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Mission emblem
Mission emblem STS-51-L
Mission dates
Mission: STS-51-L
Crew: 7th
Begin: January 28, 1986, 4:38:00 p.m.  UTC
Starting place: Kennedy Space Center , LC-39B
Landing: Crash:
January 28, 1986, 16:39:13 UTC
Landing place: -
Flight duration: 1 min 13 s
Covered track: 28.8 km
Team photo
v.  l.  No.  Front: Michael Smith, Francis Scobee, Ronald McNair;  Back: Ellison Onizuka, Christa McAuliffe, Gregory Jarvis, Judith Resnik
v. l. No. Front: Michael Smith, Francis Scobee, Ronald McNair;
Back: Ellison Onizuka, Christa McAuliffe, Gregory Jarvis, Judith Resnik
◄ Before / After ►
STS-61-C STS-26

STS-51-L ( English S pace T ransportation S ystem ) is a mission designation for the US Space Shuttle Challenger ( OV -99) of NASA . The launch took place on January 28, 1986. It was the 25th space shuttle mission and the tenth and last flight of the space shuttle Challenger.

The space shuttle broke 73 seconds after take-off, and all seven crew members perished. It is next to the Columbia accident in 2003 at the still severe accident in the space history of the United States .


The team consisted of seven people:

The following were available, but were not used:

Ground staff (extract)

  • Flight Director (Flight): Jay Greene
  • Flight Dynamics Officer (FIDO): Brian Perry
  • CapComs : Richard Covey , Frederick Gregory
  • System Data Acquisition Processing Systems Engineer (DPS): A. F. Algate
  • Guidance, Navigation, and Control Systems Engineer (GNC): Jeffrey Bantle
  • Propulsion Missile System Engineer (Booster): Jerry Borrer
  • Driving Force Engineer (PROP): AJ Ceccacci
  • Electrical, Environment, Consumables Manager (EECOM): John Rector
  • Maintenance, mechanical and upper stage systems (RMU) officer: KA Reiley

Mission planning

The start of the STS-51-L mission was originally planned for January 22, but had to be postponed by two days due to the delays in the previous mission ( STS-61-C ). The weather conditions at the take-off location and on the designated emergency landing sites as well as technical problems at the access hatch of the space shuttle forced further postponements until January 28th.

The mission had the task of deploying the communications satellite TDRS-2, and comet Halley was to be observed with various aids . Another highlight of the mission was planned for elementary school teacher Christa McAuliffe, who was part of the crew as part of a special NASA program, to hold a few teaching blocks live from space.

The intended duration of the mission was 6 days, 0 hours and 34 minutes. The landing was to take place at the Kennedy Space Center in Florida . STS-51-L was the first space shuttle mission to use launch pad 39B.

The Challenger disaster

Breaking up the Challenger

On January 28, 1986, 73 seconds after the start (11:38 a.m. local time, 5:38 p.m. CET ) of the STS-51-L mission, the space shuttle broke at an altitude of around 15 kilometers. All seven astronauts died. The Challenger disaster led to the temporary suspension of NASA's shuttle program. The failure of one or more sealing rings in one of the side solid fuel rockets (booster) was determined to be the reason.

For reasons of procurement policy, the boosters were manufactured in four parts, with two modules each preassembled and anchored in one another. The defective O-ring was in a "field joint" that was brought together by NASA technicians on site. The anchorages were sealed by means of two O-rings arranged one above the other. A connection for leak tests was located between the O-rings. By low temperatures in the night before and the morning of the start, however, the plastic lose his own elasticity, which first to a by the extreme pressure and heat loads after ignition wear of the O-rings and finally to the partial discharge of the combustion gas introduced ( blowby ) . Some of the flames inside the rocket did not exit as intended through the large nozzle at the stern, but rather on the side of the solid rocket, possibly through the connection for leak testing. Safety concerns about the quality of these rings and their elasticity in night frost were known to the manufacturer of the rockets. The Discovery had already started a year earlier at +11.6 ° C. After the booster had been recovered, the inspection of the O-rings revealed serious heat damage, which indicated a dangerous blowby at this point. On the evening before the space shuttle took off, Roger Boisjoly , an engineer from Morton Thiokol , the manufacturer of solid fuel rockets, warned about the cold before the launch. The weather forecast indicated temperatures around freezing point for midnight, −6 ° C in the early morning and −3 ° C at the planned start time. Boisjoly feared a gigantic explosion on the launch pad.

Because of this question, there were hastily scheduled conference calls between management and engineers from Thiokol and NASA in the 24 hours before the launch. Although, after a six-hour conference call, NASA was almost convinced of a delay in launch, Thiokol's management ultimately decided to overrule its own engineers and recommend the launch to its important customer, NASA.

The start took place at a temperature of +2 ° C. A few seconds after take-off - which Boisjoly had predicted quite exactly in this form, including the following disaster - one of the sealing O-rings of the solid fuel rocket failed and hot combustion gas escaped through the resulting leak on the side. However, according to the investigations into the accident, the resulting leak first closed again (possibly with hot slag), so that it temporarily did not pose an acute danger. It is believed that the cinder plug came loose when the shuttle flew through a strong gust of wind ( wind shear ) at a high altitude , which shook it. Only then did the leak develop completely. It was so inconvenient that the gases hit the connection between the booster and the large external tank filled with hydrogen . 73 seconds after take-off, this connection was destroyed by the heat from the gas at a height of 15 kilometers, after which the booster hit the tank and tore it open. The space shuttle and the tank were destroyed by the enormous aerodynamic forces; a large amount of liquid oxygen and hydrogen leaked. These compressed gases expanded greatly from the inflammation. This made the accident look like an explosion.

The cockpit area, in which the spacemen were, survived the breaking of the shuttle relatively unscathed. Calculations showed a maximum load of approx. 12 to 20 g. After two seconds, this load dropped below 4 g. Approx. 10 seconds after breaking up, the cockpit area was on a free fall trajectory . The official report therefore states that "the forces to which the crew were exposed when the orbiter broke up probably did not result in fatal or serious injuries". The astronauts may not have died until they hit the Atlantic at about 330 km / h 2:45 minutes after breaking apart in their cockpit area . It could no longer be determined whether possible damage in the cockpit area led to a decompression that was quickly fatal . Critics complained about errors in the construction and a rescue system (parachute in the cockpit area) that was saved for cost reasons, which could possibly have saved the life of the astronauts. A prominent member of the investigation committee was the physicist and Nobel Prize winner Richard P. Feynman , who presented the investigation in an autobiographical book.

The Challenger disaster not only threw back the US space program, it also came as a shock to the numerous American citizens who had witnessed the disaster live, be it in the viewing stands in Cape Canaveral or on television. The setback acted as a national trauma in the already politically tense situation at that time.

Course of the accident, causes and last radio contact

Black smoke that comes out of a sealing ring on the solids booster

Shortly after the space shuttle lifted off, control of the flight was transferred from the launch control center at the Kennedy Space Center in Florida to the Mission Control Center in Texas . The following times in seconds after the start. Below are the people involved in radio communications. " Intercom " means communication between the crews.


  • Scobee: Dick Scobee (Commander)
  • Smith: Michael J. Smith (pilot)
  • Resnik: Judith Resnik (Mission Specialist)
  • Onizuka: Ellison Onizuka (Mission Specialist)

Ground stations:

  • Booster: Booster Systems Engineer
  • CAPCOM: Capsule Communicator
  • DPS: Data Processing Systems Engineer
  • FIDO: Flight Dynamics Officer
  • Flight: Flight Director
  • GC: Ground Controller
  • PAO: Public Affairs Officer (Public Announcer)
  • RSO: Range Safety Officer

T + 0 seconds
Resnik : All right. (All right.)
Smith : Here we go. (Here we go.)

T + 5 seconds
DPS : Liftoff confirmed. (Lift-off confirmed.)
Flight : Liftoff ... (Lift-off ...)

T + 7 seconds
Scobee : Houston, Challenger roll program. (Houston, Challenger, roll program [programmed rotation around the longitudinal axis by the autopilot])

T + 11 seconds
Smith : Go you Mother (. Coll Mother referred to the spacecraft, meaning about: Go on, baby)

T + 14 seconds
Onizuka , intercom: LVLH. (Reminder for the crew to change the configuration - Local Vertical / Local Horizontal)

To keep the aerodynamic load low, the main engines in the lower atmosphere have to be throttled temporarily. The flight software registered that the SRBs (solid fuel rockets) were hot and developing more thrust than planned. The flight software parameter T_DEL_ADJUST (FIDO's T-del comment) is used to set the power of the main engines. At the same time, the SRB's thrust subsided according to a pre-defined plan. At T + 35.379 the main engines are reduced to the 65 percent previously planned.

T + 15 seconds
Resnik : [Expletive] hot. ([Sword] hot.)
Scobee : Ooohh-kaaay. (OK.)

T + 19 seconds
Smith : Looks like we've got a lotta wind here today. (Seems like we have a lot of wind here today.)
Scobee : Yeah. (Right)

T + 19.859 seconds
Booster : Throttle down to 94. ( Throttles to 94 [% thrust].)
Flight : Ninety four… (94…)

T + 22 seconds
Scobee : It's a little hard to see out my window here. (It's a little difficult to see out of my window here.)

T + 28 seconds
Scobee : There's ten thousand feet and Mach point five. (Reach 10,000 feet and Mach 0.5.)

T + 35 seconds
Scobee : Point nine. (Mach 0.9.)

T + 40 seconds
Smith , intercom: There's Mach 1. (Are at Mach 1.)
Scobee : Going through 19,000. (Reaching 19,000 feet.)

T + 43 seconds
Scobee : OK, we're throttling down (OK, we're throttling.)

T + 48,900 seconds
Booster : Three at 65. ([All] three [main engines] at 65 [% thrust].)
Flight : Sixty-five, FIDO… (65, FIDO…)
FIDO : T-del confirms throttles. (T-Del confirms throttling.)
Flight : Thank-you. (Thank you very much.)

At T + 51,860, the main engines reverted to their nominal power and the space shuttle reached the zone of maximum aerodynamic pressure, approximately 34,000  Pascals .

T + 57 seconds
Smith , intercom: Throttling up. (Thrust up [again].)
Scobee , intercom: Roger. (Understood.)

T + 58.772: A cloud of smoke can be seen on the underside of the SRB, in front of the light-shadow boundary of the external tank.

At T + 58.788, a film camera captures the first signs of smoke from the rear of the space shuttle. Unnoticed by the crew of the Challenger and the Houston ground station, burning gas begins to escape from a steadily increasing leak on the right-hand SRB.

Within a second, the smoke is very strong and a clear jet flame has formed. Even if the crew or the control center had been aware of this, nothing more could have been done at this point, as a possible abortion of the take-off was in any case only possible after the SRBs had been burned out and disconnected. Otherwise, the start seemed to be normal up to here.

At an altitude of 11,700 meters, the Challenger passes Mach 1.5.

T + 60 seconds
Smith , intercom: Feel that mother go. ( Feel the 'baby' attract.) Woooohoooo.

T + 62 seconds
Smith , intercom: Thirty-five thousand, going through one point five. (35,000 [feet], reaching Mach 1.5.)

T + 65 seconds
Scobee , intercom: Reading four eighty six on mine. (I read 486 on my display here.) (Routine Air Velocity Check)

T + 67 seconds
Smith , intercom: Yep, that's what I've got, too. (Yes, I have it here too.)

T + 68 seconds
CAPCOM : Challenger, go at throttle up. (Challenger, [you are] "Go" when the throttle is
Scobee : Roger, go at throttle up. (Understood, "Go" when the throttle is increased.)

The bug starts to develop.

Jet flame on the right-hand SRB

At T + 72.525, as a later analysis of the telemetry data shows, there was a sudden thrust (jet flame) on the right side. At T + 72.564 the pressure in the external hydrogen tank drops when it suddenly rips open, weakened by the jet flame.

T + 73 seconds
Smith , intercom: Uh oh ...

The space shuttle begins to decay at approximately T + 73.162.

That was the last word from a crew member that was recorded by the voice recorder. Smith may have been referring to the operation of the main engines or the falling pressure in the external fuel tank, possibly the sudden jolt. The space shuttle begins to decay at approximately T + 73.162.

Dialogue of the flight controller after the disintegration of the space shuttle

At T + 79,000, instead of the Challenger, a television camera shows a cloud of smoke and a ball of fire from which large pieces of burning debris emerge and fall into the ocean.

Cloud of smoke instead of the Challenger. The two SRBs continue to fly uncontrolled.

T + 89,000 seconds
Flight : FIDO, trajectories. (FIDO, the trajectories.)
FIDO : Go ahead. (Go on.)
Flight : Trajectory, FIDO. (Trajectory, FIDO.)
FIDO : Flight, FIDO, filters (radar) got discreting sources. We're go. (Flight, FIDO, the radar shows objects spreading out. We are ready.)
FIDO : Flight, FIDO, till we get stuff back he's on his cue card for abort modes (Flight, FIDO, until we get the stuff Data], he [ie the space shuttle commander] is on his emergency abort modes checklist.)
Flight : Procedures, any help? (Procedures, anything else helpful?)
Unknown : Negative, flight, no data. (Negative, Flight, no data.)
GC : Flight, GC, we've had negative contact, loss of downlink (of radio voice or data from Challenger). (Flight, GC, we could not establish contact, loss of the downlink (radio and data transmission from Challenger).)
Flight : OK, all operators, watch your data carefully. (OK, all operators, watch your data carefully.)

At T + 110,250, the responsible security officer (RSO) sends radio signals that activate the self-destruction of the SRBs. This is a normal occurrence in an emergency where free-flying objects could pose a threat to land or sea.

T + 1 min. 56 seconds
PAO : Flight controllers here are looking very carefully at the situation. Obviously a major malfunction. (The flight controllers here are watching the situation very carefully. Obviously a serious malfunction.)

T + 2 min. 1 second
GC : Flight, GC, negative downlink. (Flight, GC, no downlink.)
Flight : Copy. (Understood.)

T + 2 min. 8 seconds
PAO : We have no downlink. (We don't have a downlink.)

At T + 2 min 20 a television camera shows falling debris and white contrails in the blue sky. Large parts fall towards the ocean, drawing thin veils of smoke behind them.

T + 2 min. 25 seconds
FIDO : Flight, FIDO. (Flight, FIDO.)
Flight : Go ahead. (Go on.)
FIDO : RSO (range safety officer) reports vehicle exploded. (RSO reports the vehicle as exploded.)
Flight : [after a long break:] Copy. FIDO, can we get any reports from recovery forces? ([after a long pause:] Understood. FIDO, can we get reports from the rescue teams?)
FIDO : Stand by. (Stay tuned.)

T + 2 min. 45 seconds
flight : GC, all operators, contingency procedures in effect. (GC, all operators, emergency measures have been initiated.)

Timeline of events

This is a chronological listing of the events on January 28, 1986. The time refers to the local time at Cape Canaveral and is shown in hh: mm: ss.

Time event
11: 37: 53.738 Ignition of the three main engines of the shuttle.
11: 38: 00,010 Ignition of solid fuel rockets (SRBs).
11: 38: 00,260 The shuttle takes off.
11: 38: 00,688 A black cloud of smoke is visible at the lower end of the right solids booster.
11: 38: 00.846 In the following two seconds, eight consecutive clouds of smoke appear.
11: 38: 04,349 Main engines go to 104% power.
11: 38: 05.684 The pressure in the right booster is 8.1 bar higher than normal.
11: 38: 07.734 Roll program begins.
11: 38: 16.899 Pilot Smith reports strong crosswinds.
11: 38: 19.869 Main engine thrust drops to 94%.
11: 38: 21,134 Roll program ended.
11: 38: 35,389 Main engines are at 65% thrust.
11: 38: 37,000 The Challenger's on-board computers steer against the crosswind.
11: 38: 45,227 A luminous phenomenon is visible at the rear end of the right wing.
11: 38: 48,128 A second luminous phenomenon is visible on the front of the right wing.
11: 38: 48.428 A third luminous phenomenon is visible at the rear end of the right wing.
11: 38: 51.870 The power of the main engines increases to 104% of the maximum thrust.
11: 38: 58.798 The first signs of a flame beam are visible on the right booster .
11: 38: 59.272 Sharply demarcated flames on the right solid fuel rocket are permanently visible.
11: 38: 59.763 Flames run in the direction of flight.
11: 39: 00,014 Pressures inside the left and right booster differ greatly from each other.
11: 39: 00.258 The first indications that the flame beam hits the shuttle's external tank become visible.
11: 39: 02,494 Short, violent steering movement of the right elevator .
11: 39: 04,670 Flames change their appearance.
11: 39: 04.715 Persistent glow on the side of the outer tank.
11: 39: 04.947 The on-board computers move the nozzle cones of the main engines to keep the shuttle on course.
11: 39: 05,174 The shuttle vibrates strongly.
11: 39: 06.774 Flow rate in the fuel line for liquid oxygen from the outer tank to the main engines begins to fluctuate.
11: 39: 10.835 Last radio message from the crew.
11: 39: 12,214 Vigorous steering movements of the nozzle cones of the three main engines and the two solid fuel rockets.
11: 39: 12.574 Hydrogen pressure in the outer tank drops.
11: 39: 12.974 Rapid pressure loss in the fuel line for liquid oxygen.
11: 39: 13.020 The last valid telemetry data is being received.
11: 39: 13.054 Rapid pressure loss in the fuel line for liquid hydrogen.
11: 39: 13,134 Bright glow at the back of the outer tank.
11: 39: 13,134 Pressure inside the right booster is 1.3 bar lower than in the left.
11: 39: 13,147 The first signs of gases in the vicinity of the external tank can be seen.
11: 39: 13,153 Engines react to the changed fuel flow.
11: 39: 13,172 The tip of the right solid fuel rocket hits the outer tank.
11: 39: 13,201 A bright glow in the area between the external tank and the shuttle becomes visible.
11: 39: 13,212 A bright glow in the area of ​​the front attachment of the external tank and shuttle becomes visible.
The glow between the external tank and the shuttle increases in intensity.
11: 39: 13.292 The first signs of a white glow in the area of ​​the front attachment of the external tank and shuttle can be seen.
11: 39: 13,337 Strong increase in intensity of the white luminous phenomenon in the area of ​​the front attachment of the outer tank and shuttle.
11: 39: 13.387 Pressure fluctuations begin in the area of ​​the control nozzles.
11: 39: 13.393 Temperatures of all three main engines are in the red area.
11: 39: 13.492 The three main engines switch off one after the other.
11: 39: 14,140 The radio connection to the shuttle breaks down.
11: 39: 14.597 Bright glow in the area of ​​the shuttle's bow.
The shuttle starts breaking.
11: 39: 50,260 Self-destruct order sent for left solid fuel rocket.
11: 39: 50.262 Self-destruct order sent for the right solid fuel rocket.

Further results of the accident investigations

Richard Feynman's book contains more detailed findings that do not only concern the problem of O-rings:

Inadequate work regulations are described there: After each start, the burnt-out solid fuel booster rockets fall into the sea, where they are recovered and then sent for reuse. The manuals stated that the booster shell could be reused if the diameters measured from three points at a distance of 60 degrees are correct. It does not necessarily follow from this that this results in a regular circle . In fact, there were often deformations that were then literally bent into shape - often not in compliance with regulations.

The Challenger accident happened because the manuals from Morton Thiokol - the manufacturer of the solid rocket rockets - were ignored. In addition, the management of NASA wanted to comply with a request of the US President Ronald Reagan and have a teacher fly into space with a public appeal when Reagan's speech on the State of the Union was imminent. However, this is said not to have had any explicit influence on the decision (which can be proven in concrete terms); the general pressure to keep appointments and to start the “operational” space transport system Space Shuttle at the promised frequency will have been sufficient. The Thiokol experts advised against a start, as all previous starts have taken place at temperatures above 11 ° C. NASA management urged not to postpone the launch again after the previous delays. However, after a six-hour telephone conference, it was not convinced by the data provided by Thiokol that this was necessary, but would not have enforced a start against the recommendation of the supplier. The highest executives from Thiokol who were present, some of whom were hardly or not at all present at the preparatory meetings, made the decision to go ahead, contrary to the recommendation of their engineers, after the ambiguities in their reasons for the recommendation on the part of NASA participants (which these to NASA - Leadership should have represented if the start had been postponed because of this) were very aggressively questioned. In the press this was shortened to the assumption that they did not want to anger NASA as their most important customer.

There were also differences between NASA management and engineers regarding the error rate of the shuttles. Senior ranks claimed that only one in 100,000 flights would fatally abort a mission - but one million launches would have had to be evaluated to give this figure a plausible statistical basis. However, designers of the onboard main engine said it would fail on one in 100 to 200 flights; and the Air Force assumed failure rates of 1:50 for their missiles. The suspicion arose that a pretended high reliability of the spacecraft would help NASA to get more government money.

Management also carelessly dealt with routine checks - the space shuttle's computers and software (which at the time had ferrite core memories ) passed all tests without any problems, and so the managers lulled themselves into a false sense of security - since the tests were always successful anyway, they could be abolished. To this end, NASA played down incidents that did not directly endanger the lives of the astronauts - such as the O-rings that had shown signs of wear and tear during a few previous rocket launches.

Richard Feynman also observed and criticized the inadequate communication style within the workshops and suppliers, because suggestions from employees were often rejected. A marking was rejected that would have been very helpful when checking and reassembling the solid fuel rocket because it would have had to issue new manuals and regulations.

Feynman ended his report because of the glossed over error rates with the words:

"[...] reality must take precedence over public relations, for nature cannot be fooled."

"[...] Reality must take precedence over public relations , because nature cannot be fooled."

The investigation of the accident also showed that in the past the concerns of many engineers had been "discarded with reference to the strict schedule and tight budget".

Consequences of the accident

Memorial plaque in Hermosa Beach, California

After the accident, a general starting ban for the shuttle fleet was issued. For almost two and a half years they worked on improvements that should make the start safer. The most important change was to largely revise the solid fuel boosters . Over 2000 changes were made to the shuttle system. This included, for example, an extendable telescopic pole on which the astronauts could exit the orbiter through the hatch in an emergency situation during the landing approach. From now on, the astronauts had to wear pressure suits again for takeoff and landing. In addition, the shuttle was withdrawn from the commercial satellite business, which was transferred back to unmanned launch vehicles . In August 1987 the construction of a replacement ferry for the Challenger was commissioned, in 1991 the Endeavor was completed. On September 29, 1988, the Discovery launched a space shuttle into space ( STS-26 ) for the first time since the accident . By February 2003, when the Columbia during re-entry broke up , there was disaster shuttle at no further.

See also


Web links

Commons : STS-51-L  - Album with pictures, videos and audio files

Individual evidence

  1. Martin Holland: 30 years of the Challenger disaster: the first major catastrophe in US space travel. In: heise online . Retrieved January 28, 2016 .
  2. Disaster before the eyes of the world. In: Tageblatt . January 25, 2011, accessed August 20, 2015 .
  3. ^ Rogers Commission Report: Report of the Presidential Commission on the Space Shuttle Challenger Accident, Volume 1, Chapter 6 . 1986. Retrieved February 9, 2011.
  4. ^ The Contributing Cause of The Accident. In: Report of the Presidential Commission on the Space Shuttle Challenger Accident. Retrieved on August 20, 2015 (English): “[…] it was going to get near freezing or freezing before midnight. It could get as low as 22 degrees as a minimum in the early morning hours, probably around 6:00 o'clock, and that they were predicting a temperature of about 26 degrees at the intended launch time, about 9:38 the next morning . "
  5. a b c Mark Hayhurst: I knew what was about to happen. In: Guardian. January 23, 2001, accessed September 23, 2009 .
  6. Supporting Charts and Documents Referred to During The Commission Investigation and Report. In: Report of the Presidential Commission on the Space Shuttle Challenger Accident. Retrieved August 20, 2015 : "Camera Site 3, approximately 1,000 feet, bearing 150 degrees from Launch Pad 39B (36 degrees Fahrenheit at launch.)"
  7. ^ Roger Boisjoly: Memo from Roger Boisjoly on O-Ring Erosion (Memo from Roger Boisjoly about O-Ring Erosion). July 31, 1985, accessed September 23, 2009 .
  8. NASA: Report by Joseph P. Kerwin on the death of the astronauts
  9. ^ A b Richard P. Feynman: Do you care what other people think? 7th edition Piper Verlag, 1996, ISBN 3492221661 .
  10. NASA radio protocol
  11. ^ A b Diane Vaughan, American Council of Learned Societies (ed.): The Challenger Launch Decision: Risky Technology, Culture, and Deviance at NASA . University of Chicago Press, 1997 (English).
  12. Alexander forehead: burst dream. In: Süddeutsche Zeitung . January 28, 2011.