A satellite began beeping from space on October 4, 1957, prompting scientists to rethink what was possible. Sputnik represented the Soviet Union’s contribution to the International Geophysical Year, an international scientific effort that ran from July 1957 through December 1958. Sputnik orbited Earth every 90 minutes and did not carry scientific equipment.
The chief designer, Sergei Korolev, had intended to construct a more sophisticated satellite, but after missing its deadline, he decided to make a very simple device. It contained a transmitter whose signal could be picked up by amateur radio operators around the world.
Sputnik was the first artificial satellite put into orbit, according to a NASA historical feature.
Not long after, yet another unexpected event took place. This time the rocket carried a dog named Laika, who became the first animal to orbit Earth. As described by NASA, an R-7 rocket lifted off from the same launch region, which would later be associated with the Baikonur Cosmodrome in Soviet Kazakhstan, on November 3.
Because of the equipment required to keep the dog alive during the flight, sputnik 2 was significantly heavier than the previous spacecraft, weighing about 1,120 pounds compared with Sputnik 1’s roughly 184 pounds,.
The pace only sped up from there. Its instruments subsequently led to the discovery of the radiation belts that were named after physicist James Van Allen. Their mission provided another step toward understanding how living organisms could withstand spaceflight before humans were sent into orbit. Laika’s flight was short-lived, but it was part of a much larger effort to determine whether living organisms could endure launch, weightlessness, and re-entry. This broader history is discussed in a review called Animals and Spaceflight: From Survival to Understanding , which appeared in the Journal of Musculoskeletal and Neuronal Interactions . E.R. Morey-Holton and colleagues, from NASA Ames Research Center and Lockheed Martin Space Operations, describe how animals became part of the space program from its earliest years. As that groundwork developed, animal research became more focused on how spaceflight changes the body. Animals were used as biological models aboard crewed and uncrewed spacecraft so researchers could examine physiological responses to spaceflight. The review discusses changes observed in the forelimbs and hindlimbs of growing male rats, among other findings. These experiments were separate from Laika’s mission and provided later evidence about how reduced mechanical loading affects the body. The authors discuss the Functional Use Hypothesis, which proposes that tissues adapt to the demands placed on them and that reduced use can lead to loss of function or tissue. Laika did not return to Earth, so her flight could not provide the kind of post-flight biological measurements obtained from animals in later experiments. Her mission instead established an early milestone in testing whether a living animal could survive the launch and enter orbit. Decades later, her journey remains an important part of the history of spaceflight, while the animal experiments that followed helped scientists investigate how living bodies adapt to the space environment and what happens when they return to Earth.
On January 31, 1958, the United States sent Explorer 1, a 30-pound satellite, into space, and a group of female mathematicians at NASA’s Jet Propulsion Laboratory helped verify that it had reached orbit. Congressional hearings following Sputnik contributed to the creation of NASA, which began operations on October 1, 1958. The Soviet Union’s next successful orbital flight carrying dogs came in August 1960, when Belka and Strelka returned safely to Earth . Humans reached the Moon 12 years after Sputnik.
Earlier animal experiments showed that animals could survive and perform certain actions during launch, periods of reduced gravity, and re-entry.
There was not enough time to develop a system that could return Laika safely to Earth, and Sputnik 2 was not designed for a long-duration mission. Sputnik 2 continued orbiting until it reentered the atmosphere and burned up on April 14, 1958. The whole mission was put together on short notice. The spacecraft did, however, carry life-support equipment, including systems for supplying oxygen and food and managing the cabin environment. Laika was not expected to return alive, and the mission ended after she died several hours into the flight.
