Could Future Space Craft be Made of Concrete?

By BCBamber - November 26, 2018

A space elevator has been talked about since Konstantin Tsiolkovsky, having witnessed the building of the Effiel Tower in 1895. He proposed a tower being built to the height of 35,000 km, the hieght of geostationary orbit. However, from that time to this, there has not been a material strong enough to build a space elevator. In the 21st Century, nano technology has made it theoretically possible to build a cable that is tethered on Earth and would reach into space to 96,000 km (59,652 miles) where it would almost reach out to the Kármán Line, at an altitude of 100 km. The Kármán Line is the boundary between Earth's atmosphere and outer space. The International Space Station is 330 km, and the moon is 384,400 km from Earth.

As fans of Star Wars we've all seen that the giant destroyers and the Death Star are grey in colour. I always wondered if this grey colour might well be (if you were to think about it), some form of concrete. Concrete in space would be robust against the many impacts sustained by the Internationals Space Station for example. Currently any space craft in space, will be made of lightweight materials and would be very vulnerable from impacts of space debris and rubbish which is collecting in orbit from our past space craft and satellites. Concrete would sustain more and bigger impacts.
A prefabricated structure constructed in pieces could be put into orbit by a space elevator and then put together in space by drones.

The Obayashi Corporation in Japan plans to develop the cables that could carry a payload on 'climbers' up into space of up to 100 tons with a cable tensile strength of 150 GPa. Constructing a concrete space craft would have many benefits. Firstly, much bigger structures could be built. Secondly, it would be a safer structure for astronauts.

The type of concrete for such a craft would have to be developed specifically for space. There is a wide variety of types and methods on concrete mixes. For example there can be lightweight concrete, like Aerated Concrete, which is obtained by using cement, sand and powdered fuel ash. Another lightweight concrete mix, is an Air Entrained Concrete.

CivilSeek.com describes it as follows:

It is a specially prepared plain concrete in which air is entrained in the form of thousands of uniformly distributed particles. The Volume of air thus, entrained may range between 3-6 percent of the concrete. The air entrainment is achieved by adding a small quantity of foaming or gas-forming agents at the mixing stage. Fatty acids, fatty alcohols, and resins are some common air entraining agents.

Air entrained concrete is more resistant to;

Scaling.
Deterioration due to freezing and thawing.
Abrasion.

Or we can go the other way and have heavy weight concrete.

In this concrete type, the density varies between 3000-4000 Kg/m³. These types of concrete are prepared by using high density crushed rocks as coarse aggregates. Among such materials, Barytes is the most commonly used material, which has a specific gravity of 4.5. They are mostly used in atomic power plants and other similar structures. Because it provides good protection from all type of radiations. - Taken from: https://civilseek.com/different-types-of-concrete/.

Heavy weight concrete as stated above is used in nuclear power plants and would protect inhabitants of a space craft from radiation.

In theory the options for size and function of a concrete space craft are endless, once a space elevator had been constructed. However, because of the weight of such a structure, it would have to be constructed and positioned a long way from Earth, to prevent any unplanned return to Earth. Currently if a satellite falls back into Earth's orbit, the majority of the materials would burn up in the atmosphere and would be of little impact to people on Earth.

Structures can have propulsion to take them out of the local area to visit other planets such as Mars, and could have heavy payloads as well, facilitated by a Space Elevator. It's certainly worth thinking about.