China Wanted to Send Tortoises to the Far Side of the Moon

China was thinking about sending tortoises to the far side of the moon as part of its Chang'e-4 mission, one of the scientists involved has revealed. The plan was dropped after researchers realized they would only have enough oxygen to keep them alive for around 20 days—which is far shorter than the time it took the spacecraft to land on the lunar surface.

Xie Gengxin, from the Technology Research Institute at Chongqing University, was in charge of designing the biological experiment on board Chang'e-4. In an interview with the technology magazine IEEE Spectrum, Xie said the team had initially wanted to send a small species of tortoise to the moon. This could have provided important information about how animals react to the gravitational conditions on the lunar surface—findings that could aid future manned missions there.

However, constraints around weights on board the spacecraft prevented them from sending the first reptiles on the moon.

"The weight of the Chang'e-4 probe demanded that the weight [of the experiment] can't exceed three kilograms (6.6lbs)," he told the magazine. "Even though it is very meaningful to choose tortoise, the oxygen inside the payload can only be used for about 20 days for turtles."

Chang'e-4 was launched on December 7 last year. It entered the lunar orbit five days later and touched down on the surface of the moon on January 3. Two months before take off, the biological experiment was integrated with the spacecraft—so whatever it involved had to be kept alive for about three months before reaching the moon.

Xie said they have not ruled out sending animals on future Chang'e missions. They are hoping to send more biological payloads there in the future, and if they are given a larger payload allocations it may be possible to send animals in the future.

There is a long history of animals being send into space. The first fruit flies were sent up 62 miles into Earth's atmosphere in 1972. Two years later, the first monkeys—called Albert I and Albert II—was sent up on V-2 rockets. Both died, with Albert I suffocating and Albert II being killed on impact after a parachute failure.

In 1968, the Soviet Union sent the first tortoises to space on a craft that would orbit the moon. They survived the return trip to Earth.

Humans are currently the only living animal known to have visited the moon's surface. However, there may be thousands of tardigrades—microscopic, water-dwelling creatures known for their extreme survival capabilities—alive on the moon right now.

In August, it was announced that Israel's private lunar lander Beresheet, which crashed onto the lunar surface earlier in the year, had a box full of these creatures on board. Nova Spivack, founder of the company that sent the payload, said he had reason to believe the tardigrades survived the crash.

For Chang'e-4, instead of tortoises the team ended up sending seeds and insect eggs. This resulted in seeds sprouting on the moon—the first time humans had successfully grown a living organism on another celestial body other than Earth. The cotton seeds died a few hours later as the lunar night saw temperatures plummet—for example, at the equator, temperatures of minus 133 degrees Celsius have been recorded, NASA says. Speaking to IEEE Spectrum, Xie said their analysis of the experiments has revealed the cotton seed grew two leaves, rather than just one as was first thought.

tortoise with a suitcase
Representative image showing a tortoise going on a trip. Scientists in China were going to send tortoises to the moon but they would have died before getting there, so the idea was dropped. iStock