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Previous chapter: Preparing for Sputnik launch

The flight

The access gantries enclosing the rocket and the satellite on the launch pad were lowered at around T-15 minutes. (252) Shortly before the launch, Korolev along with top launch officials L. Voskresensky, A. I. Nosov and E. Ostashev descended into the launch control bunker to monitor a blastoff. (70) A senior technician from NII-229 test center Anatoly Korneev, who served as a operator of the main control console of the launch, pressed a "pusk" (liftoff) button. (546)

The launch vehicle with the PS-1 satellite blasted off on October 4, 1957, at 22:28:34 Moscow Time. (250) (It was already October 5 in Tyuratam.)

As the rocket disappeared in the night sky, Korolev, Tikhonravov, Bushuev, Reshetnev and Ivanvosky rushed to the cars for a ride to the assembly building at Site 2, where they hoped to "hear" the signals from the first satellite. (250)

Soon after the powered flight of the rocket was over, operators of the Tral system received the signal about the engine cutoff. After comparing the time of the signal with the count of the mechanical sports chronometer, they could happily confirm that the engine shutdown took place within the time period required to deliver the satellite into orbit. After a short pause, Lieutenant Borisov, manning a radio in a cottage at the IP-1 tracking station, heard from the satellite. The Space Age has began! The signal lasted for about two minutes until the satellite went out of range. Exhausted test personnel crowded in the cottage celebrated the success. (51)

Before the satellite completed its first orbit, TASS, the official Soviet news agency, announced the launch to the world. (51)

The flight controllers intentionally left the Tral telemetry system onboard the core stage active and its signal was detected during the second orbit.

Post-flight analysis

In the meantime, engineers started analyzing telemetry gathered during the launch. Data have shown that the rocket lifted off normally, deviating from the nominal trajectory no more than 0.3 degrees. In the meantime, the rotation of the steering thrusters did not exceed 3.6 degrees.

However, as it turned out, the main engine on the Block G strap-on booster of the rocket was late developing its intended thrust. As a result, 6.5 seconds after the launch, the rocket started to pitch, deviating around one degree from the nominal trajectory eight seconds after the liftoff. In the effort to correct the increasing pitch angle, steering engines No. 2 and 4 on the core stage rotated as much as eight degrees; similar engines on strap-on boosters of Block V and D rotated as much as 17-18 degrees, while tail air rudders rotated 10 degrees.

Only a split second remained after which the flight control system would terminate the flight of the underpowered rocket. Fortunately, the engine finally reached normal performance and rocket fully returned to nominal trajectory some 18-20 seconds after the liftoff.

In the meantime, at T+16 seconds, the SOB system, regulating the consumption of the propellant onboard failed, resulting in the excessive consumption of the kerosene fuel. During almost the entire powered flight, the combustion chamber pressure remained throttled up some four percent from standard.

The middle portion of the powered flight went with less drama: from 60th to 70th second of the mission, the deviation from the nominal pitch angle was reaching 0.75 degrees, while deviation in the course was about one degree. At the 100th second of the flight, the bank angle increased to one degree from nominal. Maximum rotation angles for steering engines of the core stage remained within 3-3.5 degrees, for thrusters on strap-on boosters these indicators remained within 6-8 degrees and for air rudders -- 2-3 degrees.

The separation between first and second stages took place after 116.38 seconds in flight. Just 0.33 seconds later, a command to shut down (first stage) main engines, known as VOD, was issued. Telemetry showed the reduction of thrust of the engines (of the first stage) within accepted parameters. In the aftermath of the staging, the attitude of the core stage, which continued firing, did not change above 0.5 degrees. Steering thrusters had no need to rotate more than 6-7 degrees on yaw and course channels, which was also within nominal parameters.

The second stage flew normally with pitch and bank parameters deviating 0.3 degrees from nominal and the course parameter off by 0.6 degrees. Steering engines No. 1 and 3 rotated up to four degrees and engines No. 2 and 4 up to six degrees. (84)

As the second stage continued to fire, telemetry registered oscillations of steering engines with the frequency of 6.5 Hz and reaching 7.5 Hz by the 280th second in flight. The amplitude of the oscillation reached 2.3 degrees. The oscillations stopped after T+280 seconds. The phenomenon was linked to the flexing of the rocket body.

At T+285 seconds a new wave of oscillations shakes engines, this time with the frequency of 1.5-1.6 Hz and the amplitude of two degrees. This time, it believed to be a result of oscillations of the liquid propellant inside the rocket. (84)

As a result of the SOB system failure, the propulsion system run out of fuel just one second before a nominal command from the programming timer to cut off the engines could be sent at T+296.4 seconds. (84) Instead, at 295.4 seconds after the liftoff (51), the engine was shot down by the AKT (Avariyny Contact Turbiny) sensor, which detected the increased spin of the fuel pump turbine, as it was no longer burdened by the flow of fuel. At that moment, 375 kilograms of liquid oxygen oxidizer still remained onboard the rocket.

At the moment of engine shutdown, the rocket was flying with the speed of 7,780 meters per second, at the altitude of 228.6 kilometers above the Earth surface, with an angle of 0 degrees 21 (24) minutes toward the local horizon. (84)

The second stage of the rocket and the satellite entered the 228 by 947-kilometer orbit, with the inclination 65.1 degrees toward the Equator, which took 96.2 minutes to complete. (52) (Another source, quoted orbit parameters as being 223 by 950 kilometers. 84) In any case, the premature engine shutdown left the satellite in the orbit some 80-90 kilometers below nominal.

The PS-1 satellite separated 314.5 seconds after the launch, or 19.9 seconds after the engine shutdown. (A built-in nominal delay for the separation was 18-20 seconds). (84)

A signal for deployment of the angular reflector mounted on the body of the core stage was sent at 325.44 seconds. The device allowed accurate tracking of the rocket's orbit parameters. (84)

Summary of launch events:

Time Event
T+0 Lift off
T+16 SOB system failure
T+116.38 Stage I and II separation
T+295.4 Stage II engine cutoff (actual)
T+296.4 Stage II engine cutoff (nominal)
T+314.5 Satellite and Stage II separation
T+325.44 Deployment of angular reflector on Stage II

End of flight

The satellite transmitted temperature data for 22 days before its power sources went dead. (217) Moscow Radio announced that on October 26, 1957. (174) The core stage of the R-7 rocket made 882 orbits and reentered on December 2, 1957. The satellite made 1,440 orbits and then burned up on the reentry into the Earth atmosphere on January 4, 1958, after 92 days in space. (84)


Next chapter: Aftermath of the Sputnik launch

Written and illustrated by Anatoly Zak. All rights reserved.

Last update: October 3, 2012

Multimedia archive

Sputnik animation

Sputnik enters orbit, opening Space Age. Click to play: Streaming QuikTime. Copyright © 2007 Anatoly Zak


The first artificial satellite of the Earth blasts off from Site 1 in Tyuratam (Baikonur) at 22:28 Moscow Time on October 4, 1957. Credit: RKK Energia

Sputnik launch

The artist impression of the first Sputnik launch. Click to enlarge. Copyright © 2007 Anatoly Zak

Sputnik's engine cutoff

Second stage of the launch vehicle with the first satellite enters orbit. Click to enlarge. Copyright © 2007 Anatoly Zak


Second stage of the launch vehicle with the first satellite shortly after reaching the orbit. Click to enlarge. Copyright © 2007 Anatoly Zak

Sputnik release

First in orbit: The world's first artificial satellite orbits Earth, shortly after separation from the launch vehicle. Click to enlarge. Copyright © 2007 Anatoly Zak


Typically for the post-Sputnik euphoria, the October 11, 1957, issue of the Vechernyaya Moskva newspaper run numerous materials on the first satellite, including this photo of Moscovites trying to catch a glimpse of the spacecraft.

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