Frozen sperm can remain viable in space for over 200 years

Life on Earth has faced immense challenges in recent years. The pandemic, heatwaves, and natural disasters remind us how fragile our existence is. These events fuel the argument for seeking a new home in space where humanity might reproduce and thrive.

However, for humans to live and grow on other planets, we must first understand if it’s possible to have children in space. This is a critical question because reproduction is essential for population growth in a new environment.

To address this, scientists are conducting novel experiments involving freeze-dried mouse sperm that is stored aboard the International Space Station (ISS). The results could provide vital insights into the possibility of mammalian reproduction beyond Earth.

Frozen sperm experiment in space

Freeze-dried mouse sperm is currently stored on the ISS in a radiation-protected environment.

In 2025, the samples will return to Earth, where Professor Teruhiko Wakayama from Japan’s University of Yamanashi will study them. He aims to determine the impact of the space environment on reproduction and assess whether these samples can create healthy offspring.

Wakayama has ambitious goals. He is developing a device to enable astronauts to conduct rodent in vitro fertilization (IVF) aboard the ISS. This could pave the way for human reproduction in space and may even provide an avenue to safeguard Earth’s genetic diversity.

“Our aim is to establish a system for safely and permanently preserving Earth’s genetic resources somewhere in space – whether on the moon or elsewhere – so that life can be revived even if Earth faces catastrophic destruction,” said Wakayama.

Sending mouse sperm to space

Wakayama is no stranger to pushing scientific boundaries. In 1997, he co-developed a method to clone the first mouse from adult cells. Since then, he has conducted various studies on reproduction in space.

His team pioneered a freeze-drying method to send mouse sperm to the ISS, where it was stored for six years. Upon its return, the sperm produced healthy baby mice.

The findings revealed that freeze-dried sperm could remain viable for up to 200 years in space.

“That’s absolutely not long enough for our future,” Wakayama admits. He is now testing a new radiation-resistant storage device to extend the viability of reproductive cells indefinitely.

Creatures that reproduced in space

Scientists have long studied Earthly organisms in space to understand how microgravity and cosmic radiation affect biological processes.

In 1989, fertilized chicken eggs traveled to space in an experiment nicknamed “Chix in Space.” Frogs and fish have also reproduced in space, though with mixed success. In 2007, a cockroach gave birth to offspring conceived in orbit, though the young displayed some abnormalities.

“We have seen that most of the specific phases of the reproductive cycle can occur in space, at least in a species or two, not always completely successfully. Going to mammals is the next natural step,” explained Virginia Wotring, a professor at the International Space University in France.

Challenge of sustaining life

Human reproduction in space faces significant hurdles. Cosmic radiation can damage DNA, increasing the risk of genetic abnormalities in offspring. Microgravity may interfere with embryo development, including critical processes like forming the nervous system and limbs.

“There is other information that we need right now in order to care for the astronauts we’re sending to space now,” said Wotring. Immediate priorities include mitigating the effects of radiation, muscle loss, and weakened immunity.

Despite these challenges, Wakayama believes his work is essential for long-term space exploration. He noted that understanding how reproduction works in space could help humans settle on other planets and even bring livestock and pets to sustain life.

Possibility of reproducing in space

Wakayama’s IVF project has been accepted by Japan’s space agency, and he hopes to launch the necessary device to the ISS within two years. His experiments could reveal whether mammals, including humans, can reproduce and develop normally in space.

“In sci-fi movies, people live on other planets and babies are born, but we don’t even know if that’s possible yet,” said Wakayama. His work aims to answer this fundamental question.

“If we can confirm that, it will bring reassurance. And if it doesn’t work, we need to understand how to address that challenge.”

Broader implications of the research

Humanity has made strides toward becoming a multi-planetary species. NASA’s Artemis program plans to return astronauts to the Moon in 2026, while SpaceX envisions a crewed mission to Mars in the near future. However, these ambitious plans hinge on solving critical issues, including reproduction.

Wakayama’s research represents a vital step in understanding how life can sustain itself in space. Whether his experiments confirm or challenge the possibility of reproduction, they will shape the future of human space exploration.

As we look to the stars, questions about survival and reproduction remind us of the complexities of leaving Earth behind. Whether or not we can thrive in space remains one of humanity’s greatest scientific frontiers.

The study is published in the journal Science Advances.

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