Space exploration is fraught with a wide variety of hazards; solar storms could irradiate astronauts, collisions with small, unseen objects could cause instant death, and the acts of both leaving Earth and coming back are high risk maneuvers that involve high speeds and highly explosive substances.
Today, I would like to address the most expensive and dangerous process, launch and landing. As it stands, currently, we use much the same process as we have since the earliest days of space exploration. We put some astronauts into a small capsule that rides atop enormous rockets, with huge tanks full of highly-flammable liquid hydrogen. We light up the rocket engines, and the astronauts ride a flame into Earth’s orbit. This is extremely expensive and, as we have seen in the past, quite dangerous. Landing involves the re-entry of the vehicle (be it just a capsule or a plane-like craft) at incredibly high speeds (in excess of 25,000 km/h) which is so high that the craft builds up an incredible amount of heat from the friction of the air it passes through.
The dream of many scientists and science-fiction authors over the years has been the construction of something called a space elevator. Such a device would reduce the cost of bringing humanity and our necessary equipment to space and would dramatically reduce the inherent danger that is found in the current launch and landing process. This concept was first proposed as long ago as 1895 by a Russian scientist named Konstantin Tsiolkovsky and was made popular in modern writing by science-fiction author Arthur C. Clarke.
The construction of something of this nature would obviously be an enormous undertaking, but how would we build such a beast and how would it help us?
First off, we wouldn’t be able to build a skyscraper that is tall enough to reach low Earth orbit. The sheer weight of such a structure would be too much for its building materials to support. Currently the tallest building in the world is the Burj Khalifa, in Dubai, which stands at 828m high. The International Space Station is at an altitude of 408 km. To reach Earth’s orbit we would need a geosynchronous counter-weight weight which is tethered to Earth by an enormous cable.
Geosynchronous refers to the station’s orbit, meaning that it spins around the Earth at exactly the same speed as the Earth is rotating, so that it remains in orbit precisely over the same spot. Many estimates suggest the weight would need to be between 40,000km and 100,000km above the Earth (the Moon’s orbit is approximately 386,000Km from the Earth). This would allow us to climb the cable with a specially-made craft and reach orbit much more safely and for much less cost per launch. In addition, descending craft could also come down the elevator and not face high-speed re-entry.
So, you might say, “This sounds like a wonderful idea, why aren’t we doing it yet?” And that is a great question. The simplest answer is that currently we don’t have a material capable of being strong enough to handle the force of its own weight when strung from Earth into a geosynchronous orbit. We need something that is both exceptionally strong and very light. There have been a variety of materials hypothesized as being able to handle this, but they either haven’t successfully been created or we don’t have a pragmatic way of manufacturing them.
On other celestial bodies we already have materials strong enough to be used in their weaker gravity, like on the Moon and on Mars. We could more easily construct an elevator on those locations, making travel between Earth and these locations an easier and less expensive prospect.
If Space is ever to be opened up for human exploration and expansion, we need a safer and less expensive route to escape the gravity well of our planet. There is no magic 8-ball to tell us how we might achieve this, in the future, but if scientists are able to achieve the necessary breakthrough in a strong but lightweight material (many people think that Carbon Nanotubes might successfully fit this role eventually) expect to see elevators rising to the stars. Until then, brave explorers continue to be shot into orbit while strapped to huge tanks of Hydrogen.
Eamonn Brosnan is a research associate with the Frontier Centre for Public Policy.
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