What Happens To Fire In Space?

What happens when you light a candle on the ISS?

How does fire behave on Earth?

Let's delve into how combustion works on Earth by imagining a bonfire with friends, roasting marshmallows on a mountainside. As the wood fuel burns, it heats the surrounding air, making it less dense. Due to gravity, the hot air rises and creates an updraft, drawing in fresh oxygen-rich air to sustain the fire. This buoyancy effect causes the flame to shoot up and flicker, creating an elongated shape.

What happens to fire in microgravity?

 Without the presence of gravity, there is no updraft. Instead, oxygen is drawn into the flame through a different mechanism called diffusion. In a microgravity environment, flames appear spherical, like fireballs, because the flame occurs at the border between the fuel and air. The entire surface of the flame effectively becomes the "bottom" and reacts with the fresh air close to the fuel source, leading to combustion in a rough sphere.

Furthermore, in microgravity, the combustion process is affected by the inability of exhaust gases like CO2 to leave the combustion area. This limits the inward diffusion of oxygen, and as a result, the flame may die shortly after ignition due to the lack of sufficient oxygen supply.

Additionally, the colour of fire appears different in microgravity. On Earth, when a candle burns, the long carbon strings in the fuel get pushed upwards and burn like charcoal, emitting a yellow glow. However, in microgravity, the carbon strings do not burn, resulting in a blue, cooler, and much dimmer flame.



Why are scientists studying fire in space?

The study of fire in microgravity has practical applications, particularly in the field of combustion engines. Engineers have been attempting to build internal combustion engines that run on a lean mixture of fuel and oxygen, similar to the flame balls observed in space. Burning a leaner fuel mixture in engines could potentially result in higher fuel efficiency and lower pollutant formation, as the chemical reaction rates in combustion are highly sensitive to temperature. Increasing the temperature by a small percentage can significantly impact the rate of pollutant formation, such as oxides of nitrogen that contribute to air pollution.

The issue of safety is a crucial consideration when studying fire in microgravity, as fire behaves significantly differently in the absence of Earth's gravity. Understanding fireballs is essential for designing effective safety measures and systems in space environments.

For example, on Earth, if a candle is burning, you might think of stomping on it to extinguish the flame. However, in a spacecraft or microgravity environment, stomping on a flame could potentially accelerate combustion, at least temporarily. This is because the stomping action creates an airflow that didn't exist before, which can affect the behaviour of the flame. Flames in low gravity tend to spread slowly, so stomping could cause the flame to jump to other objects, which might not have happened otherwise.

Moreover, flame balls in microgravity are stealthy, as they emit little or no visible light and no smoke. This makes it challenging to locate and extinguish them. Without the usual visual cues, finding and putting out a fire can be extremely difficult in space.

Therefore, studying fire behaviour in microgravity is crucial for developing effective safety protocols and systems to prevent and manage fires in space environments where traditional methods of fire extinguishment may not be as effective.

How do you put out fire in space?

Astronaut Tim Peake, who spent time on the International Space Station (ISS), shared valuable insights into the fire safety procedures and technology in place onboard the space station. While many of the fundamentals of fire safety are similar in space as they are on Earth, there are some crucial differences to consider.



Peake highlighted that certain aspects of life in space can make fire prevention and fighting easier, but they also raise the risk significantly. As a result, astronauts must be thoroughly familiar with the procedures and protocols related to fire safety in space, knowing them inside out and back to front.

In the unique environment of the ISS, where resources and escape options are limited, fire safety is of paramount importance. Astronauts must be well-trained and well-equipped to handle any fire-related emergencies that may arise during their mission. This includes understanding the specific fire prevention measures in place on the ISS, such as the use of non-flammable materials and careful management of potential ignition sources.

Additionally, the confined nature of the space station presents challenges in terms of fire detection and suppression. Smoke detectors, for example, are not as effective in microgravity as they are on Earth due to differences in airflow. Therefore, alternative technologies, such as gas sensors and thermal imaging cameras, are utilized to detect and manage fire incidents in space.

Overall, fire safety in space requires a thorough understanding of the unique environment and associated risks, as well as meticulous adherence to established procedures and protocols. The lessons learned from astronauts like Tim Peake help inform and improve fire safety measures for future space missions, ensuring the well-being and protection of astronauts and spacecraft alike.

What protection is used during fires in space?

Fire Retardant materials

Similar to how companies on Earth must adhere to safety regulations when selecting furnishings and building materials, materials used on the International Space Station (ISS) undergo rigorous testing for flammability. In a specialized chamber that replicates the conditions of space, all materials intended for use on the ISS are thoroughly evaluated before they are allowed to leave Earth's atmosphere.

Only items that are deemed mission critical and have no suitable alternative are permitted on board the ISS without passing the stringent flammability test. This ensures that all materials used on the space station meet the highest safety standards and do not pose a risk of fire in the unique microgravity environment of space.

Just like businesses on Earth prioritize safety when choosing materials for their operations, NASA and its partners take extensive precautions to prevent fire incidents on the ISS. This includes careful selection and testing of materials to minimize the risk of fire and ensure the safety of the astronauts and the space station as a whole.



By following strict safety protocols and testing procedures for materials used on the ISS, NASA and its partners prioritize the well-being of astronauts and the integrity of the space station, mirroring the safety measures followed by businesses on Earth.

Fire Detection

In space, smoke does not rise due to the absence of gravity, so traditional ceiling-mounted smoke detectors used on Earth are not effective. Instead, on the International Space Station (ISS), sensors are strategically placed in the ventilation systems for optimal early detection of smoke or other potential fire hazards.

Similarly, on Earth, the placement of fire detection devices is critical in different areas of premises to prevent false alarms and ensure effective detection. Detectors should be positioned above and near potential ignition sources and fuel sources, as well as in exits to identify safe escape routes. However, in space, other factors such as the presence of equipment that generates steam or dust need to be taken into consideration to prevent false alarms.

Just as careful consideration is given to the placement of fire detectors on Earth, NASA and its partners meticulously plan the positioning of sensors on the ISS to maximize detection efficiency in the controlled airflow environment of the space station. This emphasizes the importance of the strategic placement of fire detection systems to enhance safety measures both on Earth and in space.

Compartmentalisation of the ISS

The International Space Station (ISS) operates as an isolated island in an extremely hostile environment of space, and as such, requires finely tuned engineering systems to maintain a delicate balance. While these systems benefit the astronauts, they also increase the risk of fire incidents. Fire poses a significant threat in space as it consumes precious and limited oxygen, a critical resource. Additionally, fires can spread rapidly in the presence of oxygen, further amplifying the risk. However, the sophisticated engineering of the ISS allows for ventilation systems to be shut down in the event of a fire, effectively limiting the spread of flames between different areas of the station.

Similarly, modern buildings on Earth are designed with similar considerations. Building codes mandate ventilation systems that are specifically designed to prevent the spread of smoke from one area to another in the event of a fire. Fire doors and walls are strategically placed to contain smoke, giving occupants the best chance of safely escaping and slowing down the spread of fire within the building. This parallel between the ISS and modern buildings underscores the importance of engineered safety measures in mitigating the risks associated with fires in different environments, be it in space or on Earth.

Fire  fighting capabilities

In the event of a fire on the International Space Station (ISS), the astronauts have backup systems that can be operated remotely from Earth. These systems allow for assistance such as shutting down electrical supply to the affected area to help contain the fire.

However, the primary responsibility for fighting fires on the ISS falls on the astronauts themselves. They utilize CO2, water mist, or foam extinguishers to extinguish fires. While doing so, they must also wear breathing apparatuses, as smoke and fire are not the only hazards they face in space. Unlike on Earth, where water or foam settles with the help of gravity, in the microgravity environment of the space station, extinguishing agents will remain in the air, posing an additional risk to the astronauts' lungs.

Similar to fire safety protocols on Earth, using the correct type of extinguisher is crucial on the ISS. Regular updates to the fire risk assessment are necessary to ensure that the appropriate extinguishers are available in the right locations. Extinguishers should only be used to assist escape or to tackle fires in the early stages before they become uncontrollable. Furthermore, astronauts are trained to position themselves between the fire and the exit, to avoid being cut off from safety while using an extinguisher.



Just like on Earth, proper training, equipment, and adherence to safety protocols are critical in fighting fires on the ISS and mitigating risks associated with fire incidents in space.

Evacuation

Evacuation in space is considered an absolute last resort due to the limited options for safety and the lack of immediate backup. The distance to safety is vast and assistance may not arrive quickly. However, there are shuttles available on the International Space Station (ISS) that can be used for evacuation if necessary.



On Earth, in contrast, evacuation is a priority in the event of a fire or emergency, as safety is often just a short distance outside the building. Additionally, expert firefighters are readily available to respond and provide assistance.

Using the Soyuz

Astronauts wear space suits with built-in life support systems while shuttling in space, giving them an advantage in firefighting that firefighters on Earth do not have. Fire requires three elements to exist: oxygen, fuel, and a heat source. On the International Space Station (ISS), the fastest and most effective way to extinguish a fire is for everyone to put on their helmets and then void the station of oxygen, effectively suffocating the fire. Without oxygen, the fire cannot sustain itself and will be extinguished swiftly, minimizing the risk of further damage or danger. This unique approach to firefighting in space highlights the specialized techniques and protocols that astronauts follow to ensure the safety of the ISS and its occupants.