The problem is that if a fire breaks out on the space station, astronauts won’t have anywhere to escape. Here are some reasons why the ISS and Mars are more dangerous than Earth.

How does fire behave on the ISS?

Scientists from the Center for Applied Space Technologies and Microgravity (ZARM) at the University of Bremen have been investigating fire risks in spacecraft since 2016. They have published new research on the effects of oxygen concentration, pressure and counterflow velocity on flame spread through thin layers of the spacecraft interior lining (PMMA).

A fire on a spacecraft is one of the most dangerous scenarios in space missions. There are almost no options to reach safety or escape from the spacecraft. Therefore, it is very important to understand the behavior of fires in these special conditions.
– says Dr. Florian Meyer, head of the combustion technology research group at ZARM.

These conditions include Earth-like oxygen levels, forced air circulation, and Earth-like atmospheric pressure. NASA has done its own experiments before, and now we know what happens. Fire behaves differently in microgravity than on Earth.

• It burns with a smaller flame at first and spreads over a longer period of time. This makes it less likely that the fire will be detected in time and will therefore cover a larger area.
• Fire in microgravity is also hotter, meaning some materials that are not flammable under normal Earth conditions could burn inside the spacecraft, releasing toxic chemicals into the air of the enclosed space.

How will fire behave on Mars ships?

The spacecraft that will fly to Mars will have a different environment than the ISS. The air pressure in the environment will be lower, which has two advantages: it makes the spacecraft lighter and also allows astronauts to prepare for external missions faster. However, the lower atmospheric pressure causes another important change in the spacecraft environment: The oxygen content needs to be higher to meet the respiratory needs of astronautsThese conditions were checked in ZARM.

The interior coating currently being developed for future spacecraft is called PMMA, which stands for “polymethyl methacrylate.” It’s often simply called “acrylic.” It’s not used on the ISS because it wasn’t common at the time it was built. The Orion capsule uses acrylic fused with other materials for the windows, and future spacecraft are likely to use something similar.

In their experiments, the researchers simulated weightlessness and then acrylic films were set on fire and three environmental factors were changed: atmospheric pressure, oxygen content and air flow rate.

• Experiments have shown that low atmospheric pressure extinguishes fire.
• However, higher oxygen content has the opposite effect, as predicted.

The oxygen level on the ISS is 21%, the same as on Earth. However, future spacecraft with lower atmospheric pressure It will have oxygen levels of up to 35%. This means that the risk of fire for astronauts will increase significantly. The results show Fire can spread three times faster than terrestrial conditions.

Increased airflow spreads the fire faster, so we blow on a small flame to create a larger fire. Increased airflow provides more oxygen, increasing combustion, so in a high-oxygen atmosphere, increased airflow creates a dangerous situation for astronauts.