With the growing challenges on Earth—from pandemics to record-breaking climate disasters—the notion of humans needing a backup plan has moved from science fiction to serious discussion. For advocates of space colonization, establishing outposts on the moon or Mars offers a form of insurance against catastrophic extinction. However, there’s one critical unknown: can humans reproduce in space?
Freeze-dried mouse sperm orbiting Earth aboard the International Space Station (ISS) could hold the answer. Led by Professor Teruhiko Wakayama of Japan’s University of Yamanashi, this groundbreaking experiment seeks to determine whether mammals can procreate in the unique environment of space.
Pioneering Reproductive Science in Space
In a pioneering effort, Wakayama and his team stored freeze-dried mouse sperm in a radiation-protected box aboard the ISS. The samples, which will return to Earth in 2025, will undergo rigorous analysis to assess the impact of cosmic radiation and microgravity on their viability. The goal is not just to produce healthy offspring but to determine whether reproductive cells can be preserved indefinitely in space.
Back in Japan, Wakayama is developing a device to enable astronauts to conduct rodent in vitro fertilization (IVF) aboard the ISS within the next few years. If successful, the implications are profound—not just for human reproduction but for the preservation of Earth’s genetic resources in case of catastrophic events.
“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,” says Wakayama.
A Legacy of Breakthroughs
Wakayama is no stranger to groundbreaking research. In 1997, he co-developed a novel cloning method that resulted in the first mouse cloned from adult cells. His team also conducted the first successful freeze-drying and rehydration of mouse sperm stored in space, demonstrating that viable sperm could be preserved for up to 200 years under current methods. However, Wakayama emphasizes that this timeframe is “absolutely not long enough for our future.”
To extend the viability of genetic material, his latest experiment involves a new device designed to protect sperm stored at room temperature from radiation. This advancement could potentially make indefinite storage in space a reality.
Lessons from Space Creatures
Scientists have long studied the effects of space on biological processes, including reproduction. As early as 1989, fertilized chicken eggs were sent into orbit in the “Chix in Space” experiment. Other creatures, such as tadpoles and cockroaches, have also been studied. Notably, a cockroach named Nadezhda gave birth to 33 offspring conceived in orbit in 2007, though they displayed some abnormalities, such as darker exoskeletons.
While amphibians and fish have successfully completed full reproductive cycles in space, mammals represent the next frontier. Wakayama’s work with freeze-dried sperm aims to bridge this gap and provide critical insights into whether mammals—and ultimately humans—can reproduce in microgravity.
Challenges of Space Reproduction
Space travel poses numerous challenges for reproduction. Cosmic radiation can damage DNA, potentially causing genetic abnormalities in offspring. Microgravity complicates fundamental developmental processes, such as the formation of the nervous system and limbs, as the absence of gravity disrupts the directional signals essential for growth.
Wakayama’s work could also have practical applications for transporting animals to other planets, from livestock for food production to pets for companionship. However, he is focused on mice for now, with his IVF project approved by Japan’s space agency and a launch anticipated within two years.
Sustaining Human Life in Space
As space exploration progresses, the question of human reproduction grows increasingly urgent. NASA’s Artemis program aims to establish a sustained presence on the moon by the late 2020s, and SpaceX envisions the first crewed mission to Mars within the next four years.
Scientists already know that space travel significantly impacts the human body. Cosmic radiation increases the risk of cancer, while microgravity weakens the immune system and causes muscle and bone loss. Addressing these immediate health concerns is a priority, but Wakayama argues that understanding reproduction is equally vital for humanity’s long-term survival 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,” Wakayama says. His experiments aim to provide answers to these critical questions, offering reassurance if reproduction is feasible and guidance for overcoming challenges if it is not.
The Future of Humanity
Wakayama’s work represents a crucial step in humanity’s journey toward becoming a multi-planetary species. By exploring the feasibility of reproduction in space, he is not only pushing the boundaries of science but also addressing one of the most fundamental requirements for sustaining life beyond Earth.
“If we can confirm that reproduction in space is possible, it will bring reassurance,” Wakayama says. “And if it doesn’t work, we need to understand how to address that challenge.”
As humans prepare to venture further into the cosmos, experiments like these could hold the key to our survival—and to creating new beginnings among the stars.
