Developments in space exploration are hindered by the cost of getting to space.

Given that the first moon landing happened way back in 1969, you may feel disappointed that so little progress has since been made when it comes to getting humans further into space.

But the reality is, building rockets and launching them into space is an expensive business, which is why scientists are looking into cheaper methods of space exploration.

One such method is sort of like using a really big elevator. Imagine a giant cable stretching from a mobile sea platform on Earth all the way to a giant asteroid in orbit. It could be used to send cargo, passengers and spacecraft back and forth, eliminating the need for all that expensive and explosive rocket fuel.

Sounds good, right? However, there is currently no material that is both strong enough and light enough to make a space elevator a reality – though scientists are still eagerly looking into this idea.

Another potentially less expensive method is the spaceplane.

Spaceplanes would use two different kinds of engines. The first would use a combination of air and fuel to create a high-pressure force powerful enough to propel the plane out of the Earth’s atmosphere. Then, because there isn’t any air in space, the spaceplane would need to switch to a more traditional rocket engine that uses normal propellant. This would be cheaper than the current method where the rocket has to carry enough expensive oxidizer to power the rocket engine all the way into space.

Another important part of making space travel affordable could be asteroid mining. This has the potential to provide cheap materials that could be sent back to Earth, or used for building the settlements on other planets.

The US-based company Tethers Unlimited has already proposed a system for capturing asteroids. It essentially works like a space net, and they’ve called it “the Wrangler.”

It would allow us to trap an asteroid in a net, and then to use that asteroid as a base of operations for a settlement. We could also theoretically drag it elsewhere to create colonies in space or to mine its resources; from what we already know about the main types of asteroids, water, metal and oxygen can be extracted from them.