As we enter a new era in space travel, a study looking at how the human brain reacts to traveling outside Earth's gravity suggests frequent flyers should wait three years after longer missions to allow the physiological changes in their brains to reset.

Researchers studied brain scans of 30 astronauts from before and after space travel. Their findings, reported in Scientific Reports, reveal that the brain's ventricles expand significantly in those who completed longer missions of at least six months, and that less than three years may not provide enough time for the ventricles to fully recover.

Ventricles are cavities in the brain filled with cerebrospinal fluid, which provides protection, nourishment and waste removal to the brain. Mechanisms in the human body effectively distribute fluids throughout the body, but in the absence of gravity, the fluid shifts upward, pushing the brain higher within the skull and causing the ventricles to expand.

"We found that the more time people spent in space, the larger their ventricles became," said Rachael Seidler, a professor of applied physiology and kinesiology at the University of Florida and an author of the study.

Martian maps are full of monikers recognizing places on Earth, explorers, and even cartoon characters.

NASA's Perseverance rover is currently investigating rock outcrops alongside the rim of Mars's Belva Crater. Some 2,300 miles (3,700 kilometers) away, NASA's Curiosity rover recently drilled a sample at a location called "Ubajara." The crater bears an official name; the drill location is identified by a nickname, hence the quotation marks.

Both names are among thousands applied by NASA missions not just to craters and hills, but also to every boulder, pebble, and rock surface they study.