Travelling to Space
Why go to space, how to get there, and how to come back? The science behind our 'Travelling to Space' talk.
If we can grasp these three questions, we are more equipped to safely explore the cosmos.
Why do we go into space?
There is a large range of reasons as to why we go into space, and this answer might change depending on who you ask.
For some, it might be in search of a new home for humans to live on, such as Mars, or for others it might be to explore the cosmos and seek to understand astronomical phenomena. For many scientists and indeed, the astronauts on the International Space Station (ISS), travelling to space allows us to carry out scientific experiments in microgravity. This is key to understanding how the human body, and phenomena on Earth, react in space.
Just over 500 humans have ventured into space, but there have been thousands of satellites sent to orbit the Earth. There are two main reasons for satellites to be launched: to monitor the Earth and to observe the universe. If you’ve ever used the weather app on your phone, then you have used information collected by these satellites. Not only can these satellites help us decide between an umbrella and sunscreen, but they can warn us of severe weather such as hurricanes and tsunamis. They do this by using optical and infrared imaging.
How to get to space?
Both astronauts and satellites are launched into space using a rocket. Rockets work similar to fireworks, or at least, this is how rocket science began. To understand how rockets move we must look at the work of Sir Isaac Newton. Newton famously worked on many scientific ideas such as rainbows, gravity, telescopes and the cat flap. It is his Laws of Motion that tell us how things move. Newton established three laws of motion and it is the third law that is important to understand how rockets work. This third law says: “For every action (or force), there is an equal and opposite reaction”. When applied to rocketry this suggests that a force downwards must result in a force upwards. This is what launches rockets into the air. These forces upwards and downwards are caused by a chemical reaction called combustion.
Combustion is a scientific word for burning something and this reaction is what we can see at the bottom of rocket engines. To start a combustion reaction you need fuel, oxygen and an ignition source. The reaction itself combines the fuel and oxygen with the heat from the ignition source, and produces carbon dioxide in the form of gas, and liquid water. We see these products through energy released in the form of light (flames), heat and gas. It is the force of the gas (carbon dioxide) being released that pushes the rocket into the air.
This science has been understood for a significant period of time. As a result, rockets and combustion reactions have been launching astronauts and equipment into space for the last 60 years. Luna 1 was the first object to travel fast enough to not only orbit the Earth but to escape the gravitational pull of the Earth and make its way to the Moon. This led the way for the biggest rocket ever made, the Saturn V rocket, which was made to take humans to the Moon in the 1960s. It is expected that the NASA space launch system will be even bigger than this, once completed. A manned mission in this vehicle is likely to happen in the 2020s.
At the moment, the only vehicle taking astronauts to the ISS is the Russian Soyuz rocket and Soyuz spacecraft. This is the vehicle that took British astronaut Tim Peake into space and to the ISS in 2015. The ISS is a space station which is home to several astronauts for periods of around six months at a time. Although the ISS is orbiting the Earth it is actually in freefall. It is able to maintain its orbit because it falls at a very specific speed. This stops the ISS from plummeting down to Earth or flying off to space.
How do we get home from space?
When it is time for astronauts to return to Earth, they do so in the same Soyuz capsule that transported them into space. After the Soyuz capsule is released and separated from the ISS, it fires its thrusters and makes a “deorbit burn” that lasts for 4 minutes and 21 seconds. The journey to Earth then takes around three and a half hours. The parachute of the capsule pops out at 8.5km above ground level and slowly lowers the astronauts to the ground, where a recovery and rescue team are waiting for them.
Obviously, all astronauts sent to the ISS return to Earth, however we don’t always bring down satellites that are launched into space. Often it is too expensive and requires too much fuel to bring down every satellite. They might be sent into a graveyard orbit, sent to burn up on re-entry to Earth or left orbiting Earth.
There are over 500,000 pieces of space junk/debris being tracked at the moment, and millions of tiny pieces that are too small to track. Sometime very small pieces can break off satellites and cause danger to other spacecraft and astronauts. Even something as small as a fleck of paint can cause severe damage so it is definitely a problem that still needs to be solved!
So there you have it. Three simple steps as to why we go to space, how to get there, and how to come home again.
To see these in action, come along to our explosive new weekend talk, ‘Travelling To Space’, every Saturday and Sunday at 1pm at the National Space Centre between December 2017 and January 2018.
See a sneak peak of one of the demos here: https://www.youtube.com/watch?v=sULwZPpFdqQ
About the author: Tori Tasker is the Public Programmes Team Leader at the National Space Centre.