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Voyage Into History
Chapter 13: The Timeline

By William Harwood

© 1986


"If you get complacent about the launch phase, you don't understand what's going on. It's a very hazardous phase of flight. We understand it and the guys at the Cape understand it and the crews understand." - Flight Director Jay Greene


"Feel that mother go!" - Challenger Co-Pilot Michael Smith, 13 seconds before shuttle break up


The Rogers Commission investigation was finally over. Yet throughout the long ordeal and in the weeks and months that followed, public fascination with Challenger's last flight continued amid stories of lawsuits filed by crew family members and NASA's final admission that Challenger's astronauts were not killed instantly by the explosion of the shuttle's external fuel tank. What follows is a timeline analysis assembled from telemetry beamed down from the shuttle, recordings made of the mission control voice command circuits, the NASA-Select audio circuit and the intercom transcript. The following timeline was assembled by the author and Rob Navias, UPI radio reporter at the Kennedy Space Center at the time of the accident (times given in seconds after launch at 11:38 a.m. EST, Jan. 28, 1986).


0.000 - Solid rocket ignition command is sent.

Astronaut Judy Resnik, intercom: "Aaall Riight!"

0.008 - First of eight 25-inch-long, 7-inch-wide exploding bolts fire, four at the base of each booster, freeing Challenger from launch pad.

0.250 - First continuous vertical motion is recorded.

0.678 - Film developed later shows the first evidence of abnormal black smoke appearing slightly above the suspect O-ring joint in Challenger's right-hand solid rocket booster.

0.836 - The black smoke appears darkest; jets in puffs of three per second, roughly matching harmonic characteristics of the shuttle vehicle at launch.

0.890 - Ground launch sequence computers begin post-liftoff "safing" of launch pad structures and equipment.

1.000 - Shuttle pilot Michael Smith, intercom: "Here we go."

2.733 - Last positive evidence of smoke above the aft attach fitting that holds the rear of the right-side booster to the external fuel tank. The aft attach fitting is a little less than two feet above the fuel segment joint.

3.375 - Last positive visual indication of smoke swirling under the bottom of the external fuel tank.

Launch commentator Hugh Harris, NASA-SELECT television: "... Liftoff of the 25th space shuttle mission, and it has cleared the tower."

4.339 - The three liquid-fueled main engines throttle up from 90 percent thrust to 104 percent thrust as planned.

5.000 - Data processing systems (DPS) engineer A.F. Algate, mission control, Houston: "Liftoff confirmed."

Flight director Jay Greene, Houston: "Liftoff..."

5.000 - Loss of data from the shuttle at NASA's Merritt Island antenna complex for four data frames. Four more "data BIT-synch dropouts" occur in the next one minute and six seconds. These are normal and are caused by flame and objects on the horizon that attenuate radio signals.

5.615 - The backup flight system computer aboard Challenger commands the S-band PM (phase modulated) and S-band FM radio systems to switch antennas to maintain communications during the upcoming roll maneuver.

5.674 - Internal pressure in the right-side booster is recorded as 11.8 pounds per square inch higher than normal.

7.724 - The shuttle clears the launch pad tower and begins a maneuver to roll over, putting the crew in a "heads down" position below the external tank.

8.000 - Shuttle commander Dick Scobee, air-to-ground: "Houston, Challenger. Roll program."

10.000 - Astronaut Dick Covey, mission control: "Roger roll, Challenger."

Flight dynamics officer (FIDO) Brian Perry, mission control: "Good roll, flight."

Greene: "Rog, good roll."

11.000 - Smith, intercom: "Go you mother."

12.000 - Another antenna switch is ordered to transfer data to the Ponce De Leon tracking station.

14.000 - Resnik, intercom: "LVLH." Resnik is reminding Scobee and Smith about proper cockpit ADI configurations. "LVLH" is an acronym that stands for "local vertical, local horizontal."

15.000 - Resnik, intercom: "Shit hot!"

Scobee: "OK."

16.000 - Mission Control spokesman Steve Nesbitt in Houston, NASA-SELECT television: "Good roll program confirmed. Challenger now heading downrange."

19.000 - Smith, intercom: "Looks like we've got a lot of wind here today."

Scobee: "Yeah."

19.859 - Challenger's three main engines receive commands to begin throttling down to 94 percent power, as planned.

21.124 - The roll maneuver is completed and Challenger is on the proper trajectory.

21.604 - Right hand SRB thrust decreases before shuttle reaches maximum dynamic pressure. This is accomplished by the burn down of ridges in the solid propellant of the forward fuel segment. Thrust is a function of surface area of propellant burning.

22.000 - Scobee, intercom: "It's a little hard to see out my window here."

22.204 - Left hand SRB thrust decreases as planned.

27.000 - Booster systems engineer (Booster) Jerry Borrer, mission control: "Throttle down to 94." Challenger's three main engines begin throttling down as planned as the shuttle approaches the region of maximum aerodynamic pressure.

Greene: "Ninety four..."

28.000 - Smith, intercom: "There's 10,000 feet and Mach point five." The shuttle is 10,000 feet high traveling at half the speed of sound.

Nesbitt: "Engines beginning throttling down, now at 94 percent. Normal throttle (setting) for most of the flight is 104 percent. We'll throttle down to 65 percent shortly.

35.000 - Scobee, intercom: "Point nine."

35.379 - The three main engines begin throttling down to 65 percent power as planned.

36.990 - Telemetry data shows the shuttle's computer system responds properly to wind shear to adjust the ship's flight path.

40.000 - Smith, intercom: "There's Mach 1."

Scobee: "Going through 19,000."

43.000 - Scobee, intercom: "OK, we're throttling down."

45.000 - Nesbitt: "Engines are at 65 percent. Three engines running normally..."

45.217 - A flash is observed downstream of the shuttle's right wing.

48.118 - A second flash is seen trailing the right wing.

48.418 - A third unexplained flash is seen downstream of the shuttle's right-hand wing. 70 mm tracking camera closeup: A brilliant orange ball of flame, apparently, emerges from under the right wing and quickly merges with the plume of the solid rocket boosters. This phenomenon, observed during analysis of tracking film after launch, has been seen on previous launches but has never been explained.

48.900 - Booster systems engineer (unknown): "Three at 65."

Nesbitt: "... Three good fuel cells. Three good APUs (auxiliary power units)..."

Greene: Sixty-five, FIDO..."

FIDO: "T-del confirms throttles." The flight dynamics officer is referring to computer software monitoring the flight in real-time.

Greene: "...Thank you."

51.860 - Challenger's main engines receive commands from the onboard flight computers to begin throttling back up to 104 percent thrust as planned.

52.000 - Nesbitt: "Velocity 2,257 feet per second (1,539 mph), altitude 4.3 nautical miles, downrange distance 3 nautical miles..."

57.000 - Scobee, intercom: "Throttling up."

Smith: "Throttle up."

Scobee: "Roger."

58.788 - Tracking cameras show the first evidence of an abnormal plume on the right-hand solid rocket booster facing away from the shuttle. Scobee and Smith had no data on the performance of the solid rockets except for a software system that would have alerted them to malfunctions in the booster steering mechanism.

59.000 - Challenger passes through the region of maximum aerodynamic pressure, experiencing 720 pounds per square foot.

59.262 - A continuous "well defined intense plume" of exhaust is seen on the side of the suspect booster by tracking cameras. This is clear evidence of an O-ring joint burn through.

59.753 - First visual evidence of flame on the right-side booster. 70 mm tracking camera closeup: A flickering tongue of flame appears on the side of the right-side booster away from the shuttle and quickly becomes continuous.

60.000 - Smith, intercom: "Feel that mother go!"

Unknown, intercom: "Wooooo Hooooo!"

60.004 - Data radioed from Challenger shows the internal pressure in the right-side SRB begins dropping. This is because of the rapidly increasing hole in the failed joint.

60.238 - First evidence of flame from the rupture deflecting and impinging on the external fuel tank.

60.248 - First evidence of the anomalous plume "attaching" to the fitting that couples the aft end of the right-side rocket to the base of the external fuel tank.

60.988 - The plume deflection is continuous. 70 mm tracking camera closeup: A thick, well-defined plume of flame arcs away from right solid rocket booster.

61.724 - The shuttle rolls slightly in response to high winds aloft.

62.000 - Smith, intercom: "Thirty-five thousand, going through one point five."

62.084 - The steering mechanism of the left-hand booster suddenly moves on computer command as Challenger's flight control system compensates for wind shear. It is later noted that wind shear during Challenger's launch was more extreme than for any of the previous 24 shuttle missions, although still within design limits.

62.484 - Challenger's computers order the shuttle's right-hand "elevon," or wing flap, to move suddenly in response to wind.

63.924 - A pressure change is recorded in the right-hand outboard elevon, indicating movement.

63.964 - The shuttle's computers order a planned change in Challenger's pitch to ensure the proper angle of attack during this phase of the trajectory.

64.660 - The plume from the burn through changes shape suddenly, indicating a leak has started in the shuttle's liquid hydrogen tank to fuel the fire.

64.705 - A bright, sustained glow is photographed on the side of the external fuel tank.

64.937 - The main engine nozzles move through large arcs, trying to keep the shuttle on course as the flight computers attempt to compensate for the unbalanced thrust produced by the booster burn through. The shuttle stops the minute pitching. It is doubtful the crew was aware of the computers' efforts to keep the ship on course. At this point in the launch phase, the crew is experiencing normal longitudinal vibrations and steadily increasing acceleration forces.

65.000 - Scobee, intercom: "Reading four eighty six on mine." This is a routine airspeed indicator check.

Smith: "Yep, that's what I've got, too."

65.164 - First recorded evidence of Challenger experiencing transient motion.

65.524 - Data shows the left wing's outboard elevon moves suddenly.

66.000 - Booster systems engineer: "Throttle up, three at 104."

Greene: "Capcom (Covey), go at throttle up."

66.174 - Tracking cameras show a bright spot suddenly appears in the exhaust plume from the side of the right-side solid rocket motor and bright spots are detected on the side of the rocket facing the belly of the shuttle.

66.764 - The pressure in the shuttle's external liquid hydrogen tank begins to drop, indicating a massive leak. Smith had real-time readings of pressure in the liquid hydrogen tank, but it is doubtful he noticed anything unusual because of the rapidity of the failure. It made no difference, ultimately, because even if Challenger's pilots had suspected an SRB problem there was nothing they could have done about it. While the shuttle separates from its external fuel tank shortly before reaching orbit, it does so with no engines firing and in a benign aerodynamic environment. As Scobee and Smith well knew, separating from the tank while the SRBs were firing would drive the shuttle into the bottom of the fuel tank.

67.650 - The abnormal plumes on the bottom and top of the booster appear to merge into one. This means the flame has wrapped around the joint as the leak deteriorated.

67.684 - Telemetry indicates falling pressure in the 17-inch-wide liquid oxygen propellant lines feeding the three main engines.

68.000 - Nesbitt: "Engines are throttling up. Three engines now at 104 percent."

Covey: "Challenger, go at throttle up."

70.000 - Scobee calmly responds, air-to-ground: "Roger, go at throttle up."

72.204 - Data shows divergent up and down motions in nozzles of both solid rocket boosters.

72.284 - The two solid rocket boosters change position relative to each other, indicating the right-side booster apparently has pulled away from one of the two struts that connected its aft end to the external fuel tank. TV tracking camera: A large ball of orange fire appears higher on the other side of main fuel tank, closer to Challenger's cabin, and grows rapidly.

72.478 - A "major high rate actuator command" is recorded from one of the boosters, indicating extreme nozzle motions.

72.497 - The nozzles of the three liquid-fueled main engines begin moving at high rates: Five degrees per second.

72.525 - Data shows a sudden lateral acceleration to the right jolts the shuttle with a force of .227 times normal gravity. This may have been felt by the crew.

72.564 - Start of liquid hydrogen pressure decrease. Solid rocket boosters again demonstrate high nozzle motion rates.

72.624 - Challenger beams back what turns out to be its final navigation update.

72.964 - Main engine liquid oxygen propellant pressures begin falling sharply at turbopump inlets.

73.000 (approximate) - Smith, intercom: "Uh oh..." This is the last comment captured by the crew cabin intercom recorder. Smith may have been responding to indications on main engine performance or falling pressures in the external fuel tank.

73.010 - Last data is captured by the Tracking and Data Relay Satellite in orbit overhead, indicating structural breakup has begun in that area.

73.044 - Start of sharp decrease in liquid hydrogen pressure to the main engines.

73.045 - Another lateral acceleration, this one to the left, is possibly felt by the crew. Lateral acceleration equals .254 time the force of gravity.

73.124 - Internal pressure in the right-side rocket booster is recorded as 19 pounds per square inch below that of its counterpart, indicating about 100,000 pounds less thrust. Tracking cameras detect evidence of a circumferential white pattern on the left side of the base of the external tank indicating a massive rupture near the SRB-tank attach ring. The is nothing less than the aft dome of the liquid hydrogen tank blowing out and backwards. The resulting forward acceleration blasts the tank up into the liquid oxygen tank in the tip of the external fuel tank.

73.137 - Vapors appear near the intertank section separating the hydrogen and oxygen sections accompanied by liquid hydrogen spillage from the aft dome of the external tank.

73.143 - All three main engines respond to loss of oxygen and hydrogen inlet pressure.

73.162 - Ground cameras show a sudden cloud of rocket fuel appearing along the side of the external tank. This indicates the nose of the right-hand booster may have pivoted into the intertank area, compounding the liquid oxygen rupture.

73.191 - A sudden brilliant flash is photographed between the shuttle and the external tank. TV tracking camera: Fireballs merge into bright yellow and red mass of flame that engulfs Challenger. A single crackling noise is heard on air-to-ground radio. Engineers later say the sound is the result of ground transmitters searching the shuttle's frequency range for a signal.

73.211 - Telemetry data from the main engines exhibits interference for the next tenth of a second.

73.213 - An explosion occurs near the forward part of the tank where the solid rocket boosters attach.

73.282 - The explosion intensifies and begins consuming the external fuel tank. Television tracking camera: a ball of brilliant white erupts from the area beneath the shuttle's nose.

73.327 - The white flash in the intertank area greatly intensifies.

73.377 - Tank pressure for on board supplies of maneuvering rocket fuel begins to fluctuate.

73.383 - Data indicates the liquid-fueled main engines are approaching redline limits on their powerful fuel pumps.

73.482 - Channel A of main engine No. 2's control computer votes for engine shutdown because of high pressure fuel turbopump discharge temperature. Channel B records two strikes for shutdown.

73.503 - Main engine No. 3 begins shutdown because of high temperatures in its high pressure fuel pump. Last data captured by main engine No. 3's controller.

73.523 - Main engine No. 1 begins shutdown because of high temperatures in high pressure fuel pump.

73.543 - Last telemetry from main engine No. 1.

73.618 - The last valid telemetry from the shuttle is recorded as it breaks up: pressure fluctuations in a fuel tank in the left rocket pod at Challenger's rear and chamber pressure changes in auxiliary power unit No. 1's gas generator.

73.631 - End of last data frame.

74.130 - Last radio signal from orbiter.

74.587 - A bright flash is observed in the vicinity of the orbiter's nose. Television tracking camera closeup: The nose of the shuttle and the crew compartment suddenly engulfed in brilliant orange flame as rocket fuel in forward maneuvering jet supplies ignites.

"At that point in its trajectory, while traveling at a Mach number of 1.92 (twice the speed of sound) at an altitude of 46,000 feet, the Challenger was totally enveloped in the explosive burn," said the Rogers Commission report. "The Orbiter, under severe aerodynamic loads, broke into several large sections which emerged from the fireball. Separate sections that can be identified on film include the main engine/tail section with the engines still burning, one wing of the Orbiter, and the forward fuselage trailing a mass of umbilical lines pulled loose from the payload bay."

The nose section had ripped away from the payload bay cleanly, although a mass of electrical cables and umbilicals were torn from the cargo hold, fluttering behind the crew cabin as it shot through the thin air, still climbing. Challenger's fuselage was suddenly open like a tube with its top off. Still flying at twice the speed of sound, the resulting rush of air that filled the payload bay overpressurized the structure and it broke apart from the inside out, disintegrating in flight. Challenger's wings cartwheeled away on their own but the aft engine compartment held together, falling in one large piece toward the Atlantic Ocean, its engines on fire. The TDRS satellite in Challenger's cargo bay and its solid-fuel booster rocket were blown free as was the Spartan-Halley spacecraft. All this happened as the external tank gave up its load of fuel, which ignited in the atmosphere in what appeared to be an explosion. It was more of a sudden burning than an explosion. In any case, the two solid rockets emerged from the fireball of burning fuel and continued on, bereft of guidance from the shuttle's now-silent flight computers.

75.000 - Nesbitt (not realizing immediately there had been an explosion): "One minute 15 seconds. Velocity 2,900 feet per second (1,977 mph). Altitude 9 nautical miles. Downrange distance 7 nautical miles."

76.437 - The nose cap of the right hand solid rocket booster separates and its drogue parachute deploys. Tracking camera closeup: A lone parachute seen emerging from the plume of a solid rocket booster.

79.000 - TV tracking camera, different view: White streamers of smoking debris blossom from the cloud of smoke and flame marking the spot where Challenger had been. One large burning piece falls toward the ocean. Two solid rocket boosters emerge from the fireball and corkscrew through the sky on their own. Nesbitt's commentary stops.

89.000 - Greene in mission control utters the first words since the explosion 13 seconds ago: "FIDO, trajectories..."

FIDO: "Go ahead."

Greene: "Trajectory, FIDO."

FIDO: "Flight, FIDO, filters (radar) got discreting sources. We're go."

Ground control (GC) engineer N.R. Talbott, mission control: "Flight, GC, we've had negative contact, loss of downlink (of radio voice or data from Challenger)."

Greene: "OK, all operators, watch your data carefully."

FIDO: "Flight, FIDO, till we get stuff back he's on his cue card for abort modes."

Greene: "Procedures, any help?"

Unknown: "Negative, flight, no data."

110.250 - Range safety control officers send radio signals that detonate the self-destruct package on right-hand solid rocket.

110.252 - The left-hand booster self destructs. Tracking camera closeup: a thick cloud of black smoke suddenly engulfs rocket and brilliant but quick explosion ensues. Numerous fragments of the booster emerge from the fireball, including what appears to be a complete aft fuel segment, slowly tumbling.

----------------------------------------

(following times in minutes and seconds)

1:56 - Nesbitt: "Flight controllers here are looking very carefully at the situation. Obviously a major malfunction."

2:01 - Ground control officer: "Flight, GC, negative downlink."

Greene: "Copy."

2:08 - Nesbitt: "We have no downlink."

2:20 - TV tracking camera: falling bits of debris create white contrails arching through the blue sky. A larger object, trailing a thin cloud of vapor, plummets toward the ocean.

2:25 - FIDO: "Flight, FIDO."

Greene: "Go ahead."

FIDO: "RSO (range safety officer) reports vehicle exploded."

Greene (long pause): "Copy. FIDO, can we get any reports from recovery forces?"

FIDO: "Stand by."

2:45 - Greene: "GC, all operators, contingency procedures in effect."

2:50 - Nesbitt: "We have a report from the flight dynamics officer that the vehicle has exploded. The flight director confirms that. We are looking at checking with the recovery forces to see what can be done at this point."

3:03 - Greene: "FIDO, flight..."

FIDO: "Go ahead."

Greene: "LSO and recovery forces, any contacts?"

3:09 - Nesbitt: "Contingency procedures are in effect..."

FIDO: "We're working with them, flight."

Greene: "OK."

3:22 - Nesbitt: "We will report more as we have information available. Again, to repeat, we have a report relayed through the flight dynamics officer that the vehicle has exploded. We are now looking at all the contingency operations and awaiting word from any recovery forces in the downrange field."

3:25 - TV tracking camera: The first pieces of debris can be seen splashing into the ocean.

3:53 - FIDO: "Flight, FIDO, for what it's worth, the filter shows 'em in the water."

Greene: "Copy."

3:58 - Challenger's crew cabin smashes into the Atlantic Ocean at about 200 mph. The astronauts, still strapped in their seats, experience a braking force of 200 times normal gravity. The crew cabin disintegrates and settles to the bottom 100 feet below.

4:15 - Television tracking camera closeup shows ocean surface east of Patrick Air Force Station. A large cloud of ruddy brown smoke hangs over surface of water as objects splash on impact nearby. The cloud probably was caused by hydrazine rocket fuel from wreckage that hit the water.

4:27 - Greene: "FIDO, flight. ... FIDO flight."

FIDO: "Go ahead."

Greene: "Did the RSO's have an impact point?"

FIDO: "Stand by."

5:03 - Nesbitt: "This is mission control, Houston. We have no additional word at this time."

5:05 - FIDO: "Flight, FIDO."

Greene: "Go ahead."

FIDO: "The vacuum IP (impact point) is 28.64 North, 80.28 West."

Greene: "How does that stack with the solid (rocket) recovery forces?" Greene is referring to the Liberty Star and the Freedom Star, two NASA ships on station in the Atlantic to recover Challenger's boosters after a normal launch.

FIDO: "We're still talking to them."

Greene: "OK."

5:24 - Nesbitt: "Reports from the flight dynamics officer indicate that the vehicle apparently exploded and that impact in the water (was) at a point approximately 28.64 degrees North, 80.28 degrees West."

5:36 - TV tracking camera: A dark, irregularly shaped piece of debris - thought to be one of Challenger's wings - cartwheels down from the sky and splashes into the Atlantic. It is the largest piece of Challenger seen on TV impacting in the ocean.

5:46 - Nesbitt: "We are awaiting verification as to the location of the recovery forces in the field to see what may be possible at this point and we will keep you advised as further information is available. This is mission control."

6:15 - NASA television switches from ocean views to the grandstand area at the press site. A large cloud of white smoke remains visible towering into the sky, twisted by winds aloft and slowly dissipating. Small, helical streamers mark contrails of the solid rocket boosters.

6:41 - Greene: "OK, everybody stay off the telephones, make sure you maintain all your data, start pulling it together."

7:17 - Greene: "Flight, FIDO..."

FIDO: "FIDO, flight, go ahead sir."

Greene: "Are the LSO's on the loop?"

FIDO: "We can get 'em."

Greene: "Get 'em up on the loop, please."

LSO (coordinating recovery activity; identity unknown): "Yes sir, this is the LSO."

Greene: "OK, are there any forces headed out that way?"

LSO: "Yes sir. DOD (Department of Defense) LSO reports that all ... forces have been scrambled and they are on their way."

Greene: "OK, do we have an ETA?"

LSO: "Negative, sir."

8:00 - Greene conducts a poll of his flight controllers to determine if any data indicates what may have gone wrong.

Greene: "Booster, flight."

Booster: "Flight, booster."

Greene: "Did you see anything?"

Booster: "Nothing, sir, I looked at all the turbine temps were perfect (sic), right on the prediction. All the redlines were in good shape."

Greene: "RMU?"

Remote manipulator system, mechanical and upper stage systems officer K.A. Reiley: "We looked good, flight."

Greene: "ECOM? ECOM, flight."

Electrical, environmental, consumables and mechanical systems engineer John Rector: "Flight, ECOM, we looked normal."

Greene: "DPS?"

Data processing systems engineer A.F. Algate: "All our data's normal, flight."

Greene: "PROP?"

Propulsion systems engineer A.J. Ceccacci: "Everything looked good, flight."

Greene: "GNC?"

Guidance, navigation and control systems engineer J.W. Bantle: "Flight, the roll maneuver looked fine, what we saw of it. We were on our way decreasing roll rate as we lost data."

Greene: "Copy."

8:03 - NASA select television shows launch pad 39-B with smoke still hanging over the mobile launch platform.

8:37 - NASA select television focuses on a small parachute seen slowly drifting down out to sea.

9:11 - FIDO: "That's, uh, probably a paramedic." Later it is determined that this is the nose cap to one of the solid rocket boosters swinging from its drogue parachute.

9:19 - Nesbitt: "This is mission control, Houston. We are coordinating with recovery forces in the field. Range safety equipment, recovery vehicles intended for the recovery of the SRBs in the general area."

9:36 - Greene: "LSO, flight. LSO, flight..."

Nesbitt: "Those parachutes believed to be paramedics going into that area..."

FIDO: "We're getting them, flight."

Nesbitt: "...To repeat, we had an apparently normal ascent with the data..."

LSO: "This is LSO on flight loop."

Greene: "Rog, are you getting any inputs?"

LSO: "Sir, we've got a Jolly 1 (helicopter) on route right now. We've got ships on the way and we've got a C-130 on the way out."

Greene: "Rog."

9:41 - Nesbitt: "...coming from all positions being normal up through approximately time of main engine throttle back up to 104 percent. At about approximately a minute or so into the flight, there was an apparent explosion. The flight dynamics officer reported that tracking reported that the vehicle had exploded and impact into the water in an area approximately located at 28.64 degrees North, 80.28 degrees West, recovery forces are proceeding to the area including ships and a C-130 aircraft. Flight controllers reviewing their data here in mission control. We will provide you with more information as it becomes available. This is mission control, Houston."

11:05 - NASA select television shows the interior of mission control at the Johnson Space Center in Houston. Covey and astronaut Frederick Gregory sit silently at the Capcom console, obviously stunned.

11:39 - LSO: "Flight, LSO."

Greene: "Go ahead."

LSO: "Uh, Jolly's have not been cleared in yet, there's still debris coming down."

Greene: "Copy. Who's controlling this operation, please?"

LSO: "S & R (search and recovery) forces out of Patrick (Air Force Base)."

Greene: "Rog. Do we have a coordination loop with those people?"

LSO: "We're working with the SOC on DDMS coord right now." He is referring to a radio network used by Defense Department personnel.

LSO: "Flight, LSO."

Greene: LSO..."

LSO: "Would you like us to try to get up on DDMS coord also?"

Greene: Yes. GC, flight."

GC: "Flight, GC."

Greene: "Take that loop into one of the playback loops please, internal to the building only."

GC: "I didn't copy what you said."

Greene: "DDMS coord, patch it into one of the playback loops internal to the building."

GC: "Copy."

12:37 - Greene: "GC, flight."

GC: "Flight, GC."

Greene: "Checkpoint status, have we taken one?"

GC: "Negative."

Greene: "Take one now."

GC: "Copy."

13:27 - GC: "All flight controllers, hold inputs, lock checkpoint in progress." This is a procedure to take a "snapshot" of all computer data recorded so far to ensure its recovery for documentation.

14:24 - Greene: LSO, flight."

LSO: "LSO here, sir."

Greene: "Any updates?"

LSO: "No sir. No sir, nothing to report."

15:06 - Greene: "Operators, contingency plan copies are coming to each console position. If you have an FCOH (flight control operations handbook) you can start on the checklist, page 27 dash 4, that's page 27-4. Don't reconfigure your console, take hard copies of all your displays, make sure you protect any data source you have."

LSO: "Flight, LSO."

Greene: "LSO?"

LSO: "Looks like about 50 minutes, five zero minutes, before the helicopters are cleared in because of debris."

Greene: "Fifty minutes from what time, LSO?"

LSO: "OK, from the time of the explosion."

21:53 - Nesbitt: "This is mission control, Houston. Repeating the information that we have at this time. We had an apparently nominal liftoff this morning at 11:38 Eastern time. The ascent phase appeared normal through approximately the completion of the roll program and throttle down and engine throttle back to 104 percent. At that point, we had an apparent explosion. Subsequent to that, the tracking crews reported to the flight dynamics officer that the vehicle appeared to have exploded and that we had an impact in the water down range at a location approximately 28.64 degrees North, 80.28 degrees west.

"At that time, the data was lost with the vehicle. According to a poll by the flight director, Jay Greene, of the positions here in mission control, there were no anomalous indications, no indications of problems with engines or with the SRBs or with any of the other systems at that moment through the point at which we lost data. Again, this is preliminary information. It is all that we have at the moment and we will keep you advised as other information becomes available. We had, there are recovery forces in the general area. Others being deployed, including aircraft and ships. We saw what we believed to be paramedics parachuting into impact area and we have no additional word at this point. We will keep you advised as details become available to us. This is mission control, Houston."