How is space characterized in terms of molecular presence?

Space is characterized primarily by a lack of oxygen and a general scarcity of matter. While there are localized areas in space, such as near planetary bodies or nebulae, where molecules may exist, the vast majority of space is largely a vacuum, meaning it has extremely low pressure and is composed of very few atoms or molecules. In fact, the average density of matter in interstellar space is around one atom per cubic centimeter, which is significantly sparse compared to environments on planets where oxygen and other gases are prevalent. This understanding is crucial for fields such as astrophysics and aerospace engineering, as it influences everything from spacecraft design to the life-support systems required for human exploration.