges can require extensive time and effort to incorporate. Thecloser to the planned launch date the changes occur, the moredifficult and disruptive it becomes to repeat the cycles necessary tocomplete a mission plan. (See the Mission 51-L Milestone Summarychart.) Although there were several significant changes to the cargomanifest, most occurred early enough in the planning cycle tominimize their impact on the flight preparation.

The cargo integration review is one of thecrucial coordination meetings in the flight preparation process. Atthat meeting, requirements for all payloads are examined to ensurethat, collectively, they are within the capabilities of the vehicleand crew.

For mission 51-L, the cargo integration reviewwas rescheduled six times, primarily because of payload changes. Allmajor payload changes were made, however, before the revieweventually took place on June 18, 1985, seven months before thelaunch. Until the cargo integration review for a mission iscompleted, the development of the final flight design products cannotreally get underway. Because the mission 51-L payload changes weremade before the cargo integration review, however, changes to themanifest did not seriously disrupt the preparation cycle.

Once the principal payload items weredetermined and the cargo integration review was completed, the flightdesign process became relatively straightforward. The flight designprocess is the central element in flight preparation. The processtransforms the broad objectives of the flight into a detailedsequence of events from launch to landing. For mission 51 -L, theobjectives consisted of placing one satellite in orbit, deploying andretrieving Spartan, and conducting the six experiments. From thatbase, the flight design process produced a detailed schedule ofevents, trajectory data, requirements for consumable items,communications requirements and the necessary computer programing forthe Orbiter, the Mission Control Center, and the Shuttle simulatorused to train the crew for this particular mission.

The launch minus five months Flight Planningand Stowage Review was conducted on August 20, 1985, to address anyunresolved issues and any changes to the plan that had developed tothat point. Ideally, the mission events are firmly determined beforethe review takes place. For mission 51-L, however, Mr. Jarvis was notadded to the crew until October 25, 1985, and his activities couldnot be incorporated into mission planning until that time. The crewactivity plan, the formal flight requirements and the flight designstatus were reviewed as well as the current status of the engineeringintegration, the photo and TV requirements, and crew compartmentstowage. The Flight Planning and Stowage Review did identify the needfor further consideration of the launch window and of the thenundefined requirements for the Teacher-in-Space program.

There were changes to middeck payloads,resulting from the addition of Mr. Jarvis, that occurred less thanthree months before launch. The most negative result of the changeswas a [**14**] delay in publishing the crew activity plan. The crewactivity plan specifies the in-flight schedule for all crew members,which in turn affects other aspects of flight preparation. Becausethe NASA communications satellite training requirements were quitesimilar to those for a previous flight, the crew training began usingthat existing crew activity plan and associated checklists.Considerable time was saved as a result. The requirements unique toSpartan did not involve major departures from the standard satellitedeployment and rendezvous techniques that had been developed onmission 51-G, the experiment packages did not require any new Orbiterprocedures, and the ascent and entry techniques were standard. Thus,mission 51-L did not involve radical departures from previous flightpatterns.

The crew began training 3 7 weeks beforelaunch. Preparation in the Shuttle Mission Simulator, a fullyinstrumented mock-up of the Shuttle interior, began at launch minus36 weeks. Integrated training in the simulator, which allows the crewto train with the flight controllers who will be controlling theflight in both the Mission Control Center and remote centers, beganat launch minus nine weeks. For the crew, Shuttle simulator trainingincluded preparation for the use of the robot arm, a rendezvous inspace, Inertial Upper Stage deployment, ascent and entry procedures,and a variety of other activities.....

 

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**Graph compares training workloads ofcrews for six Shuttle missions in the nine weeks that preceded thelaunching of the space flights.**

 

[**15**] ....that must bepracticed repeatedly if a Shuttle mission is to be carried outsuccessfully.

All NASA crew members exceeded the number oftraining hours required and were certified proficient in all missiontasks. The two payload specialists also fulfilled their trainingrequirements. All mission 51 -L astronauts and flight controllerswere certified ready for flight.

From a flight design process point of view,mission 51-L was a fairly typical mission. The most noticeable effectof the delays in the production process was a delay in the start ofShuttle Mission Simulator training specific to the flight. Thattraining began at launch minus nine weeks for the crew of 51-L, twoweeks later than the original schedule required.

Compressed training time was becoming aconcern in late 1985. The crew of mission 51-L trained for an averageof 48.7 hours per week during those nine weeks before launch, withpeaks reaching 65 to 70 hours per week. Much more compression intheir training schedule would not have been possible. (See the CrewWorkload Comparisons graph.)

Launch date delays for mission 61-C alsobecame a scheduling factor for the integrated simulations for mission51-L. Originally scheduled for the third week in December, the 61-Claunch was delayed until January 12, 1986. During the last six weeksbefore the Challenger launch, the 51-L schedule was changed severaltimes as a result of launch delays of 61-C. The final impact on theChallenger crew training was reduced spacing between the ascent andentry simulations during the last two weeks before launch, but notraining time was lost.

** **

**Flight Readiness Review**

The Level I Flight Readiness Review formission 51-L took place on January 15, 1986. The Flight ReadinessReview should address all aspects of flight preparation about whichany questions have arisen. In addition, attendees confirm that allequipment and operational plans have been certified ready by theresponsible manager within NASA. Solid Rocket Booster joints were notdiscussed during the review on January 15.

The period during the day when a particularflight can be launched is determined by the requirements of theOrbiter and the payloads. The launch period for mission 51-L waslimited in order to provide the best lighting conditions forSpartan's observations of Halley's Comet. The resulting «launchwindow" was a topic of some discussion at the Flight ReadinessReview. The Challenger launch originally had been scheduled for amorning lift off. When Spartan was added to the mission, the launchwindow was changed to the afternoon. This change would have requireda landing at night if a transatlantic abort landing had becomenecessary. Because the alternate transatlantic site, Casablanca, wasnot equipped for a night landing, the afternoon launch eliminatedthat back-up site. As January drew to a close, however, theconditions for optimum telescopic viewing of the comet could not bemet. The launch window was shifted back to the morning hours so thatthe transatlantic abort site would be in daylight and a back-up site(Casablanca) would be available.

The results of the flight design process weresummarized at the Flight Readiness Review. The predicted ascentperformance, including expected trajectory, main engine throttlingprofile, expected dynamic pressure and the amount of propellantreserve expected at main engine cutoff, were presented and discussed.The expected landing parameters, weight and center of gravity figureswere also presented for a variety of contingencies. It should benoted that a waiver was required because the weight of the Orbiterexceeded the allowable limits for an abort landing. The flight designdata presented at the Flight Readiness Review are available in theAppendix in the NASA Mission Planning and Operations Team Report. Nooutstanding concerns were identified in the discussion of flightdesign.

The detailed flight plan and schedule of crewactivities also were presented at the Flight Readiness Review. TheChallenger was to circle the Earth for six days at an orbitalaltitude of approximately 153 nautical miles, landing early on theseventh day at Kennedy in Florida.

The major activities were to includedeployment of the tracking and data relay satellite 10 hours afterlaunch, deployment of the Spartan satellite on the third day of theflight and subsequent retrieval of the Spartan two days later. Asummary of the planned activities is provided in the table thatfollows.

 

[**16**] **Mission 51-L Orbital Activity Schedule**

| Day One

     |                                                                                                                                                                                                                                                                                                                                                                          | After arriving in orbit, the crew had         two periods of scheduled high activity. First, they were to         check the readiness of the NASA satellite prior to planned         deployment. After a lunch break, they were to deploy the         satellite and Inertial Upper Stage and to perform a series         of separation maneuvers. The first sleep period was         scheduled to be eight hours long starting about 18 hours         after crew wake-up on launch morning.

  |
|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Day Two

     | The Comet Halley Active Monitoring         Program experiment was scheduled to begin on the second day.         Also scheduled were the initial teacher-in-space video         taping and a firing of the orbital maneuvering engines to         place the Orbiter at the 1 52-mile orbital altitude from         which the Spartan would be deployed.

  |
| Day Three 

  | The third day was to start with the         crew programing the Spartan satellite with data sent from         Johnson. The satellite was to be deployed using the remote         manipulator system (the robot arm), and then the Orbiter         would be maneuvered to produce, by day four, a 90-mile         separation from Spartan.

               |
| Day Four           | The Orbiter was to begin closing on         Spartan while Jarvis continued the fluid dynamics         experiments started on day two and day three. In addition,         two lessons telecast live were to be conducted by Ms.         McAuliffe.

                                                                                                         |
| Day Five           | After rendezvous with Spartan, the         crew was to use the robot arm to capture the satellite and         re-stow it in the payload bay.

                                                                                                                                                                                                                  |
| Day Six            | Entry preparations were to dominate         the last full day in space: flight control system checks,         test firing of maneuvering jets needed for entry, and cabin         stowage. A crew news conference also was scheduled following         the lunch period, if requested by the NASA Public Affairs         Office.

                        |
| Day Seven          | The seventh day would have been spent         preparing the Space Shuttle for deorbit and entry into the         atmosphere. The Challenger was scheduled to land at Kennedy         144 hours and 34 minutes after launch.                                                                                                                                        |

 

[**17**] **Launch Delays**

The launch of mission 51-L was postponed threetimes and scrubbed once from the planned date of January 22, 1986.The first postponement was announced on December 23, 1985. Thatchange established the launch date as January 23, 1986, in order toaccommodate the final integrated simulation schedule that resultedfrom the slip in the launch date of mission 61-C.

On January 22, 1986, the Program RequirementsChange Board first slipped the launch from January 23 to January 25.That date subsequently was changed to January 26, 1986, primarilybecause of Kennedy work requirements produced by the late launch ofmission 61-C.

The third postponement of the launch dateoccurred during an evening management conference on January 25, 1986,to review the weather forecast for the Kennedy area. Because theforecast was for unacceptable weather throughout the launch window onJanuary 26, early countdown activities that had already started wereterminated.

The launch attempt of January 27 began the daybefore as the complex sequence of events leading to lift offcommenced. Fueling of the External Tank began at 12:30 a.m. EasternStandard Time. The crew was awakened at 05:07 a.m., and eventsproceeded normally with the crew strapped into the Shuttle at 07:56a.m. At 09: 10, however, the countdown was halted when the groundcrew reported a problem with an exterior hatch handle. By the timethe hatch handle problem was solved at 10:30 a.m., winds at theKennedy runway designated for a return-to-launchsite abort hadincreased and exceeded the allowable velocity for crosswinds. Thelaunch attempt for January 27 was canceled at 12:35 p.m. EasternStandard Time; the Challenger countdown was rescheduled for January28.

The weather was forecast to be clear and verycold, with temperatures dropping into the low twenties overnight. Themanagement team directed engineers to assess the possible effects oftemperature on the launch. No critical issues were identified tomanagement officials, and while evaluation continued, it was decidedto proceed with the countdown and the fueling of the ExternalTank.

Ice had accumulated in the launch pad areaduring the night and it caused considerable concern for the launchteam. In reaction, the ice inspection team was sent to the launch padat 01:35 a.m., January 28, and returned to the Launch Control Centerat 03:00 a.m. After a meeting to consider the team's report, theSpace Shuttle program manager decided to continue the countdown.Another ice inspection was scheduled at launch minus threehours.

Also, during the night, prior to fueling, aproblem developed with a fire detector in the ground liquid hydrogenstorage tank. Though it was ultimately tracked to a hardware faultand repaired, fueling was delayed by two and one-half hours. Bycontinuing past a planned hold at launch minus three hours, however,the launch delay was reduced to one hour. Crew wake-up wasrescheduled for 06:18 a.m., January 28, but by that time the crew wasalready up.

Because of forecast rain and low ceilings atCasablanca, the alternate abort site, that site was declared a"no-go"at 07:30 a.m. The change had no mission impact, however, because theweather at the primary transatlantic abort landing site at Dakar,Senegal, was acceptable. The abort-once-around site was Edwards AirForce Base, California.

With an extra hour, the crew had more thansufficient time to eat breakfast, get a weather briefing and put onflight gear. At the weather briefing, the temperature and ice on thepad were discussed, but neither then nor in earlier weatherdiscussions was the crew told of any concern about the effects of lowtemperature on the Shuttle System. The seven crew members left thecrew quarters and rode the astronaut van to launch pad B, arriving at08:03. They were in their seats in the Challenger at 08:36a.m.

At 08:44 a.m. the ice team completed itssecond inspection. After hearing the team's report, the programmanager decided to allow additional time for ice to melt on the pad.He also decided to send the ice team to perform one final iceassessment at launch minus 20 minutes. When the count was resumed,launch had been delayed a second hour beyond the original lift offtime of 09:38 a.m., Eastern Standard Time.

At 11: 15 the ice inspection was completed,and during the hold at launch minus nine minutes, the mission 51-Lcrew and all members of the launch team gave their "go" for launch.The final flight of the Challenger began at 11:38:00.010 a.m.,Eastern Standard Time, January 28, 1986.

 

**[**18**]         **The Flight of the         Challenger**The events that followed lift         off were brief: 
Launch Time 
Event
.

- 6.6 sec.

Space Shuttle engines ignition

O sec.

Solid Rocket Booster ignition

+ 7 sec.

"Roll program." (Challenger)

"Roger, roll, Challenger."         (Houston)

+ 24 sec.

Main engines throttled down to         94%

+ 42 sec.

Main engines throttled down to         65%

+ 59 sec.

Main engines throttled up to         104%

+ 65 sec.

"Challenger, go at throttle         up."

(Houston) "Roger. Go at throttle up."         (Challenger)

+ 73 sec.

Loss of signal from Challenger
**

 

From lift off until the signal from theShuttle was lost, no flight controller observed any indication of aproblem. The Shuttle's main engines throttled down to limit themaximum dynamic pressure, then throttled up to full thrust asexpected. Voice communications with the crew were normal. The crewcalled to indicate the Shuttle had begun its roll to head due eastand to establish communication after launch. Fifty-seven secondslater, Mission Control informed the crew that the engines hadsuccessfully throttled up and all other systems were satisfactory.The commander's acknowledgment of this call was the last voicecommunication from the Challenger.

There were no alarms sounded in the cockpit.The crew apparently had no indication of a problem before the rapidbreak-up of the Space Shuttle system. The first evidence of anaccident came from live video coverage. Radar then began to trackmultiple objects. The flight dynamics officer in Houston confirmed tothe flight director that "RSO [range safety officer] reports vehicleexploded," and 30 seconds later he added that the range safetyofficer had sent the destruct signal to the Solid RocketBoosters.

During the period of the flight when the SolidRocket Boosters are thrusting, there are no survivable abort options.There was nothing that either the crew or the ground controllerscould have done to avert the catastrophe. .

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