Hi Mathilde, I appreciate you asking such a wonderful question. Reaching space requires some effort and involves multiple steps. Let us first consider the precise beginning of “space.”
Several experts determined a while back that the boundary of “space” starts at a point that is above us. They denoted it with the Kármán line, an invisible line.
This line, which is roughly 100 kilometers above us, circles the entire planet. To put that into perspective, the average aircraft flies only about 10 km above the ground.
Is it possible for us to fly into space?
There are numerous reasons why we cannot simply launch an aircraft into space. One important one is that air density decreases with altitude, or more precisely, with decreasing amounts of “oxygen” in the atmosphere.
The aircraft is propelled through flight by its engine. Additionally, aircraft engines require oxygen to function, just like automobile engines do. Fortunately, even though you cannot see it, 21% of the air we breathe is oxygen!
Aircraft use large fans on either side to draw air in at the front. The air is then heated further by burning the fuel and oxygen mixture that is created when they combine this air with jet fuel. Subsequently, the aircraft is propelled forward by the rapidly ejecting hot air from its rear.
Still, it would be like a person trying to breathe in a room without any air if an aircraft tried to fly too close to space, where there isn’t enough oxygen.
Because of this, rockets are necessary for space travel. As rocket engines don’t require oxygen from the atmosphere, they differ significantly from jet engines used in airplanes. As an alternative, they bring their own oxygen.
This presents certain challenges, as rocket engines must carry loads that are readily obtained by an airplane from its surroundings. Thus, there is less space on a rocket for additional cargo, like people and belongings.
The good news is that rockets can operate in space, which is much higher than where most airplanes fly because they can carry oxygen with them.
How are rocket engines operated?
Rocket engines operate similarly to a jet engine in an aircraft, ejecting a blast of extremely hot gas from the rear of the rocket. The rocket is propelled forward as the gas is forced backward.
This is an illustration of the Third Law of Motion, a scientific principle that was initially identified by renowned researcher Isaac Newton. According to this law, there is an equal and opposite reaction to every action.
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