Friday, October 22, 2010

Fantastic Future Friday: Building Blocks

In one part of my book, THE SETTING EARTH, I had a 3-mile high skyscraper as a symbol of the powerful corporation that ruled the Earth. As this was more a symbolic symbol of power I didn’t really look at the science behind making a skyscraper 6 times taller what exists today. Stephanie called me out on that so I had to do a little research. Luckily I find that fun; yes I’m a geek.

Problems of a 3-mile high Skyscraper

Current skyscrapers use a core of concrete to provide the compressive strength needed to hold up the hundred plus floors. This core is reinforced by steel rebar the give it tensile strength so it can flex slightly.

In order to go higher we need to have materials that are much stronger in both compressive strength and tensile strength. I naturally turned to carbon nanotubes with strength 5,000 times that of steel and I ran into an old engineering principal, “You can’t push a rope.” In mechanical engineering many brilliantly designed machines failed while being built when the engineers realized that on paper they were pushing a rope, which doesn’t work, in the real world.

Diamonds are a girl’s best friend, but they won’t get you a skyscraper

In order to make my 3-mile high skyscraper I need a material that has a compressive strength that is many orders of magnitude higher than concrete. I first turned to carbon again in the form of a synthetic diamond. It has the strength I needed but a couple of major flaws. Building a synthetic diamond that size would be an engineering feat greater than all the other things I put in the book. It might be able to be accomplished someday but it is feat of engineering that puts terraforming other planets to shame.

The second flaw is flaws. Diamonds are split along naturally occurring flaws, the huge diamond that would have to be built for the tower would be under huge tensile stress, as well as compressive force so even the littlest flaw would split this huge diamond making it rain giant diamonds across Manhattan taking out some pretty valuable real estate.

So I had to look for an alternative.

It’s hard to build a skyscraper

It turns out there is a material that is harder than diamond, Osmium is the element that has the greatest compressive strength known to man. It is rare on Earth but abundant on asteroids.

However it has low tensile strength, so to overcome this limitation it would need to have nanotubes throughout and wrapped in Graphene, carbon bonded together to form sheets that are one molecule. This combination would give me the strength I need for my 3-mile high skyscraper.

It even works into the story nicely, as the background of the novel is about the trade war between the Earth-Moon system and the colonies in the rest of the Solar System. Since Osmium is a rare element on the Earth and Moon and abundant in the rest of the Solar System it adds another element to this conflict. As well as another pun.

In doing this research I also found another reason to support the current space program’s goal to explore a near Earth asteroid. Osmium is very useful element but because it is one of the rarest on Earth it is very expensive, roughly $100 per gram. Bringing a Space Shuttle Payload worth of it to Earth would fetch roughly $2.27 billion in today’s market.

If we could get the cost of an asteroid mission in line with the Space Shuttle, $450 million per launch, a mission to set-up a refinery on the asteroid and bring this element to Earth would easily pay for itself.

Missions to get Osmium from asteroids would make it possible to build a 3-mile high skyscraper as well as billions of other handy uses, a that will lead to a fantastic future.

By Darrell B. Nelson author of Invasive Thoughts


Stephanie Barr said...

Nice to know my being a pest was put to good use.

Fun stuff, isn't it?

(I'm a geek, too)

Project Savior said...

It's always cool, and sometimes a little scary when the real universe backs up my vision of the future.