The Tailed Spaceflight: 65th Anniversary of Belka and Strelka's Heroic Voyage!

Today marks the 65th anniversary of a major milestone in world cosmonautics. On August 19, 1960, the Soviet canine cosmonauts Belka and Strelka aboard the Sputnik 5 spacecraft completed the world’s first orbital flight and returned safely to Earth. Their mission proved the possibility of safe extended spaceflight and provided invaluable scientific data, including on radiation conditions in near-Earth orbit.

The flight of Belka and Strelka was a meticulously planned experiment. They were accompanied on board by mice, plants, and microorganisms. The spacecraft was equipped with a complex suite of scientific instruments to record cabin parameters: sensors for pressure, temperature, CO₂ concentration, and crucially, sensors for measuring radiation.

The primary medical and biological objective was to study the effects of spaceflight conditions—weightlessness, g-forces, and ionizing radiation—on living organisms.

During its 25-hour mission, the spacecraft completed 17 orbits around the Earth, reaching altitudes of up to 340 km. Throughout the entire flight, the instruments meticulously recorded the levels of radiation exposure.

The data obtained during the mission confirmed the scientists' calculations: the radiation levels in low Earth orbit did not pose a critical danger for a short-term mission. The dose received by the dogs was insignificant and caused no immediate visible effects on their health. This finding eliminated one of the major concerns for sending a human into space—the risk of immediate radiation sickness from cosmic radiation.

Belka and Strelka returned alive and healthy. Subsequently, Strelka even gave birth to a healthy litter. Thorough examinations revealed no pathological changes in their organisms caused by the radiation. This fact became the green light for Yuri Gagarin's historic flight.

While the doses received in 1960 were small, the flight of Belka and Strelka laid the foundation for the systematic monitoring of the radiation environment in space. Today, as we conduct long-term expeditions on the ISS and plan interplanetary missions (to the Moon and Mars), radiation protection is one of the highest priority tasks.

The feat of these two small dogs was not merely a propaganda triumph, but a serious scientific breakthrough. They were the first 'operators' of a spaceborne radiation monitoring system, whose flight provided an answer to a fundamental question and opened humanity's road to the stars.

The team at the Radiation Monitoring Laboratory of the SINP MSU pays tribute to this historic event, which laid the groundwork for the work we continue today!