Sending man-made objects into space is a very technically demanding and expensive process.
To get into a close orbit around the Earth, an object must be travelling at a speed of about 8 km/s. We must also raise it above the Earth’s surface by at least 100km. The amount of energy required to do this is enormous. Bear in mind also that energy is required to accelerate and lift the fuel for the journey also. To send 1 kg into space costs more than 1 million dollars.
If we want a craft to travel a very large distance, we have a choice to make. It can travel there very quickly, which would need a lot of fuel, or it could travel there very slowly. The problem with this is the time it would take to get there. If the craft was manned, then all the things needed to keep people alive for a long time would have to be brought with you adding to the weight.
Space is the most hostile environment imaginable. It is incredibly cold. One must be protected from this and huge amounts of dangerous radiation from the Sun. One could shield astronauts living spaces with the lead, but this would greatly increase the mass of the spacecraft.
There is no air to breathe so one must bring all the oxygen that one would need with you along with food and water. One must also “scrub” the air of the carbon dioxide that one breathes out or else it will soon reach poisonous levels. If a space capsule or suit was damaged, then the astronaut would die very quickly due to the lack of external air pressure. Blood vessels and cells would burst resulting in an incredibly painful death.
Imagine we wanted to send a manned mission to Mars. One would need fuel to get into space, accelerate to very high speed then slow down again as one approached Mars. A similar amount of fuel would also be needed for the return journey. One could send an unmanned mission first to dump supplies on the surface of Mars or perhaps fuel in orbit around it.
Another problem is that sometimes Mars is relatively close to Earth, sometimes it is much further away. Because of this one would either only be able to stay for a few days before one had to return or one would have to wait for over a year until one could return. Bear in mind that it would probably take about a year to travel there in the first place.
On the journey, the astronauts would be praying that nobody got seriously ill or injured.
Living in zero gravity is very bad for your health. Our bodies have evolved to cope with gravity. Our muscles and bones are strong. It has been discovered that when astronauts are in space for a long time, their muscles waste away from lack of use and their bones become much softer and weaker. Astronauts must spend several hours a day doing heavy exercise because of this.
Perhaps the most dangerous part of the journey is a re-entry into the Earth’s atmosphere. The craft must enter the atmosphere at a particular angle then use air resistance to slow itself down, reaching a manageable terminal velocity before landing. This generates a huge amount of heat which is why the space shuttle needs protective tiles on its underside. Many astronauts have died during re-entry.
- The international space station – This is effectively a garage in space. Space ships can be assembled in space.
- A new way of re-entry – Instead of trying to minimise drag on re-entry the craft spaceship 1 actually tries to create as much drag as possible. Like a shuttlecock, it reaches a safe terminal velocity very quickly.
- Artificial gravity – It is possible to simulate gravity in a large revolving space station. The astronauts are thrown against the sides like in a huge washing machine.
- Biospheres – Is it possible to contain a complete self sustaining ecosystem in a capsule? If we are going to colonise hostile environments it may be necessary to do this.
- Cryogenics – It may be possible to freeze people then thaw them out in the future. This would be a good way of passing the time on a long space journey.