|Harvard designation||1957 Beta 1|
|Mission duration||162 days|
|Launch mass||508.3 kilograms (1,121 lb)|
|Start of mission|
|Launch date||November 3, 1957, 02:30UTC|
|End of mission|
|Decay date||April 14, 1958|
|7,306 kilometres (4,540 mi)|
|211 kilometres (131 mi)|
|1,659 kilometres (1,031 mi)|
|3 November 1957|
Sputnik 2 (Russian pronunciation:
Launched by the
The plan for Sputnik 1 and Sputnik 2 was initiated and presented by Korolev, and was approved in January 1957. At that time, it was not clear that the Soviets' main satellite plan (which would eventually become
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Sputnik 2, known to Korolev's design bureau as "Prosteyshiy Sputnik-2", meaning "Simple Satellite 2", was launched into a 212 × 1660 km (132 × 1031 mi) orbit with a period of 103.7 minutes on a modified
Sputnik 2's launch vehicle had several modifications for the mission. These included modifying the launch trajectory to utilize propellant more efficiently and removing some flight control components to reduce weight. In addition, the core stage would be burned to propellant depletion instead of cutting off at a preset time. The telemetry system at engine cutoff would be switched from monitoring the booster's parameters to those of the capsule. It was also designed to only transmit data for ten minutes at a time every 90 minutes, so as to prevent battery power from being used up sending data while the spacecraft was out of range of Soviet tracking stations. The interstage section between the booster and capsule was highly polished and equipped with thermal blankets so as to reflect off sunlight and keep the latter cool; also, several deployable reflectors were mounted on the core stage. A braking nozzle was added to the core stage to prevent it from tumbling in orbit; this would work by venting excess
Ten dogs were considered for the mission, with the final selection being narrowed down to three, Laika being the flight animal, Albina the backup, and Muhka used to test equipment.
Liftoff took place at about 5:30 PM Moscow time on November 3. Booster performance was nominal and the command to terminate core stage thrust was issued at T+297 seconds, just as onboard sensors detected LOX depletion. The booster and capsule entered a 225 km × 1,671 km (140 mi × 1,038 mi) orbit at a 65 degree inclination.
During the first two orbits, it proved difficult to reliably track Sputnik 2's flight path, but ground controllers were able to intercept theodolite data from an American tracking station in
Telemetry data indicated that Laika's vital signs were normal for the first three orbits, but during the fourth orbit, the cabin temperature rose to 43 °C (109 °F) followed by movements of the dog. Data received on the second day showed no signs of breathing, heart rate, or blood pressure, but the cardio sensor was still registering a heart beat. By the morning of November 6, there were no signs of life in the capsule. On November 10, the batteries in the spacecraft ran out and all data transmission ceased, after 150 separate telemetry sessions. Sputnik 2 reentered the atmosphere on April 14, 1958 after 162 days in space and about 2500 orbits. Reentry was sighted from the east coast of the United States and surviving debris impacted in the Amazon region of South America.
The flight sparked considerable ethical debate about cruelty to animals, as Laika had been launched with the full knowledge that she could not be recovered and may have suffered a quite unpleasant death from panic and overheating, and even some Soviet space program officials reportedly felt sorry about her. An anonymously-written poem criticizing the mission and the Soviet state was circulated in Moscow.
The R-7 was also known by its GURVO designation 8K71, as well as the T-3, M-104, and Type A. The R-7 modified for the PS-2 satellite launch was designated 8k71PS. Unlike Sputnik 1, Sputnik 2 was not designed to detach from the R-7 sustainer core, since Sputnik 1's core stage had demonstrated an acceptable orbital lifespan. This allowed the core's Tral D telemetry system to be used to transmit data, but would lead to speculation that Sputnik 2 had failed to separate. After Sputnik 2 reached orbit, the interior temperature rapidly climbed to over 40 °C (100 °F), and Laika survived for only a few hours instead of the planned ten days.
|Solar radiation (ultraviolet and|
x-ray emissions) and cosmic rays