People are only just discovering what really happened to first dog sent to space and it's heartbreaking

Warning: This article contains content which some readers may find distressing.

People have just found out about a less well-known and tragic part of the space race.

At the height of the Cold War, the US and the USSR competed fiercely in the space race, with both sides seemingly stopping at nothing to hit big milestones.

From the first satellite to the Moon landings, it became symbolic of a clash of ideas.

But large parts of it may not have happened without the tragic sacrifice of one of the first astronauts, though it's not who you're thinking of.

Before humans first went out into space, experiments were carried out involving animals.

This was partly a way to test that the life support systems on the spacecraft actually worked in practice, as it's one thing to test on Earth but quite another to actually be in space.

Laika in the Sputnik 2 capsule (Sovfoto/Universal Images Group via Getty Images)

But to be sure of that, it was deemed a lesser sacrifice to the space program if an animal died than a trained astronaut.

If a mammal like a dog or a monkey could survive in space with the equipment, that apparently meant that humans would be able to as well.

Unfortunately, this meant that a number of animals had glorious but tragically short careers as astronauts.

Enter Laika the dog, whose original name was Kudryavka, and was one of the unfortunate animals who formed part of these efforts.

After being strapped into the Sputnik 2 container on November 3, 1957, Laika was launched into space.

Laika's voyage was intended to measure the survivability in space for a mammal, but the stray terrier mix was never going to see the ground again.

During the launch, Laika's heart rate reportedly tripled and would only settle when she entered weightlessness.

Laika was strapped into capsule (Sovfoto/Universal Images Group via Getty Images)

Around five to seven hours after her launch, she died due to a mixture of stress and overheating.

But the full tragedy of Laika's story is not just in that she died, but in that the people who sent her made no plans for her return trip to Earth because they knew she was going to die.

Even if she had not died due to overheating, she would have suffocated after around 10 days as oxygen ran out.

Engineer Yevgeniy Shabarov recalled the dog's final moments on Earth, saying: "After placing Laika in the container and before closing the hatch, we kissed her nose and wished her bon voyage, knowing that she would not survive the flight."

Many have only just discovered Laika's heartbreaking story, with one social media user writing: "That’s disgusting and so cruel."

Another added: "I cry whenever I am reminded of Laika. Her last moments being full of confusion, fear, and stress. No animal should ever have to endure this sort of thing."

Someone else commented: "This broke my heart omg."

While a tragedy, Laika's flight was viewed as a win by the USSR and she became the first animal to orbit the Earth.