How Did NASA Achieve Combustion in Outer Space Without Oxygen?
The mystery of how rockets and spacecraft ignite and sustain combustion in the vacuum of space has been a subject of fascination for many. The lack of oxygen and other gases that traditionally support combustion on Earth seems like a major obstacle. However, NASA and other space agencies have successfully overcome this by designing rockets that carry their own required oxidizers. This article dives into the technical details of how NASA achieves combustion in outer space.
The Requirements of Combustion
For combustion to occur, there are three essential elements called the fire triangle: fuel, heat (or ignition source), and an oxidizer. In Earth's atmosphere, the oxidizer is typically the oxygen in the air. However, in space, this is not available, and the rocket must bring its own oxidizer.
How Rockets Function in Space
Rockets utilize a principle called Newton's third law of motion: for every action, there is an equal and opposite reaction. They do this by expelling mass in one direction, which causes the rocket to move in the opposite direction. For this to happen effectively, rockets contain both a fuel and an oxidizer. The oxidizer is a substance rich in oxygen that helps the fuel burn, producing thrust and allowing the rocket to achieve the necessary velocity for spaceflight.
The Role of Oxidizers
The oxidizer is critical because it contains oxygen or another element that enables the fuel to burn. When ignited, the oxidizer reacts with the fuel to produce a high-temperature combustion reaction, which creates the thrust needed for the rocket to fly. In space, where there is no external air, the rocket carries its oxidizer with it.
Common Types of Oxidizers Used in Rockets
Different types of rockets employ various oxidizers to achieve their desired performance characteristics. Let's explore a few:
Hydrogen and Liquid Oxygen (LOX)
For the Space Shuttle, the main engines burned liquid hydrogen and liquid oxygen in a volumetric ratio of 7:1. This formulation increased the jet speed by reducing the molecular weight of the exhaust products, providing the necessary thrust for the shuttle's missions. The liquid oxygen is highly efficient and abundant, and it can be stored for long periods.
Solid Rocket Propellant
Some rockets use solid propellants, which are mixtures of an oxidizer like ammonium perchlorate and a fuel such as aluminum or iron oxide. This combination provides a robust, long-lasting burn but may produce toxic substances.
Flamable Liquids and Oxidizers
SpaceX, in its efforts to make space exploration more accessible, uses methane and liquid oxygen (LOX) as propellants. This choice of propellant is easier to handle and less toxic compared to traditional solid propellants. The first stage of the Saturn V used RP-1, a form of kerosene, in combination with LOX, while the Titan II, a liquid-fueled ICBM, utilized hydrazine and nitric acid.
Additional Considerations Inside Spacecraft
While rockets carry their oxidizers, the interiors of spacecraft, including the International Space Station (ISS), maintain an atmosphere with a controlled mix of gases, including oxygen. This ensures that astronauts and any experiments conducted inside the spacecraft can breathe and function effectively. For instances where more oxygen is needed, additional supply tanks can be brought up.
Conclusion
In summary, NASA and other space agencies achieve combustion in space by carrying their own oxygen-rich propellants. This innovative approach ensures that rockets and spacecraft can ignite and sustain combustion in the vacuum of space, propelling them to achieve their missions. By understanding the role of oxidizers and the different types of propellants used, we can better appreciate the complexity and engineering behind space travel.
Further Reading
For those interested in learning more about space propulsion and the nuances of rocket engineering, consider exploring academic papers and publications on the topic. Websites like NASA's official space mission pages and aerospace engineering journals offer detailed insights into the world of space exploration and propulsion systems.