How Does Space Fever Affect an Astronaut’s Health?

We’ve been sending humans into space for more than 60 years. We’ve spent the better part of those decades studying the effect that space travel has on the human body. Recently, we’ve discovered a new and potentially dangerous side effect of living and working in microgravity environments: space fever.

What is space fever, and how can it affect the health of the astronauts who live and work on the International Space Station?

What Is Space Fever?

When you’re on Earth, as long as you are not ill, your normal body temperature is 98.6 degrees Fahrenheit or 37 degrees Celsius. When you become sick and your body is fighting an infection, it causes your body temperature to climb higher. In some cases, if it gets too high, you can experience seizures and other ill effects.

Recent studies of astronauts’ vital signs have found that they tend to have a higher base body temperature than they would on Earth. In fact, it can rise by up to 1.8 degrees Fahrenheit or 1 degree Celsius during long-duration missions. Furthermore, it becomes harder for their bodies to naturally perform thermoregulation. In fact, researchers believe this may be caused by a combination of impaired heat dissipation in microgravity. Moreover, changes in blood circulation and metabolism also contribute, along with low-grade inflammation associated with long-duration spaceflight.

The term “space fever” is an informal name used to describe this increase in body temperature and is not currently considered a distinct medical condition.

What effect can this have on the astronaut’s health?

The Negative Effects of Space Fever

A slightly higher core body temperature isn’t necessarily a negative thing, overall. The risk becomes greater when the astronauts exercise.

Exercise is essential in low-gravity environments. Without it, astronauts who spend long stretches of time in outer space are at risk of losing muscle mass and bone density. Unfortunately, exercise also increases their body temperature. In some cases, it can sometimes reach a dangerous high of 104 degrees Fahrenheit (40 degrees Celsius).

The body doesn’t work as well at higher temperatures. When it’s consistently kept at higher temperatures, your neurotransmitters and enzymes don’t function the way they should. Consequently, this change makes it harder for your body and brain to work properly.

High fevers—higher than 102 degrees Fahrenheit or 38.8 degrees Celsius—can cause a host of long-term problems if left unchecked, up to and including cell damage and even cell death. However, astronauts do not maintain these higher exercise temperatures constantly. In addition, their resting temperatures are only modestly elevated. Scientists are still studying what long-term health effects, if any, this increase may have.

Researchers are also continuing to study how spaceflight affects sweating, blood flow, and the body’s ability to regulate temperature. They are focusing on exercise and everyday activities aboard spacecraft.

The Future of Space Travel

So what does all this mean for the future of human space travel?

Well, we still have a lot to learn about the potential impact that an elevated body temperature might have on humans during longstanding space travel. Several astronauts and cosmonauts have already spent missions lasting close to or longer than a year in orbit. However, scientists still do not fully understand how elevated body temperatures might affect crews on deep-space missions to Mars and beyond. On these missions, additional factors such as radiation and isolation come into play.

We also don’t know how things such as artificial gravity might affect the astronaut’s perpetually elevated body temperature. Is it just the lack of gravity in space that’s causing the higher temperatures, or is it a combination of other environmental factors?

It’s also possible that we will be able to continue with space exploration if we can create a way to cool astronauts’ bodies while they’re in space. Scientists are already studying improved cooling garments and better thermal control systems. In addition, other methods could help astronauts manage heat during long-duration missions. Although ideas such as cryosleep and artificial hibernation have been proposed, they remain highly speculative.

It’s almost ironic that astronauts are experiencing a fever in an area that, outside of their pressurized habitats, usually lingers around absolute zero for temperature (-459.67 degrees Fahrenheit or -273.15 degrees Celsius). Further study will have to be completed before we can determine whether or not long-term space stays are a possibility at our current technology level. As much as we want to explore the universe, we need to make sure we can do it safely before we leave our planet behind for good.