The Human Genome Project transformed scientists' understanding of human DNA. Now the latest research is expanding that legacy by examining how the absence of Earth's gravity affects the organization of the human genome.

A study led by researchers at New York University found that human cells exposed to simulated microgravity maintained much of their genome's organization over 24 hours, even as the cell nucleus changed in size and shape. The findings could help scientists understand how the human body responds to spaceflight and prepare astronauts for future long-duration missions to the moon and Mars.

Published Sept. 25, 2026, in the journal Science Advances, the study examined how simulated microgravity and fluid movement affect the structure and behavior of the genome inside living human cells.

Researchers found that simulated microgravity did not cause the DNA damage observed under certain fluid-flow conditions, suggesting that some earlier experiments may have confused the effects of gravity with those of movement within laboratory samples.

The results offer new insight into the physical forces that shape cellular biology, although the researchers caution that short-term laboratory experiments cannot establish what happens during months or years in space.

Human Genome Project Opened the Door to New Discoveries

Launched in 1990, the Human Genome Project was an international scientific effort to identify and sequence the roughly 3 billion chemical bases that make up human DNA. Researchers announced its completion in April 2003, creating a foundation for advances in genetics, disease research and personalized medicine.

The project's completion did not mean scientists had answered every question about the human genome. Researchers continue to investigate how DNA is folded, organized and regulated inside cells, and how environmental conditions affect those processes.

DNA in a human cell would stretch to roughly 2 meters if unwound, yet it fits inside a nucleus only a few micrometers across. This compact arrangement is not simply a way to store genetic material. The organization of DNA helps regulate which genes are active and how cells respond to changes in their environment.

Understanding how physical forces affect that organization may provide clues to cellular processes involved in development, aging and disease.

Researchers Simulate Microgravity on Earth

The NYU research team, led by Alexandra Zidovska of the university's Department of Physics, designed experiments to isolate the effects of gravity from those caused by fluid movement.

Instead of sending living cell cultures into orbit, the scientists used a Random Positioning Machine, a device that rotates samples along different axes. By continually changing their orientation relative to Earth's gravitational field, the samples experience a time-averaged environment that approximates certain aspects of microgravity.

The team combined the apparatus with computer modeling and three-dimensional algorithms designed to reduce unwanted fluid flows. This distinction is important because rotating a container on Earth can generate movement in the surrounding liquid, potentially affecting cells independently of gravity.

After exposing the cells to simulated microgravity or fluid-flow conditions for 24 hours, researchers used advanced imaging techniques to observe changes in the cells, their nuclei and the organization of genetic material.

The experiment allowed the scientists to compare the effects of the two conditions rather than treating every change in a rotating cell culture as a consequence of reduced gravity.

Genome Organization Remains Largely Stable

The researchers observed that simulated microgravity increased the volume of the cell nucleus. They also found changes in the behavior of structures inside the nucleus, including the nucleolus, which plays a key role in producing components of ribosomes used to make proteins.

Despite these changes, the genome's overall physical organization and dynamics remained largely preserved during the 24-hour experiment. The thickness and structure of the nuclear envelope, which surrounds the nucleus, also remained relatively unchanged.

Fluid flow produced a different result. Cells exposed to those conditions became more elongated, and the researchers detected DNA damage associated with the flow exposure.

The distinction matters because DNA damage can interfere with normal cellular function and, if not properly repaired, contribute to mutations and disease. The study suggests that mechanical effects generated by laboratory equipment must be carefully controlled when researchers investigate how cells respond to microgravity.

The findings do not establish that spaceflight poses no genetic risks. Actual spaceflight exposes astronauts to additional hazards, including cosmic radiation, altered gravity, confinement and other physiological stresses. The NYU experiment isolated a particular physical factor under controlled laboratory conditions.

Identical Twins Scott and Mark Kelly 

A separate NASA investigation involving identical twin astronauts Scott and Mark Kelly provided an important real-world comparison of how long-duration spaceflight affects the human body.

Scott Kelly spent 340 days aboard the International Space Station from March 2015 to March 2016. His identical twin brother, Mark Kelly, remained on Earth and served as a genetically matched comparison subject.

Because identical twins share nearly all their inherited genetic sequence, researchers could compare biological changes associated with Scott's space mission against measurements taken from Mark during the same period. The study involved 10 research teams examining changes in physiology, molecular biology, immune function, cognition and gene activity.

NASA Twins Study Has Many Revelations

The Twins Study was not designed to show that Scott's DNA sequence was fundamentally rewritten by spaceflight. Instead, it investigated how his body responded to the environment of space, including changes in gene expression — the process through which genetic instructions are used by cells.

NASA reported that Scott experienced changes in gene expression, telomere length, immune-related activity and other biological measures. Telomeres, protective structures at the ends of chromosomes, became longer on average during his mission, then shortened rapidly after his return to Earth. Researchers also observed changes related to inflammation, metabolism and cardiovascular health.

Most of the measured gene-expression changes returned toward preflight levels after Scott returned to Earth. NASA reported that about 91.3% of the changes in gene expression had returned to baseline within six months, although a small subset persisted.

The results demonstrated that the human body can adapt to many aspects of spaceflight, while also identifying areas that require further study.

Why the Findings Matter 

The NYU experiment and NASA's Twins Study investigate different questions. The first focuses on how simulated microgravity and fluid movement affect the physical organization of the genome in cultured cells. The second examines the broader biological effects of an actual space mission on one astronaut, using his twin as a comparison.

Together, the research highlights the importance of understanding both the stability of genetic material and the ways environmental conditions influence cellular activity.

Long-duration missions to the moon and Mars will expose astronauts to conditions that differ substantially from life on Earth. Researchers need to determine which changes are temporary adaptations, which persist after a mission and which could pose health risks.

Future Space Missions Will Reveal More

The new findings offer encouraging evidence that the genome's physical organization can remain robust during short-term exposure to simulated microgravity. However, longer experiments and studies involving actual spaceflight will be needed to establish whether the same patterns hold over extended periods.

As space agencies prepare for missions farther from Earth, research into the relationship between gravity, cellular structure and gene activity could help scientists develop better monitoring strategies and countermeasures to protect astronauts.

The Human Genome Project established a foundation for understanding the genetic instructions that make human life possible. Research into the effects of microgravity is now helping scientists investigate how those instructions operate when the physical environment changes.