There is more ionizing radiation in the space environment than on the earth, some of which are high-energy galactic cosmic rays. Under the current protective measures, these radiation will cause more DNA damage to astronauts than living on the earth, and microgravity conditions will also affect DNA repair. However, most mutations are neutral, neither beneficial nor harmful, and the amount of radiation received by astronauts in normal space missions will not significantly increase the incidence of cancer.
On 20 19, NASA conducted related experiments:
Astronaut scott kelly and his identical twin brother mark kelly were sampled for peripheral blood cell and RNA sequencing, and urine samples were also tested. After Scott's 340-day space mission, they were sampled again and compared to analyze the effect of space mission on gene expression.
The comparison results show that the most notable change is that Scott's telomeres are slightly lengthened in space and significantly shortened after returning to Earth. Some changes have taken place in the gene expression level and DNA methylation of Scott and Mark, and the contents of the changes are different. Six months after Scott returned to Earth, 8.7% of the changes in gene expression level still exist. The damage of space radiation to Scott's DNA is mainly the inversion and translocation of some chromosomes, and inversion is more than translocation.