Sputnik 2

Sputnik 2
Sputnik2 vsm.jpg
Model of Sputnik 2 at the Polytechnic Museum in Moscow
Mission typeBioscience
Harvard designation1957 Beta 1
Mission duration162 days
Orbits completed2570
Spacecraft properties
Launch mass508.3 kilograms (1,121 lb)
Start of mission
Launch dateNovember 3, 1957, 02:30 (1957-11-03UTC02:30Z) UTC
RocketSputnik 8K71PS
Launch siteBaikonur 1/5
End of mission
Decay dateApril 14, 1958 (1958-04-15)
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Semi-major axis7,306 kilometres (4,540 mi)
Perigee altitude211 kilometres (131 mi)
Apogee altitude1,659 kilometres (1,031 mi)
Inclination65.33 degrees
Period103.73 minutes
Epoch3 November 1957[1]

Sputnik 2 (Russian pronunciation: [ˈsputʲnʲɪk], Russian: Спутник-2, Satellite 2), or Prosteyshiy Sputnik 2 (PS-2, Russian: Простейший Спутник 2, Elementary Satellite 2) was the second spacecraft launched into Earth orbit, on 3 November 1957, and the first to carry a living animal, a Soviet space dog named Laika. Laika survived for several orbits but died a few hours after the launch.[2]

Launched by the U.S.S.R., Sputnik 2 was a 4-meter (13 foot) high cone-shaped capsule with a base diameter of 2 meters (6.6 feet) that weighed around 500 kg, though it was not designed to separate from the rocket core that brought it to orbit, bringing the total mass in orbit to 7.79 tonnes.[3] It contained several compartments for radio transmitters, a telemetry system, a programming unit, a regeneration and temperature-control system for the cabin, and scientific instruments. A separate sealed cabin contained the dog Laika.

Engineering and biological data were transmitted using the Tral D telemetry system, transmitting data to Earth for a 15-minute period during each orbit. Two photometers were on board for measuring solar radiation (ultraviolet and x-ray emissions) and cosmic rays. A 100 line television camera provided images of Laika.[4]Sputnik 2 was launched into space only 32 days after its predecessor Sputnik 1. Due to the huge success of Sputnik 1, Nikita Khrushchev ordered Sergey Korolev back to work creating a Sputnik 2 that needed to be ready for space for the 40th anniversary of the Bolshevik revolution.[5]

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 Sputnik 3) would be able to get to space because of the ongoing issues with the R-7 ICBM, which would be needed to launch a satellite of that size. “Korolev proposed substituting two 'simple satellites' for the IGY satellite”.[5] The choice to launch these two instead of waiting for the more advanced Sputnik 3 to be finished was largely motivated by the desire to launch a satellite to orbit before the US.

Mission profile

USSR postage stamp "Спутник-2"

Sputnik 2, known to Korolev's design bureau as "Prosteyshiy Sputnik-2", meaning "Simple Satellite 2",[6] was launched into a 212 × 1660 km (132 × 1031 mi) orbit with a period of 103.7 minutes on a modified ICBM R-7, similar to the one used to launch Sputnik 1.

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 helium gas from the propellant tank pressurization system. Several RD-107 engines were test-fired, with the best-performing units being selected for use on Sputnik 2's booster. The launch vehicle arrived at Baikonur on October 22, along with various parts of the capsule. On November 1, the booster was erected on LC-1.

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 Perth, Australia. Data showed that Laika's heart rate and breathing spiked rapidly during ascent, but she otherwise reached orbit largely unscathed. Official Soviet press releases stated that Laika survived a week in orbit, but information released in the post-Soviet era indicated that she died only a few hours into the mission. Other sources suggested it had been four days before the dog succumbed to overheating and carbon dioxide buildup.

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.[7]

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,[8] as well as the T-3, M-104,[9] and Type A.[10] The R-7 modified for the PS-2 satellite launch was designated 8k71PS.[11] 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.[12] 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.[13]

Instruments Purpose
Dog Laika Biological data
Geiger counters Charged particles
Spectrophotometers Solar radiation (ultraviolet and
x-ray emissions) and cosmic rays