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Previous chapter: Sputnik design
The rocket A version of the R-7 rocket, which was destined to carry the first satellite into orbit, carried a rather long designation -- 8K71PS No. 1 M1-PS. It featured several upgrades deferring it from previous R-7 test vehicles. (52) Along with the military warhead, gone were measurement hardware, top avionics section containing vibration monitoring system, cables connecting the rocket and the warhead and a considerable portion of the flight control hardware, including the radio-control system. The number of onboard electric batteries was also reduced. (51) As a result, the mass of the vehicle went down from 280 tons for the original R-7 rocket to 272.83 tons (or 267 tons, at the time of liftoff) for the space launcher. At liftoff, the engines would reach the total thrust of around 398 tons. (256, 52) Upon reaching the orbit, the main engine cutoff had to be performed by the gyroscopic integrator or on a command from the emergency contact of the turbine in the main engine. Such command would be issued as soon as the rocket run out of fuel or oxidizer. All tracking of the rocket in flight had to be conducted passively by means of radar, without onboard response, and with the help of ground telescopes. Both ways had a limited range and accuracy. Based on experience with the previous launch of the R-7 rocket, ground controllers expected the Binokl (binocular) tracking system to "see" no further than 200 kilometers for the rocket, and much less for a satellite. In the meantime, the P-30 radar demonstrated an effective range of 500 kilometers, when tracking aircraft. Its effectiveness would be further reduced by a relatively slow rotation of its antenna. Optical sensors Kth-41 and KT-50 available in Tyuratam at the time had a range of 100-200 kilometers, also too short for effective tracking of a satellite. (51) Modifying the rocket for Sputnik-2 mission For the launch of Sputnik-2, a second braking nozzle was added to the core stage of the rocket to prevent tumbling of the vehicle upon entering orbit. (248) As in the rocket launching the first satellite, the braking nozzle would employ gas, which pressurized oxidizer tank during the powered flight. (84) Once in orbit, a special programming device, installed on the core stage would switch the Tral-Ts telemetry system from transmitting the parameters of the rocket to channel scientific data from scientific payloads. (52) To help maintain proper temperature in the dog cabin, the transfer cone, which connected the satellite with the rocket, was thoroughly polished, additional thermal blanket were added and copper panels were installed on the telemetry boxes. The core stage was also equipped with deployable reflectors. To maximize scientific payload of Sputnik-2, some flight control equipment was removed from the rocket. For the same purpose, the flight profile was modified to ensure maximum use of onboard propellant. It was achieved by programming the flight control system to shut down the main engine only when its turbo pump detects that it run out of either propellant or oxidizer. In the previous launch, this way of shutting down the engine was only a backup mode. The R-7 development cooperation:
Base R-7 rocket tech dossier:
Next chapter: Preparing for flight |
PICTURE GALLERY
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
The artist impression of the first Sputnik launch. 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
The R-7 rocket configured to carry the second satellite of the Earth. Click to enlarge. Copyright © 2007 Anatoly Zak
The launch vehicle with the second Soviet artificial satellite on the launch pad in Baikonur. Credit: RKK Energia
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