When the Soviet Union sent the dog Laika into orbit in 1957, the public was told she had survived for days — but decades later it emerged that she had actually died within hours, after Sputnik 2’s cabin overheated.

In October 2002, at the World Space Congress in Houston, the Russian scientist Dimitri Malashenkov presented a paper that corrected the public account of one of the most widely recounted events of the early space age. Laika, the dog carried into orbit aboard Sputnik 2 in November 1957, had not lived for several days in space, as Soviet sources had long allowed the world to believe. She had died within hours of launch, after the cabin overheated.

The outline of the mission was never in question. Sputnik 2 launched on 3 November 1957, the second artificial satellite placed in orbit and the first spacecraft to carry a living animal into Earth orbit. What the 2002 paper changed was the account of how quickly, and in what circumstances, that animal died.

A mission with no return planned

Laika was a stray, a small mongrel of about five kilograms picked up from the streets of Moscow. Soviet handlers favoured strays on the reasoning that an animal which had already survived a Moscow winter would tolerate deprivation better than a purebred dog. According to Britannica’s account of the mission, she was trained over several weeks and held in progressively smaller enclosures to prepare her for the capsule.

The spacecraft could not bring her back. The technology to return a capsule through the atmosphere had not yet been built. Sputnik 2 carried no heat shield and no system for a controlled descent. Laika’s death was therefore certain before launch. The mission was designed to test something narrower: whether a mammal could survive the launch itself and the first hours of weightlessness.

The schedule was set by politics rather than readiness. After Sputnik 1 reached orbit in October 1957, the Soviet leader Nikita Khrushchev wanted a second satellite up by 7 November, the fortieth anniversary of the October Revolution. A more capable satellite was already under construction but would not be finished until December. Sputnik 2 was assembled quickly to meet the anniversary, and its life-support and thermal systems were built under that compressed timeline.

What the telemetry showed

The 2002 disclosure drew on telemetry the spacecraft had transmitted during the flight. By that account, Laika’s condition was satisfactory at the start. Her breathing and heartbeat were still being recorded through the first three orbits, though the launch had clearly stressed her body. Her pulse, measured through electrodes, had tripled during the minutes of launch and only partly settled once the craft was in orbit.

The cabin temperature was meant to stay between 15 and 30 degrees Celsius. During the third orbit it rose past 40, with one figure from the mission records putting it at 43. By around the fourth orbit, roughly five to seven hours after launch, the sensors monitoring her returned no further readings. The likely cause was a failure in the spacecraft’s thermal control, possibly worsened by the rocket core remaining attached and by the satellite’s early orbit spending unusually long periods in sunlight.

Why the official account held

The telemetry was available to Soviet scientists from the start.

The decision to leave the public with a different impression appears to have been political rather than scientific. For years the official Soviet press let the world believe Laika had lived in orbit for close to a week. Some accounts had her dying when the oxygen ran out around the sixth day. Earlier Soviet statements suggested she had been put to sleep painlessly by a poisoned final meal before the air was exhausted. Conceding that the thermal system had failed within hours would have sat uneasily with a launch that had been timed, and publicised, for the anniversary.

How the record was corrected

The correction took 45 years.

It did not come from a leak or an inquiry. It came from a scientist who had worked on the mission, speaking at a conference, long after the political reasons for the original silence had faded. The Smithsonian’s account of the declassified material traces the corrected timeline to a report from the Institute of Biological Problems describing the telemetry from the flight.

Some of those involved had already begun to speak about the mission with discomfort. In 1998, before the full disclosure, Oleg Gazenko, who had worked on the Soviet space programme during the Sputnik period, said of the flight that the more time passed, the more he regretted it.

Laika is secure in the history of spaceflight as the first animal to orbit the Earth. The longer-running interest in her case is narrower and less comfortable. It documents how far a space programme’s internal data and its public account can be held apart, and for how long, once the timing of a launch has been made to carry political weight.