(TIML NEWS) NASA is fighting a war in orbit — against space herpes.

Astronauts aboard the International Space Station and other missions have been plagued by a resurgence in the often-dormant virus because of the stress of space travel, according to a study by NASA researchers published in this month’s issue of the journal Frontiers in Microbiology.

Roughly 53 percent of astronauts on short-term space shuttle flights show signs of herpes, according to the study’s lead researcher, Satish Mehta.

Exposure to microgravity and cosmic radiation, along with the force of take-off wreaks havoc on space travelers’ immune systems.

“During spaceflight there is a rise in secretion of stress hormones like cortisol and adrenaline, which are known to suppress the immune system,” said Satish, who is a researcher at Johnson Space Center.

“In keeping with this, we find that astronauts’ immune cells — particularly those that normally suppress and eliminate viruses — become less effective during spaceflight and sometimes for up to 60 days after.”

That could be dangerous during longer spaceflight missions, such as ones sore-ing — er, soaring! — to Mars, the researchers said.

In total, 47 out of 89 astronauts on short space shuttle missions, and 14 out of 23 on long ones showed signs of the virus.