Around 17 hours into the Apollo 7 mission, Walter Schirra Jr came down with a cold. Before long, the other two astronauts were both also showing signs of being sick. Without gravity to pull it down, mucus collected in their heads and made the astronauts refuse to wear helmets during landing because of how uncomfortable they were left feeling, and fear of a change in pressure as the entered the Earth’s atmosphere. NASA then decided that all astronauts must quarantine for two weeks before launch, but this hasn’t stopped viruses making their way into space, with surface swabs of the International Space Station identifying many different viruses including around 4% which were found to be human or animal viruses.

The Science

Researchers have found that some viruses are able to remain dormant inside astronaut’s bodies, and they may sometimes reactivate in space. While dormant the host can be asymptomatic and the virus doesn’t replicate, but these reactivated viruses can become highly contagious or mutate. This leads to the problem that no amount of quarantine is able to prevent viruses getting onto Mars, and the small shared air supply is likely to be a breeding ground for pathogens which will spread quickly around the colony. While scientists are unsure exactly what causes the viruses to reactivate, there are hypothesis that it could be ultraviolet radiation exposure which has been shown to reactivate viruses in rodents and suppress the immune system in humans and other animals. Medicine will be a key component in tackling any illnesses which befall the colony, especially with an ever growing stream of new arrivals from Earth.


A virus can spread rapidly amongst the astronauts and strike down many at one time, severely hampering the colony and its ability to use the astronaut’s labor until they rest or seek medical attention. Viruses only impact astronauts and therefore may lead to brief spikes in medicine prices.




Virus hazards inflict 50 points of damage each time they damage a sponsorship card.

Items Vulnerable to this Hazard