Kenneth Glad
Space agencies are preparing for longer missions, with NASA’s Artemis program and future Mars plans aiming to extend human presence beyond Earth. Yet one basic question remains unresolved: Can humans start families in space?
Science Alert reports that new research is raising doubts about how early life forms in microgravity. The study suggests that embryo development, one of the most delicate biological stages, may be disrupted when gravity is removed.
Additionally, Digi24 reports that pig embryos in simulated microgravity showed slower progress less than a week after fertilization. At that point, cells are expected to begin organizing into the foundations of organs.
The study, published by Communications Biology, indicates that gravity may play a role not just after conception, but in how embryos implant and develop. Without it, these processes could become unstable in ways scientists are only beginning to explore.
Obstacles before conception
The difficulties appear even earlier. Fertilization itself became less reliable under simulated space conditions.
Rates fell sharply, dropping by roughly a third in mice and by about one-sixth in pigs. This pattern suggests the issue is not species-specific, but linked to the environment.
Part of the explanation lies in sperm behavior. In lab conditions designed to mirror the reproductive tract, sperm were markedly less effective at finding their way to the egg.
“Many of the proteins on the surface of sperm act as mechanosensors, molecular devices that detect physical forces. If you remove gravity, these sensors are affected, and the sperm’s ability to orient and move is disrupted,” explained Nicole McPherson of the University of Adelaide, who led the study.
Adapting to weightlessness
To investigate further, scientists used a clinostat, a device that mimics weightlessness by constantly rotating cells and removing any fixed sense of direction.
“From the cell’s perspective, there is no constant ‘up’ or ‘down,’ but a continuous state of free fall that closely mimics weightlessness in space,” McPherson said.
Researchers then explored whether progesterone could improve outcomes, since the hormone typically helps guide sperm toward the egg.
“It helped to some extent, but the concentrations required were much higher than natural levels,” McPherson noted.
Put together, the results point to a deeper issue. Human reproduction has never been tested beyond Earth, and the biological systems involved may depend more on gravity than previously assumed.
“From the moment sperm begins its journey to embryo development, gravity appears to play a role we are only starting to understand. It is not just a background condition of life, but an essential component of the biological processes that create it,” McPherson concluded.
For now, the challenge is clear—and scientists are only beginning to explore how to overcome it.
Sources: Digi24, Science Alert, Communications Biology
