Building a Space Elevator

Japanese scientists and engineers have set their sights on one of the most challenging tasks of a hard science fiction concept: the space elevator.

The space elevator, first popularised by Arthur C. Clarke in his novel Fountains of Paradise (an excellent read, if anyone's interested), appears to be a highly inexpensive way to travel to space, or at least to low-orbit space. It is a popular idea in science fiction and has also made it to scientific journals, being quite solidly based in proper physics.

The basic idea is that we connect a point on Earth to a geostationary satellite directly above it. This connection can be a tower (which is not feasible due to the weight) or merely cables that pulls a lift between these two points that are stationary in the reference frame of an Earth-bound observer. However, if we consider the Earth base as an anchor point and the cables plus satellite as a system, this system will start to swing sideways because its centre of mass is not in geostationary orbit, so we have to extend and attach some sort of mass beyond the satellite to counter this. In the novel, the construction started from the satellite and went both ways - up and down - simultaneously in such a way that the centre of mass stays in the orbit.

Of course, the cables will have a Coriolis force acting on it. On top of that, the length of the cable implies, even if it is of low density, a very strong tension throughout the cable. Therefore, this is the leap in this science fiction concept: a lack of such lightweight yet awesomely strong material. However, these Japanese scientists seem to have the solution: carbon nanotubes. But I think there is still a huge challenge since carbon nanotubes may not be strong enough yet, and mass production of large scale nanotubes are nowhere near a reality. Of course, this still does not take into account the multitude of engineering feats that has to be performed.

This space elevator, if ever built, will serve as a very cheap mode of space travel. Not only does it save the need to launch a space shuttle that gobbles fuel like an F1 race car, it also conserve energy just like a typical lift: as a lift comes down, it'll pull a weight of slightly smaller mass upwards, which will in turn act as a gravitational battery when the next lift goes up. It will also cut down the cost of space travel (to beyond geostationary orbits) by moving the launch site to the satellite, which bypasses a tremendous part of the energy consumption.

Personally, I'm sceptical about the plausibility of pulling this off. The material of the cable remains the greatest challenge, and I think carbon nanotubes are still way off from being a satisfactory material for such a construct. Moreover, as witnessed by the multiple failures in the Large Hadron Collider (LHC), new toys present new problems of their own, and this space elevator can be pretty disastrous if it fails in the wrong way. On top of that, such grand projects are bound to be costly, and I doubt Japan can pull it off by themselves. The LHC is funded by a collection of wealthy nations; I'm not sure if the space elevator will be any less.

Well, on the bright side, even if I'm wrong, at least there's a chance I can visit space in an environmentally friendly way. And what's more, the base station on Earth has to be on the equator (an off-equator geostationary orbit projects a sinusoidal curve on Earth's surface), so there's a chance the base station is in Singapore. If we reclaim southwards furiously enough, that is.

Nuclear Power in Question

In the 80s and 90s, nuclear (fission) power was greatly shunned by the public, with many advocacy groups called a complete ban of it. This was partly due to the proliferation of nuclear weapons as well as several disastrous nuclear accidents.

In recent years, nuclear power is back in the limelight, not as the object of criticism but as a possible alternative to the growing energy crisis. Considering that it is clean (no carbon emission) and its fuel not running out any time soon, it looks more and more promising as an alternative candidate with the rising price of oil and environmental concern with coal (for example, a coal-burning power plant releases radioactive products into the air, exposing people to radiation several times more than a fission power plant). Other promising alternatives like solar and nuclear fusion are still not practical.

However, not all is smooth for nuclear power. The journal Nature carried a recent news article (obtained via Slashdot) that demonstrated past methods in disposing nuclear waste is not as safe as previously thought.

Quoting from the article,

A fast-moving alpha particle knocks into hundreds of atoms in its path, scattering them like skittles. Worse still, the radioactive atom from which the particle comes is sent hurtling in the other direction by the recoil. Even though its path is even shorter than that of an alpha particle, the atom is much heavier, and can knock thousands of atoms out of place in the ceramic.

All this disrupts the crystalline structure of the ceramic matrix, jumbling it up and turning it into a glass. That can make the material swell and become a less secure trap. Farnan says that some zircons that have been heavily damaged in this way by radiation have been found to dissolve hundreds of times faster than undamaged ones. So if the ceramic gets wet, there could be trouble.

There are, of course, other concerns, such as how one can lower the chances of nuclear accidents like the Three Mile Island accident. And then of course there's always the controversy linked to nuclear weapons. I cannot, however, comment from a technical point of view, since my course on Nuclear and Particle Physics has only started, but I guess that even after that, my knowledge is still too insufficient.

Science of Santa

North Carolina State University has published a news release that argues the scientific viability of Santa Claus, backed by the university's professor of mechanical and aerospace engineering.

From the article, Santa and his elves have

advanced knowledge of electromagnetic waves, the space/time continuum, nanotechnology, genetic engineering and computer science easily trumps the know-how of contemporary scientists

and how they used scientifically fantastic innovations to carry out his duties.

Naturally, this post is written somewhat in a casual manner, ignoring the technological viability of some of methods used. It is pretty interesting to see imagination and science explain what appears to be impossible phenomena.

However, impressive explanations like

a sophisticated signal processing system filters the data, giving Santa clues on who wants what, where children live, and even who’s been bad or good

sounds pretty Nineteen Eighty-Four to me...

Machine Gun Sentry

Samsung has developed a machine gun-equipped sentry that will be planted along the demilitarised zone border in South Korea (outside of it, of course). They have even produced a commercial for it, and frankly I found it pretty funny, in particular the way the "enemies" move "in stealth". Says a lot about South Korean's (or at least Samsung's) impression of North Korea military.

You can read the news and watch the video clip on this news site, which I got to via Slashdot.